Quasi-optical simulation of the electron cyclotron plasma heating in a mirror magnetic trap

Shalashov, A. G.; Balakin, A. A.; Khusainov, T. A.; Gospodchikov, E. D.; Solomakhin, A. L.

doi:10.1134/s1063776117010162

Cited by 16 publications

(9 citation statements)

References 31 publications

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“…Such tremendous difference in T e -profiles caused by the small shift of the ECR surface was not predicted theoretically during the development of the ECRH system for GDT [10,11]. Subsequent modeling using the actual plasma profiles measured in the experiments revealed that the 'narrow' heating is indeed characterized by a more narrow ECRH power deposition profile than the 'broad' heating [5,12,13]. However, a consistent theoretical explanation of the bifurcation itself was absent in spite of our efforts.…”

Section: Introductionmentioning

confidence: 76%

Towards explanation of ‘broad’ and ‘narrow’ ECRH regimes observed in the GDT experiment

Shalashov¹,

Gospodchikov²,

Khusainov³

et al. 2022

Nucl. Fusion

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In the experiments with combined ECRH and NBI plasma heating started at the GDT facility (Budker Institute) in 2014, two quite different scenarios of plasma discharges were realized. The first one was characterized by a broad radial distribution of the absorbed ECRH power and a stable plasma with improved energy confinement of fast ions, while in the other the electron temperature profile was highly peaked with local values of Te > 500 eV, but plasma was susceptible to low-frequency instabilities that had a net negative effect on confinement. We discuss the first theoretical explanation of these phenomena. Essentially different temperature profiles are considered as a result of self-consistent evolution in time after the ECRH is switched on. To explore this concept, we combine an advanced quasi-optical model for the calculation of microwave power absorption with a simple transport model describing electron energy balance in a gas-dynamic trap.

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Section: Introductionmentioning

confidence: 76%

Towards explanation of ‘broad’ and ‘narrow’ ECRH regimes observed in the GDT experiment

Shalashov¹,

Gospodchikov²,

Khusainov³

et al. 2022

Nucl. Fusion

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“…With this approach, we meet technical difficulties when calculating the overlapping of two beams consisted of discrete rays. In the present paper, we use a more precise model based on quasi-optical code QOOT [38,39] that gives continuous wave field distribution in the incident and scattered beams so the overlapping integral may be calculated straightforwardly. By iterating such calculations for different options available at GDT, we find the restrictions on parameters listed in table 1.…”

Section: Scattering Geometrymentioning

confidence: 99%

“…These new data update the results of ray-tracing modeling (see table 1 in [34]). A size of CTS volume is about [38,39]. Colormaps show the electromagnetic field intensity in the logarithmic scale; black lines confine a region that yields 90% of a beam overlap 𝑂 b ; orange lines confine the same regions that correspond to extreme angles of focusing system.…”

Section: Scattering Geometrymentioning

confidence: 99%

“…Figure 3. Axial and radial cross-sections of CTS I and II scattering geometry for the O-mode at 54.5 GHz obtained with quasi-optical code QOOT[38,39]. Colormaps show the electromagnetic field intensity in the logarithmic scale; black lines confine a region that yields 90% of a beam overlap 𝑂 b ; orange lines confine the same regions that correspond to extreme angles of focusing system.…”

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confidence: 99%

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Development of fast-ion collective Thomson scattering diagnostics for the GDT experiment

Shalashov¹,

Gospodchikov²,

Khusainov³

et al. 2021

J. Inst.

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In this paper, we describe hardware developed for the collective Thomson scattering (CTS) diagnostic for the large open magnetic trap GDT (Budker Institute, Russia) used in fusion researches. The diagnostic utilizes 400 kW/54.5 GHz gyrotron as a source of probe radiation and is aimed at the reconstruction of fast ion distributions over transverse and longitudinal velocities driven by high-power neutral beam injection. Formation and manipulation of the probe beam and collection of the scattered microwave radiation are done with large-aperture quasi-optical mirror systems. The receiving complex consists of two identical channels for simultaneous detection of scattering in two complement geometries. Each channel includes a highly sensitive radiometer/spectrum analyzer with the band of 54.470 ± 0.550 GHz, the noise temperature of 0.35 eV, the sensitivity less than 0.025 eV, the frequency/time resolution of 5-50 MHz/10 μs, and narrow-band notch filter providing at least −40 dB rejection in the band of 25 MHz with a central frequency tunable in 54.470 ± 0.050 GHz for protection of the input RF circuit from a backlight of powerful gyrotron radiation. K: Nuclear instruments and methods for hot plasma diagnostics; Microwave radiometers

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“…The code is able to model the propagation and the electron cyclotron absorption of wave beams in weakly relativistic plasma in electromagnetically large devices (with typical size of few thousands of wavelengths) in a reasonable time. Calculations using LAQO proved the importance of taking into account these effects to describe correctly the RF power deposition profile in tokamak plasmas [3,4] and in open magnetic trap [5,6]. A small solution time for the direct problem of wave beam propagation allows the use of LAQO to solve the inverse problem, such as reconstruction of distributions of fluctuating plasma parameters using the amplitude profile of the transmitted beam.…”

Section: Introductionmentioning

confidence: 99%

Quasi-optical approach to reconstruction of plasma fluctuations using amplitude distribution of transmitted microwave beam

et al. 2017

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Quasi-optical simulation of the electron cyclotron plasma heating in a mirror magnetic trap

Cited by 16 publications

References 31 publications

Towards explanation of ‘broad’ and ‘narrow’ ECRH regimes observed in the GDT experiment

Towards explanation of ‘broad’ and ‘narrow’ ECRH regimes observed in the GDT experiment

Development of fast-ion collective Thomson scattering diagnostics for the GDT experiment

Quasi-optical approach to reconstruction of plasma fluctuations using amplitude distribution of transmitted microwave beam

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