Elimination of Pulse Shortening in High Power Microwave Tubes

Advances in high power microwave (HPM) tubes have made possible the generation of intense pulses of RF energy which output power in excess of 1 GW. Unfortunately, these tubes exhibit RF pulse shortening at power levels above 100 MW. MDS Company has extensive experience in identifying those subassemblies in HPM tubes where excessive voltage gradients lead to RF breakdown and, consequently, RF pulse shortening. Based on the high power technology established through several klystron development programs, for this Phase I, MDS proposes to investigate both analytically and experimentally the processes that lead to the onset of pulse shortening. Analytically, we will utilize computer codes such as EGUN and SUPERFISH to find the pulsed ectron gun and RF electric fields in all critical areas. For the experimental portion of this effort, we will rebuild the Relativistic Klystron Oscillator (RKO) as reported on in Physical Review Letters, Volume 76, No. 1, January 1, 1996, by researchers at HERTF. We will rework those subassemblies that exhibit excessive electric fields, reassemble the RKO and perform high power testing to verify our solutions.In Phase II, we propose to develop a new high power RF source based on the experimental results from Phase I. A pulser will also be developed and after testing with the new source, will be delivered to Phillips Laboratory.