R. T. Tsugawa

Permeation of helium and hydrogen from glass‐microsphere laser targets

Isothermal outgassing curves of hollow glass microspheres filled with helium, hydrogen, or deuterium gas have been determined. Four million 40–45‐μm soda‐lime glass microspheres, similar to laser‐fusion targets, were filled by gas permeation at 693–763 K and outgassed at 292–573 K. The permeabilities were calculated by an exponential theory, and they agree to an order of magnitude with the literature values. The outgassing curves are not pressure dependent. Two irregularities are apparent. First, the counting of target‐quality individual D‐T–filled microspheres shows a permeability spread of an order of magnitude from one microsphere to the next, which may be caused by variable chemical composition. Second, all the gases show deviations from exponential behavior in the form of tails at long times. Chemical reaction of the hydrogen with the glass, as well as incomplete filling and outgassing, may cause the hydrogen tails; the cause of the helium tails is not known.

Infrared spectra of liquid and solid HT and HD in mixtures with T2

The collision‐induced fundamental vibration–rotation spectra of liquid and solid HT and T2 in a mixture of 50% H and 50% T have been recorded. The spectra of liquid and solid HD in a 90% HD plus 10% T2 mixture have also been observed. The frequencies of the numerous single and double transitions have been compared with those calculated from the known molecular constants. Deep holes have been observed in the Q (O) phonon band of solid HD, HT, and DT. The position and extent of these holes have been related to a theoretical treatment which attributes the holes to a coupling of the rotational and translational motion of the molecules through the anisotropic part of the intermolecular interaction. The effect of J=1 impurity molecules on the intensity of the sharp Q1(O) line of liquid HD is discussed and the effect of the radioactive decay heat on the temperature of the liquid and solid samples is evaluated.The collision‐induced fundamental vibration–rotation spectra of liquid and solid HT and T2 in a mixture of 50% H and 50% T have been recorded. The spectra of liquid and solid HD in a 90% HD plus 10% T2 mixture have also been observed. The frequencies of the numerous single and double transitions have been compared with those calculated from the known molecular constants. Deep holes have been observed in the Q (O) phonon band of solid HD, HT, and DT. The position and extent of these holes have been related to a theoretical treatment which attributes the holes to a coupling of the rotational and translational motion of the molecules through the anisotropic part of the intermolecular interaction. The effect of J=1 impurity molecules on the intensity of the sharp Q1(O) line of liquid HD is discussed and the effect of the radioactive decay heat on the temperature of the liquid and solid samples is evaluated.

Collision induced infrared lines in solid hydrogens caused by tritium radioactivity

Abstract We report the first observation of infrared absorption lines due to the presence of radioactive tritium in crystals of the solid hydrogens. Two prominent lines appear at the low-frequency side of the collision-induced spectrum, and are interpreted as due to the presence of positive and negative ions or electrons created during the radioactive process.

Near-infrared optical absorption in solid DT and T2

Abstract Near-infrared optical absorption has been detected for solid DT and T 2 samples. It is suggested that this absorption is due to electrons and/or ions resulting from the radioactive decay of tritium being trapped in the solid lattice.

Electrical properties of D-T gas from 20 to 26 K☆

Abstract The dielectric constants and electrical conductivities of D-T gas at 20, 23, and 25 K are measured at 1592 Hz from 3 to 200 Vm 2 mol −1 . Tritium concentrations are 0.9, 8.8, and 98.3%. Both electrical quantities increase with density ans saturate above 400 mol m −3 . The gas is a soft dielectric, with an electrical conductivity as high as 300 × 10 −9 Ω m −1 . The saturated vapour conducts as well as the liquid beneath it. The total charge desity in pure tritium gas is about 10 12 mol −1 . Most electrons may react to form tritide ions, but the remaining electrons still carry most of the current.

Anomalous vapour pressure over liquid D-T☆

Abstract The presence of a few tenths mol % helium in hydrogen causes anomalous vapour pressures as high as 10 kPa. This effect is caused by the combination of a small cold cell, a single, long fill tube, and the insolubility of helium in liquid hydrogen. This effect is important in the handling of deuterium-tritium, as radioactive decay produces He 3 .

Dielectric constant and electrical conductivity of liquid D-T☆

Abstract The first dielectric constant and electrical condutivity measurements on liquid deuterium-tritium are reported. The samples, which contain 0.9, 8.8, and 98.3% tritium, are measured for complex capacitance at 1592 Hz with an effective electric field of 2830 Vm −1 at temperatures of 20 to 26 K. The tritium radioactivity converts the samples dielectrics, with dielectric constant as large as 4.5 and electrical conductivities of 200 × 10 −9 (Ωm) −1 . Carrier densities are about 10 10 per mol sample; both free electrons and ions are apparently present.

Reaction of liquid and solid D2-T2

Collision-induced infrared spectroscopy has been used to measure the initial rate of the chemical exchange of equimolar D2 and T2 in liquid and solid forms from 9 to 23K over 23 to 45 h. If first-order kinetics are assumed, the time constant is 100-140 h for thermal equilibrium and 160-180 h for a hot-atom equilibrium. The latter is favoured, but cannot be confirmed. Approximately three DT molecules are formed per ion pair (using the gas-phase value of 36.6 eV/ion pair). A likely mechanism is reaction of the T2+ to the T3+ ion, followed by exchange. The slowness of the exchange suggests that molecular DT can be isolated and handled for fusion applications.

An estimate of the thermal conductivity of solid T2 from pulsed nmr data

Abstract The thermal conductivity of solid T 2 below 17 K has been estimated from pulsed nmr data to be roughly temperature independent and approximately equal to 0.7 W/mK. Results for some mixtures of T 2 with D 2 and DT are also given.

Distribution of Ne gas permeabilities in glass laser targets

A 3.6 million sample of sized, soda-lime glass microbubbles was filled to various total percent fills with Ne. The batches were outgassed isothermally at 498K. The partially filled batches outgassed faster because initially only the more permeable microbubbles were filled. Two models were used to study permeation, with values of tau (the time constant) ranging from 1-100. The data agree better with the model skewed to the fast time constant side. An analysis of the dimensions indicates that the permeability must be responsible for most of the distribution. The reason for this is not known; however, it may be due to variability of chemical composition or to varying degrees of phase separation.