Laser-triggered gas switch improvements on PBFA-II
PBFA-II is a thirty-six module ion accelerator built by Sandia National Laboratories for inertial confinement fusion feasibility studies. In the water-filled, pulse-forming section of the accelerator, each module is fitted with a 5.0 MV, SF{sub 6}-filled gas switch located between an intermediate storage capacitor and the first pulse-forming line (Line 1). The intermediate storage capacitor is charged to 4.8-5.0 MV in approximately 950 ns by a Marx generator located in the oil section of the machine. The gas switch is required to close on command and transfer the stored capacitor energy to Line 1, a coaxial transmission line of 100 ns two-way electrical length. The switches are triggered by a single 3.0 J KrF laser located under the accelerator; a complex beam-splitting/distribution system is used to deliver simultaneous 20 to 40 mJ, 35 ns FWHM beamlets to the individual switches. In recent experiments on PBFA-II, gas switches have been modified and tested at different gas pressures and voltages. These modifications substantially reduced the switch runtime, jitter, and expected spread. Also, changes to the triggering KrF laser have been shown to significantly affect gas switch performance. The switch modifications will be incorporated into the machine as a retrofit planned for this summer. The laser optical set-up has also been changed as a result of these findings.
- Research Organization:
- Sandia National Labs., Albuquerque, NM (United States)
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 5587182
- Report Number(s):
- SAND-87-1512C; CONF-870656--16; ON: DE87011719
- Country of Publication:
- United States
- Language:
- ENGLISH
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