760. Surface processes on conditioned electrodes producing vacuum breakdown

Classified abstracts 759-772 cases takes a total of four hours. Rupture tests carried out subsequently indicate that the welds withstand stresses of the order of 1000 kg. The specific pressure applied during the welding operation is -7 kg/mm*. A N Petrangovskii and A F Ivanenko, Electronic Technol, Scient Tech Coil, UHF Electronics,

1912, No 6, 86-89, (in Russian). 31

759. An end-on cathode. (USSR)

An end-on cathode for use in UHF electronic apparatus is described. In order to increase the resistance to vibrations the heat screens are connected to each other alternately at the top and at the bottom by way of intermediate rings. The total axial length of the unit is quite short; this further aids vibration resistance. The diameter of the cathode unit is a little greater than the useful diameter of the end-on cathode, since constructional requirements specify a certain tolerance between neighbouring components. M B Golant and Z T Alekseenko, USSR Patent No 329596, appl 21st Jan 1971, publd 11th March 1972. 31 760. Surface processes on conditioned electrodes producing vacuum

breakdown. (USSR) Surface processes activated by field electron current on electrodes conditioned by breakdowns and producing probable pre-breakdown states of vacuum breakdown are investigated. An analysis is presented of time characteristics of surface transport on electrodes in solid or liquid phase, providing avalanche-like increase of field electron current or appearing in inter-electrode gap of micro-particles which can lead to breakdown. I L Gufeld, Zh Tekh Fiz, 42 (5), May 1972, lOlG1017 (in Russian). 31 761.

Output power saturation with discharge current in continuous wave argon lasers. (USSR) Electrical and optical parameters of argon plasma in high-current discharge in large-diameter tubes (2 10 mm) are investigated as a function of argon pressure in the range of 0.25 to 1.3 torr, in order to explain generation saturation with discharge current in continuous wave ion lasers. The results show that generation saturation is due to restriction of the excitation rate of the working levels resulting from a sharp decrease of gas atom concentration in the discharge occurring at saturation discharge currents. V I Donin, Zh Eksper Teor Fiz, 62 (5), May 1972, 1648-1660 (in Russian). 31 762. Evaluation of temperature of electrodes of gas-discharge light

sources. (USSR) A method of measurement of electrode temperature in continuous gas-discharge light sources is described. The method is based on determination of the time decrease of electrode brightness after cessation of the discharge. Yu G Basov and V A Kanunnikov, Prib Tekh Eksper, No 2, MarchApril 1972, 163-164 (in Russian). 31 763. Mechanisms of gas-discharge processes in photoelectron multipliers. (USSR) On the basis of an analysis of amplitude and time distributions of impulses produced by ionic and optical feedback in vacuum photoelectron multipliers, the mechanisms of gas-discharge processes in photoelectron multipliers are discussed. A N Pertsev et al, Vestn Belorusk Univ, Ser 1, No 1, 1972, 67-69 (in Russian.) 31 764. Method of manufacturing acicular field-emission electron emitters.

(USSR) In order to avoid the use of mercury and carbon tetrachloride, as required in the conventional process of manufacturing acicular field emitters, it is proposed that the wires employed as emitter should be etched in the vertical position in an electrolytic bath, the top of the wire being connected to a current source and the bottom passing through the layer of electrolyte and out through a hole in the bottom of the bath, the size of the hole being chosen so that surface tension prevents the liquid from running out. A sharp end is thus created in that part of the wire lying below the electrolyte layer. The etch ends automatically when the lower end of the wire becomes disconnected under its own weight. V Ya Fridman, USSR, No 328515, appl 13th Jan 1969, pub/d 3rd April 1972.

32. NUCLEONICS 765. Semiconductor gamma-spectrometers with suppression of Compton scattering component. (USSR) A review of semiconductor gamma-spectrometers with suppression of Compton scattering component is given. Constructions of the elongated vacuum cryostats of vertical and horizontal types for Ge(Li) detectors are presented. V I Shipilov, Prib Tekh Eksper, No 2, March-April 1972, 7-19 (in Russian).

32 766. Interrupter-monochromator of cold neutrons with large cross section of slit packet. (USSR) Construction and results of examination of a mechanical interruptermonochromator in a time-of-flight neutron spectrometer are described, A high-frequency induction engine operating at reduced pressure of 10 torr is used for driving the interrupter. Hermetirratinn ,-- .._.. bf the selector body is provided by graphite ring gaskets. Yu L Shitikov et al, Prib Tekh Eksper, No 2, March-April 1972, 26-29 (in Russian).

1-

767. Receiving arrangement of a mass separator for investigation yf

short-lived isotopes. (USSR) An arrangement for transport of short-lived isotopes from a mass separator to nuclear-physical spectrometers is described. The arrangement is evacuated by a diffusion pump. A T Vasilenko et al, Prib Tekh Eksper, No 2, March-April 1972, 34-36 (in Russian). 32 768. Proportional counter with movable insulator for absolute measure-

ments of activitv of nuclides in gases. (USSR) Results of investigation of two-propoitionai counters with movable insulators, for absolute measurements of the activity of nuclides in gases, are described. The counters are filled with propane and methane to a pressure of 0.5 atm. V I Albul and V G Baranov, Prib Tekh Eksper, No 2, March-April 1972, 43-44 (in Russian). 5(L

769. Efficiency of neutron counters with gas radiators. (USSR)

Graphs are presented which enable the efficiency of neutron counters with gas radiators to be determined for the cases of isotropic flow perpendicular to the counter axis as a function of radius of cylindrical counter, type of gas radiator and its pressure. Yu M Tolchenov and V G Chaykovskiy, Prib Tekh Eksper, No 2, March-April

1972, 47-48 (in Russian).

33. GENERAL

PHYSICS AND ELECTRONICS

33 770. Calculation of characteristics of the ion current bombarding the

tin of the uoint field emitter. (USSR) csing a computer, the number of ions of residual gas bombarding the tip of a point field emitter is calculated. The number of bombarding ions is found to be practically independent of the separation of the point from the anode. Space distribution of ions bombarding the point is also determined. P A Bereznyak and V V Slezov, Radiotekh Elektron, 17 (2), Feb 1972, 354-358

(in Russian). 33

771. Ion-electron image converter. (USSR)

An ion-electron image converter for ion mass-spectral microscope is described. The converter features a two-electrode magneticelectrostatic immersion lens with separated acceleration and focusing functions. The calculated and experimental data on image reduction are presented. Application of the described converter eliminates the need for additional ion acceleration before the converter system, which considerably simplifies the system of ion image recording. V T Cherepin and Yu P Mayfet, Zh Tekh Fiz, 42 (5), May 1972, 969-971 (in Russian). 33 772.

Electron impact ionization studies of ferrocene, cobaltocene, nickelocene and magnesocene. (USA) Negative and positive ions of the above compounds produced by collisions with mono-energetic electrons were studied. Appearance potentials relative to the ionization potential of krypton were determined for the products (C,,H,,M)+, (CsH,)+ and M+. The 385