K. Sawada

M. Goto

Sawada,  K.

Goto,  M.

NIFS-Repository (National Institute for Fusion Science)

§ 14. Prospect of Atomic and MolecularProcesses in PlasmaSawada, K. (Shinshu University)Gata, M.Cross section of atomic and molecular reactions andbehaviors of hydrogen Calculation results for the dissocia-tive recombination cross sections by MQDT were presentedfor molecular ions, Hi and HeH+, by PichI and Takagi, re-spectively. It was pointed out by Takagi that the results de-pended on the rotational state.Kato has considered the incident protons on the metal sur-face and has calculated the population distribution over theexcited levels of reflected atomic hydrogen produced by re-combination. The result has indicated that the atoms havinghigher ejecting velocity have higher probability to be foundin the excited states.Sawada has constructed a one-dimensional transport codeof hydrogen in which vibrational levels of molecular hydro-gen are dealt with separately, and investigated the effect ofMAR processes when molecules are released from a vac-uum vessel wall. According to the result, the molecules inthe level of v = 4, for example, have a higher ability to pro-mote the recombination of protons than those in v = 0 level.An optimized condition under which negative hydrogenion is efficiently produced has been sought by Morihira. Hereported a result of the experiment which has attempted tocontrol the density of produced negative ions by controllingthe electrons of low temperature in the boundary region ofa sheet plasma.Kajita reported about the measurement of the density ofnegative hydrogen ion and the population distribution overthe vibrational levels of molecular hydrogen in MAP-II.This study has been aiming at the understanding of the be-haviors of these species which are thought to play key rolesin MAR processes in divertor plasmas.In detached divertor plasmas of tokamaks, a periodiclarge particle effusion across the magnetic field lines hasbeen reported. Ohno has observed a similar phenomenonof the fluctuation measurement of the plasma potential inNAGDIS-II. Besides this measurement, he also reportedabout the observation with a high time resolution camera.Nakajima has measured the Ha intensity in the regionbetween the anchor and central positions of Gamma-l 0, andfound the result is consistent with that of a neutral particletransport code (Degas ver. 63).Impurities measurement High-Z materials are consid-ered to be used for the vacuum vessel wall of fusion reac-tors. Higashijima has studied the concentration of high-Zimpurities by puffing Ar, Kr, and Xe into the negative shearplasma having ITB in JT-60. It was reported that the heavierions tend to have a more peaked profile.Yoshikawa has carried out a VUV measurement in TPE-90RX and evaluated the densities of some impurity ions. Theelectron density has been also evaluated from the emissionline intensity ratios of OV and a consistent result with thatof the interferometer has been obtained.Nozato has observed the Bremsstrahlung emission witha set of 80 channel optical fibers for plasmas into which animpurity pellet has been injected. The radial profile of Zeffobtained as an analysis was presented.Laser produced plasma Aiming to obtain a better am-plification efficiency with their soft X-ray device, Okamotohas adopted a target mask and made an effort to homoge-nize the plasma in the direction of the amplification. It wasreported that when the length of the amplification mediumwas double the usual one, a record of the gain is obtained.For the soft X-ray laser having shorter wavelength thanthe present 13.9 nm, the recombining plasma is consideredto be used. Kawachi has investigated the population distri-bution over the excited levels of Li-like aluminum ion withthe help ofCR-model calculation and found that atomic pro-cesses through the doubly excited levels are important.Radiation from xenon ion is a feasible candidate as a lightsource for the EUV lithography. Sasaki has tried to iden-tify the experimentally obtained strong emission lines bycomparing them with the result of a CR-model based on theHULLAC data. So far, the results quantitatively agree witheach other.Development of diagnostic device and method Ida hasattempted an MSE measurement in LHD. The obtainedpitch angle of the magnetic field has been found to be simi-lar to the calculation result without plasma. The subtle mod-ifications caused by different magnetic field configurationsand by the effect of finite f3 has also been observed.Iwamae has constructed a population-alignment CR-model code for the Be-like oxygen and He-like carbon ions.This enabled us to evaluate the longitudinal alignment andthe velocity distribution function of the electrons in plasma.Watanabe introduced an on-board EUV imaging spec-trometer (EIS) of the "Solar-B" satellite which will belaunched in 2005. In combination with a visible telescopeSOT (solar optical telescope) and an X-ray telescope XRT,both of which will also be mounted on Solar-B, precise mea-surements of the transition region, corona, and solar flareare planed.Morita has constructed a crystal spectrometer having hightemporal and wavelength resolutions for LHD. The reso-nance line of He-like Ar has been usually observed, and theion temperature at plasma center has been routinely mea-sured from the Doppler broadening of the line.Kawazome has measured the Ha line profile with a highwavelength resolution visible spectrometer in LHD aimingto elucidate the behavior of neutral hydrogen in the diver-tor region. Asymmetric line profile has been always ob-served and the shifted broad component has indicated theatom temperature of 30-160 eV.

Prospect of Atomic and Molecular Processes in Plasma

Abstract

Similar works

Full text

Available Versions

NIFS-Repository (National Institute for Fusion Science)