642. Study by X-ray diffractions of thin layers of lanthanum fluoride

Classified abstracts 632--644 energy available to initiate electrical breakdown is equal to all or a fraction of the capacitively stored energy of the electrodes. This hypothesis is shown to be capable of predicting, at least qualitatively, m a n y of the experimental results not predicted by previous hypotheses. (USA) IV[ Rabinowitz, Vacuum, 15 (2), Feb 1965, 59-66. 18 632. Experiments on the heating of ions in a trap fitted with magnetic plugs by a variable electric field. (USSR) Results of an investigation of a new m e t h o d of internal injection of a hot plasma into a trap fitted with magnetic plugs is presented. The central diameter of the trap was 50 cm and distance between plugs 120 cm. Magnetic field at centre = 8 K Oe Working pressure : (0.5 to 1) × 10 -6 torr Residual pressure : 5 × 10-8 torr (Gas supply switched off at source). The trap was filled with a hydrogen plasma of density (1 to 2) × 10H/cm 3, the heating being carried out by a variable accelerating voltage with a frequency equal to the ionic cyclotronic one. The average ion energy was found to be 5 keV, whereas that of the electron did not exceed a few tens of eV. The plasma generated during the time of one pulse disintegrated in 150 microseconds. It is suggested that the ion heating has a stochastic nature. Intense heating occurs even at n o n - r e s o n a n t frequencies. Iv B Gutt et al, Zh ETF, 48 (3), 1965, 804. 18 : 19

633. Plasma jet as a light source for spectroscopy.

(USSR)

A simple f o r m of p l a s m a t r o n (plasma generator) is described, which enables a spectrum either f r o m the jet or the arc to be recorded t h r o u g h a quartz window in the c h a m b e r wall. Samples under investigation were introduced into the discharge space either in the f o r m of a sprayed solution or as a powder. Spectra of similar samples introduced into the direct current arc burning in the plasmatron or in the plasma jet were compared, the jet source generally yielding enhanced contrast with background. Estimated temperatures of plasma jet : 7800°K at 20 A and 8100°K at 50 A. Z h Zheenbaev and A I Polovikov, 12V A K Nauk Kirghiz SSR,

18 638. Composition of the slow ions produced during the traversal o f fast hydrogen ions through molecular gases. (USSR) Composition of slow negative a n d positive ions produced by fast hydrogen atoms passing t h r o u g h 02, N~, N O and CO was investigated with a mass spectrometer. The dependence of the intensities of the separate mass spectrum lines on the hydrogen a t o m intensity was determined and compared with the energy dependence of the cross sections for electron capture by hydrogen atoms. D V Pilipenko and Ya M Fogel, Zh Eksper Ter Fiz, 48 (2), Feb

1965, 404-415, (in Russian). 18

639. Breakdown mechanism in triggered discharge tube by varying pressure. (Japan) The experiments were conducted with a mercury pool cathode discharge tube in which the vapour pressure P could be varied between 10 -~ and 32 torr. The breakdown is of two types, depending on whether P is lower or higher t h a n a certain critical value Pc. In the former case, the discharge is similar to that taking place in an ignitron. If P>P~, a transient glow appears at first, which acts as trigger to the main discharge. The value of Pc depends mainly on the spacing between the principal electrodes. Y Gosho, Se Pap Inst Phys Chem Res, 58 (3), Sept 1964, 88-102. 18 : 19 : 40

640. Mass-spectrometric study of photoionization. II: H2, H D and D2 V H Dibeler, R M Reese and M Krauss, J Chem Phys, 42 (6), March 1965, 2045-2048. 18:40

641. Dissociative ionization of molecules by rare-gas ion impact. ( USA ) W B Maier II, J Chem Phys, 42 (5), March 1965, 1790-1804.

19. Radiation 19

Plasma jet as a light source for spectroscopy. See abstract n u m b e r 633.

6 (4), 1964, 29, (in Russian).

19 18:56

634. Focussing mechanism of ion beam devices and application to machining. (Japan)

Bakeable micro-wave cavity for measurement of electron loss rates in photoionized nitric oxide plasmas. See abstract n u m b e r 637. 19

The focussing m e c h a n i s m of the ion b e a m consists of 3 parts, which act as independent lenses. U n d e r o p t i m u m conditions, a power density of the b e a m on the work piece of the order 'of 104 W / c m 2 can be obtained. (This value, although high, is still below the corresponding value for electron beams.) S Matsui, Bull Etectrotech Lab, 28 (6), June 1964, 23-31, (in

Mass-spectrometric study of photoionization. II: I-I2, H D and D2.

Japanese).

Laser welding of interconnexions circuits. See abstract n u m b e r 711.

18

635. Design considerations for high intensity negative ion sources. (Netherlands)

See abstract n u m b e r 640. 19

Determination of ground state O, N and H by light absorption and measurement of oscillator strengths. See abstract n u m b e r 705. 19

in semiconductor

integrated 19 : 33

642. Study by X-ray diffractions of thin layers of lanthanum fluoride. (France)

The discharge c h a m b e r of a hot cathode Philips i o n gauge has been modified so as to improve the n u m b e r of negative hydrogen ions extracted f r o m the cathode. Negative ion currents in excess o f 5 m A were obtained. Ion source operating parameters are discussed and possible utilisation of this discharge geometry in negative ion cyclotrons is mentioned. (Netherlands) K W Ehlers, Nuclear Instrum Methods, 32 (2), Feb 1965, 309-316. 18

The l a n t h a n u m fluoride films were prepared by thermal evaporation in a v a c u u m of about 10 -5 torr, and had an average thickness of 2000 A_. They were deposited on an a m o r p h o u s silica substrate kept at temperatures ranging f r o m 25 ° to 300°C. The deposits were crystalline in all cases, but their exact structure depended markedly on substrate temperature. A Bourg and D Talbot, C R Acad Sc (Paris), 259 (25), Dee 1964,

636. Current oscillations in a thermionic energy converter. ( U S S R )

4608-4611.

Oscillations are due to the formation of b e a m instabilities at the cathode, which generate longitudinal plasma oscillations in the inter-electrode space. The frequency of the oscillations is shown to be inversely proportional to the inter-electrode distance at low pressures and to the square of the distance at high pressure. ( U S S R ) I P Stakhanov and A S Stepanov, Th Tekh Fig, 31 (1), Jan 1965,

132-139, (in Russian).

19 : 41

643. Effect of the partial pressure of water vapour on the optical properties of thin films of calcium. (France) In order to ensure stability, calcium films m u s t be prepared and the optical properties examined under h i g h - v a c u u m conditions. It is especially i m p o r t a n t that all traces of water vapour be exctuded. B Robrieux, C R Acad Se (Paris), 259 (21), Nov 1964, 3744-

18 : 19 637. Bakeable micro-Wave cavity for measurement of electron loss rates in photoionized nitric oxide plasmas. (USA)

644. Photo current through thin films of A1203.

T h e design to construction of an X - b a n d cavity resonator for use in the study of electronic processes in nitric oxide plasmas is described. The cavity can be outgassed at 350°C and is suitable for use in conjunction with ultra-high v a c u u m systems. ( U S A ) T M Shaw et al, Rev Sci Instrum, 36 (4), April 1965, 748-780.

The experiments were carried out with Al~O3 films ~ 1 0 0 ~ thick placed between two thin films of pure a l u m i n i u m (sandwich construction). The c o m b i n a t i o n exhibited a photo current when illuminated with light in the wavelength range 2600 to 11,000 A. The a u t h o r deduced a relative .work function of 1.0 eV at the

:3747. 19 : 41

(USA)

381