Thermonuclear fusion will be a promising energy source soon. Sophisticated systems are called tokamaks (toroidal chambers with magnetic coils) to generate hot plasma. Currently, the fusion process is not yet fully controlled. To better understand it, scientists use diagnostic systems that record plasma behavior. A particular group of diagnostic systems is responsible for the analysis of plasma impurities. The article briefly discusses the method of producing energy from a controlled nuclear fusion. Then, it presents groups of diagnostic systems in terms of their functions and focuses on systems dedicated to monitoring and analyzing plasma impurities. Parameters and limitations of representative currently used diagnostics systems for plasma impurities are described. In the end, the functional and technical requirements of plasma diagnostic systems designed for new tokamaks such as ITER and DEMO are discussed.
KEYWORDS: Field programmable gate arrays, Computing systems, Data acquisition, Signal processing, Sensors, Signal detection, Plasma, Data processing, X-rays, Analog electronics
The presented system is used for monitoring of the plasma impurities in the tokamak. It is done by measuring radiation in Soft X-Ray range with the use of a GEM-based detector. Acquired data is transferred through the whole system with low latency. Presented system can be divided into many parts - detector, analog electronics, FPGA, PCIe transmission line and computer system with high-performance CPU. This work will concentrate on synchronization between FPGA, which write data to the memory on the CPU side and computational part, which is executed in the computer. In long-running measurements, there is a synchronization problems which can arise. There is a difference in variables based on which the execution time of both parts is dependent. Working on measurements of radiation of plasma impurities requires limits in terms of latency. This paper presents reasons, descriptions and solutions for such problems.
KEYWORDS: Systems modeling, Data modeling, Field programmable gate arrays, Control systems, Plasma diagnostics, Plasma systems, Sensors, Human-machine interfaces
The paper describes the communication model implemented for tokamak plasma diagnostics systems. The approach was tested for the SXR measurement system working with the GEM detector. The model describes the interfaces used for integration of various firmware and software implementations, done in the system. The purpose of the applications is to control and manage the system with acquisition of measurement data. The applications are often design by various authors, therefore it is necessary to create a common communication model, for easy integration and upgrades of the components in the system.
This paper focuses on implementation of the charge signal sequencer in FPGA chip dedicated for GEM detector. First is described structure of GEM detector for WEST experiment developed by IPPLM and Warsaw University of Technology. Then the article explains why signal sequencer is needed in the new system and shortly presents how it works. It collects data from all detector channels and sends it out in unambiguous order to PC. It plays a big role in a data pipeline. Proper order of data improves parameters of the system, decreases the latency and simplifies computations on PC side. The article explains technical aspects of the implementation like architecture, blocks, dataflow or configuration features. In the end, there are presented results of the implementation.
The search for new technologies in the field of plasma diagnostics entails the increasing demands on the radiative stability of the used materials due to development and usage of fusion facilities, where the study of processes occurring during the interaction of radiation with matter has become particularly important. Currently, a new X-ray imaging detection technology is required for tokamaks such as ITER. X-ray detectors that are being used in existing equipment may rapidly degrade due to large neutron fluxes characteristic for the tokamak environment. Despite the relatively wide use of semiconductor detectors to record SXR radiation (generally ionizing radiation), gas detectors are promising candidates that are suited much better for use in future fusion reactors given their resistance to neutron radiation. The most promising representative of the new gas detector class is the so called Gas Electron Multiplier (GEM), which is characterized by high amplification factor of the primary charge that is originated from photon absorption. Its main advantages are the compactness of the detector, good temporal and spatial resolutions, the ability to discriminate against photon energy and better neutron resistance compared to existing systems. All this makes such a detection system a potentially better candidate for soft X-ray measurements in the ITER and DEMO reactors. In this work, a new type of detection system based on GEM technology was proposed for soft X-ray measurements in the ITER reactor-oriented research, which is being developed at IPPLM.
The Gas Electron Multiplier (GEM) is a detector used to register ionizing radiation, e.g., soft X-rays. The detector of this type, built and developed at the IPPLM institute, allows registering X-rays in the energy range of 2-20keV and determining its intensity in time, as well as its spatial position and energy. Simulating the work of such a detector, performed in parallel to experimental research, and sometimes preceding it, allows for optimization of construction and operation parameters of this detector with respect to the requirements set in the experiment, and allows for a better understanding of the physical processes occurring in the detector. The paper presents how simulations are performed, i.e. describes applied programs, main stages of simulation such as the construction of a three-dimensional model of the detector for calculations, the efficiency of X-ray detection, its conversion to primary electrons and the process of avalanche formation. Finally, the results obtained in this way are also presented.
We present the concept of data distribution and dispatching software which is prepared for low latency and high throughput SXR measurement system developed by our group. Its scope includes handling data acquisition from multiple FPGA chips, execution of numerical algorithms with the use of multiple threads and post calculation storage and transfer. Data transfer to CPU side is done with usage of DMA via PCIe interface with specially developed Linux driver. This paper describes the need and details of discussed part of the system.
The measurement system based on GEM - Gas Electron Multiplier detector - is developed for soft X-ray diagnostics of tokamak plasmas. The multi-channel setup is designed for estimation of the energy and the position distribution of an Xray source. The focal measuring issue is the charge cluster identification by its value and position estimation. The fast and accurate mode of the serial data acquisition is applied for the dynamic plasma diagnostics. The charge clusters are counted in the space determined by 2D position, charge value and time intervals. Radiation source characteristics are presented by histograms for a selected range of position, time intervals and cluster charge values corresponding to the energy spectra.
The advanced Soft X-ray (SXR) diagnostics setup devoted to studies of the SXR plasma emissivity focusing on the energy range of tungsten emission lines is at the moment a highly relevant and important for ITER/DEMO as W became a plasmafacing material and, therefore, plasma contamination by W and W transport in the plasma must be understood and monitored. The Gas Electron Multiplier (GEM) based SXR radiation detecting system under development by our group with a spatial and energy-resolved photon detecting chamber may become such a diagnostic setup; however, many physical, technical and technological aspects must be taken into consideration. This work presents the results of preliminary tests and simulations of the research into the optimal design of the detector’s internal chamber. The study of the influence of different GEM foils on the properties and distribution of the electron avalanche as well as the effect of the high rate photon flux on GEM foil performance was performed. Effect of electrodes alignment allowed choosing the gap distances which maximize electron transmission was also examined. Finally, the optimal readout structure design was identified suitable to collect a total formed charge effectively.
