On a burning plasma low recycling regime with P _DT = 23–26 MW, Q _DT = 5–7 in a JET-like tokamak

Abstract

The recent invention of a continuously flowing liquid lithium system, called 24/7-FLiLi, opens the opportunity to design a plasma pumping divertor which can significantly suppress plasma edge cooling by recycling. The paper describes the expected performance of deuterium–tritium burning plasma with low recycling using a tokamak of JET size, magnetic field and plasma current as an example. So far, only the technological aspects of flowing lithium have been tested on the HT-7 and EAST tokamaks (ASIPP, Hefei, China) with no attempts to create the low recycling regime. The compatibility of 24/7-FLiLi with tokamak plasma was confirmed and some mistakes in the design were revealed, thus, requiring another fabrication approach. Now, with the proper design of the Li system, recycling as low as 0.5 seems to be achievable. The suppression of plasma cooling by recycling in combination with neutral beam injection (NBI) for core plasma fueling by energetic particles automatically leads to ‘the best possible confinement regime’, uniquely compatible with burning plasma. This paper outlines the conceptual details of the 24/7-FLiLi divertor for a JET size tokamak. The main focus is in regard to the physics of the low recycling regime as well as to the expected performance of the burning plasma. In comparison with the results of 1994 on TFTR and 1997 on JET, the projected performance is astonishing: fusion power –26 MW, fusion efficiency , tritium burn up 7.8%–8.7% with modest NBI power MW, and energy keV. This new regime could resolve the outstanding plasma physics issues related to burning plasma that are unsolvable with the currently dominant approach.

Investigating the role of edge neutrals in exciting tearing mode activity and achieving flat temperature profiles in LTX-β

“…It is worthwhile to note here that lithium as a first wall will be liquid in a reactor. Hence, extremely high edge temperatures would indeed be part of the proposed lowrecycling reactor approach, while the unique properties of liquid lithium would make it feasible, as discussed in previous works [5,6,34].…”

“…Due to strong hydrogen retention and lower recycling of lithium, edge cooling can be minimized, and the plasma is thermally decoupled from the wall, permitting the edge temperature to approach the core temperature [4]. The resulting low or zero temperature gradients eliminate thermal conduction, and energy losses become limited by particle diffusion [5,6]. Reduction or elimination of the core temperature gradient removes the temperature gradient driven instabilities like micro-tearing mode [7][8][9], electron and ion temperature gradient modes [10][11][12][13][14].…”

First lithium experiments in HIDRA and evidence of helium retention during quasi-steady-state stellarator plasma operations

“…The ramifications are then that the machine would be cheaper in terms of its power and monetary budgets [51]. For example, it has been calculated by Zakharov et al that a low recycling burning plasma device could be built at the size scale of JET [52]. This would be a P DT = 23-26 MW machine with a Q DT of 5-7 [51].…”

Magnetohydrodynamics in free surface liquid metal flow relevant to plasma-facing components

“…These designs broadly fall under two categories: fast-flowing and slow/static LM surfaces. Slow/static LM-PFCs, being self-healing, primarily target improving the plasma performance [18] and protecting the underlying substrate [19]. Heat is transferred from the liquid to the solid through thermal conduction and dissipated by an active cooling mechanism.…”