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The introduction of advanced Multistage Depressed Collectors (MDC) to high-power fusion gyrotrons will be the key to increase the gyrotron overall efficiency above 60 % as required for future DEMOnstration power plant. MDCs which base on the E×B drift concept might solve the fundamental issue of handling the secondary electrons. To consider the effect of secondary electrons in a stationary state,...
Karlsruhe Institute of Technology (KIT) is doing research and development in the field of high power gyrotrons for W7-X, ITER, and, towards a future DEMOnstration fusion power plant. While the initial installation of the ECRH system at W7-X is finished and operating very successfully, KIT is still involved in the development of gyrotrons for ITER. This work is coordinated by F4E and ongoing in frame...
The recently revealed special Smith-Purcell radiation (S-SPR) is quite attractive since it has better monochromaticity and higher intensity in comparison with the ordinary SmithPurcell radiation. It offers effective ways of generating terahertz radiations. Based on the S-SPR mechanism, we proposed and investigated a series of terahertz sources. They substantially enhanced the operation frequency and...
A possibility of gyrotron operation at a very low voltage, 1.5–2 kV, is considered in the context of dynamic nuclear polarization (DNP) application. Simulations predict that a low-voltage device has some specific but useful features like efficiency operation at high axial modes and capability of wide-band frequency tuning.
Recent progress of QST high power high frequency gyrotrons is reported. Main motivation of the high power gyrotron is the application to the plasma heating and current drive and control of the magnetic confinement fusion devices. Using a multi-frequency operation, 1 MW Gaussian beam output was obtained at four frequencies; 203 GHz (TE37,13), 170 GHz (TE31,11), 137 GHz (TE25,9), 104 GHz (TE19,7). In...
To meet demands of DNP, sub-mm-wave radar and other THz frequency markets, CPI Canada continues the performance improvements of CW and pulsed compact EIKs. The novel model of a 266 GHz oscillator generates up to 15 W of CW power, while the expected power of a 264 GHz pulsed amplifier currently in fabrication is 50 W. Together with power enhancements, major attention is paid to reliability, lifetime...
Here we report in the development of the first room-temperature broadband local oscillator source in the 4.7 THz range to enable galactic and extra galactic observations of atomic oxygen. All the multiplication stages up to 1.6 THz have been fabricated and assembled and are currently under test. A world record output power of 550 mW in the 190 GHz range has been measured and provides enough power...
This article presents the investigation of millimeter wave extended interaction oscillation using both pencil and sheet-shaped pseudospark (PS)-sourced electron beams. A W-band (75–110 GHz) pencil beam extended interaction oscillator (EIO) was designed and constructed. In the first experiment the output power of 38 W was achieved from a four-gap PS discharge operating at 30.5 kV. PS-sourced beam generation...
A 0.13THz 6W folded waveguide oscillator (FWO) is experimentally investigated for compact high-power terahertz radiation source. Because of absolute instability near the band edges, the tube may fall into oscillation when the beam current is sufficiently high. The output characteristics of oscillator is examined by using simulation code. The prototype tube has been fabricated and tested. The experimental...
A 0.38THz Traveling Wave Tube (TWT) based on the sine waveguide and sheet beam tunnel is proposed to amplify the terahertz wave. In this paper, the high frequency characteristics of sine waveguide with sheet beam tunnel are calculated by 3-D high frequency simulation software. From the particle-in-cell simulation results, this beam-wave interaction can produce output power 13W at 0.38THz, and the...
In this paper, we present the preliminary results of an ongoing experimental study of a novel double-beam gyrotron, which has been designed to operate in CW regime on the second harmonic of the cyclotron resonance with a frequency of 0.79 THz. A number of fundamental and second harmonic modes can be excited in the frequency range 0.3–0.8 THz. The observed output power levels of the order of several...
Gyrotron tests were recently carried out on CPI gyrotrons at frequencies of 117.5 GHz and 140 GHz. At 117.5 GHz, output power levels of 1.67 MW were obtained under short-pulse conditions and long-pulse tests with pulse durations of 1–10 s have been performed with power levels up to 700 kW. Further long-pulse testing to higher power levels will be carried out after shipment of the gyrotron to General...
A G-band rectangular beam multi-gap Extended Interaction Klystron (EIK) with unequal-length gaps is proposed. The high-frequency features indicates that the designed model has wide frequency intervals with π mode, which has a good uniformity in field distribution with the maximum (R/Q)•M2. The PIC simulation shows a stable output power of 1378 W without oscillation in 218.9 GHz, with the efficiency...
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