US2086579A - Electron discharge device - Google Patents

Description

4 w J F Filed April 27, 1954 A L SAMUEL ELECTRON DISCHARGE DEVICE July 13, 193?.

Patented July 13, 1937 UNITED STATES PATENT ()FFICE ELECTRON DISCHARGE DEVICE Arthur L. Samuel, Orange, N. J., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application April 27, 1934, Serial No. 722,705 6 Claims. (Cl. 250-215) This invention relates to electron discharge to the outer anode compensates for the capacidevices and more particularly to such devices tance between the inner and outer anodes.

adapted for the generation of ultra-high fre- If used as a suppressor electrode, the third or quency oscillations and of the type generally outermost of the perforate or grid electrodes may known as electron coupled oscillators. be connected to the cathode and so designed and 5 One object of this invention is to isolate the positioned that its capacitance to the outer anelements which determine the frequency at which ode compensates for the capacitance between the the device is to oscillate from the elements of control electrode and the outer anode. the device included in the output circuit. The invention and the features thereof will be Another object of this invention is to increase understood more clearly and fully from the fol- 10 the power output and oscillation efficiency of lowing detailed description with reference to the high frequency oscillation generators. accompanying drawing in which:

In one embodiment of this invention, an elec- Fig. 1 is a perspective view of an electron distron discharge device comp-rises a cathode, an charge device illustrative of one embodiment of outer anode, and two perforate or grid electrodes this invention, portions of the enclosing vessel 15 between the cathode and anode. The perforate being broken away to show the electrode assemor grid electrode nearest the cathode is operbly more clearly;

ated at a negative potential and serves as the Fig. 2 is an enlarged end view of the electrodes control electrode. The other perforate or grid showing the configuration and relative position electrode serves as an inner anode and is operated thereof; 0

at a positive potential usually of less magnitude Fig. 3 is a diagrammatic view showing the posithan the positive potential of the outer anode, tion of the electrode leading-in conductors with The cathode, control grid and inner anode are respect to ne a a associated through an external circuit, the tun- Fig. 4 is a diagrammatic end view showing the ing of which determines the frequency at which position and configuration of the electrodes in an 25 the device oscillates. The outer anode is couelectron discharge de having fi electrodes pled to one of the first three electrodes to proand constructed in accordance with this invenvide an output circuit. tion.

In accordance with a feature of this invention, Referring now to the drawing, the electron disthe electrodes are designed and spaced so that charge device shown in 1 Comp s a eVa 30 the capacitance effect between the two anodes is uated enclosin Vessel l0 having a b se W H substantially neutralized by the capacitance effrom which a cathode, an anode, and two perfect between the control electrode and the outer forate or grid electrodes are mou t d. The p anode. forate or grid electrode nearest the cathode is In accordance with another feature of this intended to be operated as a control electrode, 35 invention, the electrodes are so spaced and deand the other perforate or grid electrode is insigned that under operating conditions, the electended to be operated as an anode. tron transit time to the inner anode is small, The inner r d or p rforat el ctrode, which preferably substantially negligible, while the may be of the general construction described and 40 transit time of an electron between the inner claimed in my copending application, Serial No. 40 and outer anodes is relatively large and of the 722,704, filed April 27, 1 34, comprises a central order of a half period of the frequency at which linear metallic support or rod 12 sealed in the the device is intended to oscillate. base wall ll of the enclosing vessel and carrying The invention may be embodied also in an an oval or flattened helical grid I3, each of the electron discharge device comprising five eleclonger sides of each turn of the grid l3 being 45 trodes, namely, a cathode, an anode and three suitably secured, as by welding, to the central perforate or grid electrodes between the cathode support or rod I2. and anode. The perforate or grid electrode near- The grid I 3 encompasses a hairpin or elonest the cathode serves as a control electrode, gated U-shaped filamentary cathode M, for exthe next as an inner anode, and the third as a ample of thoriated tungsten, the arms of the 5 suppressor or control electrode. cathode being disposed on opposite sides of the The third or outermost of the perforate or support or rod l2. Each arm of the cathode is grid electrodes, if used as a control electrode, is secured to a rigid bent wire or rod l5 sealed in connected to the inner control'electrode and is the base wall I l of the enclosing vessel. The

5 i positioned and designedso that its-capacitance cathode is supported at its other or upper end by a hook member i6 secured to one end of a flexible J-shaped member or spring H, which is carried by a metallic support or rod i8 sealed in the base wall I i adjacent the periphery thereof.

The grid 53 is encompassed by a perforate inner anode comprising a pair of parallel metallic uprights or wires i9 carrying an oval or flattened helical grid 20 which is uniformly spaced from the grid l3. One of the uprights or wires I9 is secured to a rigid support or wire stub 21 sealed in the end wall H of the enclosing vessel.