This paper focuses on the model of the sequencer algorithm created in Matlab. The sequencer is used in the measurement system of 2nd generation for GEM detector. First, are described and compared two generations of the system. The article explains why sequencer is needed in the new system and presents how it works. It can collect data from many sources and send it out in unambiguous order. The model of the sequencer designed in Matlab allows adjusting its parameters to the specific process. The article explains technical aspects of the model, describes basic objects that were used to build the model. In the end, there are presented results. The sequencer is implemented in FPGA device.
This document was prepared to discuss the high voltage generator module which can be used to supply X-ray Gas Electron Multiplier (GEM) detector. Emphasis was placed on the description of the module’s hardware structure. Furthermore, the detector protecting mechanisms the against the damage have been presented and described.
KEYWORDS: Field programmable gate arrays, Diagnostics, Sensors, Plasma diagnostics, Plasma, Data processing, Signal processing, Digital signal processing, Computer architecture, Physics
This paper discusses the model and the development methodology that was proposed in the implementation process of the heterogeneous system for the WEST thermal fusion reactor. The objective was to provide a systematic approach to provide a heterogeneous device to handle high-throughput workloads with low-latency for the WEST Soft X-Ray impurities diagnostic. The presented mechanism is dedicated to augment the system applicability to a wider area of instrumentation for high-scale physics experiments.
KEYWORDS: Field programmable gate arrays, Feedback loops, Telecommunications, Computing systems, Data communications, Particle accelerators, Data processing, Algorithm development, Operating systems, Control systems
The paper presents the evaluation study of the performance of the data transmission subsystem which can be used in High Energy Physics (HEP) and other High-Performance Computing (HPC) systems. The test environment consisted of Xilinx Artix-7 FPGA and server-grade PC connected via the PCIe 4xGen2 bus. The DMA engine was based on the Xilinx DMA for PCI Express Subsystem1 controlled by the modified Xilinx XDMA kernel driver.2 The research is focused on the influence of the system configuration on achievable throughput and latency of data transfer.
The requirements given for GEM (Gaseous Electron Multiplier) detector based acquisition system for plasma impurities
diagnostics triggered a need for the development of a specialized software and hardware architecture. The amount of
computations with latency and throughput restrictions cause that an advanced solution is sought for. In order to provide a
mechanism fitting the designated tokamaks, an insight into existing solutions was necessary. In the article there is
discussed architecture of systems used for plasma diagnostics and in related scientific fields. The developed solution is
compared and contrasted with other diagnostic and control systems. Particular attention is payed to specific requirements
for plasma impurities diagnostics in tokamak thermal fusion reactor. Subsequently, the details are presented that justified
the choice of the system architecture and the discussion on various approaches is given.
One of the requests from the ongoing ITER-Like Wall Project is to have diagnostics for Soft X-Ray (SXR) monitoring in tokamak. Such diagnostics should be focused on tungsten emission measurements, as an increased attention is currently paid to tungsten due to a fact that it became a main candidate for the plasma facing material in ITER and future fusion reactor. In addition, such diagnostics should be able to withstand harsh radiation environment at tokamak during its operation. The presented work is related to the development of such diagnostics based on Gas Electron Multiplier (GEM) technology. More specifically, an influence of neutron radiation on performance of the GEM detectors is studied both experimentally and through computer simulations. The neutron induced radioactivity (after neutron source exposure) was found to be not pronounced comparing to an impact of other secondary neutron reaction products (during the exposure).
We present study of a software-hardware environment for developing fast computation with high throughput and low latency methods, which can be used as back-end in High Energy Physics (HEP) and other High Performance Computing (HPC) systems, based on high amount of input from electronic sensor based front-end. There is a parallelization possibilities discussion and testing on Intel HPC solutions with consideration of applications with Gas Electron Multiplier (GEM) measurement systems presented in this paper.
Soft X-ray plasma measurement systems are mostly multi-channel, high performance systems. In case of the modular construction it is necessary to perform sophisticated system discovery in parallel with automatic system configuration. In the paper the structure of the modular system designed for tokamak plasma soft X-ray measurements is described. The concept of the system discovery and further automatic configuration is also presented. FCS application (FMC/ FPGA Configuration Software) is used for running sophisticated system setup with automatic verification of proper configuration. In order to provide flexibility of further system configurations (e.g. user setup), common communication interface is also described. The approach presented here is related to the automatic system firmware building presented in previous papers. Modular construction and multichannel measurements are key requirement in term of SXR diagnostics with use of GEM detectors.
KEYWORDS: Sensors, MATLAB, Data modeling, Data acquisition, Field programmable gate arrays, Data processing, Clocks, Algorithm development, Detection and tracking algorithms, Process control
This article presents method of modeling in Matlab hardware architecture dedicated for FPGA created by languages like VHDL or Verilog. Purposes of creating such type of model with its advantages and disadvantages are described. Rules presented in this article were exploited to create model of Serial Data Acquisition algorithm used in X-ray GEM detector system. Result were compared to real working model implemented in VHDL. After testing of basic structure, other two structures were modeled to see influence parameters of the structure on its behavior.
This article is an overview of what has been implemented in the process of development and testing the GEM detector based acquisition system in terms of post-processing algorithms. Information is given on mex functions for extended statistics collection, unified hex topology and optimized S-DAQ algorithm for splitting overlapped signals. Additional discussion on bottlenecks and major factors concerning optimization is presented.
