Measuring the X-ray environment generated at the center of the NIF target chamber is a core capability
required for understanding target implosions and other physics experiments. Recently an upgrade was
performed to the recording systems employing modern digital technology and additional remote-control
capabilities. Together, significantly decreasing manual setup burdens, increasing accuracy, stability and
availability while contributing to shot rate improvement, overall efficiency and cost of operations reduction on
NIF. We present the systems chosen, improved calibration techniques employed and some of the key features
including the addition of self-test capabilities.
The goal of this paper is to outline the process for characterizing the S-parameters of passive two-port electrical
devices to calculate the input signal from a measured output signal when standard two-port VNA measurements are
not possible. For long cables such as those used at NIF to transmit analog electrical signals long distances from target
diagnostics to their respective data digitizer, standard two-port VNA measurements cannot be used to determine the
cables’ transfer functions due to the large physical separations between the ports of the cables. Traditionally, this
problem was addressed by recording input and output waveforms with two oscilloscopes and then comparing their
spectral composition. A new method is to take reflection measurements at one port and substitute three known loads
at the other port to generate a system of simultaneous equations that will allow for S21 to be quantified.