Mixed element plasmas in a Z-pinch on Double-EAGLE: radiation tunability and reliability

Summary form only given, as follows. We have recently completed experiments on the Double-EAGLE generator at Physics International which have demonstrated that the radiation output from mixed-element, Z-pinch plasmas is wavelength tunable. Our tests used mixtures of argon and krypton gas, ranging from 50% to 98% Ar (balance Kr). Measurements of the resulting output portions showed that Kr L-shell emissions (centered about 1.8 keV) dominate the Ar K-shell emissions (above 3.1 keV) until very high portions (90%) of Ar gas are used. Not until a 95% Ar mixture is used does the balance tip in favor of the Ar emissions. We believe that the lower energy (as well as the larger number) of L-shell emission channels for a krypton plasma provide more accessible energy escape mechanisms than the K-shell transitions of argon. Density and temperature values of the mixed plasmas inferred from spectral measurements will be presented. To demonstrate the reliability of the mixed Ar-Kr source, an extensive series of tests was performed using the 80% Ar, 20% Kr mix. This reliability demonstration showed that over a series of 28 shots, the output fraction for Ar X-rays averaged 26% with a standard deviation of 4%. Furthermore, the total X-ray output was reliable also. If we eliminate the first three tune-up shots and the three low-yield shots (due to excessive jitter between the two modules of Double-EAGLE), the total X-ray yield (Ar Kand Kr L-) had a standard deviation of 11%.