KEYWORDS: Algorithm development, Sensors, Plasma, Field programmable gate arrays, Data acquisition, Signal detection, Calibration, Plasma diagnostics, Diagnostics, Iron
The measurement system based on GEM - Gas Electron Multiplier detector - is developed for soft X-ray diagnostics of tokamak plasmas. The multi-channel setup is designed for estimation of the energy and the position distribution of an Xray source. The focal measuring issue is the charge cluster identification by its value and position estimation. The fast and accurate mode of the serial data acquisition is applied for the dynamic plasma diagnostics. The charge clusters are counted in the space determined by 2D position, charge value and time intervals. Radiation source characteristics are presented by histograms for a selected range of position, time intervals and cluster charge values corresponding to the energy spectra.
KEYWORDS: Sensors, Signal detection, X-rays, Field programmable gate arrays, X-ray detectors, Fusion energy, Data acquisition, Diagnostics, Amplifiers, Signal processing
The Triple Gas Electron Multiplier (T-GEM) is presented as soft X-ray (SXR) energy and position sensitive detector for high-resolution X-ray diagnostics of magnetic confinement fusion plasmas. Multi-channel measurement system and serial data acquisition for X-ray energy and position recognition is described. Fundamental characteristics are presented for two dimensional detector structure. Typical signals of ADC – Analog to Digital Converter are considered for charge value and position estimation. Coinciding signals for high flux radiation cause the problem for cluster charge identification. The amplifier with shaper determines time characteristics and limits the pulses frequency. Separation of coincided signals was introduced and verified for simulation experiments. On line separation of overlapped signals was implemented applying the FPGA technology with relatively simple firmware procedure. Representative results for reconstruction of coinciding signals are demonstrated.
KEYWORDS: Field programmable gate arrays, Data acquisition, X-rays, Diagnostics, Data processing, Signal processing, Data storage, Computer simulations, Detection and tracking algorithms, Sensors
Soft X-ray (SXR) measurement systems working in tokamaks or with laser generated plasma can expect high photon fluxes. Therefore it is necessary to focus on data processing algorithms to have the best possible efficiency in term of processed photon events per second. This paper refers to recently designed algorithm and data-flow for implementation of charge data acquisition in FPGA. The algorithms are currently on implementation stage for the soft X-ray diagnostics system. In this paper despite of the charge processing algorithm is also described general firmware overview, data storage methods and other key components of the measurement system. The simulation section presents algorithm performance and expected maximum photon rate.
KEYWORDS: MATLAB, Sensors, Data processing, Data communications, Optimization (mathematics), Field programmable gate arrays, Data acquisition, Data analysis, Control systems, X-ray detectors
This article concerns optimization methods for data analysis for the X-ray GEM detector system. The offline analysis of collected samples was optimized for MATLAB computations. Compiled functions in C language were used with MEX library. Significant speedup was received for both ordering-preprocessing and for histogramming of samples. Utilized techniques with obtained results are presented.
KEYWORDS: Detection and tracking algorithms, Operating systems, Field programmable gate arrays, Digital signal processing, Sensors, Data processing, Parallel computing, Data communications, Data modeling, Signal processing
This article is an assessment of potential parallelization of histogramming algorithms in GEM detector system. Histogramming and preprocessing algorithms in MATLAB were analyzed with regard to adding parallelism. Preliminary implementation of parallel strip histogramming resulted in speedup. Analysis of algorithms parallelizability is presented. Overview of potential hardware and software support to implement parallel algorithm is discussed.
KEYWORDS: Field programmable gate arrays, Data acquisition, Sensors, Detection and tracking algorithms, Telecommunications, Data communications, Data transmission, Data storage, MATLAB, Data processing
This article proposes new method of storing data and transferring it to PC in the X-ray GEM detector system. The whole process is performed by FPGA chips (Spartan-6 series from Xilinx). Comparing to previous methods, new approach allows to store much more data in the system. New, improved implementation of the communication algorithm significantly increases transfer rate between system and PC. In PC data is merged and processed by MATLAB. The structure of firmware implemented in the FPGAs is described.
An increased attention to tungsten material is related to a fact that it became a main candidate for the plasma facing material in ITER and future fusion reactor. The proposed work refers to the studies of W influence on the plasma performances by developing new detectors based on Gas Electron Multiplier GEM) technology for tomographic studies of tungsten transport in ITER-oriented tokamaks, e.g. WEST project. It presents current stage of design and developing of cylindrically bent SXR GEM detector construction for horizontal port implementation. Concept to overcome an influence of constraints on vertical port has been also presented. It is expected that the detecting unit under development, when implemented, will add to the safe operation of tokamak bringing creation of sustainable nuclear fusion reactors a step closer.
This paper describes architecture of a new data acquisition system (DAQ) targeted mainly at plasma diagnostic experiments. Modular architecture, in combination with selected hardware components, allows for straightforward reconfiguration of the whole system, both offline and online. Main emphasis will be put into the implementation of data transmission subsystem in said system. One of the biggest advantages of described system is modular architecture with well defined boundaries between main components: analog frontend (AFE), digital backplane and acquisition/control software. Usage of a FPGA chips allows for a high flexibility in design of analog frontends, including ADC ↔ FPGA interface. Data transmission between backplane boards and user software was accomplished with the use of industry-standard PCI Express (PCIe) technology. PCIe implementation includes both FPGA firmware and Linux device driver. High flexibility of PCIe connections was accomplished due to use of configurable PCIe switch. Whenever it's possible, described DAQ system tries to make use of standard off-the-shelf (OTF) components, including typical x86 CPU & motherboard (acting as PCIe controller) and cabling.
KEYWORDS: Sensors, Data acquisition, Control systems, Electronics, Plasma, Telecommunications, Data processing, Diagnostics, Calibration, Double positive medium
This paper presents the system integrating the dedicated measurement and control electronic systems for Gas Electron Multiplier (GEM) detectors with the Control and Data Acquisition system (CODAS) in the JET facility in Culham, England. The presented system performs the high level procedures necessary to calibrate the GEM detector and to protect it against possible malfunctions or dangerous changes in operating conditions. The system also allows control of the GEM detectors from CODAS, setting of their parameters, checking their state, starting the plasma measurement and to reading the results. The system has been implemented using the Python language, using the advanced libraries for implementation of network communication protocols, for object based hardware management and for data processing.
