An H minority heating regime in Tore Supra showing improved L mode confinement

Abstract

Tore Supra experiments are at present devoted to the study of high density regimes with radiofrequency heating. Recently, an improved L mode confinement regime has been observed in plasmas heated by ion cyclotron hydrogen minority heating, at relatively high densities up to 80% of the Greenwald limit. The quality of energy confinement is as good as that of ELMy H mode. The main physical mechanism of this regime has not been clearly identified. However, some features very similar to those of previous improved confinement modes using neutral beam heating in other tokamaks have been observed.

Toroidal rotation and momentum transport in Alcator C-Mod plasmas with no momentum input

“…Despite the fact that there is no momentum input in Alcator C-Mod plasmas, ICRF [16,17] and Ohmic [16,18,19] H-mode discharges are found to have substantial spontaneous co-current toroidal impurity rotation. Similar observations have been made on other devices such as JET [20,21], COMPASS [22] and Tore Supra [23][24][25]. The Alcator C-Mod rotation results are summarized in the following.…”

Radial Electric Field in Tokamak Plasmas as a Physical Consequence of Ehrenfest’s Paradox

“…If the sum of (10) be (this often indicates the suppression of electron losses at plasma periphery) then the plasma core begins rotating in the current direction (which correlates with experimental data [20,38]). …”

“…are difficult to explain using simple approaches, see for example [36][37][38][39][40]. Therefore, it is often necessary to use complex contemporary theories.…”

“…Below we present important quantitative and qualitative correlations of theoretical results (using Equations (6), (9) and (10)) with tokamak experimental data [20,[36][37][38][39][40][41][42].…”

Overview of toroidal momentum transport

“…These experiments were performed using neutral beam heating (NBH) which exerts a large torque on the plasma, and the understanding was that without external momentum input, the plasma rotation would be negligible. This picture radically changed through the discovery of the so-called intrinsic rotation [19][20][21][22][23][24][25][26][27][28][29], i.e. the finite rotation a plasma develops without an external toroidal torque.…”