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Nagasaki, K.; Itoh, Yasuyuki; Morioka, Hiroshi; Obiki, T.

doi:10.1023/a:1021766016121

Cited by 23 publications

(9 citation statements)

References 13 publications

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“…The angle between the wave vector and the magnetic field at the magnetic axis, for example, is θ = 64 deg in vacuum, corresponding to the parallel refractive index of N || = 0.44. The polarization of injected waves is controlled by a polarizer assembled on a miter bend in the HE 11 mode transmission line [4]. A power monitor with two multi-hole arrays, which works as directional couplers, is installed on the miter bend, detecting two orthogonal polarized waves transmitting through plasmas simultaneously.…”

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confidence: 99%

Measurement of Single Pass Electron Cyclotron (EC) Absorption Using Transmitted Waves in Heliotron J

Nagasaki

Tsuji

Nosaku

et al. 2007

Plasma and Fusion Research

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Single pass absorption of second-harmonic EC waves propagating obliquely to the magnetic field has been studied in Heliotron J. Two orthogonal signals of transmitted high power EC waves are measured to estimate the single pass absorption rate. The experimental results agree well with ray tracing calculation results based on a linear absorption theory under the condition that the refraction effect is not strong, n e /n c < 0.3 (n c is a cutoff density of second-harmonic X-mode), that is, the waves reach the diagnostic port.

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mentioning

confidence: 99%

Measurement of Single Pass Electron Cyclotron (EC) Absorption Using Transmitted Waves in Heliotron J

Nagasaki

Tsuji

Nosaku

et al. 2007

Plasma and Fusion Research

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“…In the actual PMB, wavy grooves are carved in the reflector plate. 14,15) To realize wavy grooves in the numerical simulation, the numerical region must be subdivided into small meshes, and huge memory and calculation cost are required. Thus, we assume that rectangular grooves are carved in the reflector plate in order to realize PMB.…”

Section: Analysis Model and Simulation Methodsmentioning

confidence: 99%

Finite-difference time-domain analysis of electromagnetic wave propagation in corrugated waveguide: Effect of miter bend/polarizer miter bend

Fujita

Ikuno

Kubo

et al. 2015

Jpn. J. Appl. Phys.

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The effect of the polarizer miter bend (PMB) reflector on polarization is numerically investigated by using the finite-difference time-domain (FDTD) method. The Drude model is implemented to take into account the fact that the waveguide wall is prepared from a dispersive medium. In electron cyclotron resonance heating (ECRH), the corrugated waveguide and miter bend are adopted for transmitting millimeter electromagnetic waves. In addition, PMB is employed to improve the plasma heating efficiency. The results of computations show that modes other than the input mode are also generated owing to the reflection at the miter bend mirror/PMB reflector. Moreover, it is found that elliptical polarization is observed after the linear polarization passes through PMB.

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“…5 (e), polarization purity (coincidence degree) between experimental and numerical calculation results was more than 80 % at almost all rotation angles. This numerical calculation is based on the integral method well known as the vector theories of the grating mirror [9][10][11][12].…”

Section: Development Of Polarizersmentioning

confidence: 99%

Direct Measurement of the Millimeter Wave Phase Singularity with Helical Wavefront using Heterodyne Detection System at Two Spatial Points

Goto

KUBO

Tsujimura

et al. 2022

Plasma and Fusion Research

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In this paper, we measured the one-dimensional phase and polarization structure of a millimeter-wave with a helical wavefront (vortex beam) using a simultaneous heterodyne detection system at two spatial points. This is a novel approach, and it provides us with the relative phase of the vortex beam. We measured the phase discontinuity of the vortex beam by scanning the one-dimensional path where an antenna passes through the optical axis. It was found that relative phases gradually increase or decrease when the antenna does not pass through the optical axis. Additionally, we measured polarization parameters, which were indefinite near the optical axis. In other words, the optical axis of the vortex beam is a singular point about the phase.

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Cited by 23 publications

References 13 publications

Measurement of Single Pass Electron Cyclotron (EC) Absorption Using Transmitted Waves in Heliotron J

Measurement of Single Pass Electron Cyclotron (EC) Absorption Using Transmitted Waves in Heliotron J

Finite-difference time-domain analysis of electromagnetic wave propagation in corrugated waveguide: Effect of miter bend/polarizer miter bend

Direct Measurement of the Millimeter Wave Phase Singularity with Helical Wavefront using Heterodyne Detection System at Two Spatial Points

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