Development of Novel Spectroscopic Diagnostics for Plasma Radiation Sources

Abstract : This report gives the details of experiments performed to measure the levels and the angular distribution of oscillating electric fields in an aluminum plasma produced by the Phoenix advanced pulsed radiation source. The electric field values were obtained by measuring the L (beta), L (gamma), L (sigma), and L (epsilon) line profiles of Al XIII and fitting the profiles to a model for the Phoenix plasma source. The model attempts to take into account all of the mechanisms which lead to broadening of the observed profiles for the conditions present in the Phoenix plasma. The main broadening mechanisms used in the model include Doppler broadening from the bulk motion of the plasma, stark broadening by electrons, ions and oscillating electric fields, and self absorption. In addition to the flat crystal and two curved crystal spectrometers used to measure the lines profiles, a pinhole camera and a four frame camera were used to try and obtain the size of the most dense retions in the plasma. The size of these "hot spots" were found to be less than 500 microns. From fits of the experimental profiles to the data, the level of anomalous electric fields in the Phoenix plasma source were found to be Eo = 1 - 9 Gv/cm, indicative of a strong Langmuir turbulence. The fields were also found to develop anisotropically, primarily along the direction of the discharge.