Study of a prototype of a new compact hohlraum configuration at the 1.7 MA UNR zebra generator

A new hohlraum configuration for radiation physics/ICF was proposed [B. Jones et al., PRL 104, 125001 (2010)]. Multiple compact (mm-scale) planar wire array (PWA) sources that surround a central hohlraum allow reduced hohlraum surface area and potentially provide a hotter x-ray environment than in a double-ended scheme with cylindrical arrays. The current multiplication technique became possible because of high impedance of Zebra and increase of the current up to 1.7 MA. We have demonstrated previously that the PWA plasma at stagnation dissipates the magnetic energy greater than ΔL*I²/ 2, operating mainly as a resistor R(t) [V. Kantsyrev et al., Dense Z-pinch 2011 CP]. This allowed us to redistribute the generator current between two magnetically decoupled PWA without significant loss of radiation yields. With half the current flowing through each PWA, the kinetic energy Ek coupled to it, which scales as I², will be 1/4 of the energy coupled to a single PWA carrying the same total current and experiencing the same change of inductance ΔL at implosion. The total Ek delivered to two PWAs at stagnation would thereby be 1/2 of Ek delivered to a single PWA. In experiment, the current was split between two decoupled sources (0.75 MA to each), and the total yield EΣ was at least 85 % compared to total yield ET from single PWA at 1.6 MA. Then, new hohlraum configuration with two decoupled PWAs was tested. The VisRad code (Prism Comp. Sci.) predicted hohlraum radiation temperature >30 eV which correlates with strong hohlraum output radiation (hυ > 17 eV). Scaling using VisRad on different hohlraum multisource configurations for higher current 20 MA scale generators is discussed. The experimental comparison of planar foil liners (another promising x-ray radiator) with PWAs is also presented.