High-temperature dynamic hohlraums on the pulsed power driver Z

In the concept of the dynamic hohlraum an imploding Z pinch is optically th ick to its own radiation. Radiation may be trapped inside the pinch to give a radiation temperature inside the pinch greater than that outside the pin ch. The radiation is typically produced by colliding an outer Z-pinch liner onto an inner liner. The collision generates a strongly radiating shock, a nd the radiation is trapped by the outer liner. As the implosion continues after the collision, the radiation temperature may continue to increase due to ongoing PdV (pressure times change in volume) work done by the implosio n. In principal, the radiation temperature may increase to the point at whi ch the outer liner burns through, becomes optically thin, and no longer tra ps the radiation. One application of the dynamic hohlraum is to drive an IC F (inertial confinement fusion) pellet with the trapped radiation field. Me mbers of the dynamic hohlraum team at Sandia National Labs have used the pu lsed power driver Z (20 MA, 100 ns) to create a dynamic hohlraum with tempe rature linearly ramping from 100 to 180 eV over 5 ns. On this shot zp214 a nested tungsten wire array of 4 and 2 cm diam with masses of 2 and 1 mg imp loded onto a 2.5 mg plastic annulus at 5 mm diam. The current return can on this shot was slotted. It is likely the radiation temperature may be incre ased to over 200 eV by stabilizing the pinch with a solid current return ca n. A current return can with nine slots imprints nine filaments onto the im ploding pinch. This degrades the optical trapping and the quality of the li ner collision. A 1.6 mm diam capsule situated inside this dynamic hohlraum of zp214 would see 15 kJ of radiation impinging on its surface before the p inch itself collapses to a 1.6 mm diam. Dynamic hohlraum shots including pe llets were scheduled to take place on Z in September of 1998. (C) 1999 Amer ican Institute of Physics. [S1070-664X(99)90905-9].