Ion sources for fusion plasma diagnostics

Sasao, M.; Connor, K. A.; Ida, K.; Iguchi, H.; Ivanov, A. A.; Nishiura, M.; Thomas, D. M.; Wada, M.; Yoshinuma, M.

doi:10.1109/tps.2005.860097

Cited by 13 publications

(5 citation statements)

References 165 publications

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“…It is well known that the self-heating of a DT plasma by alpha-particles is the key to realize a selfsustainable thermonuclear plasma. The alpha-diagnostics for a fusion reactor is reviewed in some recent papers [1,2]. As described in the review papers, it is still difficult to measure the distributions of confined and escaping alphaparticles and several proposals to solve such difficulties and related problems are now under examination [2].…”

Section: Inroductionmentioning

confidence: 99%

Development of a Simple and Tough Alpha-Particle Detector Used at High Temperature

Iida

Sato

Kato

et al. 2007

Plasma and Fusion Research

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Several ceramic detectors were made by use of the insulation layer formed on two types of substrate, i.e. aluminum and silicon. Each detector was irradiated with alpha-rays from an Am-241 source and the electric charge induced in the detector was measured in the temperature range from room temperature up to 450 K. The alpha-ray detection signals were well observed with an oscilloscope at the properly high bias-voltage only for very short time from several seconds to several tens of seconds before the start of the sweeping insulation breakdown. Though this type of the simple detector made of a thin ceramic layer can be hardly used for the energy analysis, it might be effectively applicable to the measurement of the flux of alpha-particles at high temperature. Keywords: alpha-particle detector, ceramic detector, insulation breakdown, surface oxidation, anodic oxidation, alpha-particle flux monitor DOI: 10.1585/pfr.2.S1085 InroductionIt is very important to measure neutrons and confined/escaping alpha-particles in the burning plasma experiments. It is well known that the self-heating of a DT plasma by alpha-particles is the key to realize a selfsustainable thermonuclear plasma. The alpha-diagnostics for a fusion reactor is reviewed in some recent papers [1,2]. As described in the review papers, it is still difficult to measure the distributions of confined and escaping alphaparticles and several proposals to solve such difficulties and related problems are now under examination [2].We find difficulty in using normal alpha-particle detectors such as a semiconductor detector and a scintillation detector under the condition of high temperature. Ceramic material is fundamentally tough against the effects of highenergy particles, high temperature, high voltage and other severe conditions. Thus we have examined the possibility of the substitution of ceramic material for the semiconductor and scintillation material. If an alpha-particle detector is made of ceramic material, such a detector will be more effectively and conveniently used for the alpha-diagnostics. The purpose of this paper is to show fundamental data from some experiments for the development of the ceramic detector. At first, this paper describes how to make two types of ceramic detectors and then shows results on alpha-ray response of the detectors. Experiment Formation of detector samplesSeveral detector samples were formed on two types author's e-mail: iida@eei.eng.osaka-u.ac.jp of substrate, i.e., aluminum and silicon. The thickness of the substrate was 0.5 mm. The surface of each substrate was first polished and then was oxidized for the formation of an insulation layer. Finally an about 400 Å thick silver film was made as an electrode on the insulation layer by an evaporation process. The size of the electrode was 10 mm in diameter.The anodic oxidation method [3] was applied to the aluminum substrate (A-type detector) for the formation of the thick insulation layer on the surface, though the quality of the layer may be poor. A current of 500 mA was gi...

