Abstract
In this paper, the mode selection, ohmic loss quality factor, mode competition, and beam–wave interaction of a 220 GHz coaxial-cavity gyrotron with two electron beams are studied by using the linear and nonlinear theories of a gyrotron. Research shows that a coaxial-cavity gyrotron with two electron beams has more advantages than a coaxial-cavity gyrotron with one electron beam in mode selection, suppressing mode competition and increasing output power, and the eigenvalue and the ohmic loss quality factor of modes have similar monotonicity in the direction of the gyrotron axis. Results find that (1) the current ratio K of the gyrotron has a greater influence on the beam–wave interaction efficiency of the two electron beams, (2) under B = 8.90 T, I = 136 A, α = 1.40, and K = 0.45, the coaxial-cavity gyrotron with two electron beams can operate steadily in the TE51,32− mode, which has an efficiency of 37.67% and an output power of 4.53 MW at f = 220.04 GHz, and (3) the total ohmic loss power of the gyrotron accounts for 1.3% of the output power.
Highlights
Megawatt-level gyrotrons operating at 110 GHz, 140 GHz, and 170 GHz are being developed, which are used in electron cyclotron resonance heating (ECRH), electron cyclotron current driving (ECCD), instability control, and diagnostics of magnetically confined plasmas in controlled thermonuclear fusion and the International Thermonuclear Experimental Reactor (ITER)
A megawatt-level 220 GHz coaxial-cavity gyrotron with two electron beams is investigated on mode selection, ohmic loss quality factor, mode competition, and beam–wave interaction by using the numerical method
Research found that the coaxial-cavity gyrotron with two electron beams has more advantages than the coaxial-cavity gyrotron with one electron beam in mode selection, suppressing mode competition and increasing output power, and the eigenvalue and the ohmic loss quality factor of modes have similar monotonicity in the direction of the gyrotron axis
Summary
The gyrotron, an important radiation source, has been extensively studied since its emergence. It has two developmental goals: to increase the radiated power and to shorten the wavelength. At present, megawatt-level gyrotrons operating at 110 GHz, 140 GHz, and 170 GHz are being developed, which are used in electron cyclotron resonance heating (ECRH), electron cyclotron current driving (ECCD), instability control, and diagnostics of magnetically confined plasmas in controlled thermonuclear fusion and the International Thermonuclear Experimental Reactor (ITER).. It is necessary to increase the cavity radius This leads to the gyrotron to operate in a higher-order mode. It was found that the gyrotron has advantages in suppressing mode competition and increasing output power On this basis, mode competition of a coaxial gyrotron with a double electron beam having unequal current is studied.. In order to further improve the output power, a 220 GHz coaxial-cavity gyrotron with two electron beams is researched through the paper, which is shown, where Figs. The paper is organized as follows: In Sec. II, equations of the starting current and multi-competition for a coaxial-cavity gyrotron with two electron beams are shown.
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