A novel double hohlraum target to create a moderately coupled plasma for ion stopping experiments

Abstract

We present a new double hohlraum target for the creation of a moderately coupled (0.1<Γ<1) carbon plasma for energy loss and charge state measurements of projectile ions interacting with this plasma. A spherical cavity of 600μm in diameter is heated with a 150-J laser pulse (λL=527nm) within 1.2ns to produce a quasi-Planckian X-ray source with a radiation temperature of Tr≈100eV. These X-rays are then used to heat volumetrically two thin carbon foils in a secondary cylindrical hohlraum to a dense plasma state. An axi-symmetric plasma column with a free-electron density of up to 8×1021cm-3, a temperature of T≈10eV, and an average ionization degree of Z≈3 is generated. This plasma stays in a dense and an almost uniform state for about 5ns. Ultimately, such targets are supposed to be used in experiments where a heavy ion beam is launched through the sample plasma, and the ion energy losses as well as the charge distributions are to be measured. The present paper is in a certain sense a symbiotic one, where the theoretical analysis and the experimental results are combined to investigate the basic properties and the prospects of this type of plasma targets.