The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
A second-harmonic frequency step-tuning gyrotron is under development. The oscillation frequencies are separated by approximately 15-GHz steps in a range from 270 to 420-GHz. The operation modes were selected to convert into Gaussian like radiations by one internal mode converter. A triode electron gun was designed in order to operate in a wide range of magnetic fields. The oscillation tests were...
Novel schemes of powerful multichannel planar FEMs was developed based on two parallel sheet beams 0.8 MeV / 1 kA forming by the accelerator ELMI. In 75 GHz frequency band two-channel planar FEM operating with two-dimensional distributed feedback was elaborated. For record transverse size of interaction space (up to 45 × 2.5 wavelengths) synchronization of emission from both electron beams and realization...
Previously negative differential conductivity caused by Bloch oscillations of electrons was demonstrated in SiC natural superlattice for bipolar n++ — π — n+ structures at T=300 K. Here we investigate THz emission and electrical characteristics of the similar structures at 7 K and show common nature of both phenomena (the THz emission and the negative differential conductivity) caused by the Bloch...
Ka-band surface wave oscillator of a cylindrical geometry driven by tubular electron beam 300 keV / 100 A / 3 μs has been realized. Narrow-band regime of oscillations in strongly oversized system (perimeter-to-wavelength ratio is about 16) was achieved using periodical structure with two-dimensional corrugation. Output power of 1.5–2 MW level was obtained. High stability of the oscillation frequency...
Oscillation of 1MW at quad-frequency 203GHz, 170 GHz, 137GHz and 104GHz were demonstrated with a high-order mode (TE31,11) gyrotron developed for ITER. The final design of the ITER equatorial launcher has being implemented. The RF prototype testing to validate the millimeter wave design of the launcher were carried out and the results confirmed the steering range and quality of mm-wave beam and in-directly...
The paper describes recent results of theoretical and experimental studies of powerful relativistic masers based on linac LIU-3000. The key components of the oscillators are advanced Bragg resonators based on coupling of propagating and quasi-cutoff waves that possess high selectivity over transverse coordinates and allows establishment of narrow-band operating regime in strongly oversized system...
[100]-tilt YBa2Cu3O7−x bicrystal Josephson junctions with the resistances Rn from 0.4 up to 400 Ohm have been fabricated and studied with Josephson admittance spectroscopy. In these junctions intrinsic ac shunting has been found, that is characterized by broadband admittance Y1 of the order of Rn−1 and low-level resonant contributions with the admittances ReY2(fk) of two signs. Two different types...
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...
A W-band backward wave oscillator (BWO) based on metamaterial (MTM) slow wave structure (SWS) is presented as a novel high power microwave generator. Particle-in-cell (PIC) simulation is performed to evaluate the efficiency of the W-band MTM-based BWO (MTMBWO), and the MTMBWO can reach saturated output power of 2.78MW with an electronic efficiency of 31.68% at frequency of 84.87GHz.
Development of resonant-tunnelling diodes (RTDs) and THz RTD oscillators in the recent years is described. Strategies and concepts to increase their operating frequencies are pointed out, different types of fundamental RTD oscillators outlined. Novel concepts of THz RTD oscillators are indicated.
We propose a leaky-wave antenna (LWA) driven by a resonant-tunneling diode (RTD) oscillator with an aim to reduce the size of terahertz radar system. In the proposed structure, RTD provides oscillation at 675 GHz, and the antenna is with a directivity of 19 dBi and a beamwidth of 4-degrees. Theoretical calculation estimates the output power of 60 μW. The approach will pave a way for integrated terahertz...
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...
We demonstrate a novel approach to the problem of THz emission and detection by quantum Faraday effect that manifests itself in conductance of topological edge channels of silicon nanosandwich-structures.
This paper describes general considerations for the design of highly efficient and distributed room-temperature Terahertz detectors and transmitters in (Bi)CMOS technologies. It discusses the design of industrial-grade scalable terahertz imaging systems. This necessitates a deep understanding of the process technologies front-end and the back-end, as well employing innovative architectures of terahertz...
The possibility of generation of high-power (multi-megawatt) broadband terahertz radiation during stimulated backscattering of an intense millimeter-wavelength pump wave by a high-current reletivistic electron beam (REB) is shown. With allowance for a significant parameter spread that is typical for high-current REBs, the kinetic interaction regime is expedient, This regime leads to the broadening...
Frequency tunability in multi frequency bands was experimentally demonstrated in Gyrotron FU CW XA. Frequency tunable modes were searched for with measurement of the radiation pattern outside the vacuum window of the gyrotron with no mode converter. The frequency variation is due to the gyro-BWO mechanism and the same radiation pattern is kept within a finite range of the magnetic field for each oscillation...
A 300 GHz pulse gyrotron has been developed for collective Thomson scattering diagnostics in the Large Helical Device with a careful design consideration. Single-mode oscillation of more than 320 kW was attained. The frequency spectrum was very narrow and stable across the pulse width up to 80 μs. No parasitic mode was observed during the whole pulse width including the turn-on and turn-off phases...
We achieved frequency increase in resonant tunneling diode terahertz oscillator by reducing conduction loss in the slot antenna with thick antenna electrode. By a graded increase in electrode thickness for 0.1, 1, 2, and 3 μm, increase in oscillation frequency was obtained. A highest oscillation frequency of 1.98 THz was achieved with an optimum electrode thickness of 2 μm.
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.