Performance Scaling in Magnetized Liner Inertial Fusion Experiments

Abstract

We present experimental results from the first systematic study of performance scaling with drive parameters for a magnetoinertial fusion concept. In magnetized liner inertial fusion experiments, the burnaveraged ion temperature doubles to 3.1 keV and the primary deuterium-deuterium neutron yield increases by more than an order of magnitude to 1.1 × 10 13 (2 kJ deuterium-tritium equivalent) through a simultaneous increase in the applied magnetic field (from 10.4 to 15.9 T), laser preheat energy (from 0.46 to 1.2 kJ), and current coupling (from 16 to 20 MA). Individual parametric scans of the initial magnetic field and laser preheat energy show the expected trends, demonstrating the importance of magnetic insulation and the impact of the Nernst effect for this concept. A drive-current scan shows that present experiments operate close to the point where implosion stability is a limiting factor in performance, demonstrating the need to raise fuel pressure as drive current is increased. Simulations that capture these experimental trends indicate that another order of magnitude increase in yield on the Z facility is possible with additional increases of input parameters.

Exploring extreme magnetization phenomena in directly-driven imploding cylindrical targets

“…For instance, in this work fuel pre-heating is intentionally not considered as it increases the thermal pressure of the hot-spot at the cost of reducing B-field compressibility. Pre-heating is otherwise essential in the MagLIF design to enhance the neutron yield [28]. Therefore, the proposed research is distinct -albeit complementary-to the current mini-MagLIF studies.…”

“…Due to fuel magnetization and pre-heating, MagLIF aims at nearadiabatic stable cylindrical compression with lower implosion velocity (∼ 100 km/s, instead of > 300 km/s) and lower convergence ratios than conventional ICF. MagLIF has shown promising results through different experimental campaigns by demonstrating thermonuclear neutron generation at fusion-relevant conditions, a high enough fuel magnetization for α-particles trapping [25][26][27] and reporting first performance scaling studies [28].…”

“…Magnetized plasmas are thought to exhibit complex behavior in the electron population and, above resistive-MHD, extended-MHD additionally accounts for temperature-gradientdriven transport -such as the Nernst term moving magnetic fields down electron temperature gradients-and electric-current-driven transport -such as the Hall term moving magnetic fields with the flow of charge-. The Nernst term, in particular, is of great interest to the scientific community, with importance in a broad range of experiments [16,28,[35][36][37] with expectations of plasma demagnetization [23,[38][39][40][41]. Even with its wide applicability, Nernst advection of magnetic field is yet to be directly measured.…”

Self-similar solutions for resistive diffusion, Ohmic heating and Ettingshausen effects in plasmas of arbitrary $β$

“…There are many MIF schemes currently operating, such as the MagLIF experiment at Sandia National Laboratories 18 , where pulsed power is used to implode a beryllium liner onto a laser pre-heated and axially pre-magnetised column of deuterium. MagLIF has observed neutron yields of more than 10 13 , but flux compression has been hampered by the Nernst effect 19,20 . Recent "mini-MagLIF" experiments on OMEGA have attempted to use laser-driven cylindrical implosions to assist with this effort 21 .…”

Perpendicular subcritical shock structure in a collisional plasma experiment

“…This leads to difficulty in defining the critical Mach number (due to the lack of downstream thermodynamic equilibrium) and determining the plasma resistivity. Recent progress in magneto-inertial fusion [13][14][15][16], has stimulated renewed interest in MHD shocks propagating through dense, collision-dominated plasmas. In particular, recent experiments studying the implosion of magnetised inertial confinement fusion capsules have shown an increased yield and anisotropic shock structure [17,18].…”