Generalized Scaling Laws of the Formation and Effects of Plasma-Confining Potentials for Tandem-Mirror Operations in GAMMA 10

Abstract

The main operations from 1979 to 2000 in the GAMMA 10 tandem-mirror, characterized in terms of the high-potential mode having kV-order plasma-confining potentials and the hot-ion mode yielding fusion neutrons with 10-20 keV bulk-ion temperatures, are summarized and generalized as a result of scalings of the formation and the effects of the potentials. The wide validity of potential-formation physics from Cohen's theory and the validity of the generalized Pastukhov's theory for the effects of thermal-barrier potentials on electron confinement are verified and consolidated through electron-energy balance.

Sheared Radial Electric-Field Effects on Turbulence Suppression due to Doubly Advanced Potential-Height Formation

“…1, recent achievement of a factor of two progress in data on φ c , in comparison to those attained 1992-2002, is shown in accordance with the physics scaling law of φ c with thermal-barrier potentials φ b as a function of the density ratio of the plug to central densities n p /n c (see the solid theoretical curves) [2]. Here, a 20% increase in plug ECH powers along with a factor of 2 improvement in recycling hydrogen particles is applied to the hot-ion mode plasmas at several keV ion temperatures (T i ) on the GAMMA 10 tandem mirror [2]. This progress provides the basis for the following remarkable effects of a strong dE r /dr, given that dE r /dr is proportional to the Φ c height, which is closely connected with and raised by plug potential rise due to plug ECH Gaussian beams.…”

“…A remarkable characteristic advantage of open-ended mirror devices is the ease of control of a radial potential profile due to locally heated electron axial flow from a plug region [2] into a machine end region along the lines of magnetic force. This potential control ability in mirrors allows for flexible experimental studies of relations between radially produced electric shear profiles and the suppression of fluctuationdriven radial losses (or transverse plasma confinement).…”

“…Here, electron-cyclotron heatings (ECH) for ion-confining potential (φ c ) formation [2,3] are applied in association with a significant rise in the absolute value of the central-cell potential Φ c and the resulting formation of a strong shear of electric fields of the order of 10 kV/m 2 in the radial direction of the plasma column (dE r / dr).…”

Extended possibility of an active control of co-axially nested shear plasma formation due to electron cyclotron heatings

“…The detailed machine parameters in the employed standard operation were easily found in various references (Cho et al. 2001, 2005 a , b ).…”

“…Mirror devices (Budker, Mirnov & Ryutov 1971; Pastukhov 1974; Fowler & Logan 1977; Post 1987; Cho et al. 2001; Pastukhov & Chudin 2011) having open ended regions, provided intrinsic advantages in terms of easy control of radial potential or sheared rotation profiles on the basis of axial particle loss control (Pastukhov 1974; Cho et al. 2005 a , 2006, 2008; Pastukhov & Chudin 2011).…”