High yield inertial fusion design for a z-pinch accelerator

In this paper we discuss design calculations for high yield inertial fusion capsules, indirectly driven by a double-ended z-pinch-driven hohlraum radiation source. The z-pinches are imploded by a high current (- 60 MA) accelerator while enclosed within a hohlraum. Radial spoke arrays and shine shields isolate the capsule from the pinch plasma, magnetic field and direct x-ray shine. Our approach places minimal requirements on z-pinch uniformity and stability, usually problematic due to magneto- Rayleigh Taylor (MRT) instability. The hohlraum smooths the radiation field at the capsule, even in the presence of large millimeter scale inhomogeneities of the pinch and the high-spatial-frequency pertur- bation of the spoke array. The design requires simultaneity and reproducibility of the x-ray output to 5- 10%, however. Reproducibility at this level may be achievable based on experience with the Z and Sat- urn accelerators. Recent Z experiments also suggest a method for generating the required x-ray pulse shape, through implosion of a multi-shell z-pinch. X-ray bursts are calculated and observed to occur at each shell collision. Variation of shell masses and radii allows considerable latitude for creating the desired pulse shape. For the design considered, a capsule absorbing 1 MJ of x-rays at a peak drive tem- perature of 210 eV is found to have adequate stability and produces 400 MJ of yield. A larger capsule with slightly longer drive and similar peak temperature absorbs 2 MJ with a yield of 1200 MJ