5304. Time-resolving extreme ultraviolet spectrograph for fusion diagnostics

Classified abstracts 5301-5313 using sputtering techniques may have fundamental advantages over thermal evaporation. K Mayer et ai, J. Appl Phys, 52 (9), 1981, 5803-5805. • 31 5301. X-Ray photoelectron spectroscopy of spattered platinum thin films enntainin~o large amounts of carbon. (GB) Polycrystalline thin films of platinum containing amounts of carbon up to 17 a t m ~o have been prepared by dc reactive sputtering. Although bulk properties were investigated mainly by X-ray diffraction, electrical measurements and nuclear analysis for composition, emphasis is given in this paper to the study of surface properties of these films by X-ray photoelectron spectroscopy (XPS). From a catalytical point of view, parallel study of CO oxidation reaction (at atmospheric pressure and temperatures between 100°C and 200°C) on those films has been also achieved. Low percentages of CH 4 in argon at 5.10 -2 torr were used as reactant to introduce carbon in platinum. Carbon concentrations have been accurately measured by means of nuclear reaction (12C(d, no)13C). They are related to the electrical resistivities (1.10- s to 2.10-'t f~cm ), to the sputtering power and to the gaseous composition of the discharge. (Belgium) A Hecq et ni, Vacumn, 31 (10--12), 1981, 527-534. 31 5302. Sputtered thin film electrodes for photoelectrochemical cells. (Canada) Semiconducting "rio 2 film photoelectrodes were prepared by dc sputtering from a simple hot pressed TiOz powder target. To make the target semiconducting, it was first heated in a hydrogen atmosphere. Films so produced on heated glass substrates were polycrystalline and strongly adhered to the substrates. When tested for photoelectrolysis, these films were chemically stable and did not exhibit any photodecomposition. The spectral response was investigated and a main absorption edge at ~4(X) nm was obtained. The technique appears attractive for inexpensive large scale production of photoelectrodes for solar-hydrogen conversion. A A Soihnan and H J J Segein, Can J Phys, 59 (11), 1981, 1674-1679. 33. NEUCLEONICS 33 5303. High resistance mode in a modified Penning discharge. (USA) The high-resistance mode of a modified Penning discharge has been studied under different operating conditions both experimentally and theoretically. The experiment reveals the conditions for the existence of different modes and their properties. A theory of non-neutral plasma gives the insight of the physics of made transitions and the properties of different modes. (India) Chitro Sen, J Appl Phys, 52 (9), 1981, 5489-5495. 33 5304. Time.resolving extreme ultraviolet spectrograph for fusion diaganstics. (USA) A time-resolving spectrograph for the simultaneous measurement of emissions at extreme ultraviolet wavelengths (300-2200 A) is described. The spectrograph is a 400-mm normal incidence f/30 system with seven gratings. Together two of the gratings cover the entire wavelength range at low resolution. The other five gratings have higher dispersion and cover adjacent intervals of the spectrum. The spectral resolution varies between 0.7--4 A. The detector consists of a windowless microchannel plate/phosphor screen image intensifier, coupled by fibre optics to a 1024-element self-scanning integrated photodiode array. The output from the array is digitized and stored by a small desktop computer which has sufficient memory to record up to 80 spectra during a single plasma discharge. R E Bell et al, Rev Sci lnstrum, 52 (12), 1981, 1806-1813. 33 5305. A note on the creation of condensation nuclei by negative corona discharges in air at low pressure. (GB) The production of condensation nuclei by a negative point-plane corona discharge is discussed in the light of experimental results in which the occurrence of 'large' ions of low mobility, the concentrations of condensation nuclei and the identification of ionic species by mass spectrometer, have been separately studied. It is concluded that the nuclei occur mainly in the outer regions of the discharge. N L Allen et al, J Phys D: Appl Phys, 14 (12), 1981. L207-L209 33 5306. 10.6 Inn Faraday rotation measurement of the azimuthal magnetic field in a Z-pinch plasma The Faraday rotation of a plane-polarized CO2 laser probe beam passing

