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First Confinement Time Evaluation for Particles Axially Injected into a Non-Adiabatic Trap

Sena SAITO¹⁾, Toshiki TAKAHASHI¹⁾, Naoki MIZUGUCHI²⁾

1)

Graduate School of Science and Technology, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma 376-8515, Japan

2)

National Institute for Fusion Science, National Institutes of Natural Sciences, 322-6 Oroshi-cho, Toki, Gifu 509-5292, Japan

(Received 14 January 2025 / Accepted 3 February 2025 / Published 28 March 2025)

Abstract

This study presents the first detailed investigation of confinement times in non-adiabatic traps during the axial injection of thermal plasma from the mirror edge, using particle trajectory calculations. Plasma is supplied from a coaxially positioned plasma source through an orifice with a ring-shaped aperture. The results of the analysis show that the longest confinement time occurs when the ring radius of the aperture is approximately equal to the ion Larmor radius at the mirror region. Under these conditions, the confinement time is found to be approximately four times the time it takes for particles to traverse the device length at thermal velocity.

Copyright (c) 2025 The Japan Society of Plasma Science and Nuclear Fusion Research

Keywords

non-adiabatic trap, stochastic motion, particle fueling, particle-tracking calculation, confinement

DOI: 10.1585/pfr.20.1203023

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References

• [1] D. Adachi et al., Plasma Fusion Res. 13, 3401069 (2018).
• [2] R. Matsumoto et al., Plasma Fusion Res. 14, 2401035 (2018).
• [3] H. Momota et al., J. Fusion Energy 27, 77 (2008).