David R. Sar

Experimental results from a J-band relativistic klystron amplifier developmental effort

Experimental results to-date will be presented from a developmental effort to a produce a J- band (5.85 - 8.2 GHz) relativistic klystron amplifier (RKA) of the high current Naval Research Laboratory (NRL) genealogy. The nominal experimental parameters of this RKA are: V0 approximately equals 600 kV; I0 approximately equals 2 - 4 kA; Bz approximately equals 1.5 T; (tau) beam approximately equals 300 ns; vin approximately equals 6.6 GHz; Pin <EQ 500 kW. Because of the smaller component sizes which accompany this frequency ((lambda) approximately equals 4.5 cm as compared with (lambda) approximately equals 30 cm for the bulk of other RKA research efforts), much of the discussion will concentrate on the physical principles, fabrication issues, and experimental pitfalls associated with scaling the RKA design.

Recent experimental results from a long-pulse J-band relativistic klystron amplifier developmental effort

Recent experimental results, supporting simulations, and design modeling are presented from a developmental effort to produce a long pulse (approximately 1 microsecond(s) ) J-band (5.85 - 8.2 GHz) relativistic klystron amplifier (RKA) of the high current NRL genealogy. This RKA is designed to operate at approximately 6.6 GHz, with a desired rf output approximately 700 MW. Conversion of electron beam energy to microwave energy is obtained by a mock magnetically insulated coaxial converter which, in various incarnations, can be made to be either a cavity gap extractor or an inverse cathode.

RETROFIT CONVERSION OF A LOW IMPEDANCE, SHORT PULSE ELECTRON BEAM ACCELERATOR TO HIGH IMPEDANCE, LON

Abstract : An existing relativistic electron beam generator has been modified to increase its output pulse width from 100 ns to either 300 ns or 1,000 ns. In its original form, the generator consisted of a water insulated, 5.25 omega coaxial pulse forming line (PFL) that discharged into a field emission diode through a low inductance gas-pressurized spark gap switch. A twenty stage Marx generator charged to the PFL to as high as 2 MV. At this voltage, an 1 MV output pulse is developed into a matched load. An adjustable resistor shunting the PFL permitted matching its output to load impedances higher than 5.25 omega.