Plasma Switch for 11.4 GHz Active Sled-II RF Pulse Compressor

70518 The high pulsed radio frequency (rf) power, needed for a future electron-positron collider such as NLC, will require rf pulse compression, for which a number of approaches are currently under study. Active rf pulse compression can - in principal - provide greater flexibility in compressor design than passive compression, because higher compression ratios can be achieved at higher efficiency. This project will develop a plasma switch for an active SLED-II rf pulse compressor with a compression ratio greater than 8:1 and an efficiency greater than 80%. The plasma switches will be used with resonance structures having a reflection coefficient that can be rapidly shifted during the rf pulse from a klystron. Changing both the reflection coefficient of the switch and the phase of the klystron output will allow high compression ratios with high efficiency. In Phase I, designs will be optimized (at both high and low nitrogen gas pressure in the discharge tubes, and for a variety of X-band resonance structures) in order to couple the rf power from a klystron into a pair of relatively short delay lines and then, upon switching, into an accelerator structure. Low-power cold tests will be conducted on the most promising designs, in order to select the best design for fabrication and high-power testing in Phase II. Commercial Applications and Other Benefits as described by awardee: The rf plasma switches, with reflectivity that can be changed rapidly to produce rf pulse compression greater than 8:1 with efficiency >80%, could be adopted for use in a future electron-positron collider. Thousands of these switches would be required, constituting a potential commercial market of several tens of millions of dollars.