Determination of x-pinch micropinch parameters using a slit-step-wedge camera

Summary form only given. X pinch experiments with a streak camera have shown that the X pinch X-ray burst starts with strong continuum in the 1-5 keV spectral band. The plasma conditions at that initial moment are still unknown and are difficult to determine. In this stage most X pinches do not radiate intense spectral lines of multicharged ions, and so plasma spectroscopic techniques based on emission lines are not applicable. Measurements based on the X pinch continuum radiation are potentially useful. The common way to do this is to determine the exact shape of the continuum spectrum and compare it with calculated spectra for different plasma conditions. There are several experimental problems in such measurements. First of all, spectrally well calibrated detectors covering wide spectral bands are required. Secondly, the initial stage must be "extracted" from the total micropinch radiation. That can be done in space, in time or in spectrum. Spatially, the radiating area (source size) in the first stage is very small (~1 mum) and devices with extremely high spatial resolution would have to be used. In this paper we describe a new technique of plasma temperature determination based on the use of a device called a slit-step-wedge camera (SSW-camera) that is based upon spectrum and source size. The SSW-camera enables a comparison of intensities of X-ray radiation passed through filters with K-edges in the spectral band being studied. This technique enables us to avoid absolute detector calibration and to increase temperature measurement accuracy. Experimental results of micropinch temperature determination for X pinches made from different wire materials are presented. It is shown that with the assumption of a Planckian spectrum for the micropinch radiation, the value of the temperature typically lies in the interval 400-800 eV, and sometimes reaches 1 keV