A diagnostic method for both plasma ion and electron temperatures under simultaneous incidence of charge-exchange particles and x rays into a semiconductor detector array

Abstract

An idea for using semiconductor detectors to simultaneously observe both plasma ion Ti and electron Te temperatures is proposed. The idea is also experimentally verified in tandem-mirror plasma shots. This method is developed on the basis of an alternative “positive” use of a semiconductor “dead layer” as an energy-analysis filter. Filtering dependence of charge-exchange neutral particles from plasmas on the thickness of a thin (on the order of nm thick) SiO2 layer is employed for analyzing Ti in the range from hundreds to thousands of eV. Even under the conditions of simultaneous incidence of such particles and x rays into semiconductor detectors, the different dependence on their penetration lengths and deposition depths in semiconductor materials makes it possible to distinguish particles (for Ti) from x rays (for Te). In this letter, proof-of-principle plasma experiments for the proposed idea are carried out to verify the availability of this concept of distinguishing and identifying each value of Ti and Te by the use of various thin filtering materials prior to the use of thinner dead layers.