KEYWORDS: Sensors, Field programmable gate arrays, Plasma, Imaging systems, Data acquisition, Signal detection, Calibration, Analog electronics, Single photon, X-rays
A novel approach to two dimensional Gas Electron Multiplier (GEM) detector readout is presented. Unlike
commonly used methods, based on discriminators and analogue FIFOs, the method developed uses simulta-
neously sampling high speed ADCs with fast hybrid integrator and advanced FPGA-based processing logic to
estimate the energy of every single photon. Such a method is applied to every GEM strip / pixel signal. It is
especially useful in case of crystal-based spectrometers for soft X-rays, 2D imaging for plasma tomography and
all these applications where energy resolution of every single photon is required. For the purpose of the detector
readout, a novel, highly modular and extendable conception of the measurement platform was developed. It is
evolution of already deployed measurement system for JET Spectrometer.
KEYWORDS: Diagnostics, Field programmable gate arrays, Plasma systems, Plasma, Data storage, Sensors, Telecommunications, Data communications, Tungsten, Analog electronics
This paper describes the concept of data management software for the multichannel readout system for the GEM
detector used in WEST Plasma experiment. The proposed system consists of three separate communication
channels: fast data channel, diagnostics channel, slow data channel. Fast data channel is provided by the FPGA
with integrated ARM cores providing direct readout data from Analog Front Ends through 10GbE with short,
guaranteed intervals. Slow data channel is provided by multiple, fast CPUs after data processing with detailed
readout data with use of GNU/Linux OS and appropriate software. Diagnostic channel provides detailed feedback
for control purposes.
This article debates about data fast acquisition and histogramming method for the X-ray GEM detector. The whole
process of histogramming is performed by FPGA chips (Spartan-6 series from Xilinx). The results of the histogramming
process are stored in an internal FPGA memory and then sent to PC. In PC data is merged and processed by MATLAB.
The structure of firmware functionality implemented in the FPGAs is described. Examples of test measurements and
results are presented.
KEYWORDS: Sensors, Data acquisition, Calibration, X-rays, Signal detection, Data processing, Fusion energy, Plasma, X-ray detectors, Field programmable gate arrays
The Triple Gas Electron Multiplier (T-GEM) is presented as soft X-ray (SXR) energy and position sensitive detector for high-resolution X-ray diagnostics of magnetic confinement fusion plasmas [1]. Multi-channel measurement system and essential data processing for X-ray energy and position recognition is consider. Several modes of data acquisition are introduced depending on processing division for hardware and software components. Typical measuring issues aredeliberated for enhancement of data quality. Fundamental output characteristics are presented for one and two dimensional detector structure. Representative results for reference X-ray source and tokamak plasma are demonstrated.
Presented 2D gaseous detector system has been developed and designed to provide energy resolved fast dynamic plasma radiation imaging in the soft X-Ray region with 0.1 kHz exposure frequency for online, made in real time, data acquisition (DAQ) mode. The detection structure is based on triple Gas Electron Multiplier (GEM) amplification structure followed by the pixel readout electrode. The efficiency of detecting unit was adjusted for the radiation energy region of tungsten in high-temperature plasma, the main candidate for the plasma facing material for future thermonuclear reactors. Here we present preliminary laboratory results and detector parameters obtained for the developed system. The operational characteristics and conditions of the detector were designed to work in the X-Ray range of 2-17 keV. The detector linearity was checked using the fluorescence lines of different elements and was found to be sufficient for good photon energy reconstruction. Images of two sources through various screens were performed with an X-Ray laboratory source and 55Fe source showing a good imaging capability. Finally offline stream-handling data acquisition mode has been developed for the detecting system with timing down to the ADC sampling frequency rate (~13 ns), up to 2.5 MHz of exposure frequency, which could pave the way to invaluable physics information about plasma dynamics due to very good time resolving ability. Here we present results of studied spatial resolution and imaging properties of the detector for conditions of laboratory moderate counting rates and high gain.
This paper describes current status of electronics, firmware and software development for new plasma measurement
system for use in WEST facility. The system allows to perform two dimensional plasma visualization (in time) with
spectrum measurement. The analog front-end is connected to Gas Electron Multiplier detector (GEM detector).
The system architecture have high data throughput due to use of PCI-Express interface, Gigabit Transceivers and
sampling frequency of ADC integrated circuits. The hardware is based on several years of experience in building X-ray
spectrometer system for Joint European Torus (JET) facility. Data streaming is done using Artix7 FPGA devices.
The system in basic configuration can work with up to 256 channels, while the maximum number of measurement
channels is 2048. Advanced firmware for the FPGA is required in order to perform high speed data streaming and analog
signal sampling. Diagnostic system management has been developed in order to configure measurement system, perform
necessary calibration and prepare hardware for data acquisition.
KEYWORDS: Sensors, Field programmable gate arrays, Control systems, Data acquisition, Calibration, Operating systems, Computing systems, Diagnostics, Power supplies, Reliability
This paper describes the embedded controller used for the multichannel readout system for the GEM detector. The controller is based on the embedded Mini ITX mainboard, running the GNU/Linux operating system. The controller offers two interfaces to communicate with the FPGA based readout system. FPGA configuration and diagnostics is controlled via low speed USB based interface, while high-speed setup of the readout parameters and reception of the measured data is handled by the PCI Express (PCIe) interface. Hardware access is synchronized by the dedicated server written in C. Multiple clients may connect to this server via TCP/IP network, and different priority is assigned to individual clients. Specialized protocols have been implemented both for low level access on register level and for high level access with transfer of structured data with "msgpack" protocol. High level functionalities have been split between multiple TCP/IP servers for parallel operation. Status of the system may be checked, and basic maintenance may be performed via web interface, while the expert access is possible via SSH server. System was designed with reliability and flexibility in mind.
