Imploding plasma liners as a standoff driver for magneto-inertial fusion

Abstract

Summary form only given. By enabling a fusion ignition regime with plasma density intermediate between that of MFE and ICF, magneto-inertial fusion (MIF) offers the potential for a low-cost development path to fusion energy. A standoff driver that eliminates repetitive destruction of solid materials (e.g., metal liners or transmission lines) further improves the attractiveness of MIF. With the Plasma Liner Experiment (PLX) starting experimental operation at LANL, we are exploring the feasibility of forming imploding plasma liners using an array of spherically convergent dense plasma jets. PLX is focused on the investigation (at modest pulsed power energies ≤1.5 MJ) of scientific issues such as jet propagation/merging and plasma liner formation, convergence, and stagnation, including the validation of simulations that are needed to help guide experimental campaigns, interpret PLX data, and design future experiments. In the near term, PLX will focus on the generation of cm/μs-scale plasmas in the Mbar range for fundamental HEDLP science. There are proposed plans to introduce magnetic fields via laser generated beat wave current drive and to field astrophysical jet and collisionless shock related experiments. Initial 1D radiation-hydrodynamic simulations indicate that a ~375 kJ imploding plasma liner (assumed to be formed by 30 Ar plasma jets each initially with n~10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">17</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> , v~50 km/s, E~12 kJ) results in peak stagnation pressure of ~1.3 Mbar with sustained pressure ~0.1 Mbar for over ~4 μs. The simulations also show that an MIF-relevant pressure of ~50 Mbar sustained for ~0.6 μs may be achieved with v~150 km/s and liner kinetic energy of ~50 MJ. Inclusion of additional physics, e.g., 3d effects, will undoubtedly increase the liner and stored energy requirements, which nevertheless ought to remain relatively modest. Furthermore, theoretical analysis indicates that the dwell time can be significantly increased with proper liner profile shaping, adding versatility to the plasma liner concept. This presentation will provide a concept-level description of plasma liner driven MIF, an overview of PLX status/plans, and a summary of the initial theoretical/modeling results.