A simple, zero-dimensional model describing the temporal behaviour of an imploding-shell, magnetized fuel inertial confinement fusion target is formulated. The model includes effects not normally considered in inertial confinement fusion such as magnetic back-pressure on the imploding shell, magnetic reduction of thermal conductivity, magnetic diffusion, and Ohmic heating. The model is simple enough to permit a survey of the parameter space available for magnetized fuel by computing the behaviour of thousands of targets. The survey predicts the existence of a totally new region in parameter space where significant thermonuclear fuel burn-up can occur. The new region is characterized by very low fuel densities, very low implosion velocities, and,most important, driver requirements reduced by several orders of magnitude, suggesting that “break-even” experiments may be possible with existing inertial confinement fusion drivers. The computed results are in reasonable agreement with more complete two-dimensional magnetohydrodynamic simulations.
Ignition of sub-milligram fusion targets is critically dependent on DT temperature, density, radius, radiation temperature, implosion velocity, and other parameters that characterize the target and its implosion. This paper discusses the interplay of such major physical processes as bremsstrahlung, Compton scattering, DT fusion, hydrodynamics, and thermal conduction during the implosion and especially near turnaround where the potential for ignition or failure most critically depends on the small differences between large rates of energy loss and gain. The phase plane analysis presented here proves to be most advantageous in understanding the DT ignition problem. Four examples are discussed in order to illustrate the interplay of the various physical processes.
A one dimensional parameter study of a Magneto-Inertial Fusion (MIF) concept indicates that significant gain may be achievable. This concept uses a dynamically formed plasma shell with inwardly directed momentum to drive a magnetized fuel to ignition, which in turn partially burns an intermediate layer of unmagnetized fuel. The concept is referred to as Plasma Jet MIF or PJMIF. The results of an Adaptive Mesh Refinement (AMR) Eulerian code (Crestone) are compared to those of a Lagrangian code (LASNEX). These are the first published results using the Crestone and LASNEX codes on the PJMIF concept
Magnetized target fusion (MTF) consists of the hydrodynamic compaession of a wall confined, hot, magnetized DT plasma to ignition conditions. The most notable MTF experiments were the Phi-target done on an electron beam machine at Sandia National Lab (Widner, 1977), but imploding liner fusion and some impact fusion schemes 5hare the same principles as MTF. MTF takes advantage of two benefits of a magnetic field in a plasma: reduction of the thermal conductivity (Landshoff, 1945) and potentially the enhancement of the charged particle reaction product energy deposition in the plasma (Guskov, et al., 1984). However, even in the absence of self heating (i.e., no D T alpha energy deposition), parameter studies have shown that targets with gains as high as ten are possible (Lindemuth and kirkpatrick, 1983). Synchrotron radiation is an undesired consequence of the field, but it is unimportant for MTF (Kilcrease, 1988). To reduce the radiative energy loss from the plasma so that ronduction is the major energy loss mechanism (even when supressed by the magnetic field) the initial density of the DT is much lower than thatt used for inertial confinement fusion (ICF). This makes the targets larger, and the reduced losses allow a lower compression rate, so that the implosion time can be long and the necessary power and intensity on target can be very low. The parameter space for MTF is intermediate in density and time scales between those of IC17 and magnetic-confinement for fusion energy (MFE). The energy required for ignition of a magnetized target is comparable to that for an ICF target with the same mass of DT, but the power and power density required are much less, so that some existing pulsed power machines may be capable of igniting an MTF target. The igniition of a cold fuel layer by a burning central magnetized fuel should significantly increase the gain of an magnetized fuel target (Lindemuth and Kirkpatrick, 1991).We report on some elementary analyses, parameter studies, and computer simulations, as well as a few relevant experiments.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.