3,231,779 . '
ELASTIC WAVE RESPONSIVE. APPARATUS.‘ Richard M. White, Palo» Alto, Calif.,_ assignor to General
Electric Company, a corporation of-New. York '
Filed June 2.5, 1962, Ser.. No. 204,880
16 Claims. (Cl. 3I5--4), ' _
This invention relates to the generation, transmission, and reception of elastic" waves and, more particularly, to the generation of elastic waves by atomic-‘sized and sub"atomic particles; the transmission, of such waves; and the subsequent detection and‘ measurement of the waves.
An elastic Wave, sometimes known as. a mechanical wave, may be defined as a mechanicalj vibration in an elastic medium, which results in a change in the volume, density, pressure or some other property of the medium‘. An elastic wave may also be considered to be the progression of stresses and strains’ along a particular path" in a medium, such as a solid or a liquid. One form ‘of an elastic wave is the acoustic wave", a» wave audible to the human ear. e l
Heretofore, in apparatus employing. elastic waves, the waves have been generated by mechanical sources, or by electrical sources employing magnetostrictive and piezoelectric conversion" apparatus. For example, elastic waves are generated by an alternating ‘electric signal applied across a piezoelectric crystal, which provides correspond’ing deformations of the crystal. By elasticallycoupling the crystal to an elastic medium the deformations induce elastic waves to propagate in the medium. An electrically excited‘ piezoelectric crystal affixed to one end[o_f a quartz rod induces the propagation of elastic waves along the length of the rod; A piezoelectric crystal affixed to the other end of the rod converts the elastic waves received at that end to corresponding electrical‘ signals; ‘ Thus, the electrical signals applied to the .input.piezoelectric crystal are temporarily stored inthe quartzrod in the form of the stresses and strains propagatingtherealong and comprising the elastic waves._ Such a device may be; used for information storage or as a signal delay apparatus. In a similar manner, an electrically" excited piezoelectric crystal immersed" inone end of a longtube of mercuryinduces the propagation, of elastic waves in the mercury .al_ong the length of the tube. ‘ ‘ _ _ _
The above described apparatus for converting electrical signals to elastic wave energy is often relatively ineflicient and has relatively low upper frequencyeof operation. Accordingly, it is desirable to provide a more efiicient method and apparatus for generating elastic waves andto provide a method and apparatus for generating, elastic waves having higher frequencies. _ 1 .
‘ Therefore, it is the principal object of this invention to provide improved apparatus for generating elastic waves.
Another object of this invention is to provide an improved" method for generating elastic waves, e
Another object of this invention. is to provide improved apparatus for the generation, transmission, and‘ reception of elastic waves. . ' ‘
Another object of this invention is to provide improved apparatus for the storage of information in the form. of elastic waves. H _ V
Another object of this invention is to provide improved apparatus for the. delay of signals in the form of‘ elastic waves. ‘ ' "
The foregoing objects are achieved, accordingto the instant invention, by. generating elastic waves. employing the incidence of atomic-sized or sub-atomic particles on the surface of an elastic member and by providing, for the subsequent reception of the resulting elastic waves. by a detector of elastic waves. Atomic-sized particles which may be employed include molecules and atoms. 7Sub
atomic particles which maybe used include protons, ,neu.trons, and electrons‘. According to one embodiment‘ of the invention, _an‘ electron gun is disposed within an evacuated" envelope... The electron stream produced by the electron gun is directed to be incident onthe surface of. an elastic member‘ provided. Within the envelope. Elastic waves" are thereby induced in, the member and travel along at selected path in the member. The path length for the propagation of the elastic waves. may be as long as desired. , A detector of elastic waves is coupled to_a selected location on the member. This detector comprises a piezoelectric crystal for converting elastic Waves received to. electric signals. Thus, elastic waves are, generated, transmitted, and received in, a. high eflicient and novel manner; this generation, transmission, and reception occurring over a greater frequency range than heretofore attainable.‘ A V . _ V
In the above-described embodiment of the instant invention, various electrodes may be mounted within the evacuated envelope and proximate to. the electron stream. In traveling along its path in the. evacuated envelope the electron stream may intentionally or inadvertently strike one of the electrodes. ‘ Accordingly, it is. desirable to. provideapparatus for detecting the location of electron stream interception in an electron stream device. _
Therefore it is another object of thisinvention to pro.vide apparatus for detecting the point of interception of a stream of charged particlesby the electrodes of a device directing. a stream of charged‘ particles along a particular path. V
Another object of this invention is to provide apparatus for detecting the presence of a stream of atomic-sized. or sub-atomic particles withinan evacuated structure.
The. above objectives are achieved, according, to one embodiment of the invention, by providinga, detector of elastic. waves movable along the exterior of the vacuum envelope. The elastic wave detector is elastically coupled to the vacuum envelope adjacent to the location wherein it is desired to determine whether an electron streanris being intercepted. The electron stream, upon being intercepted, induces elastic. waves inthe, interception mem‘ber, _ The elastic waves are transmitted through the member and the vacuum envelope to the elastic, wave_detector,.
The invention will be described with reference, to the accompanying drawings wherein: . '
FIGURE 1' is an elevatio,nal' view, partly in cross.section, of one embodiment of the invention;
FIGURE 2 is an elevational‘ view, partly in. cross-section, of another embodiment of the invention; A e FIGURE 3‘ is an end view, in cross-section, of the. embodiment of FIG. 2;,
FIGURE 4‘ is an elevational view, partly in cross-section, of the elastic wave detector of FIGS, 1 and 2;
FIGURE 5 is-an elevational view, in cross-section, of another embodiment of the invention; ~
FIGURE 6 is- a end. view, in cross-section,. of the embodiment of FIG. 5; and" ,
FIGURE‘ '7 is an elevational view, partly in cross-section, of another-embodiment of the invention.
In the embodiment of FIG. 1 a klystron is shown as the exemplary structure embodying, the invention. The. klys-tron illustrated is-. rotationally symmetrical about the longitudinal axis thereof, such, axis. being an imaginary horizontal straight line and passing through the center of the figure. The klystron comprises a hollow metallic cylinder 10 having disposed t-herein a plurality of centrally. apertured metallic. Wall discs 1-1, 12, 1-3, 14, and 15. The outer cylindrical surface of each of discs I1-15 is affixed, as by soldering, to the: opposed internal cylindrical. surface. of cylinder 10. Cylinder 10‘ and wall discs 11-1-5 may be com-posed of, for e_xa-mplc, copper. A