Kan Ashida^a, Kuniaki Watanabe^a, Toshio Okabe^b

^aHydrogen Isotope Research Center, Toyama University, Gofuku 3190, Toyama 930, Japan

^bDepartment of Physics, Faculty of Science, Toyama University, Gofuku 3190, Toyama 930, Japan

Abstract

    Carbon films containing hydrogen were prepared on quartz and Be plates of a plasma discharge in C₂H₄. Raman spectroscopy revealed that the carbon film on quartz was stable to heating in vacuo up to 800℃. On the other hand, X-ray diffraction measurements of the film prepared on the Be plates revealed that Be₂C was formed above 500℃. The intensity of the Be₂C peak increased with increasing temperature. Thermal desorption spectroscopy showed that hydrogen molecules were desorbed from the carbon films containing hydrogen by two different mechanisms. One is the reaction of C and adsorbed water to form H₂ and CO at around 400℃, and the other is the reaction of C and Be to form H₂ and Be₂C above 500℃.

W.M. Shu, K. Watanabe

Hydrogen Isotope Research Center, Toyama University, Gofuku 3190, Toyama 930, Japan

Abstract

    An analytic model taking account of multiple structures and temperature gradient was developed for tritium permeation and inventory in an international thermonuclear experimental reactor. It was applied to calculate the tritium permeation and inventory in Be/Cu and W/Cu options of the divertor components. The total tritium permeation and mobile inventory in the Be/Cu option were calculated to be 0.81 mg/s and 6.0 kg, and those in the W/Cu option were 0.0071 mg/s and 6.7 g. The mobile inventory in the Be/Cu option decrease with increasing operation time, while that in the W/Cu option decrease initially and then increases.

W.M. Shu, K. Watanabe

Hydrogen Isotope Research Center, Toyama University, Gofuku 3190, Toyama 930, Japan

Abstract

    A general formula for simultaneous gas- and plasma-driven permeation of hydrogen (tritium) has been developed by an electrical circuit analog, in which the permeation potential and resistance are defined for both diffusion in the bulk and recombination on the surface and the gradient of permeation potential against permeation resistance is considered to be the general driving force for permeation through a laminate. This formula is applied to calculate the permeation flux of hydrogen through 316 stainless steel.

Kan Ashida, Kuniaki Watanabe

Hydrogen Isotope Research Center, Toyama University, Gofuku 3190, Toyama 930, Japan

Abstract

    Changes in the chemical states of co-existing layers of Be and C with vacuum heating were studied by mean of X-ray photoelectron spectroscopy (XPS), secondary ion mass spectroscopy (SIMS) and X-ray diffractometry (XRD). Two different samples were prepared. One was a Be plate covered with evaporated carbon film, [C/Be] and the other was a Be plate covered with carbon film containing which was deposited by ethylene plasma, [C(H)/Be]. The XPS and XRD measurements disclosed that Be₂C was formed on both sample surface by vacuum heating above 600℃. Thermal desorption spectroscopy showed that a large amount of hydrogen molecules was desorbed from the carbon film containing hydrogen above 600℃. Kinetic measurements of Be₂C growth revealed that the rate is controlled by a random nucleation process. The SIMS measurements also demonstrated evidence of Be₂C formation by detecting BeC- (M/e = 21). Hydrogen atoms captured by Be₂C, however, were not observed, suggesting that Be-carbide has little ability to capture/trap hydrogen isotope atoms.

Keywords: X-ray photoelectron spectroscopy; Secondary ion mass spectroscopy; X-Ray diffractometry; Thermal desorption spectroscopy; Beryllium; Carbon; Plasma facing materials

Kuniaki Watanabe^a, Masao Matsuyama^a, Tohru Kobayashi^b, Shigeru Taguchi^b

^aHydrogen Isotope Res. Centr., Toyama Univ., Gofuku 3190, Toyama 930, Japan

^bDept. Chem., Faculty of Science, Toyama Univ., Gofuku 3190, Toyama 930, Japan

Abstract

    A new type of chromatography for hydrogen isotope separation was developed by use of a Pd-Pt alloy as functional material. It could separate H₂-D₂ mixtures (90% H₂ -10% D₂ and 50% H₂ -50% D₂) and HD to H₂ and D₂ in a temperature range from 274-303 K in a short time with simple operation procedures without introducing any replacement gas. The new chromatography promises great potential for the application to an isotope separation system of thermonuclear fusion devices.

Keywords: Hydrogen; Deuterium; Isotope; Separation; Chromatography