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Extended interaction oscillator (EIO) operated in the terahertz range puts greater demand on current density and brightness of electron beam. The pseudospark-sourced (PS) electron beam is an attractive candidate to drive such high frequency EIOs. The study of a THz EIO driven by a PS sheet electron beam is presented. This enables the advantages of a interaction circuit combined with the merits of...
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...
Nowadays, the sensitivities of the ionization gauges with carbon nanotube (CNT) cathodes are generally low, which is unfavorable for the measurement of extremely high vacuum (XHV). In order to solve the problems, a spherical oscillator gauge with CNT cathode, which has high gauge sensitivity, is simulated using SIMION 8.0 and experimented preliminarily. The numerical simulation results show that the...
The findings of experimental investigations into and the field fests of the X-band cold, secondary — emission cathode magnetron referred to as “Buton” are presented. The primary — electron producing source in this system are the field emitters (FE). In addition to this, the data on 3-D simulation of the secondary-electron multiplication (SEM) process in this type of magnetron are given. The batch-produced...
Two types of thermionic cathodes were constructed to investigate the effect of thermal insulation gaps on the performance of a gyrotron. They were installed and tested in a 0.2-THz gyrotron, FU-CW-GIA. The simulation results have shown substantial deterioration in the electron beam quality and decreases in the output power in case of a cathode which has the thermal insulation gaps at the edge of the...
Design and operation principle of a diode oscillator with a field-emission cathode placed into a photonic-crystal (PC) cavity resonator are described. The PC resonator is composed by a defect in a 2D photonic-band-gap lattice of dielectric rods. Results of cold simulations of electromagnetic parameters of the PC cavity are presented. Output power and efficiency of the oscillator in millimeter and...
The paper presents the results of numerical simulation of a miniature dual bean monotron with three-gap resonator, made by technology of integrated circuits. Was studied the stability of this device to different oscillation modes. It is shown that when working on main mode output power of the device on the 2,2 GHz is in the range from 150 to 350 watts with the change cathode voltage from 2 to 3,5...
In this paper, we report on the development of a prototype of 500W Ka-Band Helix TWTs. Based on the length and frequency of start oscillation calculated, a phase velocity taper is designed to suppress backward-wave oscillation and improve electronic efficiency of the TWT. The testing results show that this device is capable to deliver more than 500W (pulsed) power with a gain of 39dB over a bandwidth...
Two types of compact, THz radiation sources are developed in An Hui Huadong Photoelectric Technology Institute recently. One is Oroton and the other is backward wave oscillator (BWO). This paper will give the main technical characteristics of these two THz sources.
This study focuses on the achieving wide tunabiltiy of a compact reflex triode virtual cathode oscillator (vircator). The cathode is of a bimodal carbon fiber (CF) material paired with a pyrolytic graphite anode. These materials where chosen for their operating characteristics which including but not limited to, long lifetime > 106 shots, high operating temperatures > 1000 K, and large current...
We suggest the novel vacuum microelectronic device that operates at subterahertz frequency range above 100 GHz with output power of 1W. It is based on the use of the overcritical electron beams with oscillating virtual cathode. In this work we discuss the results of numerical simulation and optimization of this novel compact vacuum device called as nanovircator. The results of the numerical studies...
Tungstate cathodes have been prepared by impregnating a mixture of the barium-strontium tungstate and zirconium hydride at 1840 °Cb. Emission characteristics and evaporation properties were tested. The result shows that the dc emission current density reaches 4.30A/cm2 at 1000 °Cb, 7.54A/cm2 at 1050 °Cb, 9.43A/cm2 at 1100 °Cb. The evaporation rate of the cathode is lower than an uncoated aluminate...
The design of 220GHz folded waveguide (FWG) backward-wave oscillator (BWO) is presented in this paper. A prototype tube has been fabricated successfully though technical study and the backward oscillation has been observed in the hot test. The signal of peak power 36mW, frequency 229GHz is achieved with beam voltage 17.5kV, collected current 12.2mA, transmission rate 77% and working duty 1/20.
In this study, we focused on the dc-rf efficiency and back-bombardment of a 2.45 GHz oven magnetron. We conducted 3D particle-in-cell (PIC) simulations for estimating the dc-rf efficiency and the back-bombardment quantitatively. The back-bombardment causes short lifetime by deteriorating the cathode. In addition, the increase of back-bombardment reduces dc-rf efficiency. We compared two types of filament...
This paper presents an optimization of a virtual cathode oscillator (Vircator) with axial extraction using a novel evolutionary algorithm (EA) thought to reduce the number of evaluations. The EA was tested on a Vircator optimization with two objective functions to maximize the radiated energy and to tune the resonance frequency at 5GHz. The simulations were made on CST Particle Studio. The EA was...
The study of the generation regimes with intense higher harmonics taking place in a high-power vircator [1] consisting of a relativistic electron beam (REB) with a virtual cathode (VC) has been made. The characteristics of these regimes, in particular, the typical spectra of output signal and their variations with the change of the system parameters (beam current, the induction of external magnetic...
Recently developed method of dynamic time-domain reflectometry (DTDR, [1]) provides a picosecond time reference of the emitted electron beam with a subnanosecond voltage front applied to the accelerating gap of magnetically insulated coaxial diode (MICD) which is widely applicable i relativistic backward wave oscillators (BWOs). Ou additional motivation of presented investigation is relate with DTDR...
First version of relativistic BWO with TM02 operating mode has been tested also in [1]. The cyclotron-resonance mode selection was used. In this case, because of requirement to the defined values of magnetic field and e-beam radius, the efficiency of oscillator was not very high (approximately 10%). Now, the different electrodynamic codes are available to optimize the geometry of Slow Wave Structure...
The pseudospark discharge is a form of low-pressure gas discharge capable of generating extremely high currents with short rise times by means of a unique hollow cathode structure [1-6]. A high-quality electron beam is generated during the later phases of the discharge process, which possesses high current density and brightness, as well as the ability to self-focus via ion channel focusing. This...
Velvet is widely used in magnetically insulated transmission line oscillator (MILO) as emission material of cathode. However, short lifetime (usually less than 50 shorts) and large outgassing rate of velvet make it difficult to be applied in repetitively operated MILO. To find a substitution of velvet for higher performance or repetitive operation of MILO, metal array cathode is applied. This paper...
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