Tokuo Suita

Distribution Coefficients of Various Impurities in Alkali Halides

Distribution coefficients of several monovalent and divalent impurities were obtained for NaCl, KCl, NaBr and KBr by the method of zone melting performed in the respective halogen atmosphere. Dependence of the impurity distribution on the speed of a zone pass and on the concentration of impurity were studied in KCl doped with lead ions, whose concentration was determined by the measurements of optical absorption as well as by the usual chemical analysis. For the monovalent impurities, the distribution coefficients obtained from distribution curves agree well with those calculated from the thermodynamical expression of distribution coefficient using the theoretical energy of solid solution. The energy of solid solution of divalent impurities was calculated from the experimentally obtained distribution coefficients taking the equilibrium of Schottky defects into account and was compared with that of lattice calculation.

Study of the Enhancement of X-Ray Coloration of NaCl by Divalent Impurities

The growth of F centers and the change of d. c. conductivity by X-irradiation were measured around room temperature in NaCl grown in chlorine atmosphere both pure and doped with Ca ++ , Cd ++ , Sr ++ , and Mn ++ . The enhancement of coloration by divalent impurities at room temperature was found to be proportional to the square root of the concentration of each impurity. It was also found that the ionic conductivity in doped NaCl was decreased by X-irradiation in such a way that the decrease in the concentration of the positive ion vacancies was nearly equal to the increase in the F center concentration. From these results it was concluded that the isolated positive ion vacancies are the source of the F centers at the early stage of coloration. The temperature dependence of the formation rate of F centers in doped NaCl was measured and the activation energy 0.08±0.01 ev was obtained.

A Study of a Manganese Paramagnetic Center in Irradiated NaCl:Mn^ Crystals

An E.P.R. study of Mn ++ -doped NaCl irradiated at liquid nitrogen temperature was made at the X- and K-band frequencies. A new paramagnetic manganese center with the principal axes of [100], [010] and [001] and in the extraordinary large crystalline field was found. Rhombic field parameters are obtained to be D =-1450±20 and E =107±10 gauss by analyzing the K-band spectra. Computer diagonalization of the matrix of the spin Hamiltonian including the Zeeman and crystalline field energies is made and the observed X-band spectra are explained qualitatively. Broadening of the line width takes place as the temperature is raised, giving an activation energy of (0.32±0.05) eV. It is considered that the observed spectra are associated with the complex of an Mn ++ and an interstitial halogen ion, and a tentative model is suggested which accounts for the observed experimental results.

ENERGY LOSS OF LOW-ENERGY PROTONS AND DEUTERONS IN EVAPORATED METALLIC FILMS.

The energy losses, the energy stragglings, and the charge-exchanges of protons and deuterons in the evaporated metallic films Be, Al, Cu, Ag, and Au were measured in the energy range of the incident particles from 7 to 40 keV. The experimental stopping cross-sections of Be, Al, Cu, Ag, and Au for protons are approximately proportional to V 0.8 and are also approximately proportional to square roots of the atomic numbers of the stopping substances. The electronic stopping cross-section of Cu for protons shows a good agreement, in the velocity scale, with that for deuterons measured with the same foil within the experimental error. The experimental energy straggling \(\varOmega^{2}/\varDelta E\) is proportional to E 0.8 and to the 0.68-th power of the atomic number of the stopping substance. The experimental stopping cross-sections and energy stragglings are compared with the Lindhards theoretical calculations. The measured population ratios of hydrogen atoms to protons in the emergent beam were found to a...

Thermoluminescence of Gamma-Irradiated KCl

Wide-band spectra of intense long-duration outbursts are studied. In a course of such an outburst there occur three distinctive components of outburst. One is long-duration outburst of cm-waves and the other is believed to be original type IV burst of m-waves. These groups occur with a clear gap in the frequency range or are mixed in some frequency ranges by accompanying another group of dmwaves. In order to account for the above characteristics, acceleration of electrons due to hydromagnetic waves is discussed. In order that the accelerations proceed to relativistic energies, redistribution of the velocity of accelerated electrons must be made. This redistribution may be made by Coulomb collisions with thermal electrons before their energies are lost by the collisions. The accelerated electrons tend to accumulate in the places where the magnetic field is greater to radiate synchrotron radiations. At intense eruption, a few magnetic bulges would be separate radio sources for m-IV, dm-IV and cm-IV outbursts. It is also shown that hard x-ray bursts and microwave bursts with short durations are consistently explained by the same electrons accelerated at moderate eruptions. (auth)

