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This paper presents the theory and design of a novel, low-power, compact, room-temperature, tunable, solid state THz source of Smith-Purcell radiation. The design comprises a Transferred Electron Device and a metal transmission grating separated by a high-K dielectric. When a sufficiently high electric field is applied across the cathode and anode of the device, space-charge regions (also known as...
This paper described the 3D simulation method and results of electron gun and beam transport for the 0.14THz TWT with the help of CST. The hot test results show that the design of the electron beam optics system satisfied the need of the TWT. It bases the manufacture of the 0.14THz travelling wave tube.
This paper presents the results of experimental testing of diode electron guns with sheet and multiple electron beams based on thermionic minicathodes for TWT of terahertz frequency range. The results of study in pulse mode of impregnated thermionic blade cathode with linear dimensions 0.1×0.7 mm with a current density of 114 A/cm2 are presented. A version of the five-beam electron gun is proposed...
A 0.670 THz Power Module based on a vacuum electronic (VE) power amplifier and a solid-state power amplifier (SSPA) has produced >100 mW, operating from 0.640–0.685 THz in a bread-board demonstration. The driver amplifier is a power-combined, MMIC SSPA module based on InP HEMT technology. The compact VE power amplifier is based on a DRIE-fabricated folded waveguide slow-wave circuit, together with...
A 220 GHz vacuum electronic (VE) power amplifier has been designed and is being tested as part of the DARPA HiFIVE program. Minimum power goal is 50 watts at 220 GHz. This amplifier uses advanced, high current density cathodes, a folded waveguide slow-wave circuit, and a depressed collector for improved overall device efficiency. Operation at duty cycles of 50–100% is anticipated.
Experimental testing of electron beam formation, transport, and depressed collection is performed in a beamstick for a 670 GHz extended interaction klystron with a 25 kV, 100 mA nominal operating point. Beam transmissions of 77–86% are achieved through a 125 micron diameter by 1.7 cm long beam tunnel.
The development of terahertz power amplifiers presents significant new challenges as it brings into focus design, fabrication, and measurement issues that are not important factors at lower frequencies. In this paper, we describe our design approach to meet these challenges with particular emphasis on a 0.67 THz Extended-Interaction Klystron (EIK). This device is being designed to generate a peak...
High power terahertz (THz) sources and amplifiers hold the potential to greatly improve remote sensing and high bandwidth communication. To enable these applications, a Traveling Wave Tube (TWT) operating at 0.22 THz and a multi-cathode Field Emission (FE) electron gun are developed and characterized using a Particle-in-Cell simulation. Three candidate high current density cathode materials, Halfnium...
Vacuum electronic (VE) power amplifiers are being developed between 100 GHz and 1 THz. Minimum power goals are 50 watts at 220 GHz, and 100 mW at 670 GHz. These devices will use advanced, high current density cathodes, a folded waveguide as the slow-wave circuit, and a depressed collector for overall device efficiency. Operation at duty cycles of 50-100% is anticipated.
The two major components, sheet beam electron gun and interaction circuit, consisting the 0.5 THz Smith-Purcell device under development are being investigated in separate diagnosis systems. The thermionic cathode showed the required emission current density of 50 A/cm2 and assembled into the electron gun. The interaction circuit fabricated by laser machining is being investigated using the precise...
Generation of a sheet beam directly from a scandia-doped dispenser cathode has been investigated and optimized by means of beam-profile simulations and measurements. Rectangular beams 600 mum wide and 100 mum thick with current densities over 50 A/cm2 have been generated. The beams are stable for at least several hundred hours with the cathodes operating at 950degCb, making them promising candidates...
The development of high current density sheet beam electron gun for Terahertz devices is carried-out. It operates at beam voltage of 12 kV and perveance 0.0136 mup to meet ours requirement of high beam current density 100 A/cm2 and low emittance 0.068 pi-mm-mrad at the beam-waist position. Currently, mentioned gun is being fabricated. Work has been initiated to test the performance of Scandate cathode...
A design study of a 0.1-THz coupled-cavity backward-wave oscillator (CCBWO) is presented using a finite element method and a particle-in-cell simulation. In experiments, the Si-based technology of 2-step deep reactive ion etching (DRIE) and eutectic bonding shows a good potential for the microfabrication of the interaction circuit. A miniaturized field emission cathode using carbon nanotubes grown...
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