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along chords across an argon Z-pinch plasma, current 31 kA, has been measured and the azimuthal magnetic field B 0 calculated using 633 nm interferometric electron density measurements. The results are consistent with the total current being carried by the pinched discharge column, and confirm the validity of the technique. S A M AI-Chalabi et al, J Phys E: Sci lnstrum, 15 (2), 1982, 232-234. 33 5307. Electron energy distribution in CO and He--CO discharges: II. (GB) A method for simultaneously calculating the electron energy distribution function and the vibrational population in CO and He--CO discharges is described. The solution is self-consistent and includes the interdependence between the CO vibrational population and the electron energy distribution function. This mutual influence is accounted for by incorporating the electron-impact excitation of vibrationally excited molecules as well as superelastic collisions. The cross-sections for stepwise excitation are calculated here, using a model based on experimental data. The electron energy distribution function is given in an analytical form. The calculations are carried out for different He-CO mixtures and for several values of the electron concentration, the gas temperature and the ratio E/N. (Israel) Y Kanfmau and Yu M Kagan, J Phys D; Appl Phys, 14 (12), 1981, 2215-2223. 33 5308. Radiation cooling instabilities in laser-heated plasma. (GB) Recent observations of small scale features in laser-produced plasmas may be influenced by an instability associated with the density dependence of radiative losses. Dense, cold streams of plasma may be produced between the critical density surface and the solid material, and also at lower densities after the laser has turned off. R G Evans, J Phys D: Appl Phys, 14 (I0), 1981, L173-L177. 33 5309. Anode spots and cathodic plasma flow in a vacuum arc. (GB) The current-threshold values associated with the onset of anode spots in a vacuum arc are shown to correlate with the solid angle subtended by the anode of the cathode centre while the angular distribution of the normalized current collected at the anode compares with that of the erosion products emitted from the cathode. Thus the cathodic vapour flux appears to control the onset of anode spots. (Canada) Michael G Drouct, J Phys D: Appl Phys, 14 (12), 1981, L211-L214. 33 5310. Spectroscopic investigation of the helium plasma produced by linear focusing of a TEA.-CO 2 laser beam. (GB) The breakdown in helium is achieved by linear focusing of a TEA-CO2 laser beam with reflective axicon. The plasma produced is cylindrical in shape, 5 mm in diameter and 30 mm long. The plasma parameters N, and 7", as a function of time up to 20 ps were deduced from spectroscopic measurements. From the Stark width of ionized and neutral helium lines the values of N, were determined starting from Ne = 7 x 1023 m - 3 at 0.25 ~s after the breakdown. The time dependence of Tewas determined from the He II/He I intensity ratio and He I/continuum ratio. (Yugoslavia) Lj M Cirkovi~ et al, J Phys D: Appl Phys, 15 (2), 1982, 229-235. 33 5311. Experiment on the relation between discharge noise and light output in He-Ne plasmas. (GB) The relation between discharge noise in a mixed gas (He-Ne) positive column and its light output is studied by measuring the autocorrelation and the spatial pattern of side light modulated by noise, particularly striations, variation in this light with current, and correlation between striations and the laser. Effects of the laser on the wave dispersion are also demonstrated. (Japan) H Amemiya, J Phys D: Appl Phys, 15 (2), 1982, 207-218. 33 5312. An appendix to the paper 'T, determination in low-density plasmas from the He ! 3889 .~ and 5016 ~ line intensities'. (GB) The use of the He I 3889 A line for measurements of plasma electron temperature is discussed. The reduction in line intensity due to absorption is calculated, and a 'useful range' of parameters is determined, within which the T, determination is uninfluenced by the effects of absorption. (Sweden) N Brenning, J Phys D: Appl Phys, 15 (1), 1982, LI-L2. 33 5313. Determination of the Penning excitation cross-sections of individual Cd(li) states for He metastable atoms using Penning electron spectroscopy. (GB) The relative Penning excitation rates for the individual Cd(II) states by He