Development of microwave pre-ionization source for GLAST tokamak

Khan, R.; Nazir, M.; Ali, Ahsan; Hussain, Shafqat; Vorobyev, G.M.

doi:10.1016/j.fusengdes.2017.11.002

Cited by 14 publications

(2 citation statements)

References 6 publications

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“…GLAST-III is a spherical tokamak based on a Pyrex VV [29,30] with a major radius = R 0.2 m, and a minor radius = a 0.1 m. Microwaves are injected into the chamber through a rectangular waveguide (WR-340), as depicted in figure 1(a). For pulsed-mode operation, the microwave source was indigenously developed by modifying a domestic microwave oven circuit [31]. A 1 kW microwave source (operating at 2.45 GHz) is installed at GLAST-III.…”

Section: Methodsmentioning

confidence: 99%

Microwave-assisted pre-ionization experiments on GLAST-III

Khan¹,

Shakir²,

Ali³

2021

Plasma Sci. Technol.

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GLAss Spherical Tokamak (GLAST-III) is a spherical tokamak with an insulating vacuum vessel that has a unique single-passage capability for incident microwaves. In this work, electron cyclotron resonance heating (ECRH)-assisted plasma pre-ionization in GLAST-III is explored for three radio-frequency (RF) polarizations (the O-, X-, and M-modes) at different toroidal-field (TF) strengths and filled gas pressures. The optimum hydrogen pressure is identified for efficient plasma pre-ionization. A comparison of the plasma pre-ionizations initiated by the O-, X-, and M-modes shows prominent differences in the breakdown time, location, and wave absorption. In the case of O-mode polarization, microwave absorption occurs for a relatively shorter duration, resulting in a bell-shaped electron-temperature temporal profile. Microwave absorption is dominant in the case of the X-mode, leading to a broader temporal profile. The M-mode discharge contains features of both the X- and O-modes. Efficient plasma pre-ionization is achieved in the X-mode polarization for the intermediate TF strengths (with a central toroidal magnetic field ). Traces of the electron-number density show a similar tendency, as revealed by These results suggest that the X-mode is the best candidate for efficient plasma pre-ionization at low filled gas pressures in small tokamaks.

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Section: Methodsmentioning

confidence: 99%

Microwave-assisted pre-ionization experiments on GLAST-III

Khan¹,

Shakir²,

Ali³

2021

Plasma Sci. Technol.

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“…In addition, the microwave preionization can improve the quality of the plasma and discharge. Since 1980s, a number of microwave preionization experiments have been practically demonstrated on the SUNIST [6], TST-2 [7,8], NSTX [9,10], VEST [11,12], QUEST [13], START [14] and MAST [14] STs and SINP [15], T-10 [16], Tore Supra [17], KSTAR [18,19], Taban [20], HT-6B [21], DIII-D [22][23][24], GLAST [25], Aditya [26], KAIST [27] and JT-60 [28,29] tokamaks. For inductive plasma current startup, the ECR preionization is known to be very effective for minimizing the loop voltage.…”

Section: Introductionmentioning

confidence: 99%

Microwave preionization and electron cyclotron resonance plasma current startup in the EXL-50 spherical tokamak

Chen

Zhu

Zhou

et al. 2021

Plasma Sci. Technol.

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Preionization has been widely employed to create initial plasma and help the toroidal plasma current formation. This research focuses on implementing a simple, economical and practical electron cyclotron resonance (ECR) preionization technique on the newly constructed EXL-50 spherical tokamak, and evaluating the effectiveness on improving the plasma current startup. Two types ECR microwave preionization experiments for the plasma initialization without the central solenoid are reported: (1) 2.45 GHz microwave preionization and current startup with 2.45 GHz ECR source; (2) 2.45 GHz microwave preionization and current startup with 28 GHz ECR source. Application of the 2.45 GHz ECR microwave preionization to the experiments has contributed to (1) getting rid of the plasma breakdown delay; (2) the significant improvement of the discharge quality: the discharge is much longer and more stable while the driven plasma current is larger, compared to the discharge without preionization.

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First Results and Plasma Current Start-Up in Taban Tokamak

Mirzaei

Amrollahi

2019

J Fusion Energ

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Development of microwave pre-ionization source for GLAST tokamak

Cited by 14 publications

References 6 publications

Microwave-assisted pre-ionization experiments on GLAST-III

Microwave-assisted pre-ionization experiments on GLAST-III

Microwave preionization and electron cyclotron resonance plasma current startup in the EXL-50 spherical tokamak

First Results and Plasma Current Start-Up in Taban Tokamak

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