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Experimentally characterizing actual micron sized sheet beams is essential to the development of terahertz sheet beam guns and devices. We have tested a terahertz sheet beam gun and produced 3D electron beam density plots. The terahertz sheet beam analyzer was designed to automatically collect high resolution scan data using LabVIEW software. The collected data were plotted to show the electron current density profile and size of the sheet beam.

An extremely high efficient cathode modulator utilizing an energy recovery concept for non-gridded tubes is proposed. Long rise- and fall-times of conventional line-type modulators are greatly reduced through the use of high speed MOSFET switches which efficiently recirculate cathode capacitance energy between pulses. This paper presents the overall design concept, and provides both PSPICE simulation and experimental results of a proof-of-principle demonstration modulator using single device (∼1 kV) MOSFET switches.

S c2 O 3 -doped W powder for use in high current density thermionic cathodes has been made by the sol-gel method with different particle sizes. S c2 O 3 -W matrix cathodes have been prepared from these powders, and have shown excellent emission properties. A space charge limited current density of 80 A/cm2 at 1150°C, 50 A/cm2 at 1050°C have been obtained by using 500 nm Sc 2 O 3 -doped W powders. Life testing is ongoing with a continuously pulsed loading of 50 A/cm2 at 1050°C after 5448 hours. The maximum current density of the cathode made from 1–2 micro size S c2 O 3 -doped W powder can reach 106 A/cm2 at 1150°C.

In this paper we report on a development program aimed at producing a travelling wave tube amplifier with significant gain and power at 220 GHz in a compact and lightweight package. This paper provides an overview of the program, describing development of nanoparticle scandate cathodes with current densities exceeding 100 A/cm2, MEMS fabrication and test of mm-wave waveguides and slow-wave structures with bandwidths exceeding 50 GHz centered at 220 GHz, and the production of a sheet electron beam with a current density exceeding 230 A/cm2 and an aspect ratio of 26∶1. These components may allow us to produce a 220 GHz, 50W high power amplifier with a hot bandwidth of > 20 GHz and a power-bandwidth product > 1000 W-GHz.