Observation of energetic electron confinement in a largely stochastic reversed-field pinch plasma

Journal Article · Fri Jan 15 00:00:00 EST 2010 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.3292658· OSTI ID:21344660

Clayton, D J; Chapman, B E; O'Connell, R; Almagri, A F; Burke, D R; Forest, C B; Goetz, J A; Kaufman, M C ^[1]; Bonomo, F; Franz, P; Gobbin, M; Piovesan, P ^[2]

---

1. Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)
2. Consorzio RFX, Euratom-ENEA Association, Corso Stati Uniti, 4 35127 Padova (Italy)

Runaway electrons with energies >100 keV are observed with the appearance of an m=1 magnetic island in the core of otherwise stochastic Madison Symmetric Torus [Dexter et al., Fusion Technol. 19, 131 (1991)] reversed-field-pinch plasmas. The island is associated with the innermost resonant tearing mode, which is usually the largest in the m=1 spectrum. The island appears over a range of mode spectra, from those with a weakly dominant mode to those, referred to as quasi single helicity, with a strongly dominant mode. In a stochastic field, the rate of electron loss increases with electron parallel velocity. Hence, high-energy electrons imply a region of reduced stochasticity. The global energy confinement time is about the same as in plasmas without high-energy electrons or an island in the core. Hence, the region of reduced stochasticity must be localized. Within a numerical reconstruction of the magnetic field topology, high-energy electrons are substantially better confined inside the island, relative to the external region. Therefore, it is deduced that the island provides a region of reduced stochasticity and that the high-energy electrons are generated and well confined within this region.

• OSTI ID: 21344660
• Journal Information: Physics of Plasmas, Vol. 17, Issue 1; Other Information: DOI: 10.1063/1.3292658; (c) 2010 American Institute of Physics; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
CONFINEMENT TIME
ELECTRON LOSS
MAGNETIC ISLANDS
PLASMA
PLASMA CONFINEMENT
REVERSE-FIELD PINCH
RUNAWAY ELECTRONS
STOCHASTIC PROCESSES
TAIL ELECTRONS
TEARING INSTABILITY
CONFINEMENT
ELECTRONS
ELEMENTARY PARTICLES
FERMIONS
INSTABILITY
LEPTONS
MAGNETIC FIELD CONFIGURATIONS
PINCH EFFECT
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES