Low Recycling Divertor for JET Burning Plasma Regime ($P_{\mathrm{DT}}$ > 25 MW, $Q_{\mathrm{DT}}$ > 5), Insensitive to Plasma Physics

Abstract

Lasting for already six decades, the current high recycling approach to tokamak fusion is still unable to demonstrate the fusion gain factor Q <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DT</sub> = 1, which is the minimal milestone on the path to fusion energy. Clearly, an alternative approach is needed. Recently, such an approach was proposed as the low recycling regime with plasma pumping by continuously flowing liquid lithium (24/7-FLiLi) and physics of a burning plasma was described in application to the JET tokamak. This article complements the plasma physics by consideration of feasibility and specifics of the low recycling divertor (LRD). Its significant difference from existing high recycling divertors is in the absence of a sheath potential on the open field lines, resulting in small angle impingement to the target surfaces by high energy plasma particles. For the first time, this article presents the design guidance for LRD suitable for JET-like tokamak. Being the only new element in the machine, the LRD with other existing JET facilities, e.g., neutral beam power (NBI) P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">NBI</sub> = 4 MW, E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">NBI</sub> = 120 keV, opens up the opportunity for demonstration of fusion power P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DT</sub> > 25 MW, Q <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DT</sub> > 5 and of outstanding tritium burn up, exceeding 7%.