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The Orotron is a device which is capable of producing moderate (few watts) to high power levels (few kilowatts) of millimeter and sub-millimeter wavelength radiation in the frequency range from GHz to Terahertz. It consists of an open resonator containing rectangular metal grating periodic RF structure and a sheet electron beam. In this paper, 100 GHz RF interaction structure for Orotron has been...
A low-loss polymer tube which can trap a large part of mode power inside the air core is proposed and experimentally demonstrated for Terahertz wave guiding. Simulation results also show that an elliptical polymer tube can be used as a highly birefringent low-loss Terahertz waveguide.
Amplification studies of a Ka-band harmonic multiplying gyrotron traveling wave tube are reported. Coupled cavity and the precise control of focusing magnet field were used to improve the coupling between the fundamental and the harmonic and to adapt the sensitivity of the effect of focusing magnet field on the beam-wave interaction in the tube with a high order mode operation. Some experimental phenomena...
To cover a so-called terahertz gap in available sources of coherent electromagnetic radiation, the gyrotron with a pulsed solenoid producing up to 50 T magnetic field has been designed, manufactured and tested. At 38.5 T magnetic field, the gyrotron generated coherent radiation at 1.022 THz frequency with pulse duration about 50 microseconds. The microwave power and energy per pulse were about 5.3...
Results of elaboration of continuous-wave 258.6 GHz gyrotron with output power about 100 W with high stability of output parameters is presented. This paper includes results of calculation, design, experiments and technical requirements for main subsystems of gyrotron and auxiliaries. The gyrotron setup is a main part of a complex experimental system for NDP spectroscopy.
A possibility of the frequency doubling inside the orotron cavity is experimentally demonstrated at the frequency of 190 GHz. The excitation of the surface mode allows a significant reducing the operating current of the orotron mode that is important in the terahertz frequency range.
A few years ago the author had the opportunity to cochair a government review on the state of compact THz source technology. As a point of reference, THz was defined in the study as covering the classical sub-millimeter frequency band (from 300 GHz to 3 THz). Compact coherent radiation devices, with average powers in roughly the 100 μW to 1 W range, in the laser, optoelectronic, solid state, and vacuum...
In the recent decade there has been a growing interest of the researchers all over the world in the design and development of the high frequency (in terahertz range), moderate power and efficient devices based on MEMS (semiconductor) and vacuum electronics technologies. Development of so-called vacuum microelectronic devices (VMDs) for the mm and sub-mm wave devices surmount the limitations of conventional...
The mathematical model of folded waveguide TWT is described. Features of frequency characteristics formation of a TWT in the range of frequencies 600-3000 GHz are noted. Influence of various TWT parametres changing on formation of frequency characteristics is investigated.
Results of investigations of one, two and three section TWT on wavelike bent rectangular waveguides are presented. It is shown, that gain of multisection TWTs might reach 30-60 dB. The analysis of physical processes in such TWTs was carried out; type of a mode of self-excitation was defined. It was observed that gain band depended on the length of drift tubes. Electronic returning of gain band is...
With the fast development of Terahertz (THz) related technologies, more and more applications, such as high bandwidth communications, radar, and secure detection, which require higher power, more reliable THz radiation sources. There are different approaches to generate THz radiation. In this paper, we mainly focus on the vacuum electronic technology, which has the potential to provide a sufficient...
Three-cavity 225 GHz fourth harmonic gyroklystron with successive frequency-doubling in each cavity is presented and analyzed with linear and nonlinear theories. The input coupler for the TE11 mode was designed and simulated with CST code. Starting currents and nonlinear wave-beam interactions were calculated with linear and self-consistent nonlinear theories. When the 225 GHz fourth harmonic gyroklystron...
A novel high power sub-terahertz gyrotron operating at second harmonic resonance was designed. This gyrotron is intended for use as a probe beam source for collective Thomson scattering diagnostics in nuclear fusion plasma research. The resonant cavity mode, cavity radius, and its length were optimized from various aspects such as resonant frequency, coupling between the electron beam and the RF-electric...
High power THz radiation sources - gyrotrons are being applied to high power THz technologies including enhancement of NMR sensitivity by a dynamic nuclear polarization, direct measurement of hyperfine structure of positronium, X-ray detected magnetic resonance measurement, sub-THz ESR echo spectroscopy and new medical technology. In this paper, such applications of THz gyrotrons are presented.
We have developed the Gyrotron FU CW VII for 300 MHz and 600 MHz DNP-NMR spectroscopy. For high frequency DNP-NMR experiment, high power sub-THz radiation sources are required. Gyrotron is able to emit enough power and appropriate frequency in sub-THz region for DNP. This Gyrotron emits electromagnetic waves with high power and appropriate frequency for each DNP-NMR spectroscopy (used cavity modes...
Summary form only given: Dynamic nuclear polarization (DNP) can be used to increase the sensitivity of nuclear magnetic resonance (NMR) experiments by transferring the much higher polarization of unpaired electrons spins to nuclear spins. The polarization transfer is driven by high frequency millimeter wave irradiation. Communications and power industries is an original equipment manufacturer of gyrotron...
Summary form only given: Terahertz gyrotrons are not wide-spread yet because of the strong magnetic field required when operating at fundamental and second cyclotron harmonics, and severe mode competition when operating at higher harmonics. These problems can be significantly mitigated in the large orbit gyrotron (LOG), where all the electrons describe helical trajectories with the axes coinciding...
We report detailed simulations of a two-stream instability using co-propagating electron beams of differing energies By adjusting parameters such as beam currents and the energy difference, a remarkable amount of self-modulation occurs at controllable and predictable frequencies. The typical frequencies of oscillation traverse the sub-millimeter and terahertz range, and the power associated with the...
The frequency of radiation higher than 1 THz has been recently demonstrated in pulse gyrotrons. The output power P = 1,6 kW at 1 THz and 0.5 kW at 1,3 THz has been obtained at the fundamental harmonic. Gyrotrons demonstrate single-mode operation with a frequency of 1 THz in the long pulse (1 ms) operation regime at the 2nd cyclotron harmonic (P~100 W) and at the 3rd harmonic (P = 0,4 kW).
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