006 THE BELL SYSTEM TECHNICAL JOURNAL, MAY 1952 



Nullification of ^^pace-Charge Effects in a Converging Electron Beam hy 

 a Magnetic Field. M. E. Hines\ Proc. Inst. Radio Engrs., 40, pp. 61-64, 

 Jan., 1952. (Monograph 1935). 



This paper presents the conditions necessary for maintaining a uniformly 

 converging conical electron beam in the presence of space charge, It is an ex- 

 tension of the Brillouin focusing condition to conical flow, requiring a con- 

 verging rather than a uniform magnetic field. In this type of electron flow, the 

 diverging effects of space charge are balanced against magnetic reaction forces 

 for reasonably small cone angles of convergence. Though the balance of forces 

 is exact only for infinitesimal angles, it is reasonably accurate for cones of half- 

 angle as great as 10 degrees. The minimum beam size will be limited only by the 

 effects of thermal \'elocities, by gun aberrations, and by the magnetic field ob- 

 tainable. 



Continuous Motion Picture Projector for Use in Television Film Scan- 

 ning. A. G. Jensen\ R. E. Graham\ and C. F. Mattke\ Bibliography. 

 J. Soc. Motion Picture and Television Engrs., 58, pp. 1-21, Jan., 1952. 



The projector used for this equipment drives a 35-mm motion picture film 

 at the standard (nonintermittent) speed of 24 frame/sec and produces a tele- 

 vision signal of 525 fines and 30 frames interlaced 2 to 1. The projector utilizes 

 a system of movable plane mirrors mounted on a rotating drum and controlled 

 by a single stationarj- cam. Vertical jitter in the television image is minimized 

 by means of an electronic servo system operating on the film sprocket holes, 

 resulting in a residual vertical motion of about 1/2000 of a picture height. A 

 second electronic servo system is incorporated to suppress flicker. The combina- 

 tion of this scanner and a high-grade monitor is capable of producing a tele- 

 vision picture with a resolution corresponding to about 8 mc and with good 

 tone rendition over a range up to 200 to 1. 



Low Temperature Polymorphic Transformation in WO3. B. T. Mat- 

 TmAS^ and E. A. Wood'. Phys. Rev., 84, p. 1255, Dec. 15, 1951. 



The Concentration of Molecules on Internal Surfaces in Ice. E. J. 

 Murphy\ J. Chem. Phys., 19, pp. 1516-1518, Dec, 1951. 



In this paper the experimental expression for the "local conductivity" of ice 

 is given. This expression has two terms, one of which has already been discussed 

 and brought into close relation with the structure of ice, that is, with its heat of 

 sublimation and its lattice constant. This paper brings out another relation, 

 deriving it from the second term of the experimental expression. It is concluded 

 from an analysis outlined here that the second term of the local conductivity 

 gives the concentration of molecules in "internal surfaces". For the specimen of 

 ice to which this method was applied the concentration of molecules on internal 

 surfaces comes out as 1.03 X 10*' molecules /cc. This is proposed as a new 

 method of studying imperfections (internal surfaces) in dielectric crystals, and 

 one which seems to be well suited to this purpose. It gains its advantages from 



* Bell Telephone Laboratories 



