Improved confinement in a high pinch parameter region of the reversed field pinch plasma

Abstract

Discharges with improved plasma confinement in a high pinch parameter region (0 -2) have been discovered in the TPE-1RM2O reversed field pinch experiment. These discharges become possible with careful control of the waveforms of the plasma current and the toroidal magnetic field after intensive discharge cleaning and are called the 'Improved High Theta Mode' (IHTM). In these discharges the increase of electron density is distinct when compared with low 0 cases (-1.55). The electron temperature increases slightly with 0 but the ion temperature remains almost constant. Consequently, the poloidal beta increases, from 8% at 0 N 1.55 to 18% at 0 N 2.0, and the energy confinement time increases from 0.2 to 0.4 ms. The fluctuation level of the magnetic field corresponding to the dynamo activities is reduced by about a factor of 3 in IHTM, which may explain this improvement. Possible causes of IHTM are discussed. It is found that the m = 1 mode rotates continuously during IHTM, while it always stops rotating just before a large soft X ray emission crash occurs.

StrongE×BFlow Shear and Reduced Fluctuations in a Reversed-Field Pinch

“…At 500 kA, the minimum F ϳ 20.2, and the maximum ͗n e ͘ ϳ 1.2 3 10 13 cm 23 . Enhanced confinement discharges requiring strong toroidal field reversal were also observed in the TPE-1RM20 RFP [10]. Magnetic fluctuations were reduced in these discharges, but neither electrostatic fluctuations nor the radial electric field profile were measured.…”

High confinement plasmas in the Madison Symmetric Torus reversed-field pinch

“…23, but the datum for TPE-1RM20 was taken from Ref. 24, and the data for the MST ͑a-e͒ are from the plasmas described in this paper and from the previously reported improved-confinement plasmas. 5,6 The diagonal line is the best fit to the data listed in Ref.…”

Reduced Edge Instability and Improved Confinement in the MST Reversed-Field Pinch

“…4 are confinement data from different RFP devices. Most of these data were taken from Table I in [14], but the datum for TPE-1RM20 was taken from [15], and the data for the MST (a)-(e) are from the plasmas described in this Letter and from previously reported improvedconfinement plasmas [5,6]. The diagonal line is the best fit to the data listed in [14], t E 10.2͑a 2 I 3 f ͞N 3͞2 ͒.…”