KEYWORDS: Field programmable gate arrays, Sensors, X-rays, Photons, X-ray detectors, Signal detection, Signal processing, Calibration, Time metrology, Electronics
This article presents a fast charge histogramming method for the position sensitive X-ray GEM detector. The energy
resolved measurements are carried out simultaneously for 256 channels of the GEM detector. The whole process of
histogramming is performed in 21 FPGA chips (Spartan-6 series from Xilinx) . The results of the histogramming process
are stored in an external DDR3 memory. The structure of an electronic measuring equipment and a firmware
functionality implemented in the FPGAs is described. Examples of test measurements are presented.
KEYWORDS: Sensors, Field programmable gate arrays, Amplifiers, X-rays, Signal detection, Connectors, Clocks, Temperature metrology, Analog electronics, Calibration
A novel approach to the Gas Electron Multiplier1 (GEM) detector readout is presented. Unlike commonly used
methods, based on discriminators, and analogue FIFOs,[ the method developed uses simultaneously sampling
high speed ADCs and advanced FPGA-based processing logic to estimate the energy of every single photon.
Such method is applied to every GEM strip signal. It is especially useful in case of crystal-based spectrometers
for soft X-rays, where higher order reflections need to be identified and rejected. For the purpose of the detector
readout, a novel conception of the measurement platform was developed.
KEYWORDS: Signal processing, Field programmable gate arrays, Linear filtering, Sensors, Signal detection, Electronic filtering, Amplifiers, Silicon, Analog electronics, Prototyping
This paper presents analysis of processing method of the signal from Gas Electron Multiplier (GEM) detector acquired in
our Field-Programmable Gate Array (FPGA) based readout system. We have found that simple processing of GEM signal
received from the charge amplifier, sampled at 100MHz with 10-bit resolution, after low-pass filtering with 15 MHz cut-off
frequency, provides accuracy similar to obtained by processing of the raw GEM signal sampled at 2.5 GHz frequency with
8-bit resolution. Even when 3 bits are lost due to long term instability of the detector and analog part of the system - resulting
in 7-bit effective resolution, the reasonable accuracy is still preserved. Additionally we have analyzed computational
power required to perform the real-time analysis of the GEM signal, taking into consideration resources offered by the
FPGA chip used in the prototype platform.
KEYWORDS: Sensors, Field programmable gate arrays, Electronics, Signal detection, Prototyping, X-rays, Amplifiers, Signal processing, Diagnostics, Power supplies
A novel approach to the Gas Electron Multiplier (GEM) detector readout is presented. Unlike commonly used methods, based on discriminators[2],[3] and analogue FIFOs[1], the method developed uses simultaneously sampling high speed ADCs and advanced FPGA-based processing logic to estimate the energy of every single photon. Such method is applied to every GEM strip signal. It is especially useful in case of crystal-based spectrometers for soft X-rays, where higher order reflections need to be identified and rejected[5].
K. Pozniak, T. Czarski, G. Kasprowicz, W. Dominik, M. Lorenc, R. Dabrowski, K. Jakubowska, L. Karpinski, I. Kudla, K. Kierzkowski, A. Komarzewski, J. Rzadkiewicz, Z. Salapa, M. Scholz, W. Zabolotny
The paper describes construction of a scalable, automatic measurement system to research GEM detectors. The testbench
enables concurrent and precise measurements of many discharge current signals originating from the charges
generated by the avalanche process in gas in the GEM micro-holes where the electric field gradient is high. We used
Tektronix scopes MSO/DPO4104 and MSO/DPO5104 and Matlab to collect and process the data. Construction of the
test-bench is presented in terms of hardware and software. The examples of lab condition measurements were presented.
Analysis of these data enable the estimation of the quality of the GEM detector.
KEYWORDS: Control systems, Field programmable gate arrays, Device simulation, Data acquisition, MATLAB, Signal detection, Analog electronics, System identification, Digital signal processing, Telecommunications
A digital control, as the main part of the Low Level RF system, for superconducting cavities of a linear accelerator is
presented. The FPGA based controller, supported by MATLAB system, was developed to investigate a novel firmware
implementation. The complex control algorithm based on the non-linear system identification is the proposal verified by
the preliminary experimental results. The general idea is implemented as the Multi-Cavity Complex Controller (MCC)
and is still under development. The FPGA based controller executes procedure according to the prearranged control
tables: Feed-Forward, Set-Point and Corrector unit, to fulfill the required cavity performance: driving in the resonance
during filling and field stabilization for the flattop range. Adaptive control algorithm is applied for the feed-forward and
feedback modes. The vector Simulator table has been introduced for an efficient verification of the FPGA controller
structure. Experimental results of the internal simulation, are presented for a cavity representative condition.
KEYWORDS: Digital signal processing, Control systems, Field programmable gate arrays, Device simulation, Computer simulations, Signal processing, Data acquisition, Modulators, Free electron lasers, Multiplexers
The work describes integrated system of hardware controller and simulator of superconductive cavity. The controller was realized on FPGA chip Xilinx-VirtexII-V4000. The solution uses DSP EMBEDDED BOARD positioned on a LLRF Modular Control Platform. The algorithm was realized in VHDL using hardware multiplication components existing in VirtexII series of chips. There was obtained implementation of a device working in real-time according to the control condition demands of LLRF system for TESLA superconductive cavities. The system is predicted as a developmental stage for FLASH accelerator and FEL laser and next for XFEL. The paper describes in detail functional layer, parameter programming, control basics for particular blocks, monitoring of real-time processes. There are presented results of system usage for control of the module ACC1 of FLASH laser.
KEYWORDS: Control systems, Calibration, Superconductors, Field programmable gate arrays, Surface plasmons, MATLAB, System identification, Systems modeling, Adaptive control, Detection and tracking algorithms
A digital control of superconducting cavities for a linear accelerator is presented. The LLRF - Low Level Radio Frequency system for FLASH project in DESY is introduced. FPGA based controller supported by MATLAB system was developed to investigate the novel firmware implementation. Algebraic model in complex domain is proposed for the system analyzing. Calibration procedure of a signal path is considered for a multi-channel control. Identification of the system parameters is carried out by the least squares method application. Control tables: Feed-Forward and Set-Point are determined for the required cavity performance, according to the recognized process. Feedback loop is tuned by fitting a complex gain of a corrector unit. Adaptive control algorithm is applied for feed-forward and feedback modes. Experimental results are presented for a cavity representative operation.
