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The design of a 340GHz two-beam folded waveguide (FW) traveling-wave amplifier with >4 W of power over with the input power of 20mW is presented. The amplifier is driven by two electron guns (70mA×2, 14.9kV) and 1T magnetic field. The design is performed by CST Particle Studio. Particle-in-cell (PIC) simulations were carried out to predict and optimize the performance of the folded waveguide TWT.
Paper presents the experimental results on temporal dynamics of spectra of high power 4-mm radiation generated by a two-channel planar free electron maser with two-dimensional distributed feedback.
In an effort to develop compact millimeter and THz wave radiation power sources, two types of traveling wave amplification concept with multi-beam have been studied using Pierce small signal analysis and particle-in-cell (PIC) simulation. Our prior work includes theoretical and numerical assessment on performance of the aluminum-nitride (AlN)-loaded multi-beam structure, indicating that the TM31-mode...
Using the simple unified theory, the beam-wave interactions are analyzed in high-power Cerenkov-type microwave generators composed of periodic metal slow-wave structure (SWS) with a magnetized plasma column.
A short pulse gyrotron was designed, fabricated and tested for 300 GHz oscillation. The oscillation mode is TE32, 18 and its neighborhoods and the power is output from the top of the gyrotron. The superconducting magnet has 110 mm room temperature bore diameter, and the maximum magnetic field is 13 T. In the preliminary experiment, the 300 kW power was obtained at ∼300 GHz.
The design of a high power gyroklystron amplifier operating with circular TE011 cavity modes is presented. The amplifier will be driven by a 70-kV, 6-A electron beam with a pitch angle (vt/vz) of 1.4 and velocity spread of 2.4% generated by a double-anode magnetron injection gun (MIG). The amplifier is predicted by particle-in-cell simulation to generated 145 kW at 94.1GHz with 35% efficiency, 38-dB...
A gyrotron traveling wave amplifier (gyro-TWA) with a cusp electron gun and a helically corrugated waveguide operating in the W-band is presented. When driven by an electron beam of energy 40 keV and current 1.5 A, the simulated microwave output power is 5 kW (CW) with a 3 dB frequency bandwidth of 90–100 GHz and a saturated gain of 37 dB. Linear analyses, numerical simulation and the latest experimental...
The Facility for Accelerator science and Experimental Tests (FACET) at SLAC National Accelerator Laboratory provides a 23-GeV high charge, sub-picosecond bunched electron beam that is ideal for pulsed THz light generation in the few-THz range. Pulsed THz lights based on coherent transition radiation have been demonstrated at FACET, with high peak electric field and high pulse energy. The intense TeraWatt...
Scattered x-rays were utilized for determination of the electron energy distributions at a gyrotron collector. Performed calculations and experiments demonstrated that scattering in the diagnostic window has only minor effect on the radiation spectra in the gyrotron-relevant conditions. The primary advantage of the proposed diagnostic scheme consists in reduction of the density of treated x-rays flux...
Nonlinear simulations show that compared to an axial guide magnetic field, the ion-channel guide field has the advantageous properties in confining the electron motion and stability, resulting in smaller velocity spread and configuration spread of the electrons. The intrinsic factor of this physical phenomenon is that the ion-channel guide field provides the electron motion a smaller Larmor radius...
In this paper, with the help of a two-dimensional (2D) particle-in-cell (PIC) code, a simulation of Smith-Purcell (SP) radiation from the dielectric loaded grating is performed in the terahertz regime. The results show that the SP radiation frequency is in good agreement with the theoretical curve. Comparing with the general grating, the usage of dielectric loaded grating enhances the evanescent wave,...
Results of the continued work on 1.5–1.7 MW CW gyrotron development are presented. Last year 1.5-MW power was attained at 92 kV beam voltage and 52 A beam current. This year the gyrotron with modernized electron-optical system was tested yielding up to 1.5-MW power at 72–77 kV beam voltage and 64–70 A beam current.
The development of the modular short-pulse pre-prototype as base for the 2 MW, 170 GHz, CW coaxial-cavity gyrotron for ITER upgrade and beyond is in progress at Karlsruhe Institute of Technology (KIT). The current modular pre-prototype configuration allows the generation of >2 MW RF output power in short-pulses with a reasonable electronic efficiency of approximately 30 % without depressed collector...
The extended interaction oscillator (EIO) is regarded as a novel type of high power terahertz (THz) source, which has promising application prospects in radar, medical imaging etc. Up to now, CPI and other institutes have developed many types of EIO. For satisfying with the application request, the EIO with operation frequency exceeding 300GHz is designed and studied with three-dimensional particle-in-cell...
Structures based on a periodic surface lattice (PSL) of planar geometry have been studied. It is shown that volume and surface fields can couple to form a cavity eigenmode, demonstrating the potential for novel mm-wave sources when combined in appropriate configurations with an electron beam.
For the development of Electron Optics System (EOS) for Extended Interaction Amplifier (EIA) at frequency of 330GHz, the parameters of EOS are studied with a help of EGUN and Superfish. The design of EOS and permanent magnetic field for EIA has been conducted. The simulation results show that electron beam has highly pass rate, low ripple and good laminarity.
Increase of the saturation power may be approached by means of the parameter adjustment even in a uniform wiggler configuration, which is comparable to the enhancement by using a tapered wiggler. Instead of the beam-wave interaction being lengthened by the use of a wiggler taper, a substantial saturation length may be shortened by virtue of the parameter adjustment.
The effect of cathode emission nonuniformities on electron beam quality in gyrotrons and a method for suppressing this effect by optimization of the electric field distribution in the gun region are studied experimentally and using computer modelling.
This study is aimed at development of a moderate power sheet-beam traveling wave tube (TWT) amplifier with grating slow-wave structure (SWS). A fast and accurate code for calculation of eigenwaves in the grating SWS is developed, and results of numerical modeling of a G-band TWT are presented. Electron gun producing an intensive sheet electron beam is developed. Beam focusing and transportation is...
Numerical FDTD and PiC simulations demonstrate the successful electron wave interaction in a Cherenkov maser utilizing a cylindrical 2D PSL as a mode selective cavity. Optimization of this structure's physical properties results in the design of a cavity with 16 longitudinal periods of 1.6 mm length, 7 azimuthal variations and an unperturbed inner radius of 4 mm. In numerical simulations this design...
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