Plasma and Fusion Research

Volume 21, 1202010 (2026)

Rapid Communications

Quasi-Periodic Mitigation of Runaway Electron Beam via Interaction with Kinetic Instabilities in the QUEST Spherical Tokamak

Thomas K. CLOAREC¹⁾, Ryuya IKEZOE²⁾, Kazuaki HANADA²⁾, Makoto HASEGAWA²⁾, Hiroshi IDEI²⁾, Takeshi IDO²⁾, Toshiki KINOSHITA²⁾, Yoshihiko NAGASHIMA²⁾, Takumi ONCHI²⁾

1): Université Paris-Saclay, ENS Paris-Saclay, DER de Physique, 91190, Gif-sur-Yvette, France
2): Research Institute for Applied Mechanics, Kyushu University, Fukuoka 816-8580, Japan

(Received 4 August 2025 / Accepted 4 November 2025 / Published 21 January 2026)

Abstract

Runaway electron (RE) driven kinetic instabilities have been observed in the QUEST spherical tokamak. A strong correlation between decay of the plasma current and activity of kinetic instabilities was first found with quasi-periodic behaviour during current quench. An efficient mitigation of RE by interaction with kinetic instabilities was experimentally demonstrated.

Keywords

runaway electron, kinetic instability, current quench, RE mitigation, spherical tokamak

DOI: 10.1585/pfr.21.1202010

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References

[1] C. Liu et al., Phys. Rev. Lett. 120, 265001 (2018).
[2] D.A. Spong et al., Phys. Rev. Lett. 120, 155002 (2018).
[3] W.W. Heidbrink et al., Plasma Phys. Control. Fusion 61, 014007 (2018).
[4] A. Lvovskiy et al., Nucl. Fusion 59, 124004 (2019).
[5] C. Paz-Soldan et al., Nucl. Fusion 59, 066025 (2019).
[6] R. Ikezoe et al., Proc. of the 29th IAEA-FEC, (Queen Elizabeth II Centre, London 2023).
[7] M. Wang et al., Nucl. Fusion 64, 126021 (2024).
[8] H.L. Kang et al., Nucl. Fusion 64, 106025 (2024).
[9] H. Idei et al., Nucl. Fusion 57, 126045 (2017).
[10] R. Ikezoe et al., Plasma Fusion Res. 18, 2402066 (2023).