Bleaching of F-Centers and Formation of Complex Centers in Gamma-Irradiated KCl at Room Temperature

The optical bleaching of F centers in gamma-irradiated KCl at various dosage was measured. The amount of F centers which bleached quickly, denoted by N q , was studied as a function of irradiation dose and bleaching temperature. It was found that N q includes the decrease of F center concentration due to complex center formation and due to recombination with positive holes, that the latter part of N q is closely related to the F centers formed in the first stage of gamma-irradiation, and that the complex centers are only formed by the bleaching of F centers formed in the second stage of irradiation. The rate of complex center formation by intermittent light pulses was studied, the results indicating that the amount of complex centers formed by a given number of pulses depends on the time interval between successive light pulses. The relaxation time for the formation of complex center was obtained at various temperatures from these results, and the activation energy (0.95±0.2) eV was obtained. An analysis ...

Stabilization of Flute Instability by Means of High Frequency Field

Flute instability is studied theoretically from the point of view of the non-linear interaction of charged particles with an inhomogeneous high frequency field whose electric field component is parallel to the confining magnetic field. The reciprocal action between the high frequency field and the instability is supposed to occur as a result of the particle motions induced by the field parallel to the wave number vector of the instability wave. The two effects of the field are found out; one is attributed to the electron drifts motivated by a quasi-potential derived from the high frequency field and the other is owing to the induced periodic displacement of ions or electrons. The instability is stabilized by the electron drifts whose velocities are nearly equal to or larger than those of ions driving the instability and moreover may be effectively stabilized by the above additional periodic displacements of ions or electrons oscillating with their cyclotron frequencies. These displacements are excited by ...

Condensing Heat Transfer in Steam-Water Condensing-injector

An experiment on the direct heat transfer process between supersonic steam and subcooled water jet was performed, using a steam-water condensing-injector. Photographic observation provided information on the state of flow, and establishment of a critical separate steam-water flow was confirmed. The temperature and pressure distributions along the flow were measured and the effective coefficients of condensing heat transfer were evaluated from the observed data, based on a model embodying an idealized interface between vapor and liquid. In the vicinity of the water nozzle exit, where the vapor-liquid interface was distinct, the heat transfer coefficients obtained were 14–28 (cal/°C.cm2.sec), and some correlation was observed among Nusselt, Reynolds and Jakob numbers, upon adopting the velocity and the physical properties of the steam phase. The relations Nu=6.0.Re 0.9(Pr=1.04–1.10), and Re=1.8×108.Ja 3.0, i.e., Nu=1.6×108.Ja 2.7 were derived as a rough estimation. No clear correlation could be discerned in...

Secondary Electron Emission Type Neutral Particle Detector

Experimental studies have been made on the secondary electron emission yields from metal surfaces bombarded by H10, H1+, and H20 with energies ranging by 10 to 40 KeV. The yields increase with the incident beam energy. The yield from H10 is smaller than that by H1+ and is proportional to the cosecant of the incidence angle. The yield by H20 is larger by a factor of two than that by H10 with the same velocity. The mechanism of the secondary electron emission is discussed by comparing the yield by H10 with that by H1+ and by considering the observed angular dependence. The observed difference in the yields by H10 and H1+ is considered to originate essentially from the difference between the ionization cross-sections of the two particles within the shallow layer below the surface. A neutral particle detector has been made on the basis of the angular dependence results.

Stabilization of Flute Instability by High Frequency Field

The effects of external inhomogeneous high-frequency field on the flute instability is studied theoretically from a point of view of non-linear particle interaction instead of an approach using a time averaged quasi-static potential or the Mathieu stability diagram. In this paper, it is assumed that the electric field component of the high-frequency field is perpendicular to the steady state confining magnetic field. It turns out that the h f field can compensate the perturbation of the flute instability with the aid of the ion drift induced by the field. The results appear to show that this field has the stabilizing effect in case that ω 0 >ω c i and has the exciting effect in case that ω 0 <ω c i , provided that the h f intensity increases with distance outwardly from the plasma, where ω 0 is the h f field frequency and ω c i is the ion cyclotron frequency.