Development of a spectroscopic technique to measure electric fields in plasma radiation sources

The intensity ratio of forbidden-to-allowed transitions in Li and He have been used to determine both turbulent electric fields due to plasma instabilities and quasi-static applied electric fields in low density and temperature plasmas. HY-Tech proposes to extend this technique to the plasma temperatures and densities encountered in plasma radiation sources. In this case uv spectra of Li-like and He-like ions of low Z elements will be measured with a grazing incidence grating spectrometer during the implosion phase of the pinch. A crystal spectrometer would be used to measure Li-like Ar spectra in the assembled pinch. Quasi-static electric fields inferred from these measurements would provide information about current channels flowing in the load, and turbulent electric fields would indicate the role of plasma instabilities in coupling the generator energy to the pinched plasma. In particular, the line broadening of the Ar XVI spectra at 18.5 angstroms would provide information about the coronal plasma that surrounds the core. This diagnostic technique would provide insight into the generator-load coupling processes which could be used to benchmark predictions of model calculations not previously open to scrutiny.