Scaling of confinement with isotopic content in deuterium and tritium plasmas

Abstract

The scaling of the electron thermal diffusivity, Xe, with relative gyro radius, p, has been measured on TFTR by comparing nearly identical ICRF-heated discharges which differ only in hydrogenic isotopic content. Contrary to the gyro-Bohm scaling (xe -X B~, where XB is the Bohm diffusivity) observed on DIII-D when p* was varied through a scan of magnetic field strength, Xe is found to scale inversely with p*. Hence, global energy confinement is 8-11% higher in deuterium-tritium plasmas than in deuterium only plasmas, with the higher stored energy attributed almost entirely to the electrons. PACS 52.55.Fa, 52.50 Gj DISCLAIMERThis report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracj, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

Deuterium–tritium plasmas in novel regimes in the Tokamak Fusion Test Reactor

“…An experiment was conducted to compare the confinement of nominally D-only ͑80% D, 1% T, 8% H, 2%-3% C͒ and D-T ͑ϳ40% D, ϳ40% T, 5% H, 2%-3% C͒ plasmas fueled by gas puffing. 30 The ICRF power up to 4.4 MW at 43 MHz was applied for 1.2 s. The H-minority heating profile was calculated to be similar and the total stored energy in the energetic minority-ion tail, determined from the pressure anisotropy measured by the magnetic diagnostics, was the same for the D and D-T plasmas. Calculations showed negligible absorption of the ICRF power by either the secondharmonic D or the third-harmonic T resonance in either case.…”