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.

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We apply a few simple first-principles equations to identify the parameter space in which controlled fusion might be possible. Fundamental physical parameters such as minimum size, energy, and power as well as cost are estimated. We explain why the fusion fuel density in inertial confinement fusion is more than 10 11 times larger than the fuel density in magnetic confinement fusion. We introduce magnetized target fusion as one possible way of accessing a density regime that is intermediate between the two extremes of inertial confinement fusion and magnetic confinement fusion and is potentially lower cost than either of these two.

In this community white paper, we describe an approach to achieving fusion which employs a hybrid of elements from the traditional magnetic and inertial fusion concepts, called magneto-inertial fusion (MIF). The status of MIF research in North America at multiple institutions is summarized including recent progress, research opportunities, and future plans.Keywords Magneto-inertial fusion Á Magnetized target fusion Á Liner Á Plasma jets Á Fusion energy Á MagLIF DescriptionMagneto-inertial fusion (MIF) (aka magnetized target fusion) [1][2][3] is an approach to fusion that combines the compressional heating of inertial confinement fusion (ICF) with the magnetically reduced thermal transport and magnetically enhanced alpha heating of magnetic confinement fusion (MCF). From an MCF perspective, the higher density, shorter confinement times, and compressional heating as the dominant heating mechanism reduce the impact of instabilities. From an ICF perspective, the primary benefits are potentially orders of magnitude reduction in the difficult to achieve qr parameter (areal density), and potentially significant reduction in velocity requirements and hydrodynamic instabilities for compression drivers. In fact, ignition becomes theoretically possible from qr B 0.01 g/cm 2 up to conventional ICF values of qr * 1.0 g/cm 2 , and as in MCF, Br rather than qr becomes the key figure-of-merit for ignition because of the enhanced alpha deposition [4]. Within the lower-qr parameter space, MIF exploits lower required implosion velocities (2-100 km/s, compared to the ICF minimum of 350-400 km/s) allowing the use of much more efficient (g C 0.3) pulsed power drivers, while at the highest (i.e., ICF) end of the qr range, both higher gain G at a given implosion velocity as well as lower implosion velocity and reduced hydrodynamic instabilities are theoretically possible. To avoid confusion, it must be emphasized that the wellknown conventional ICF burn fraction formula does not apply for the lower-qr ''liner-driven'' MIF schemes, since it is the much larger mass and qr of the liner (and not that of the burning fuel) that determines the ''dwell time'' and fuel burnup fraction. In all cases, MIF approaches seek to satisfy/ exceed the inertial fusion energy (IFE) figure-of-merit gG * 7-10 required in an economical plant with reasonable recirculating power fraction. A great advantage of MIF is indeed its extremely wide parameter space which allows it greater versatility in overcoming difficulties in implementation or technology, as evidenced by the four diverse approaches and associated implosion velocities shown in Fig. 1.MIF approaches occupy an attractive region in thermonuclear q-T parameter space, as shown in a paper by

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