Laminar Beam Research Articles

1-Inch Saticon for high-definition color television cameras

A high-resolution 1-in TV camera tube with the Saticon photoconductive layer has been developed for live color image pickup in the high-definition television system based on 2:1 interlaced 1125 scanning lines and 60 fields per second. The inherent high-resolution capability of the Saticon photoconductive target is fully demonstrated by the use of a diode-operation electron gun having no beam crossover point. The electrons emitted from a flat barium-impregnated tungsten cathode are formed into a narrow and laminar electron beam of high current density and low beam temperature using a fine beam-defining aperture about 12 µm in diameter in the positively biased G <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</inf> disc electrode. The tube has an outstanding resolving power and a low lag characteristic as well as sufficient beam current margin to handle the standard peak signal current of 0.5 µA required for a reasonably high <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S/N</tex> ratio in the wide-band video signal system. The applicability of the design concept to the tubes for standard TV systems is also discussed.

Fluid and Vlasov Stability of Intense Ion Beams in Periodic Channels

Transverse beam behaviour of an intense beam through long periodic systems is reviewed critically. In view of the uncertainty about the proper choice of a distribution function the applicability of a hydrodynamical approach is discussed. Starting from a laminar beam, structure resonances and their shift by finite temperature are introduced as hydrodynamic features. The Vlasov treatment brings in additional structure resonances and entirely new features, like velocity space instabilities, if a loss-cone distribution (for instance K-V distribution) is chosen. The relevance of these instabilities for beam transport considerations is briefly discussed.

A variant of the refined theory of bending for a laminar plastic beam

The present article considers the bending of a beam fabricated from a material with a low shear rigidity. A bending-theory variant that does not involve the hypothesis of plane cross sections is presented, assuming the material to be incompressible in the direction of the transverse coordinate. Results previously obtained in this area and an appropriate bibliography were given in an earlier article [3]. A solution is given that permits precise satisfaction of the condition for rigid fastening of the end of the beam. An attempt is made to take into account the actual character of the mounting.

Correlations of Acoustoelectric Instabilities with Inhomogeneities in CdS Measured by Optical Probe

In order to correlate some aspects of the acoustoelectric instabilities with the sample inhomogeneites, the internal inhomogeneity in resistivity profile in semiconductive CdS single crystals is measured by means of an optical probe, utilizing the local photo-conductance produced by the projection of a laminar light beam through the sample. Results indicate marked inhomogeneities. Several aspects of the acoustoelectric instabilities are found to be related to the variation in resistivity of a sample, i.e., there occurs moving domain and pinned domain depending upon the resistivity profile. The presence of a somewhat higher resistance region, near the cathode where acoustoelectric gain is higher, induces easily the moving domain. On the contrary, if there is such a high resistance region near the anode, the domain is pinned there without its destruction.

A nonreentrant crossed-field amplifier with cycloiding injected beam

Nonreentrant injected-beam crossed-field amplifiers usually employ a thin laminar beam positioned well above the sole electrode. In operation, the beam is gradually bunched by a phase-focusing action. This paper describes the analysis and demonstration of such an amplifier, with an important difference: the electrons of the beam have random cycloidal trajectories extending to the sole instead of following the usual linear paths, Rapid and effective bunching is accomplished by collecting antiphase electrons on the sole. Experimental results are presented to show that the approach is useful for high current beams. For example, an output power of 600 watts was obtained at 10 dB gain from an 800 mA beam. The advantages and disadvantages of the cycloidal motion are discussed. The results of computations are given to show the desirable characteristics attainable; for example, a design for an amplifier with a cycloiding beam requires only 35 percent of the interaction length of a laminar-beam type for the same computed power output, gain and efficiency at the same cathode voltage.

Stiffness of Electron Beams†

A new parameter for use with electron-beam devices is defined as a quantitative measure of the extent to which the beam withstands the effects of transverse forces. The new figure of merit can be used to compare the effectiveness of various methods of constraining the beam, as illustrated by application to the cases of space-chargebalanced flow (including Brillouin flow and immersed flow), periodic focusing, Harris flow, E- and C-type flow, and M- type flow. Stiffness is defined as the rate of change of force (in the direction transverse to that of beam travel) that acts to restore a displaced electron to its equilibrium trajectery in a laminar beam. (auth)