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K. Ashida, K. Ichimura, K. Watanabe
Abstract
A study was made on the effect of iron impurities on the trapping-detrapping processes of hydrogen isotopes implanted to graphite by using XPS and thermal desorption spectroscopies. XPS measurements revealed that the deposited iron changed its state to iron-carbide (Fe3C) type by vacuum heating at above 800℃ and increased the electron density of graphitic carbon atoms. The modified graphite surface showed considerably different thermal desorption spectra (TDS) from those observed for clean graphite surfaces. Namely, the iron caused to disappear the desorption peak T (the lowest desorption peak for the clean graphite), and to appear a new desorption peak ([Fe/C] peak) in TDS. The new peak was found to be equivalent to the desorption peak U for the clean graphite. Its desorption mechanism was explained by the second order surface recombination of trapped hydrogen isotope atoms. The rate constants for three hydrogen isotopes were determined as
Where the frequency factor and activation energy are in [/molec. s] and [cal/mol] units, respectively. The results indicate that the impurity effect on the trapping-detrapping processes is due to the increase in electronic change on carbon atoms caused by iron dopant.
Kiyoshi Kusabiraki, Takashi Kubo, Takayuki Oaka, Masao Matsuyama, Kuniaki Watanabe
Abstract
The tritium thermal desorption analysis for iron was carried out in order to
elucidate the trapping sites of hydrogen and to obtain the activation energy of tritium desorption
from each trapping site in iron.
The results obtained in this study are as follows:
K. Ashida, K. Ichimura, M.Matsuyama, K.Watanabe
Tritium Research Center, Toyama University, Gofuku 3190, Toyama 930, Japan
Abstract
The thermal desorption of deuterium implanted into graphite with iron dopant was studied by means of mass analyzed thermal desorption spectroscopy. Deuterium ions were implanted into the sample at room temperature with 5 keV using a conventional ion gun. An impurity modification phenomenon was found for the mass analyzed thermal desorption spectra (MATDSs). Namely, a new desorption peak (denoted as [Fe/C]-peak) appeared at 970 K in the MATDS for the graphite doped with iron (3 at%), whereas a broad spectrum ranging from 750 to 1275 K was observed for pure graphite. The desorption mechanism for the [Fe/C]-peak was explained by the second order surface association reaction. The rate constant was determined as
K[Fe/C] (D2) = (5×10-4)exp(-59×103/RT),
where the frequency factor and activation energy are in [/molecule s] and [cal/mol], respectively. The broad spectrum for pure graphite was deconvoluted into three component peaks, [T] and [U]. The rate constants for them are determined as
K[T] (D2) = (2×10-7)exp(-46×103/RT),
K[U] (D2) = (8×10-5)exp(-61×103/RT).
Katsunori MoriIa, Kiichiro Kasaib, Yosikau Isikawaa, Kiyoo Satob, Kan Ashidac, Kuniaki Watanabec
a College of Liberal Arts, Toyama University, 3190 Gofuku, Toyama 930 Japan
b Faculty of Science, Toyama University, 3190 Gofuku, Toyama 930 Japan
c Tritium Research Center, Toyama University, 3190 Gofuku, Toyama 930 Japan
Abstract
The variation of the superconducting transition temperature, Tc in NbHx and NbDx films, which were prepared by a method of hydrogen (deuterium) - reactive sputtering at room temperature, was investigated. The effect of hydrogen or deuterium absorption reduced Tc and a pronounced normal isotope effect was observed.
Kenji Ichimura, Masao Matsuyama, Kuniaki Watanabe
Tritium Research Center, Toyama University, Gofuku 3190, Toyama 930, Japan
Abstract
Gettering materials, most of which are alloys, have wide applicability to tritium processing function in fusion and fission reactors such as storage, supply, recovery, separation, and so on. However, required getter properties differ depending on unit process conditions. To develop suitable getters for each unit process, it is important to investigate fundamentals of alloying effects on their properties. Therefore, we studied the activation processes of three Zr-alloy getters (Zr-Al, Zr-Ni, and Zr-V-Fe) by means of x-ray photoelectron spectroscopy-secondary ion mass spectrometry and thermal desorption spectroscopy. It was observed that the formation of a metallic Zr surface is the principal process for activation, by which the getters show pumping action for various gases. A considerable effect was observed on the activation processes of the three getters. The activation temperature varied with alloying elements: 800℃ for Zr-Al, 700℃ for Zr-Ni, and 400℃ for Zr-V-Fe. It was concluded that the activation temperature is determined by the balance between the stability of corresponding oxides and carbides present on the surface and the diffusivity of oxygen and carbon from the surface into the bulk.
Hitoshi Miyake, Masao Matsuyama, Kuniaki Watanabe1987_06
Abstract
To evaluate the absolute pressure of hydrogen isotopes with ionization gauges and quadrupole mass spectrometers in tritium handling systems as well as thermonuclear fusion devices, we determined the relative sensitivities of two kind of Bayard-Alpert (B-A) gauges and a quadrupole mass spectrometer among hydrogen isotope molecules. The relative sensitivities of the B-A gauges (normalized to H2) were RHDB = 1.08, RD2B = 0.99, RHTB = 1.03, RDTB = 0.97, and RT2B = 0.95. In the case of the quadrupole mass spectrometer, they were RHDM = 1.09, RD2M = 0.99, RHTM = 1.06, RDTM = 0.96, and RT2M = 0.88. These values
Kuniaki Watanabe, Hitoshi Miyake, Masao Matsuyama
Tritium Research Center, Toyama University, Gofuku 3190, Toyama 930, Japan
Abstract
To apply mass spectrometers and ionization gauges to thermonuclear fusion devices such as pressure gauges, we measured the relative sensitivities (normalized to H2) of Bayard-Alpert(B-A) gauges (UGD-1S and UGS-1A, ANELVA Co.) and a quadrupole mass spectrometer (MSQ-150A, ULVAC Co.) for hydrogen isotopes. In the case of the B-A gauges, the relative sensitivities were determined as RHDB = 1.07, RD2B = 0.99, RHTB = 0.97, and RT3B = 0.95. In the case of the quadrupole mass spectrometer, they were RHDM = 1.09, RD2M = 0.99, RHTM = 1.06, RDTM = 0.96, and RT3M = 0.88. These values agreed quite well with those observed by Dibeler et al. for the mass spectrometer of the magnetic deflection type. It was revealed that the relative sensitivities of the quadrupole mass spectrometer were essentially the same as those for the B-A gauges except T2.
Isao Kanesakaa, Hiroyuki Nishimuraa, Kan Kanamoria, Kiyoyasu Kawaia, Kenji Ichimurab, Kuniaki Watababe
a Faculty of Science, Toyama University, Gofuku, Toyama 930, Japan
b Tritium Research Center, Toyama University, Gofuku, Toyama 930, Japan
Abstract
The infra-red spectrum of [Co(en)3]Cl3・3T2O has been observed over a period of 5 months. The spectrum changes considerably even in 2 days after preparation of the hydrate, revealing quite different features from the parent. Initially some bands due to the NH2 group disappear, while new bands appear. These are explained in terms of a change in bonding character or as an interaction between the complex ion and the chloride anion in the crystal. Subsequently, the bands due to ethylenediamine decrease in intensity and almost vanish, while additional new bands appear. The new bands are explained in terms of ammine complexes. It is proposed that a decomposition reaction of en → 2NH3 + HCCH takes place through intermediates such as vinylamine and so on. After one month the spectrum still changes slowly with further new bands due to a H-T exchange reaction.