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Section: Inroductionmentioning

confidence: 99%

Development of a Simple and Tough Alpha-Particle Detector Used at High Temperature

Iida

Sato

Kato

et al. 2007

Plasma and Fusion Research

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“…This finding is particularly influential in the context of applications that use a plasma and sheath to create a high emittance ion source, such as in plasma etching of semiconductors or ion beam generation [2][3][4][5] . It may also be applicable to some electric propulsion systems, where ions are accelerated to higher velocities to generate thrust, usually in the presence of hot electrons 6,7 , and to energy transport controlled by ion-acoustic instabilities in other contexts.…”

Section: Introductionmentioning

confidence: 99%

Simulations of ion heating due to ion-acoustic instabilities in the presheath

Beving,

Hopkins,

Baalrud

2021

Preprint

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Particle-in-cell direct simulation Monte Carlo simulations reveal that ion-acoustic instabilities excited in presheaths can cause significant ion heating. Ion-acoustic instabilities are excited by the ion flow toward a sheath when the neutral gas pressure is small enough and the electron temperature is large enough. A series of 1D simulations were conducted in which neutral plasma (electrons and ions) was uniformly sourced with an ion temperature of 0.026 eV and different electron temperatures (0.1 -50 eV). Ion heating was observed when the electron-to-ion temperature ratio exceeded the minimum value predicted by linear response theory to excite ion-acoustic instabilities at the sheath edge (T e /T i ≈ 28). When this threshold was exceeded, the temperature equilibriation rate between ions and electrons rapidly increased near the sheath so that the local temperature ratio did not significantly exceed the threshold for instability. This resulted in significant ion heating near the sheath edge, which also extended back into the bulk plasma; presumably due to wave reflection from the sheath. This ion-acoustic wave heating mechanism was found to decrease for higher neutral pressures, where ion-neutral collisions damp the ion-acoustic waves and ion heating is instead dominated by inelastic collisions in the presheath.

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“…Heavy-ion beams play an important role in plasma research, particularly for plasma probing in the heavy-ion beam probe (HIBP) method (see reviews in Crowley (1994) and Sasao et al (2005)). The general idea of this diagnostic technique, proposed in the seventies by Hicock and co-workers, is to send a fast singly charged positive ion beam inside a plasma and to detect secondary beam particles deflected by the magnetic field (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…Several different beams have been used during the last decades, such as Cs and Tl at energies below 1 MeV (Crowley 1994) and, more recently, gold beams at megaelectronvolts energies (Ishii 1994, Taniike et al 1994a, Nishiura et al 2008. The progressive use of higher energy beams is a consequence of the increase in the size of fusion devices (Sasao et al 2005). The use of tandem accelerators is attractive for megaelectronvolts energies, as these accelerators may produce intense and stable singly charged beams (Taniike 1995).…”

Section: Introductionmentioning

confidence: 99%

Electron-loss cross sections for heavy-ion beam probe using gold beams: experiment and theory

Sant’Anna¹,

Zappa

Jalbert

et al. 2009

Plasma Phys. Control. Fusion

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We present cross section experimental data required for modeling beam production, attenuation and energy loss in the heavy-ion beam probe technique, namely, electron-loss cross sections for anionic gold projectiles and Ar and N 2 targets in the energy range from 30 keV to 1 MeV. The results agree well with low-energy measured values from the literature for the Ar target. The present results are also compared with literature results for the H − projectile and the Ar target, displaying similar velocity dependences. This similarity led to the use of a simple semi-classical model to calculate the projectile-electron-loss cross sections in a wide energy range. This model employs the total scattering cross sections for free electrons and the momentum distribution of the Au − electrons. The present experimental results are in good agreement with this model, allowing a reliable estimate of the cross section values up to 100 MeV. Our results indicate that previously calculated cross sections are overestimated by at least a factor of two. This previous overestimation of electron-loss cross sections leads to significant errors in the modeling of charge-state fractions of gold beams, with consequences in the optimization of beam energy resolution and intensity for HIBP with megaelectronvolts gold beams.

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Ion sources for fusion plasma diagnostics

Cited by 13 publications

References 165 publications

Development of a Simple and Tough Alpha-Particle Detector Used at High Temperature

Development of a Simple and Tough Alpha-Particle Detector Used at High Temperature

Simulations of ion heating due to ion-acoustic instabilities in the presheath

Electron-loss cross sections for heavy-ion beam probe using gold beams: experiment and theory

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