Experimental Results of Ion Heating by Magnetic Reconnection Using External Coils

Kamio, S.; Watanabe, T.; Yamasaki, K.; Cao, Qinghong; Yamada, Teppei; Inomoto, Michiaki; Ono, Yasushi

doi:10.1585/pfr.9.3402038

Cited by 2 publications

(1 citation statement)

References 11 publications

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“…rapid conversion from magnetic energy to plasma thermal energy [18]. So far, the ion heating effect of magnetic reconnection has been intensively investigated in plasma merging experiments [19][20][21][22], but the details of electron heating remained unclear because of the poor electron energy confinement of those experimental devices dedicated to magnetic reconnection. However, a merging experiment in high TF in MAST [23] recently revealed significant electron heating at the reconnection X-point, suggesting the possibility of direct formation of NBI target plasma by the combination of outer-PF-coil start-up and the merging technique.…”

Section: Introductionmentioning

confidence: 99%

Centre-solenoid-free merging start-up of spherical tokamak plasmas in UTST

Inomoto

Watanabe

et al. 2015

Nucl. Fusion

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A centre-solenoid-free merging start-up scheme for spherical tokamak plasmas was developed in a University of Tokyo spherical tokamak (UTST) experiment by using outer poloidal field coils. Torus breakdown was initiated at null points and two spherical tokamak plasmas with a total current up to 80 kA were generated inductively. Their merging process provided substantial ion and electron heating by magnetic reconnection. The obtained dependence of heating on plasma current suggests that high-temperature and high-current plasma suitable for neutral beam injection is attainable under the realistic conditions in the merging start-up method.

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Section: Introductionmentioning

confidence: 99%

Centre-solenoid-free merging start-up of spherical tokamak plasmas in UTST

Inomoto

Watanabe

et al. 2015

Nucl. Fusion

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Laboratory study of diffusion region with electron energization during high guide field reconnection

et al. 2015

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Floating potential profile was measured around the X-point during high guide field reconnection in UTST merging experiment where the ratio of guide field (Bg) to reconnecting magnetic field (Brec) is Bg/Brec>10. Floating potential measurement revealed that a quadrupole structure of electric potential is formed around the X-point during the fast reconnection phase due to the polarization by inductive electric field. Also, our floating potential measurement revealed the existence of parallel electric field in the vicinity of the X-point. While field-aligned components of inductive electric field (E∥ind) and electrostatic electric field (E∥es) cancel out with each other away from the X-point, E∥ind exceeds E∥es around the X-point, indicating the deviation from ideal MHD criterion within the region. The diffusion region extends in the outflow region and the scale length of region is an order of ion skin depth, which is quite different from the VTF experiment result. Based on the measured magnetic field and electric field profile, our particle trajectory analysis indicates that fast electrons with energies over 300 eV are produced within 1 μs around the X-point in the non-ideal MHD region. These results indicate that production of fast electrons or electron heating are expected to be observed in the vicinity of the X-point.

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Experimental Results of Ion Heating by Magnetic Reconnection Using External Coils

Cited by 2 publications

References 11 publications

Centre-solenoid-free merging start-up of spherical tokamak plasmas in UTST

Centre-solenoid-free merging start-up of spherical tokamak plasmas in UTST

Laboratory study of diffusion region with electron energization during high guide field reconnection

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