Z-Pinch Generated X-Rays in Static-Wall Hohlraum Geometry Demonstrate Potential211 for Indirect-Drive ICF Studies

摘要

Hohlraums of full ignition scale (6-mm diameter by 7-mm length) have been heated211u001eby x-rays from a z-pinch target on Z to a variety of temperatures and pulse 211u001eshapes which can be used to simulate the early phases of the National Ignition 211u001eFacility (NIF) temperature drive. The pulse shape is varied by changing the on-211u001eaxis target of the z pinch in a static-wall-hohlraum geometry (Fusion TechnoL 211u001e35,260 (1999)). A 2-pm-thick walled Cu cylindrical target of 8-mm diameter filled 211u001ewith 10 mg/cm3CH, for example, produces foot-pulse conditions of -85 eV for a 211u001eduration of -10 ns, while a solid cylindrical target of 5-mm diameter and 14-211u001emg/cm3CH generates first-step-pulse conditions of -122 eV for a duration of a few 211u001em. Alternatively, reducing the hohlraum size (to 4-mm diameter by 4-mm length) 211u001ewith the latter target has increased the peak temperature to -150 eV, which is 211u001echaracteristic of a second-step-pulse temperature. In general, the temperature T 211u001eof these x-ray driven hohlraums is in agreement with the Planckian relation T-211u001e(P/A) is the measured x-ray input power and A is the surface area of the 211u001ehohlraum. Fully-integrated 2-D radiation-hydrodynamic simulations of the z pinch 211u001eand subsequent hohlraum heating show plasma densities within the useful volume of 211u001ethe hohlraums to be on the order of air or less.