Search results for "Gyrotron"
showing 10 items of 38 documents
Study of Mode Competition in the Third Harmonic Gyrotron with Inclusion of the Electron Velocity Spread and the Beam Width
2018
Influence of the electron velocity spread and the beam width on the mode competition and efficiency is investigated in the 1.185- THz third harmonic gyrotron to be used in dynamical nuclear polarization - nuclear magnetic resonance (DNP-NMR) spectrometer.
Optimization of Gyrotron Resonator’s Dimensions
2021
This paper explains the procedure of determining the initial dimensions of a gyrotron resonator. In particular, the paper discusses which geometrical parameters impact the wave properties of the resonator. The solution is implemented using Matlab software and estimations are performed with the use of the SMath Studio spreadsheet. © 2021 National Institute of Telecommunications. All rights reserved.
Gyrotron interaction simulations with tapered magnetostatic field
2010
We investigate the interaction of the electron beam with the RF wave in a gyrotron, in the presence of an axially tapered magnetic field. The simulation results of three interaction codes are compared and the different modelings are discussed.
Possible gyrotron operation in the “no start current” zone caused by the axial dependence of the phase of the resonator field
2018
It is known that gyrotrons (as well as other electron beam driven microwave and millimeter-wave oscillators) can operate in the regime of either soft or hard self-excitation. In the regime of soft self-excitation, the beam current exceeds its starting value; thus, the oscillations can start to grow from the noise produced by electrons. In the regime of hard self-excitation, the beam current is less than its starting value. Therefore, for exciting the oscillations, a certain start-up scenario is required, which may include the variation of the mod-anode and/or beam voltage or the guiding magnetic field. It was found recently [O. Dumbrajs and G. S. Nusinovich, Phys. Plasmas 25, 013121 (2018)]…
Zones of soft and hard self-excitation in gyrotrons: Generalized approach
2020
It is known that the gyrotron theory is developed in a general form that allows one to draw many important conclusions about gyrotron operation, which are valid for gyrotrons operating in arbitrary modes, at arbitrary frequencies, and driven by electron beams with different voltages and currents. One of important issues in this theory is the analysis of possible start-up scenarios, i.e., the methods allowing, first, to excite the desired mode prior to competitors in the region of soft self-excitation of this mode and, then, drive it into the zone of hard self-excitation where, as a rule, the operation with high efficiency is possible. So far, in all studies, these zones of soft and hard sel…
Neutron generator for BNCT based on high current ECR ion source with gyrotron plasma heating
2015
BNCT development nowadays is constrained by a progress in neutron sources design. Creation of a cheap and compact intense neutron source would significantly simplify trial treatments avoiding use of expensive and complicated nuclear reactors and accelerators. D-D or D-T neutron generator is one of alternative types of such sources for. A so-called high current quasi-gasdynamic ECR ion source with plasma heating by millimeter wave gyrotron radiation is suggested to be used in a scheme of D-D neutron generator in the present work. Ion source of that type was developed in the Institute of Applied Physics of Russian Academy of Sciences (Nizhny Novgorod, Russia). It can produce deuteron ion beam…
Gyrotron-driven high current ECR ion source for boron-neutron capture therapy neutron generator
2014
Abstract Boron-neutron capture therapy (BNCT) is a perspective treatment method for radiation resistant tumors. Unfortunately its development is strongly held back by a several physical and medical problems. Neutron sources for BNCT currently are limited to nuclear reactors and accelerators. For wide spread of BNCT investigations more compact and cheap neutron source would be much more preferable. In present paper an approach for compact D–D neutron generator creation based on a high current ECR ion source is suggested. Results on dense proton beams production are presented. A possibility of ion beams formation with current density up to 600 mA/cm 2 is demonstrated. Estimations based on obt…
Effect of the tilt on the gyrotron operation
2013
The effect of the tilt of the electron beam axis on the gyrotron operation is investigated. It is commonly accepted that the tilt deteriorates the efficiency of cylindrical cavity gyrotrons. Our study showed that this deterioration can be mitigated by a proper displacement of the electron beam axis at the entrance. Also, in some cases, when the aftercavity interaction lowers the gyrotron efficiency, the tilt can reduce this interaction and, therefore, slightly increase the efficiency.
Influence of possible reflections on the operation of European ITER gyrotrons
2010
The theory describing the influence of reflection s on operation of gyrotrons with radial output is used for evaluating the effect of reflections on the operation of the ITER 170 GHz 2 MW coaxial cavity gyrotron, which is under development, and the 170 GHz 1 MW cylindrical cavity gyrotron as a fall back solution.
Gyrotron Operation in the ‘No-Start-Current’ Zone
2018
It is conventionally assumed that the gyrotrons can operate either in the regime of soft self-excitation, where the beam current exceeds the start current, or in the regime of hard excitation, where the beam current is lower than the start current. The authors have found one more possibility of gyrotron operation: in the region where there is no start current at all. Although it is not clear whether this region represents a special interest for gyrotron operation, it can be useful to learn that such opportunity may exist and can be used for interpreting some experimental results.