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This paper reviews the current status of cathodes, highlights some recent advances in real world cathode performance and assesses promising thermionic cathode technologies and directions for future research in order to meet the needs of high frequency, high power, electron beam devices. Technical problems are identified that must be addressed to further advance cathode capability. Research approaches...
Devices operating at frequencies above 100GHz have been an area of intense development recently within both the solid-state and vacuum electronics worlds. This talk will discuss some of the recent results in both electronic domains and considers salient features of some applications which are creating an opportunity for vacuum electronics to once again be an enabling technology for extending the available...
The state of the art in medical and industrial microwave accelerators is reviewed, with attention to the microwave system, structure design, performance and reliability.
Vacuum electronics play a large and expanding role in communication and broadcasting networks. It is well known that TWTs are commonly used in satellite downlink transmitters because of their high efficiency and low weight. But vacuum electronics are also essential to many forms of earth-based communications. Uplink satellite stations use TWTs, EIKs, CCTWTs and Klystrons to provide communications...
Downlink amplifiers on geostationary communications satellites are required to operate in harsh environments for extended mission lifetimes (of up to 20 years) with a challenging combination of performance parameters and ultra-high reliability. TWTAs were the only option for systems designers nearly 50 years ago at the birth of the space age that were capable of providing the required power/frequency...
Northrop Grumman Corp. (NGC) has continued to develop a VE-based folded waveguide (FWG) technology as part of DARPA's terahertz imaging focal plane array technology (TIFT) source development program. The THz source consists of a thermionic electron gun, a FWG regenerative oscillator circuit, a depressed collector, and a 10 kG Nd-Fe-B permanent magnet solenoid to confine the electron beam. Significant...
The development of a selective metallization process capable of metallizing only the top of a microfabricated, raised meander line ridge is described. This fabrication process has unique potential in the development of millimetre-wave and terahertz regime slow wave structures for travelling wave tubes. The fabrication process will be described and the latest images and measured data will be presented.
Attenuators for W-band folded waveguide TWT have been successfully fabricated using BeO and Al2O3 respectively. And these samples could meet the strict dimension requirements based on former design after repetitious attempts. Test system of attenuator was developed to test them, and test results showed good performance that can meet the practical requirements in W-band folded waveguide TWT.
Applications of high frequency radiation, in the ranges of 30-300 GHz (millimeter-wave) and 300-1000 GHz (terahertz), require the development of specialized components, specifically low-loss waveguides and antennas. Conventional waveguide antennas must be flared in both lateral dimensions requiring a large space and are challenging to fabricate. Previous work has shown the promise of tapered dielectric...
We demonstrate a fully integrated, on-chip, vacuum microtriode capable of handling voltages up to 800 V. The ability to operate at such high voltages is achieved by the addition of a 10 mum-thick silicon dioxide layer to the device. The device is fabricated using MEMS fabrication principles and utilizes carbon nanotubes as field emitters. A dc amplification factor of 600 was obtained. To the best...
Electron cyclotron systems of fusion installations are based on powerful millimeter wave sources - gyrotrons, which are capable to produce now microwave power up to 1 MW in very long (hundreds seconds) pulses. The paper presents the latest achievements in development at IAP/GYCOM of MW power level gyrotrons for fusion installations (compare to [G.G. Denisov et al., 2007]). Main development efforts...
The development of a 2 MW, CW, 170 GHz coaxial cavity gyrotron at Forschungszentrum Karlsruhe (FZK) is in progress in cooperation with several European research institutions. The gyrotron is foreseen as a source for heating, current drive and stabilization of plasmas in the International Thermonuclear Experimental Reactor (ITER). Tests with a first industrial prototype started recently at CRPP Lausanne...
A 95 GHz, multi-megawatt continuous-wave (CW) gyrotron oscillator is currently under development at CPI. The gyrotron consists of a single-anode magnetron injection gun designed to operate at 75 A and 90 kV, a TE22,6 mode cylindrical interaction cavity, an internal mode converter to transform the TE22,6 mode to a Gausssian beam, an edge-cooled CVD diamond output window, and a single-stage depressed...
As part of an ongoing program to develop a high power mm-wave source for use on a mobile platform, CPI is developing two prototype gyrotrons designed to produce more than 2 MW of output power at a frequency of 95 GHz. The first prototype employs a cylindrical noncoaxial interaction circuit designed to operate in the TE22,6 mode, and is currently undergoing preliminary factory testing (discussed at...
We present results of modelling and details of fabrication of a pulse gyrotron to produce powers up to 10 kW peak and 10 W average at frequencies from 600 GHz to 2 THz. The gyrotron uses a pulse magnet that generates fields to 40 Tesla.
Results of Ukrainian researchers on development, emission properties investigations and applications of cathode materials based on LaB6, LaB6-MeIV-VIB2 and also impregnated and pressed oxide cathodes are presented.
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