Determination of total gas in lithium tritide-deuteride compounds

Abstract

Lithium tritide-deuteride samples are enclosed in a copper foil and decomposed by heating to 850°C in a copper reaction tube in vacuum. The temperature and pressure of the evolved gas, collected in a measured volume using a Toepler pump, are measured to determine the total moles of gas released from the sample. The gas is transferred to a removable sample bulb and, if required, analyzed for gaseous constituents by mass spectrometry. Based on 14 total gas determinations for a lithium deuteride sample, the calculated relative standard deviation was 1.0% and the estimated bias was Pressure regulator, one, low-pressure, capable of regulation at 2.5 to 3.7 kPa (10-15 in. of water); and one, capable of regulation at 103 kPa (15 psi). Spatula, vibrating type preferred for loading copper foils. Total gas analysis apparatus, consisting of the following items, assembled as shown in Fig. 1. Deaiccant tube, borosilicate glass, filled with anhydrous magnesium perchlorate and plugged with glass wool at each end to contain reagent dust. Furnace, resistance, for heating 9.5-mm (0.375-in.) copper tube to 850°C. Laboratory jack, for adjusting furnace height. Magnet, for operating sample dumper. Mercury diffusion pump, pumping speed ~120 i/s or faster. Mercury reservoir Micromanometer, with sensor head that can be used with tritium (MKS single-sided head or equivalent). Reaction tube, made from hard-drawn copper tubing, 9.5-mm (0.375-in.)-o.d., 1.65-mm (0.065-in.) wall thickness, and 203-mm (8-in.)-long, sealed at one end by flowing helium through the tube while heating the end in a gas-oxygen flame and striking with a hammer. A copper coupling is hard soldered to the other end and the ridge left by the inserted tube is beveled using a 9.5-mm (0.375-in.) counter sink. The other end of the coupling is hard soldered to a Kovar metal-glass seal connected to a 14/35 standard-taper borosilicate glass outer joint. Sample bulbs, 25-m£, equipped with pressure stopcock. Sample dumper Solenoid valves, two, 6-W, 115/230-V, 172-kPa (25-psi), 6.35-mm (0.25-in.) pipe, 5.55-mm (0.218-in.) orifice for activating Toepler pump. Stopcocks, five, straight-bore, 4-mm; two, oblique-bore, 4-mm; and two, oblique-bore, 3-way, 4-mm. Thermocouple gauges, two, 0-to 133-Pa (1-torr). Thermometer, digital or otherwise, readable to 0.1°C. Timers, two, electric, 30-s, wired to solenoid valves so that one controls the vacuum half of the Toepler pump cycle and the other controls the pressure half of the cycle. Toepler pump, 250-m£, with 4-mm, straight-bore, stopcock inserted between bulbs. Tubing, stainless steel, 19-mm (0.75-in.)-o.d. Valves, three, stainless-steel, bellows, with 19-mm (0.75-in.) tube connections, and two metering valves, with 6.35-mm (0.25-in.) tube connections. Reagents Argon, tank. Desiccant, magnesium perchlorate, anhydrous. Grease, silicone. Mercury, distilled. Caution Any work that involves the handling of tritium-containing materials should be done only under approved safe conditions and in laboratories designed for adequate protection of th...