KEYWORDS: MATLAB, Field programmable gate arrays, Device simulation, Control systems, Calibration, Free electron lasers, Data acquisition, Superconductors, Algorithm development, Visualization
The note describes integrated system of hardware controller and simulator of the resonant superconducting, narrowband niobium cavity, originally considered for the TTF and TESLA in DESY, Hamburg (now predicted for the W V and X-Ray FEL). The controller bases on a programmable circuit Xilinx VirtexII V3000 embedded on a PCB XtremeDSP Development Kit by Nallatech. The FPGA circuit configuration was done in the VHDL language. The internal hardware multiplication components, present in Virtex II chips, were used, to improve the floating point calculation efficiency. The implementation was achieved of a device working in the real time, according to the demands of the LLRF control system for the TESLA Test Facility. The device under consideration will be referred to as superconducting cavity (SCCav) SIMCON throughout this work. This document is intended to be used by end users and operators. It describes step by step how to install SIMCON in specific configuration, how and what software to copy to computer. There is described set of basic Matlab functions for developers of control algorithms. This paper also contains brief description how to use Matlab function of one algorithm with its graphic user panels. This TESLA Report is in close relations with the following TESLA Reports published previously: 2005-05, 2005-02, 2004-10. Together, these Reports make a full SIMCON manual.
KEYWORDS: MATLAB, Field programmable gate arrays, Control systems, Algorithm development, Device simulation, Digital signal processing, Interfaces, Computer simulations, Telecommunications, Control systems design
The paper describes the concept and realization of the DOOCS control software for FPGA-based TESLA cavity controller and simulator (SIMCON). It bases on universal software components, created for laboratory purposes and used in MATLAB based control environment. These modules have been recently adapted to the DOOCS environment to ensure a unified software to hardware communication model. The presented solution can be also used as a general platform for control algorithms development. The proposed interfaces between MATLAB and DOOCS modules allow to check the developed algorithm in the operation environment before implementation in the FPGA. As the examples two systems have been presented.
KEYWORDS: Digital signal processing, Device simulation, Clocks, Control systems, Field programmable gate arrays, Computer simulations, Signal processing, Computer programming, Free electron lasers, Telecommunications
The paper describes integrated system of hardware controller and simulator of the resonant superconducting, narrowband niobium cavity, originally considered for the TTF and TESLA in DESY, Hamburg (now predicted for the VUV and X-Ray FEL). The controller bases on a programmable circuit Xilinx VirtexII V3000 embedded on a PCB XtremeDSP Development Kit by Nallatech. The FPGA circuit configuration was done in the VHDL language. The internal hardware multiplication components, present in Virtex II chips, were used, to improve the floating point calculation efficiency. The implementation was achieved of a device working in the real time, according to the demands of the LLRF control system for the TESLA Test Facility. The device under consideration will be referred to as superconducting cavity (SCCav) SIMCON throughout this work.
The following components are described here in detail: functional layer, parameter programming, foundations of control of particular blocks and monitoring of the real time processes. This note is accompanied by the one describing the DOOCS interface for the described hardware system. The interface was prepared in DOOCS and in Windows. The hardware and software of SIMCON was tested in CHECIA. The results were presented. While giving all necessary technical details required to understand the work of the integrated hardware controller and simulator and to enable its practical copying, this document is a unity with other TESLA technical notes published by the same team on the subject. Modeling was omitted, as it is addressed in detail in the quoted references.
KEYWORDS: Digital signal processing, Signal processing, Data acquisition, Device simulation, Computer programming, Multiplexers, Control systems, Free electron lasers, Computer simulations, Modulators
The paper describes integrated system of hardware controller and simulator of the resonant superconducting, narrowband niobium cavity, originally considered for the TTF and TESLA in DESY, Hamburg (now predicted for the VUV and X-Ray FEL). The controller bases on a programmable circuit Xilinx VirtexII V3000 embedded on a PCB XtremeDSP Development Kit by Nallatech. The FPGA circuit configuration was done in the VHDL language. The internal hardware multiplication components, present in Virtex II chips, were used, to improve the floating point calculation efficiency. The implementation was achieved of a device working in the real time, according to the demands of the LLRF control system for the TESLA Test Facility. The device under consideration will be referred to as superconducting cavity (SCCav) SIMCON throughout this work.
The following components are described here in detail: functional layer, parameter programming, foundations of control of particular blocks and monitoring of the real time processes. This note is accompanied by the one describing the DOOCS interface for the described hardware system. The interface was prepared in DOOCS and in Windows. The hardware and software of SIMCON was tested in CHECIA. The results were presented.
While giving all necessary technical details required to understand the work of the integrated hardware controller and simulator and to enable its practical copying, this document is a unity with other TESLA technical notes published by the same team on the subject. Modeling was omitted, as it is addressed in detail in the quoted references.
KEYWORDS: Control systems, Field programmable gate arrays, Data acquisition, Device simulation, Free electron lasers, Digital signal processing, Standards development, Switching, Optical simulations, Vacuum ultraviolet
The paper describes integrated system of hardware controller and simulator of the resonant superconducting, narrowband niobium cavity, originally considered for the TTF and TESLA in DESY, Hamburg (now predicted for the VUV and X-Ray FEL). The controller bases on a programmable circuit Xilinx VirtexII V3000 embedded on a PCB XtremeDSP Development Kit by Nallatech. The FPGA circuit configuration was done in the VHDL language. The internal hardware multiplication components, present in Virtex II chips, were used, to improve the floating point calculation efficiency. The implementation was achieved of a device working in the real time, according to the demands of the LLRF control system for the TESLA Test Facility. The device under consideration will be referred to as superconducting cavity (SCCav) SIMCON throughout this work.
