One-dimensional radiation-hydrodynamic scaling studies of imploding spherical plasma liners

Abstract

*awetj@lanl.govOne-dimensional radiation-hydrodynamic simulations are performed to develop insight into the scaling of stagnation pressure with initial conditions of an imploding spherical plasma shell or "liner." Simulations reveal the evolution of high-Mach-number (M), annular, spherical plasma flows during convergence, stagnation, shock formation, and disassembly, and indicate that cmand µs-scale plasmas with peak pressures near 1 Mbar can be generated by liners with initial kinetic energy of several hundred kilo-joules. It is shown that radiation transport and thermal conduction must be included to avoid non-physical plasma temperatures at the origin which artificially limit liner convergence and thus the peak stagnation pressure. Scalings of the stagnated plasma lifetime (τ stag ) and average stagnation pressure (P stag , the pressure at the origin, is also found for a wide range of liner-plasma initial conditions.

Experimental evidence for collisional shock formation via two obliquely merging supersonic plasma jets

“…5,12,49,51 A concern is that jet merging would lead to shock formation and heating that would significantly decrease M (compared to its initial value) and, thus, implosion performance. The results reported here are encouraging in that the experimentally inferred increases in T e [by up to a factor of (2.3 eV)/(1.4 eV) = 1.64] andZ (by up to a factor of 1.4/0.94 = 1.49) lead to an increase in C s ∼ (ZT e ) 1/2 of 56% (we caution that more data is needed to establish a more accurate upper bound on T e in the merged case).…”

“…In our first set of experiments, the parameters and evolution of a single propagating plasma jet were characterized in detail. 2 The next step beyond this work, a thirty-jet experiment to form and assess spherically imploding plasma liners, has been designed 3,5,12 but not yet fielded. A related jet-merging study [13][14][15] was also conducted recently by HyperV Technologies.…”

Tendency of spherically imploding plasma liners formed by merging plasma jets to evolve toward spherical symmetry

“…The initial temperature and velocity are set to the same values as the uniform case, while the density (ρ j0 = 5x10 -3 kg/m 3 ) is scaled so that the total mass matches that of the uniform liner. To be consistent with the 1D study by Awe et al 12 , the jet radius (r j0 = .05 m) is chosen based on the expected size of the jets discussed in that paper. The estimate provided a means for calculating the merging radius for the initialization of the 1D simulations and was selected based on the expected jet radius to be produced by pulsed plasma accelerators 19 .…”

Possible energy gain for a plasma-liner-driven magneto-inertial fusion concept

“…The efficiency of plasma guns creating and launching the jets can be optimized for a given velocity. Several recent studies have investigated various aspect of PJMIF: [11][12][13][14][15][16][17][18][19][20][21]. Methodical experimental efforts were initiated at Los Alamos National Lab (LANL) [22,-24] in collaboration with Hyper V Technologies [10,25], and the University of New Mexico [26].…”