Masatoshi Kitaichi

Advanced tokamak concepts

AbstractA coin-shaped proton conductor made from metal oxides of strontium and cerium can be charged in a hot D2 gas atmosphere to produce excess heat. Anomalous heat evolution was observed from the proton conductors charged with alternating current at 5 to 45 V at temperatures ranging from 400 to 700°C. The anomalous heat produced temperature increases as much as 50°C. Excess heat was estimated as a few watts in most cases, totaling up to several kilojoules.

Anomalous γ peak evolution from SrCe solid state electrolyte charged in D2 gas

Abstract A proton conductor, the solid state electrolyte, made from an oxide of strontium, cerium, niobium and yttrium can be charged in a hot D2 gas atmosphere. Anomalous radioisotopes were detected in all samples charged with an alternating current with voltages ranging from 5 to 45 V, at temperatures ranging from 400 to 700 °C. No radioisotopes were detected from the sample treated in a H2 gas atmosphere. The radioisotopes may be induced from a catalytic reaction between the metal and oxide interface to deuterium atoms.

Fluence to Dose Conversion Coefficients for Electrons up to 200 MeV in Localized Exposure

To estimate radiation hazards in the accidental exposure to energetic electrons, effective doses were calculated with the EGS4 Monte Carlo simulation code and the MIRD-5 human phantom for high energy electron beams like those from a LINAC in which non-uniform exposure of the human body would occur. The calculations show that the effective doses depend on the incident electron energy and beam size and on the place of the exposure of the body.

Response of a wireline pickup for subnanosecond electron beam pulses

The response of a wireline-type beam monitor was measured for electron beams with energies of 28 MeV and pulsewidths of 20 ps from an electron linear accelerator. The output waveform from the wireline pickup was calculated according to the general formulation for responses of beam monitors based on electromagnetic interaction. In the calculations, a transfer function H(/spl omega/) and an effective length l/sub eff/ are introduced to express all the effects not included in the analysis. The function H(/spl omega/) is assumed to be Gaussian, and the FWHM of H(/spl omega/) and l/sub eff/ is experimentally determined. The effects of the termination, wireline length, height, and angle between the wireline and the beam direction are discussed. The test supported the analysis and, for the standard pickup, a charge sensitivity of 20 V/nC and an FWHM of H(/spl omega/) of 55 ps are obtained.

Pulse radiolysis studies on the oxide glasses

A pulse radiolysis was applied to the alkali silicate, alkali borate and thallium borate glasses. The optical absorption spectra immediately after irradiation were found to differ largely from those by the X-ray or γ-ray steady state irradiation. This is due to the presence of the unstable defect centers in the short time period. In the alkali silicate glasses, the peak energies of the transient spectra increased with a decrease in the radius of the alkali ions. From the doping experiment with Cd(II) ion, it was concluded that the short lived defect centers in silicate glasses were electrons trapped on the alkali ions in the glass networks. In the binary alkali borate glasses the transient absorption due to the electrons trapped on the alkali ions could also been detected. The intensity of this absorption increased with an increase of the alkali content. On the other hand, in the X-ray irradiated thallium borate glasses, the absorption due to Tl∘ was observed in the visible range only when the thallium content is low. The absorption due to this center was already found in ps range and its intensity decreased gradually with time and becomes to the ones obtained by X-ray irradiation. When thallium oxide content exceeds 20 mol %, the the absorption due to Tl∘ could not be seen in the X-ray irradiated glasses, although in the early stage spectrum a broad component presumably due to Tl∘ was observed. This was understood by the the difference of the electron capturing strength of the thallous ion which depends on the glass composition.

Optical Absorption Spectra of the Pulse Irradiated Oxide Glasses (Part 3)

K2O・2B2O3並びにNa2O・2B2O3ガラスにパルス電子線照射をし, 吸収スペクトルを測定した. ガラスに誘起されたスペクトルの強度は温度上昇とともに低下し更に時間減衰も速められた. K2O・2B2O3ガラスでは, 400℃においては, 照射後1.5μsでその吸収は大きく低下した. 1.6eVに吸収を持つ短寿命種は, 照射によって同時に生ずる非架橋酸素に関係する正孔中心との拡散律速による再結合によって消失していくことが推論された. 減衰速度の活性化エネルギーはガラス転移温度の下限とされる約300℃を境に大きく変化した.