LLRF control system consists of a few basic subsystems with the basic aim to give good quality beam from the XFEL laser. Some of the se subsystems, which are described here are: transient detector, finite state machine, precise timing distribution network, EM field stabilization control loop, etc. The paper summarizes the latest developments of these systems done during the last year.
The UV Free-Electron Laser (UVFEL) , The X-Ray Free-Electron Laser (XFEL)  and The International Linear Accelerator (ILC)  projects will require phase synchronization of various RF frequency subsystems on kilometer distances with accuracy better than 1ps. To fulfill these requirements, a phase reference distribution system concept was proposed and a prototype was developed for tests in the TESLA Test Facility 2 (TTF2). An important part of the phase reference system is the fiber-optic phase stable, long distance link described in this paper. An interferometrical scheme with feedback on phase, suppressing long term phase drifts induced by temperature changes was developed and tested in laboratory and under accelerator conditions. A motorized optical delay line was used in the system to compensate for phase errors. Described are error considerations and most important project issues like the hardware development and the
real time phase controller software. The presented measurement results satisfy the design requirements. Experience gained during the experiments yielded proposals for system improvements.
Proc. SPIE. 5948, Photonics Applications in Industry and Research IV
KEYWORDS: Digital signal processing, Optical amplifiers, Clocks, Interfaces, Power supplies, Field programmable gate arrays, Control systems, Telecommunications, Analog electronics, Free electron lasers
A new version of the SIMCON system is presented in this paper. The SIMCON stands for the microwave, resonant, superconductive accelerator cavity simulator and controller (embracing the hardware and software layers). The current version of the SIMCON is 3.1. which is a considerable step forward from the previous 8-channel version 3.0. which was released at the beginning of 2005 and was made operable in April. Many important upgrades were implemented in SIMCON 3.1. It is a stand-alone VME board (whereas SIMCON 3.0 was modular) based on the Virtex II Pro 30 chip with two embedded Power PCs and DSP blocks. It has Ethernet and multiple gigabit optical I/Os. The Simcon 3.1 board provides 10 ADC channels. The architecture idea and block diagrams of the PCB for SIMCON 3.1. are presented. Some of the applied novel technical solutions, Protel"R" views and schemes are shown. A number of initial conclusions were drawn from a few month experience with the development of this new board. The tables of predicted system parameters are quoted.
The UV Free-Electron Laser (UVFEL) and The TeV-Energy Superconducting Linear Accelerator (TESLA) projects will require phase synchronization of 0.1 ps short term (millisecond), 1 ps short term (minutes) and 10 ps long term (days). The stringent synchronization requirement of 10fs was given for the X-Ray Free- Electron Laser (XFEL). To fufill this requirement the XFEL may use a fiber laser as reference generator. But this requirement applies for a special location only, therefore the RF phase reference distribution system developed UVFEL and TESLA will also be used in the XFEL. The RF phase reference distribution system must deliver phase stable signals to hundreds of stations over a length of 33 km. Long, optical fiber based links are planned to be an important part of the entire distribution system. This paper describes the concept of a long optical link, with a feedback system suppressing long term drifts of the RF signal phase. Stability requirements are given and most important design issues affecting system performance are discussed. Finally, an experimental setup and measurement results demonstrating system performance is shown.
The RF Phase Reference Distribution System (PRDS) must deliver a highly RF phase stable signal to many various RF subsystems of the X-ray Free Electron Laser (XFEL) and in the future the TESLA linear collider. The required phase synchronization corresponding to the short term stability of 1 ps must be guaranteed. Taking into consideration large amount of devices to be synchronized, long distances and necessity of delivering different frequencies, the design of PRDS becomes a very difficult and challenging task. This paper describes the main considered issues. Such parameters as distribution frequency, waveguide attenuation, multiplier noise and temperature influence on the system are taken into account. The advantages and disadvantages of coaxial cables and optical fiber as the distribution medium are compared. The feedback system stabilizing long term phase drifts is presented and the structure of PRDS which may fulfill the design requirements is proposed.