Plasma and Fusion Research

Volume 17, 2402043 (2022)

Regular Articles

Effect of Initial-Plasmoid Density Reduction on Collisional Merging Process of Field-Reversed Configurations
Daichi KOBAYASHI, Taichi SEKI, Tomohiko ASAI, Yasuaki TAMURA, Hiroki SOMEYA, Tsutomu TAKAHASHI, Jordan MORELLI1) and Shigefumi OKADA
College of Science and Technology, Nihon University, Tokyo 101-8308, Japan
Department of Physics, Engineering Physics & Astronomy, Queen's University, Kingston, Ontario K7L 3N6, Canada
(Received 10 January 2022 / Accepted 6 March 2022 / Published 22 April 2022)


A super-Alfvenic/sonic collisional merging formation of field-reversed configurations (FRCs) with low-density and high-temperature initial-FRCs was attempted on the FAT-CM device at Nihon University. To vary the density and temperature of initial-FRCs, the low-density/high-temperature (LD/HT) FRC formation technique was applied to the initial-FRC formation. The electron density of initial-FRCs formed using the LD/HT FRC formation technique was reduced to about 50% of that in the standard cases. The ion temperature was increased as the electron density decreased because the plasma pressure completely balances with the external magnetic pressure in an ideal FRC. The ion mean-free-path also increased to the equivalent value of the diameter of the initial-FRCs. Therefore, the initial-FRCs will be collision-less. These collision-less initial-FRCs were successfully translated. The observation results of the collisional merging formation process of FRC from the internal magnetic probe array and two axially arranged interferometers indicate that the performance of the FRC formed after the collision and merging declined in cases with collision-less FRCs and it depends on the kinetic energy in the collision process.


field-reversed configuration, high beta plasma, FRC merging, collision-less plasma, energy regeneration

DOI: 10.1585/pfr.17.2402043


  • [1] M. Tuszewski, Nucl. Fusion 28, 2033 (1988).
  • [2] L.C. Steinhauer, Phys. Plasmas 18, 070501 (2011).
  • [3] M.W. Binderbauer, T. Tajima, L.C. Steinhauer, E. Garate, M. Tuszewski et al., Phys. Plasmas 22, 056110 (2015).
  • [4] M.W. Binderbauer, H.Y. Guo, M. Tuszewski, S. Putvinski, L. Sevier et al., Phys. Rev. Lett. 105, 045003 (2010).
  • [5] D. Kobayashi and T. Asai, Phys. Plasmas 28, 022101 (2021).
  • [6] H. Gota, M.W. Binderbauer, T. Tajima, A. Smirnov, S. Putvinski et al., Nucl. Fusion 61, 106039 (2021).
  • [7] T. Asai, T. Takahashi, J. Sekiguchi, D. Kobayashi, S. Okada, H. Gota, T. Roche, M. Inomoto, S. Dettrick, Y. Mok et al., Nucl. Fusion 59, 056024 (2019).
  • [8] D. Kobayashi, T. Asai, T. Takahashi, A. Tatsumi, N. Sahara et al., Plasma Fusion Res. 16, 2402050 (2021).
  • [9] N. Sahara, T. Asai, D. Kobayashi, T. Takahashi, H. Ogawa et al., Rev. Sci. Instrum. 92, 063501 (2021).
  • [10] T. Asai, D. Kobayashi, T. Seki, Y. Tamura, T. Watanabe et al., Nucl. Fusion 61, 096032 (2021).
  • [11] Y. Ohkuma, M. Urano, M. Nakamura, Y. Narushima T. Takahashi et al., Nucl. Fusion 38, 1501 (1998).
  • [12] T. Watanabe, T. Asai, T. Takahashi, D. Kobayashi and D. Harashima, Rev. Sci. Instrum. 92, 053541 (2021).
  • [13] T.S. Green and A.A. Newton, Phys. Fluid 9, 1386 (1966).
  • [14] L.C. Steinhauer, Phys. Fluid 26, 254 (1966).