The following components are described here in detail: functional layer, parameter programming, foundations of control of particular blocks and monitoring of the real time processes. This note is accompanied by the one describing the DOOCS interface for the described hardware system. The interface was prepared in DOOCS and in Windows. The hardware and software of SIMCON was tested in CHECIA. The results were presented. While giving all necessary technical details required to understand the work of the integrated hardware controller and simulator and to enable its practical copying, this document is a unity with other TESLA technical notes published by the same team on the subject. Modeling was omitted, as it is addressed in detail in the quoted references.
KEYWORDS: MATLAB, Device simulation, Field programmable gate arrays, Control systems, Algorithm development, Data communications, Systems modeling, Interfaces, Safety, Digital signal processing
The paper describes the concept and realization of the DOOCS control software for FPGA-based TESLA cavity controller and simulator (SIMCON). It bases on universal software components, created for laboratory purposes and used in MATLAB based control environment. These modules have been recently adapted to the DOOCS environment to ensure a unified software to hardware communication model. The presented solution can be also used as a general platform for control algorithms development. The proposed interfaces between MATLAB and DOOCS modules allow to check the developed algorithm in the operation environment before implementation in the FPGA. As the examples two systems have been presented.
FPGA based cavity simulator and controller is the next generation control system dedicated for high performance, low latency control algorithm development and implementation. The usage of FPGA technology gives users possibility to create many devices on one board and easy exchange, modify or improve VHDL programmed algorithms. In order to provide the full functionality of the system to the user, and meet the requirements of flexibility and extensibility, an appropriate control software is needed. This paper describes the idea and implementation of control environment dedicated for FPGA based devices. As an example of implementation, two control environments have been implemented; the laboratory software based on Matlab, and the application for accelerator operation using DOOCS environment.
KEYWORDS: Field programmable gate arrays, Control systems, Calibration, MATLAB, Resonators, Distortion, Data modeling, System identification, Sensors, Superconductors
The digital control of the TESLA (TeV-Energy Superconducting Linear Accelerator) resonator is presented. The laboratory setup of the CHECHIA cavity in DESY-Hamburg has been driven by the FPGA (Field Programmable Gate Array) technology system. This experiment focused attention to the general recognition of the cavity features and projected control methods. The electrical model of the resonator is taken as a consideration origin. The calibration of the signal channel is considered as a key preparation for an efficient cavity driving. The identification of the resonator parameters is confirmed as a proper approach for the required performance: driving on resonance during filling and field stabilization during flattop time with reasonable power consumption. The feed-forward and feedback modes were applied successfully for the CHECHIA cavity driving. Representative results of experiments are presented for different levels of the cavity field gradient.
The paper describes possible configuration of hardware and a bunch of Matlab functions of controller and simulator of the resonant superconducting, narrowband niobium cavity, originally considered for the TTF and TESLA in DESY, Hamburg (now predicted for the VUV and X-Ray FEL). The configuration of the hardware can be done in different ways to achieve the most adequate setup to the requirements.
There is described set of basic Matlab functions for advanced users and developers of control algorithms. The functions allow to configure basic features and functionality of the SIMCON device.
KEYWORDS: MATLAB, Control systems, Device simulation, Field programmable gate arrays, Control systems design, Superconductors, Free electron lasers, Human-machine interfaces, Data communications, Data conversion
The paper describes design and performance of the DOOCS (distributed, object oriented) based control system for the cavity simulator and controller (SIMCON). A concise description of the DOOCS system is given. Resident data types and data flow throughout the Simcon system are discussed. The basic ideas and implementation issues of the server and client application are described as well as some alternatives to the DOOCS solution (considered as partial) is presented.
KEYWORDS: Digital signal processing, Field programmable gate arrays, Optical fibers, Control systems, Signal processing, Optical networks, Data modeling, Transmittance, Diagnostics, Modulation
The work presents a structural and functional model of a distributed low level radio frequency (LLRF) control system for the TESLA-XFEL accelerator. The design of a system basing on the FPGA chips and multi-gigabit optical network was debated. The system design approach was fully parametric. The major emphasis is put on the methods of the functional and hardware concentration to use fully both: a very big transmission capacity of the optical fiber telemetric channels and very big processing power of the latest series of the, DSP enhanced and optical I/O equipped, FPGA chips. The subject of the work is the design of a universal, laboratory module of the LLRF sub-system. Initial parameters of the system model under the design are presented.
The paper describes design and practical realization of software for laboratory purposes to control FPGA-based photonic and electronic equipment. There is presented a universal solution for all relevant devices with FPGA chips and gigabit optical links. The paper describes architecture of the software layers and program solutions of hardware communication based on Internal Interface (II) technology. Such a solution was used for superconducting Cavity Controller and Simulator (SIMCON) for the TESLA experiment in DESY (Hamburg). A number of practical examples of the software solutions for the SIMCON system were given in this paper.
KEYWORDS: Digital signal processing, Field programmable gate arrays, Device simulation, Control systems, Clocks, Signal processing, Analog electronics, Multiplexers, Data acquisition, Computer simulations
The paper describes an integrated, hardware system for the control and simulation of a superconducting cavity of the linear accelerator. The photonic and electronic control system was realized using a programmable FPGA chip Xilinx Virtex II 3000. The chip was placed on a board Xtreme DSP Development Kit by Nallatech. The system was implemented using the VHDL technology. The hardware multiplying blocks from the Virtex II series chip were used. The resultant controller device worked in the real time, in accordance with the requirements of the TESLA Test Facility project, for the LLRF sub-system of the resonant cavities. In particular, the paper describes the functional layer of the system. Individual executing blocks of the controller implemented in the FPGA chip were debated. The functional structure and hardware implementation of the controller communication layer were presented. Some examples of the system in action were chosen. A number of the real time processes were monitored.
