Spectroscopy of composite Z-pinches in the Angara-5-1 device

Results are presented from spectroscopic studies of a composite Z-pinch in the Angara-5-1 device. A load that was used to create the composite Z-pinch consisting of an outer annular gas (argon or propane) shell and a solid in ner cylinder (fiber) made from a foamlike material (agar-agar with the addi tion of KCI or NaCl) with an initial density of similar to 10(-2) g/cm(3). Zn experiments, the intensity of line emission was measured for various she ll compositions and for the shell mass per unit length from 3 to 60 mu g/cm . The fiber mass per unit length varied from 55 to 80 mu g/cm, and the weig ht content of salt additives varied from 30 to 57%. The measurements show t hat the temperature of a substantial fraction of the fiber material is comp arable with the shell temperature. During compression, the electron density and electron temperature of the pinch (gas-jet and fiber) plasma reaches v alues of n(e) approximate to 10(21) cm(3) and T-e approximate to 1 keV, res pectively. The spatially resolved spectroscopy shows that luminous regions of the gas-jet and fiber ions coincide with each other and occupy at most o ne-half of the pinch length (about 5 mm for Ar ions and 3-4 mm for K and CI ions). The measurements of the electron temperature near the cathode (simi lar to 500 eV, which is lower than the electron temperature in the central part of the pinch) show the presence of a temperature gradient along the pi nch axis. Possible mechanisms for fiber heating are discussed.