Masamoto Otsuka

Optical escape factors and population densities for TPD-plasma

Abstract Optical escape factors and recalculated population densities are presented in connection with a remark by Hegde and Ghosh. It is shown that the optical escape factors given by these authors are too small for the experimental conditions used and, contrary to their results, the population densities for levels with principal quantum numbers larger than 4 of He(II) may be described by the optically-thin assumption.

Spectroscopic observation of a quasi-steady-state plasma in contact with a neutral gas☆

Abstract Very intense spectral lines of He + were observed when a He plasma was brought into contact with a He gas. The population densities of the excited levels of He + ions were found to be much larger than the values expected in the steady state for the given electron temperature and density. The contact mechanism and a method of determining the electron temperature and the electron and ion densities are discussed for the quasi-steady state.

Intensity calibration of a VUV system by branching line pairs of low ionized light atoms

A method for determining the relative sensitivity of a vacuum ultraviolet (VUV) monochromator is described for the wavelength region from 200 to 1200 A. Eleven VUV line pairs of low ionized atoms of nitrogen and oxygen are selected for which recent data of transition probabilities or branching ratios are available. Calibration is made by measuring the intensity ratios of these line pairs emitted from a stationary helium plasma into which a nitrogen or an oxygen gas is introduced. The results are in good agreement with those obtained using the usual atomic branching ratio method for hydrogen and helium.

Grotrian diagrams for highly ionized iron FeVIII-FeXXVI

Abstract Energy levels and Grotrian diagrams for FeVIII-FeXXVI are presented. Wavelengths, configurations for each transition, oscillator strengths, and radiative transition probabilities are tabulated with references.

Population inversion in a stationary recombining plasma

Population inversion, which occurs in a recombining plasma when a stationary He plasma is brought intocontact with a neutral gas, is examined. With hydrogen as a contact gas, noticeable inversion between low-lying levels of H has been found. The overpopulation density is of the order of 10(8) cm(-3), which is much higher than that ( approximately 10(5) cm(-3)) obtained previously with He as a contact gas. Relations between these experimental results and the conditions for population inversion are discussed with the CR model.

The relation between the optical escape factor and the thermalization length

Abstract The dependence of the optical escape factor on the thermalization length is discussed for a plane-parallel plasma composed of two-level atoms. Expressions for an upper and a lower bound for the escape factor are given. The radiative transfer equation is solved numerically in the case of a Doppler profile and escape factors on the midplane of the plasma slab are given. The variation of the escape factor with the thermalization length is very small; an expression given by Drawin has been found to be erroneous.

A High Resolution Echelle Monochromator and Its Application to Ion Temperature Measurement of He Plasma

For the measurement of the profile of a spectral line, a high dispersive monochromator with an Echelle grating and 12 channels of photoelectric devices using thin glass sheets to separate the line profile was constructed. The measured resolving power is about 2×105 and the linear dispersion at the image plane is 1.2 mm/A at 5000A. This instrument was used to measure the ion temperature of a BSG device by employing the 4686A line of He II.

Relation between Photographically Observed Electron Beam Spot of a Synchrotron and the Amplitude of Betatron Oscillation

The shape of the cross section of the electron beam of an electron synchrotron observed photographically (spot) is discussed in relation to the distribution function for the amplitude and the phase of the betatron oscillation and also that for the coordinates of a particle and the inclination of its orbit to the equilibrium orbit. It is found that the probability density that particles move on the quilibrium orbit is zero, when the observed spot has a non-cusped finite intensity at its center. For example, a gaussian distribution for the spot intensity results from the rayleighan distribution for the amplitude. In this case the full half-width of the spot is given by 4(ln 2/π)1/2 , where is the mean amplitude of the betatron oscillation.

Photographic Observation of the Electron Beam Spot of the INS Synchrotron

The shape of the cross-section of the electron beam (spot) of the electron synchrotron was observed photographically with the 1.3 GeV electron synchrotron of the Institute for Nuclear Study (INS), University of Tokyo. The size of the spot was measured as a function of the electron energy. The intensity distribution over the spot is approximately gaussian and the full half-width is 2.8 mm in height and 2.2 mm in width at an energy of 910 MeV. The half-width is inversely proportional to the square root of the energy, as expected from betatron oscillation. Empirical formulae for the half-width as a function of the electron energy are given also.

Measurements of Ion Temperature of He Plasma by Echelle Spectrometer with Multichannel Photoelectric Devices

For the measurement of a profile of spectral line, a high dispersive monochrometer with an Echelle-grating and 12 channels of photoelectric devices using thin glass sheets, to separate the line profile are constructed. The measured resolving power is about 2×105 and the linear dispersion at the image plane is 1.2 mm/A. This instrument is applied to measure the ion temperature of MACETIE device by using the line of He II 4686 A.