X-ray studies of various shapes of electron-velocity distribution functions and of electron confinement affected by kilovolt-range electrostatic potentials

Journal Article · Sat Feb 15 04:00:00 EST 1992 · Physical Review A. General Physics; (United States)

DOI:https://doi.org/10.1103/PhysRevA.45.2532· OSTI ID:7046928

Cho, T; Hirata, M; Takahashi, E; Ogura, K; Masai, K; Yamaguchi, N; Kondoh, T; Matsuda, K; Hojo, H; Inutake, M; Ishii, K; Kiwamoto, Y; Mase, A; Saito, T; Yatsu, K; Miyoshi, S ^[1]

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1. Plasma Research Centre, University of Tsukuba, Tsukuba, Ibaraki 305 (Japan)

Several types of x-ray diagnostics, such as x-ray energy spectrum analyses, x-ray absorption methods, and x-ray tomographic reconstructions using various types of x-ray detectors (i.e., a Si(Li), a pure Ge, a NaI(Tl), Si surface-barrier detectors, as well as microchannel plates) have been employed for obtaining various shapes of electron-velocity distribution functions as well as their spatial profiles: (i) a plateau-shaped electron-velocity distribution function in the plug region, supporting a scaling theory between thermal-barrier potentials and ion-confining potentials (Cohen's strong electron-cyclotron heating theory); (ii) mirror-trapped 60-keV relativistic Maxwellian electrons in the thermal-barrier region; and (iii) two-component Maxwellian electrons in the central cell have been observed in the tandem-mirror GAMMA 10. During experiments with thermal barriers, it has been observed that the bulk-electron temperature and its evolution with time in the central cell are quite different from the electron energy and its temporal evolution in the plug region. These differences as well as the different shape of the electron-velocity distribution function in each region have clearly demonstrated the existence of a thermal-isolation effect due to the thermal barriers between the central cell and the plug region. X-ray tomography data in these three regions have shown good axisymmetric radial profiles peaked on the magnetic axis; this axisymmetric shape is useful for reducing nonambipolar radial particle losses. Furthermore, the validity of the Pastukhov theory for electron-energy confinement that is enhanced due to the formation of thermal-barrier potentials has been demonstrated using the electron-energy balance analyses. These data have represented a good electron-energy confinement capability due to the formation of thermal barriers.

• OSTI ID: 7046928
• Journal Information: Physical Review A. General Physics; (United States), Journal Name: Physical Review A. General Physics; (United States) Vol. 45:4; ISSN 1050-2947; ISSN PLRAA
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700320* -- Plasma Diagnostic Techniques & Instrumentation-- (1992-)
700350 -- Plasma Production
Heating
Current Drive
& Interactions-- (1992-)
700412 -- Magnetic Confinement Devices-- (1992-)
DIAGNOSTIC TECHNIQUES
DISTRIBUTION FUNCTIONS
ELECTROMAGNETIC RADIATION
ELECTRONS
ELEMENTARY PARTICLES
ENERGY RANGE
FERMIONS
FUNCTIONS
HEATING
IONIZING RADIATIONS
KEV RANGE
KEV RANGE 10-100
LEPTONS
MAGNETIC MIRRORS
OPEN PLASMA DEVICES
PLASMA
PLASMA DIAGNOSTICS
PLASMA HEATING
POTENTIALS
RADIATIONS
RELATIVISTIC PLASMA
RF SYSTEMS
TANDEM MIRRORS
THERMONUCLEAR DEVICES
TOMOGRAPHY
VELOCITY
X RADIATION