C60-fullerene composite plasma jets formation and acceleration for application to disruption mitigation and magneto-inertial fusion

Abstract

We present the progress on the development of a new idea of using high-Mach number high-density composite plasma jets from coaxial plasma guns for disruption mitigation in tokamak1 and magneto-inertial fusion2 (MIF). The key element of the idea is the solid state pulsed power source with TiH 2 (or TiDT) grains and C 60 micron size powder3. Very fast injection of the molecular gas mixture provided by hydrogen release and sublimation of C 60 into the plasma gun is achieved by a special filter grid with supersonic Laval nozzles. The estimations based on the physical models of TiH2 grains heating, C 60 powder sublimation, molecular gas injection, mass separation, and plasma slug acceleration will be detailed. For disruption mitigation, our calculations show that the plasma gun is able to provide the required impurity mass1 (∼1–2 g) and the ram pressure to penetrate the tokamak hot plasma and to overcome the confining magnetic field pressure. Core tokamak plasma penetration can be achieved and impurity mass delivered in less than 1 ms, as required by ITER tokamak. The magnetized target fusion (MTF) plasma for MIF is created by injecting two high-Mach number (M≫5) high-density (≫1017 cm−3) plasma jets composed of fuel (D-T) and “pusher” (C 60 /C) along the axis of a pulsed magnetic (∼1–2 T) mirror into a metallic cylindrical liner. The high-density (∼1018 cm−3) cylindrical MTF created by head-on collision and stagnation in the magnetic field is compressed radially by the Z-pinch of the liner and prevented to expand axially by the incoming C 60 /C end-plugs. We estimated that, due to the much longer MTF axial dimension (∼30 cm) as compared to other inertial confinement fusion plasmas, the electron thermal conduction time to the C 60 /C end-plugs is longer than liner implosion time.