Analyzers for modelling electro-vacuum devices. (USSR)

Classified abstracts

398-410

0.1 to 1 torr, total pressure of mixture in the range of 1 to 3.5 torr and various compositions of the mixture. On the basis of the obtained results it is supposed that van der Waals interaction of atoms forms the main process of line broadening. G A Mikhnenko et al, Optika Spektroskop, 32 (4), April 1972, 8098 13 (in Russian). 398. Active element surface. (USSR)

of helium-neon

laser

with metallic

31 inner wall

It is shown that presence of metallic foil on the inner wall surfaces of the active element in a helium-neon laser enhances the power of generation by 10 to 20 per cent on all investigated wavelengths: 0.63, 1.15 and 3.39 urn in the investigated pressure range of 0.4 to 2 torr. The maximum power of generation in active elements with metallic inner surface is obtained at higher pressures and higher discharge currents than with normal active elements. V G Leontev (in Russian).

et al, Optika

399. Vacuum breakdown face. II. (USSR)

Spektroskop,

32 (4), April

1972, 798-801

31 under controlled conditions of electrode sur-

Results of investigation of a vacuum gap, under prolonged application of voltage, are reported. Molybdenum electrodes were cleaned by a glow discharge treatment in inert gas at pressure of 1 torr and prebreakdown currents smaller than lo-* A were obtained after this treatment. Periodically during the treatment, checking of the electrode surfaces was performed with the aid of post-discharge exoelectron emission. In the final state of the electrode surfaces the post-discharge emission was absent. A gap of 1 mm in oil-free vacuum at 10F8 torr under the given conditions withstands without breakdown voltages of 55 to 60 kV for tens of hours and the pre-breakdown currents are smaller than 1Oe8 A. In some cases the first breakdown occurs at a voltage above 90 kV. The first breakdowns result in the appearance of field electron currents. P N Chistyakov et al, Zh Tekh Fiz, 42 (4), ApriI 1972, 821-825 (in Russian). 400. Comparison of the results of theoretical and experimental on the parameters of an arc thermionic converter. (USSR)

31 studies

Comparison of the experimental data obtained for the arc stage of caesium thermionic converters with the results of the analytical theory of a low-voltage arc in caesium vapour is presented. Dependence of the electron temperature on the caesium vapour pressure in the range 4 x 10-l to 3.6 torr is given. V P Karmaxin Russian).

et al, Zh Tekh Fiz, 42 (4), Aprd

1972, 800-808

(in 31

401. Analyzers

for modelling electro-vacuum

devices. (USSR)

Analyzers for modelling electro-vacuum devices are described. Construction of analyzers for investigation of the emission capability of cathodes in dependence on their fabrication process, for investigation of electron beam formation and for investigation of factors influencing electric strength of electro-vacuum devices are presented. A T Aleksandrova et al, Tram Moscow Inst Electronic Construction, No 20, 1972, 55-66 (in Russian). 402. Relation between the mechanism of pulsed discharge and the generation processes in a CO, gas laser. (USSR)

Equipment 31 formation

High-voltage pulsed discharge is investigated in long glass tubes, with internal aluminium mirrors, filled with-a mixture of 1.5 torr of CO, and 1.5 torr of N,. The relationshin between the mechanism of pulsed discharge formation and the generation processes in CO, gas laser is discussed. V V Belous and V N Kostin, Zzv VUZ Fiz, No 4, 1972, 17G173 (in Russian). 403. Experimental laser. (USSR)

production of optical pumping for a molecular

31 CO,

404. Impulse source of flat spectrum vacuum ultraviolet. (USSR)

calibrated

in brightness

31 in the

An impulse source of a flat spectrum based on a capillary discharge with an evaporating wall was developed which provides absolute measurements in vacuum ultraviolet region by photographic and photoelectron methods. I V Podmoshenskiy (in Russian).

et al, Zh Prikl Spektroskop,

405. Evacuation of electro-vacuum devices vacuum system in tbe hot state. (USSR)

16 (3), 1972, 415-421

with separation

31 from the

At the end of evacuation, the pressure difference between the vacuum system and the device is small, and the pressure in the device during cooling can be lower than the pressure in the vacuum system. In this case, a flow of gas from the vacuum system into the device takes place, which is undesirable in vacuum systems with oil diffusion pumps. Knowledge of the optimum evacuation time is required and sealing must be performed in the hot state to avoid backflow of gases. It is shown that sorption of gases by the cooled walls of the device has considerable influence on the residual pressure in the device after sealing. The construction of a mechanism for sealing devices in the hot state on a semi-automatic carousel machine is described. A I Pipko et al, Tram Moscow No 20, 1972, 3-10 (in Russian).

Electronic

Equipment

Construction,

32. NUCLEONICS 32 406. Potential distribution

in a gas-filled diode. (Czechoslovakia) The potential distribution and current-voltage characteristics of a gas-filled planar diode with a thermionic cathode were determined with the aid of an approximative theory taking into account electron space charge, initial velocities of electrons emitted with Maxwellian distribution, and their elastic collisions with neutral gas particles. The presence of positive ions was not considered. E Tomkova, Czech J Phys, B 22 (5), 1972, 356-363. 32 407. Plasma-inertial measuring instruments of the parameters of motion based on inplatrons. (USSR) Possibilities of utilizing the plasma-inertial effect for development of measuring instruments are considered. The plasma-inertial effect is observed in low-temperature glow discharge plasma in rough vacuum and at discharge currents of 10m4to 1O-3 A. Under these conditions a contracted filament is formed. Principles of “inplatron” gasdischarge devices for measurement of the parameters of motion are explained. Characteristics and electro-mechanical models of inplatrons are presented. Yu I Iorish, Izmerit Tekh, No 4, April 1972, 31-39 (in Russian). 32 408. Influence of transverse magnetic field on toroidal discharge in Tuman-2 machine. (USSR) A toroidal olasma machine. Tuman-2. is described which is intended

for adiabatic contraction of plasma with rapid increase of the longitudinal magnet field. The discharge chamber is evacuated to 5 x 10-r torr by an oil diffusion pump equipped with a liquid nitrogen trap. Plasma heating was performed during hydrogen admission in the range of 6x 10e5 to 2x 1O-3 torr. Influence of a transverse magnetic field on the equilibrium of the plasma filament is investigated. M G Kaganskiy Russian).

et al, Zh Tekh Fiz, 42 (4), April

409. Measurement of electron concentration erosion accelerator. (USSR)

1972, 762-768

(in

32 in plasma of an impulse

Measurement of the electron concentration of the plasma in an impulse erosion accelerator near the dielectric surface is described. Pressure of lo-& torr was maintained in the accelerator. V Ya Gubarev Russian).

et al, Zh Tekh Fiz, 42 (4), April

1972, 826-829

(in

A generation system based on mixture CO,-N, pumped by black body radiation from a heated molybdenum foil is described. To eliminate heat exchange with surrounding ambient, the tube of the laser was placed in a quartz enclosure evacuated to 10m5 torr. P A Bokhan, Optika Spektroskop, 32 (4), April 1972, 826-827 (in

(USSR) The method and results of measurement of cathode losses in an impulse microtron accelerator with a lanthanum hexaboride cathode are described.

Russian).

E L Kosarev, Zh Tekh Fiz, 42 (4), April

32 410. Measurement

of cathode losses in the microtron.

1972, 841-843

(in Russian). 151