Plasma startup using neutral beam injection assisted by 2.45 GHz microwaves in Heliotron J

Kobayashi, S.; Nagasaki, K.; Yamamoto, Satoshi; Sakamoto, K.; Mizuuchi, T.; Okada, H.; Minami, Takashi; Hanatani, K.; Nakamura, Yuji; Konoshima, S.; Ohshima, S.; Takeuchi, Masaki; Mukai, K.; Lee, H.Y.; Kishi, S.; Minami, Kazuaki; Takabatake, Y.; Yoshino, Hideaki; Sano, F.

doi:10.1088/0029-5515/51/6/062002

Cited by 11 publications

(15 citation statements)

References 5 publications

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“…It also explains why this scenario can only be started if there are previously existing relativistic electrons. In this experiment these electrons were produced by resonant ECRH, but other methods, like a finite loop voltage, could be similarly efficient [6]. The residence zone of the fast particles close to the antenna field was detected by a movable probe.…”

Section: Discussionmentioning

confidence: 99%

Stochastic acceleration of relativistic electrons and plasma heating and current drive with 2.45 GHz frequency at the WEGA stellarator

Laqua

Chlechowitz

Otte

et al. 2014

Plasma Phys. Control. Fusion

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MeV electrons were produced with less than 6 kW of non-resonant 2.45 GHz microwave heating at magnetic fields of 0.3-0.5 T with no applied loop voltage at the WEGA stellarator. The maximum toroidal plasma current, carried by the electrons, was 1 kA. Broadband radiation, similar to synchrotron radiation, was measured in the 0.5-120 GHz range. X-ray radiation from the plasma and directed γ-ray emission from collisions of the electrons with nearby plasma facing components was measured as well. The acceleration process was modeled by a tail formation due to stochastic interaction with the RF-field at the antenna mouth. The characteristic time for tail formation could be reproduced with power modulation experiments.

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Section: Discussionmentioning

confidence: 99%

Stochastic acceleration of relativistic electrons and plasma heating and current drive with 2.45 GHz frequency at the WEGA stellarator

Laqua

Chlechowitz

Otte

et al. 2014

Plasma Phys. Control. Fusion

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“…One way to achieve these ionization grades could be e.g. by 2.45 GHz microwaves, as in Heliotron J [7].…”

Section: Parameter Studies For W7-xmentioning

confidence: 99%

“…Collisions between the beam and hydrogen particles are given in table 7 and those between the beam and helium particles in table 8. The dependence of reaction rate coefficients involving hydrogen species on electron temperature is shown in figure 13.…”

Section: Appendixmentioning

confidence: 99%

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Assessment of the plasma start-up in Wendelstein 7-X with neutral beam injection

et al. 2015

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Abstract. Plasma start-up by neutral beam injection was investigated for stellarators.A 0-dimensional collisional model was extended to evaluate the temporal evolution of the plasma start-up in a confining toroidal magnetic field. Inclusion of different beam energy components indicated a substantial effect due to the energy dependence of beam-gas collisions. Additional collision processes and particle equations were considered to simulate the plasma start-up in helium-hydrogen mixtures. The isotope effect between operation with hydrogen and deuterium beams was also investigated. As a major objective the conditions necessary for a plasma start-up with neutral beams in W7-X have been examined. The assessed beam configuration in W7-X was found not to allow plasma start-up by neutral beam injection alone. The model has been validated for experimental data from W7-AS and LHD. Quantitative predictions of this study show that the ratio of the beam-plasma interaction length and the plasma volume is an essential quantity for the successful plasma start-up with neutral beams.

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“…Here, the blue and orange lines are the ΔT averaged in the upper-half and lower-left regions of the foil, respectively. A seed plasma is produced with the assistance of 2.45 GHz non-resonant pre-heating and a high-temperature plasma is produced using NBI [6]. The ΔT gradually increases in the upper region at the timing of the magnetron turn-on and a sharp increase in ΔT is observed immediately after NBI injection.…”

mentioning

confidence: 99%

First Application of an InfraRed Imaging Video Bolometer to Heliotron J Plasma

Miyashita

Mukai

Ohshima

et al. 2021

Plasma and Fusion Research

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The spatial radiation distribution has been measured with an infrared imaging video bolometer (IRVB) in a neutral beam injected (NBI) plasma from the Heliotron J device. The temperature distribution on the IRVB foil is consistent with radiation simulated by the three-dimensional transport code, EMC3-EIRENE. The foil temperature increase is proportional to the radiation intensity measured with an Absolute eXtreme UltraViolet (AXUV) diode diagnostic. These results suggest that the IRVB can be used for plasma radiation measurements in small and medium size devices.

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Plasma startup using neutral beam injection assisted by 2.45 GHz microwaves in Heliotron J

Cited by 11 publications

References 5 publications

Stochastic acceleration of relativistic electrons and plasma heating and current drive with 2.45 GHz frequency at the WEGA stellarator

Stochastic acceleration of relativistic electrons and plasma heating and current drive with 2.45 GHz frequency at the WEGA stellarator

Assessment of the plasma start-up in Wendelstein 7-X with neutral beam injection

First Application of an InfraRed Imaging Video Bolometer to Heliotron J Plasma

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