Demonstration of a 100-kW Solenoidally Focused Sheet Electron Beam for Millimeter-Wave Amplifiers

The design and development of a high-perveance sheet electron beam is reported. A beamstick that employs a novel sheet beam gun together with a permanent magnet solenoid has been fabricated and tested up to 4.8 A at 22 kV. At the nominal operating point of 19.5 kV and 3.3 A, this beamstick has transported 98.5% of the emitted electron current through a 0.4 × 5 mm beam tunnel over a distance of 20 mm in a uniform 8.5-kG field. The beamstick collector has been depressed to -9 kV with very little effect on the beam transport. The performance very well agrees with simulations. This beamstick will be the basis for a high-power (~10-kW) W-band extended-interaction-klystron amplifier that is currently under development.