Removing gaseous contaminants in {sup 3}He by cryogenic stripping

The Tritium Operations Group at LLNL, Tritium Facility has recently developed a {sup 3}He recovery system to remove argon, xenon, neon, hydrogen, and all other contaminants from the {sup 3}He stream in an Accelerator Production of Tritium (APT) experimental apparatus. In this paper the authors will describe in detail the background information, technical requirements, the design approach, and the results of their experimental tests. The authors believe this gas purification system may have other applications as it provides at a reasonable cost an efficient method for purification of gaseous helium

A Search for Magnetic Resonance of Ruthenium in Octahedral Coordination with Oxygen

We have searched, without success, for microwave-frequency magnetic resonance of Ru4+ and Ru5+ ions in a number of materials for which the Ru are in octahedral coordination with six oxygen. A number of ruthenates including RuO2, SrRuO3, Sr3Ru2O7, Ba3Ru2NiO9, Ba2GdRuO6, Sr2YRuO6, and Ba2YRuO6, which include paramagnetic, antiferromagnetic, and ferromagnetic spin configurations, have been examined. We present analysis which shows that the last material provides an optimized opportunity to detect antiferromagnetic Ru resonance for temperatures less than TN=39 K; none is detected for frequencies as high as 35 GHz in magnetic fields up to μoH=2 T. This result indicates that the antiferromagnetic magnon energy gap exceeds the energy associated with the signal frequency. SrRuO3 is a known ferromagnetic contaminant phase in the rutheno-cuprates. We report neutron diffraction measurements on SrRuO3, finding it to have an appreciable local moment at low temperatures, 1.25(0.1)μB; this moment vanishes near 165 K. We show that it also fails to exhibit ferromagnetic resonance, at least in the range 10-35 GHz. As a result of the diffraction and resonance studies, it is concluded that the reports of ferromagnetic resonance in superconducting rutheno-cuprates are actually due to antiferromagnetically ordered Cu in these materials, and the presence of even a few percent of SrRuO3 as a potential contaminant is of little importance

The mercury laser system – An average power, gas-cooled, Yb:S-FAP based system with frequency conversion and wavefront correction

We report on the operation of the Mercury laser with fourteen 4 $\times$ 6 cm$^{2}$ Yb:S-FAP amplifier slabs pumped by eight 100 kW peak power diode arrays. The system was continuously run at 55 J and 10 Hz for several hours, (2$\times$10$^{5}$ cumulative shots) with over 80% of the energy in a 6 times diffraction limited spot at 1.047 $\mu$m. Improved optical quality was achieved in Yb:S-FAP amplifiers with magneto-rheological finishing, a deterministic polishing method. In addition, average power frequency conversion employing YCOB was demonstrated at 50% conversion efficiency or 22.6 J at 10 Hz