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Plasma Window Performance. Leslie Bromberg Katie Maurer Ady Herskovitch* MIT Plasma Science and Fusion Center ARIES meeting Madison, WI April 23, 2002 *Brookhaven National Laboratory, NY. HIBD-Chamber Vacuum Interface. Heavy Ion Beam Driver requires high vacuum for operation
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Plasma Window Performance Leslie Bromberg Katie Maurer Ady Herskovitch* MIT Plasma Science and Fusion Center ARIES meeting Madison, WI April 23, 2002 *Brookhaven National Laboratory, NY
HIBD-Chamber Vacuum Interface • Heavy Ion Beam Driver requires high vacuum for operation • 10-6-10-9 Torr • Chamber operation requires low to intermediate vacuum • 10-3 - 10 Torr • Because of the large openings required for beam propagation, large gas throughput across the HIB final focus and the chamber exits • Large vacuum pumping speeds required • Not clear whether it is possible to maintain that large pressure differential with the available space for pumps. • Can Flinabe pump Xe?
Plasma Window • Experiments at MIT for supporting work on a compact neutron source (Dr. R. Lanza, Dr. A. Herskovitch) • Funded in the past through LLNL
Throughput calculations • In the viscous regime (usually p > 100 mTorr), the throughput through a channel is Here, Q is the throughput, h is the gas viscosity, a is the diameter, and P’s are the pressure • Increased viscosity and decreased number density results in decreased flow through the opening. • If the channel is filled with a thermal plasma, both the viscosity increases and the number density decreases, decreasing the particle throughput.
Plasma windows for applications to HID • Demonstrated technology for intermediate pressure (in the viscous regime) • Preliminary experiments with Ar at atmospheric and higher pressures • Minimum pressure at low pressure side is ~30 mTorr (down from 100 mTorr) • Not clear how low it can reach with different gases, different size openings and lowered pressure at high pressure side of window • Need scaling experiments • Additional experiments at lower pressures and with other gases to come in the summer • Power consumption, per window, is probably (?) on the order of 50-200 W for 1 Torr operation with Xe • Requires dielectrics (?) • Already a conducting media