602
Classified Abstracts 1289--1292
experimental units of more than four times this capacity are being developed. The authors describe the various types of electron guns in use at the moment and consider that only two of them, the Pierce G u n and the so-called Flatspray G u n are likely to satisfy future demands. Furnace details including vacuum locks and methods of loading and unloading are described. Reference is made to a method for prevention of fouling of observation windows. The article concludes with performance details of a 260kW furnace operating at 10-~-5 x 10 -6 torr with the help of an oil diffusion pump of 30,000 1./sec pumping speed. Cylindrical ingots, 80 x 600 ram, were prepared from sintered powders of tantalum, niobium, hafnium, molybdenum and tungsten, the speed of melting varying between 6 and 12 kg/h. At the lower rates of melting, the surface condition of the ingots was satisfactory and the material could be used for the manufacture of semi-finished products after a skin removal of less than 1 mm. (Germany). w. J. s. H. Gruber, et. al., Vakuum-Technik, 12 (3), April 1963, 65-77. 37 • 56 1289. A radio-frequency generator for the continuous recording of mass spectra with an omegatron. (Germany) The radio frequency generator described has a range from 30kc/s to 3.7 Mc/s, which can be run through at a chosen rate. A calibrating generator marks the frequency of the radio frequency
generator at intervals of 10 kc/s or 100 kc/s on the mass axis of the spectrogram. Circuit diagrams for both generators are given. (Germany). w. J. s. G. Krause, Vakuum-Technik, 12 (3), April 1963, 77-79. 37 1290. Mass spectrometer for quantitative gas analysis in high vacuum systems. (Great Britain) Anon, Industr. Electron. 1, Aug. 1963, 578. 37 : 56 1291. High vacuum melting plane. (Great Britain) G. Krause, Industr. Electron., 1, June, 1963, 493. 37 : 29 : 16 Measurement of sorption, vaporization and decomposition of materials used in vacuum technology by means of an electromagnetic microbalance. SeeAbstr. No. 1206.
39.
Miscellaneous Applications
39 : 30 1292. Domain walls in thin Ni-Fe films. (U~S.A.) S. Middelhock, J. Appl. Phys., 34 (4), Part II, April 1963, 1054.