KEYWORDS: Digital signal processing, Field programmable gate arrays, Control systems, Computer simulations, Functional analysis, Superconductors, Chemical elements, Clocks, Signal processing, Computer programming
The paper contains the analysis of the application possibilities offered by the new generation of the FPGA chips. The new generation of the FPGA chips contain DSP blocks. The new functionalities are well suited for the application in the TESLA LLRF cavity simulation and control system (SIMCON). A debate on the programming methods of the new chips and the algorithm parameterization was presented. The aim of the, FPGA chip based, system analysis is the optimal chip usage to increase the maximum frequency at which the system can work efficiently, and the optimal usage of the accessible chip resources (DSP blocks). The exemplary results for a few practical calculated implementations were presented and analyzed. The implementations included some basic DSP operations performed in the FPGA chips of Altera and Xilinx. There were compared the results for a few different chips. The TESLA superconducting cavity simulator was efficiently implemented. The results were presented for the first time, for the pure FPGA/VHDL solution. The realization costs were debated in the dependence of given system parameters and the applied type of the FPGA chip.
KEYWORDS: Control systems, Field programmable gate arrays, Simulink, MATLAB, Signal processing, Performance modeling, Device simulation, Electronic filtering, Data modeling, Feedback control
The cavity control system for the TESLA -- TeV-Energy Superconducting Linear Accelerator project is initially introduced in this paper. The FPGA -- Field Programmable Gate Array technology has been implemented for digital controller stabilizing cavity field gradient. The cavity SIMULINK model has been applied to test the hardware controller. The step operation method has been developed for testing the FPGA device coupled to the SIMULINK model of the analog real plant. The FPGA signal processing has been verified according to the required algorithm of the reference MATLAB controller. Some experimental results have been presented for different cavity operational conditions.
KEYWORDS: Control systems, Detection and tracking algorithms, Signal detection, MATLAB, Feedback control, Modulation, Digital signal processing, Simulink, Phase shift keying, Signal analyzers
The paper is an introduction to the optimization methods of the linear accelerator cavity control system. Three distinct time periods of cavity operation are considered; filling with the EM field energy, field stabilization, and field decay. These periods represent completely different states and behavior of the cavity. The cavity could be operated by several different methods in each work phase: During the filling -- feedback and feed-forward alone, feedback and feed-forward together, self-tuning; During the flattop -- feed-forward and feedback alone or together, During the decay -- detuning and quality factor may be measured. The optimization is understood as a choice of the most efficient way of the cavity control during each period. The control may be done in terms of minimum power consumption from the klystron during whole work cycle and efficient field stabilization in the cavity, during flattop period. The introductory analysis of the cavity operational modes in three mentioned periods is presented in this paper. Additionally the alternative more precise algorithm of the cavity voltage envelope detection is proposed.
KEYWORDS: Computer simulations, Field programmable gate arrays, Digital signal processing, Multiplexers, Superconductors, MATLAB, Control systems, Systems modeling, Clocks, Computer programming
This paper presents a FPGA based DSP system for realtime simulation of superconducting accelerator's cavity. The superconducting linacs require sophisticated control systems for maintaining the constant amplitude and phase of accelerating field in the accelerator's cavities. The debugging of these systems on real hardware can be both difficult and dangerous. To allow testing of the real LLRF systems in the real time and with different cavity parameters, the FPGA based system has been developed.
KEYWORDS: Control systems, Resonators, Signal analyzers, Simulink, Resistance, Free electron lasers, Digital signal processing, Feedback control, Optical simulations, Modeling and simulation
The cavity control system for the TESLA -- TeV-Energy Superconducting Linear Accelerator project is initially introduced. The elementary analysis of the cavity resonator on RF (radio frequency) level and low level frequency with signal and power considerations is presented. For the field vector detection the digital signal processing is proposed. The electromechanical model concerning Lorentz force detuning is applied for analyzing the basic features of the system performance. For multiple cavities driven by one klystron the field vector sum control is considered. Simulink model implementation is developed to explore the feedback and feed-forward system operation and some experimental results for signals and power considerations are presented.
KEYWORDS: Field programmable gate arrays, MATLAB, Control systems, Digital signal processing, Device simulation, Simulink, Signal processing, Resonators, Feedback control, Signal analyzers
The cavity resonator modeling for the TESLA -- TeV-Energy Superconducting Linear Accelerator project is initially introduced. The electromechanical model including Lorentz force detuning and beam loading is applied for analyzing the basic features of the plant. The continuous SIMULINK and digital MATLAB model implementation is developed as a reference for the hardware simulator based on the FPGA -- Field Programmable Gate Array technology. The step operation mode has been applied for testing of the FPGA device coupled to the software control block. The FPGA signal processing has been verified according to the desired model of the real cavity plant. The numerical aspects have been investigated for the efficient design. Some experimental results have been presented for different cavity operational conditions. The following considerations have lead to the synthesis of the efficient algorithm for the cavity model, then implemented in the FPGA system.
KEYWORDS: Digital signal processing, Field programmable gate arrays, Control systems, Control systems design, Linear filtering, Clocks, MATLAB, Signal processing, Algorithm development, Chemical elements
This paper presents a new FPGA based solution of the Low Level RF Control System for TESLA Test Facility. The LLRF Control System is responsible for maintaining the constant amplitude and phase of accelerating field in set of accelerator's cryomodulaes driven by single klystron. To obtain shorter processing time and less complicated hardware an FPGA based solution was selected. The proposed simulation has been simulated in software, and appeared to be faster and less complex than DSP based solutions.
KEYWORDS: Control systems, Demodulation, Feedback control, Modulation, Signal analyzers, Systems modeling, Cavity resonators, Superposition, Free electron lasers, Superconductors
The pioneering TESLA linear accelerator and free electron laser project is initially introduced. Elementary analysis of cavity resonator with signal and power considerations is presented. Two alternative simulation models of cavity control system are proposed.
KEYWORDS: Control systems, Signal analyzers, Simulink, Cavity resonators, MATLAB, Systems modeling, Free electron lasers, Feedback control, Demodulation, Modulation
The fundamental knowledge containe in the previous paper on "cavity control system essential modeling for TESLA linear accelerator and free electron laser" is applied for Matlabs' Simulink implementation of the basic models for the cavity resonator. Elementary simulations of the cavity behavior are carried out and some experimental result for signals and power considerations are presented.
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