Demonstration of a high-power (>6 KW) W-band sheet beam extended interaction klystron (EIK)

Summary form only given. A compact, 94-GHz extended interaction klystron (EIK) amplifier has been developed and tested. A peak power of over 6.6 kW has been measured at the output flange of the device (in air), corresponding to over 8 kW at the output cavity aperture (in vacuum). The observed output is in excellent agreement with 3-D PIC simulations. The EIK is driven by a 19-21 kV, 3.5-4 A sheet beam in a permanent magnet solenoid, with 99% of the beam current transmitted through a 0.4 × 5 mm × 2.6-cm-long beam tunnel. The circuit consists of three identical 5-gap cavities that can be tuned individually. Tuning the buncher cavity allows gain to be traded for peak power. A sample drive curve is shown below. This amplifier demonstrates the significant increase in power that can be achieved at a given operating voltage by substituting a sheet beam for the pencil beam used in conventional vacuum electronic amplifiers. It also validates the use of solenoidal focusing for high-perveance sheet beams. High-peak-power testing and the potential for high-average-power operation will be discussed.