Measurements of plasma temperature in indirect drive targets from the shock wave velocity in aluminum in the Iskra-5 fac
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STICS OF HIGHTEMPERATURE PLASMAS
Measurements of Plasma Temperature in Indirect Drive Targets from the Shock Wave Velocity in Aluminum in the Iskra5 Facility V. V. Vatulin, N. V. Zhidkov, A. G. Kravchenko, P. G. Kuznetsov, D. N. Litvin, V. V. Mis’ko, A. V. Pinegin, N. P. Pleteneva, A. V. Senik, K. V. Starodubtsev, and G. V. Tachaev AllRussia Research Institute of Experimental Physics, Russian Federal Nuclear Center, Sarov, Nizhni Novgorod oblast, 607188 Russia Received July 17, 2009
Abstract—Results are presented from the development of a method for measuring plasma temperature in indirect (Xray) drive targets by recording the shock wave velocity in the Iskra5 facility. The samples under investigation were irradiated by Xrays in a converter box, and the shock wave velocity was determined from the time at which the wave reached the back surface of the sample and the surface began to emit visible radi ation. This emission, in turn, was detected by a streak camera. The results of experiments on the interaction of X radiation with a hot dense plasma, as well as the accompanying gasdynamic processes in aluminum samples, are analyzed both theoretically and numerically. In experiments with Al and Pb samples, the shock wave velocity was measured to vary in the range U = 8–35 km/s, and the range of variation of the temperature of the box walls was measured to be Te = 140–170 eV. DOI: 10.1134/S1063780X10050065
1. INTRODUCTION One of the tasks of experiments on highpower laser devices with indirect (Xray) drive targets is to determine the plasma temperature within the con verter box. The most widely used methods for temper ature measurements are Xray techniques that record the absolute fluxes of X radiation from the target in the range 0.1–1.5 keV [1, 2]. Measurements of the velocity of a shock wave (SW) in the target also provide a fairly reliable tool for deter mining the plasma temperature within the converter box [3–5]. In this case, the SW velocity measured in a material is recalculated to the pressure exerted on the sample and to the plasma temperature. The usual practice is to use aluminum foils as a loaded sample. We carried out numerical and theoretical analysis of experiments on the interaction of X radiation with a hot dense plasma and the gasdynamic processes occurring in aluminum samples in the Iskra5 facility. Based on the results of our calculations, we obtained an approximating dependence of the mean velocity of an SW in aluminum on the plasma temperature at the surface of an aluminum sample heated by an Xray flux. Earlier, in the Iskra5 laser facility, a method for measuring the SW velocity was developed for experi mental studies of the states of matter when the samples were directly irradiated by laser light [6]. We used this technique to create a method for measuring the plasma temperature. To adapt to the spherical geome
try of the interaction chamber, we constructed a new optical scheme with which to record the emission from a sample under the action of an SW and fabri cated a strea
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