Advances on the High Field Ultra-Low Aspect Ratio Tokamak (HF-ULART)

The High Field Ultra-Low Aspect Ratio Tokamak (HF-ULART) is a medium-size device proposal[1]. The major objective is to explore the high beta and plasma pressure under broad range of toroidal field and operational modes, yet using present day technology. This might be one of pathway scenarios for a potential ultra-compact pulsed neutron source (UCP-NS) based on the spherical tokamak (ST) concept, which may lead to more steady-state NS or even to a fusion reactor, via realistic design scaling. The HF-ULART pulsed mode operation is created by applying quasi-simultaneous adiabatic compression (AC) in both minor and major radius of a very high beta plasma, possibly with further help of passive-wall stabilization, as envisaged in the RULART concept[2]. This may help the revival of the studies of the AC technique in tokamaks. In addition, by similarities, studies in HF-ULART as a UCP-NS may also help to test the feasibility of the compact NS via the spheromak concept, which also uses the AC technique[3]. Simulations of AC and in plasma equilibrium and stability in HF-ULART plasmas will be presented.

[1] C. Ribeiro IAEA-RUSFD 2017

[2] C. Ribeiro Proc. 26th SOFE 2015

[3] S. Woodruff et al, Fus. Sci. Tech.-2017