Test stand for linear induction accelerator optimization

Lawrence Livermore National Laboratory has designed and constructed a test stand to improve the voltage regulation in our flash X-Ray (FXR) accelerator cell. The goal is to create a more mono-energetic electron beam that creates an X-ray source with a smaller spot size. Studying the interaction of the beam and pulse-power system with the accelerator cell improves the design of high-current accelerators at Livermore and elsewhere. On the test stand, a standard FXR cell is driven by a flexible pulse-power system and the beam current is simulated with a switched center conductor. The test stand is fully instrumented with high-speed digitizers to document the effect of impedance mis-matches when the cell is operated under various full-voltage conditions. A time-domain reflectometry technique was also developed to characterize the beam and cell interactions by measuring the impedance of the accelerator and pulse-power component. Computer models are being developed in parallel with the testing program to validate the measurements and evaluate different design changes. Both 3D transient electromagnetic and circuit models are being used.