The outer anode comprises four sections each including an arcuate portion 22 forming an oval member uniformly spaced from the grid 20, and flanges 23, the flanges on adjacent sections being disposed in face to face relation and secured together by bent integral tabs 24 on one flange extending through apertures 25 in the adjacent flange. Two of the flanges are provided with flutes or grooves 26 forming a channel in which an arm of a bent support or rod 21 extends, the support or rod being suitably secured to these flanges, for example, by welding. The other arm of the support or rod 21 is secured to a rigid wire or rod 28 sealed in the base Wall H of the enclosing vessel.

Ametallic disc 29 having a getter material, such as magnesium, thereon is supported from a stub 30 sealed in the top portion of the enclosing vessel. During the fabrication of the device, the disc and getter 29 may be heated, for example, by high frequency induction, whereby the getter is vaporized to flx residual gases in the enclosin vessel ill.

The circuit including the control electrode l2, l3 and the inner anode I9, 20 may be tuned to the frequency at which the device is desired to oscillate; the circuit including the outer anode may be tuned to obtain the maximum operating efficiency. It will be seen, therefore, that the cathode, control electrode and inner anode constitute a three-electrode oscillator from which electrons are released at periodic intervals to the outer anode, the periodicity being determined by the tuning of the circuit including the three first mentioned electrodes.

In order to effectively segregate the output circuit from the frequency determining element so that variations in the load will not affect the .tuning, it is desirable that the outer anode be coupled to the other electrodes only by the electron stream. In accordance with this invention, this is attained by designing and positioning the electrodes so that under operating conditions, the alternating potential appearing on the inner anode, by virtue of the capacitance existing between it and the outer anode, is substantially neutralized by the potential appearing on the control electrode, by virtue of the capacitance existing between the control electrode and the outer anode. In other words, the electrodes are of such configuration and design, and are so spaced that the capacitance between the inner and outer anodes is compensated for by the ca.- pacitance between the control electrode and the outer anode. The capacitance between electrodes in an electron discharge device may, of course, be ascertained in ways well known tothose skilled in the arts.

The operating characteristics of an electron discharge device at extremely high frequencies are materially dependent upon the transit times of electrons between the various electrodes of the device. Preferably the cathode and inner anode are so spaced that in the range of" potentials at;

which the inner anode is operated, the electron transit time between these electrodes is so small as to be substantially negligible. With this condition, more electrons leave the cathode during that portion of the cycle when the control electrode is in the positive half of its potential excursion and the total work per electron for this period is negative.

In the region between the inner and outer anodes, it has been found that for any value of electron transit angle some relative phase exists between potentials on the inner and outer anodes for which the total work per electron is negative. Furthermore, it has been'found that the maximum total work is substantially independent of the transit angle for values of the transit angle up to 1r. Hence, it is very desirable, in order to obtain a relatively high output and operating efficiency, that the transit time of an electron between the inner and outer anodes be relatively large and of the order of a half period of the frequency at which the device is intended to operate.

The invention is not limited to electron discharge devices of the specific construction shown and described hereinbefore. The features thereof may be embodied in devices having more than four electrodes. In one modification, illustrated in Fig. 4, an electron discharge device comprises a cathode 3!, an anode 32, and three oval, helical or perforate electrodes 33, 34 and disposed between the cathode and anode. The electrode 33 may be utilized as the control electrode and the electrode 34 as an inner anode usually operated at a potential of less magnitude than the potential of the outer anode 32.

The electrode 35 may be connected to the control electrode 33 as indicated schematically by the line 36, and so designed and positioned that the capacitance between. it and the outer anode compensates for the capacitance between the inner and outer anodes. When used connected to control electrode 33, the electrodev 35 produces an increased bunching of the electrodes which enter into the region between the inner and outer anodes and thus serves to increase the efficiency of the device. It will also serve to suppress secondary electrons so that the device may be operated with larger potential variations on the anodes than would otherwise be possible.

The electrode 35 may be utilized also as a suppressor electrode, in which case it is connected to the cathode, as indicated schematically by the line 31, and is designed and positioned so that its capacitance to the outer anode compensates for or substantially neutralizes the capacitance be tween the control electrode and the outer anode.

Although specific embodiments of this invention have been shown and described, it will be understood, of course, that various modifications may be made therein without departing from the scope and spirit of this invention as defined in the appended claims.

What is claimed is:

1. An electron coupled oscillator comprising an anode and a frequency determining element operatively associated with saidanode including a cathode, a control electrode and an anode, said control electrode and said anodes being so constructed and arranged that when proper potentials are applied-to said first anode and to the electrodes of said frequency determining element to produce aperiodic release of electrons from said frequency determining element to said first anode, the potential appearing, upon said first 75.

anode by virtue of the capacitance between said anodes is substantially neutralized by the capacitance appearing upon said first anode by virtue of the capacitance between said control electrode and said first anode.

2. An electron coupled oscillator comprising a frequency determining element including a cathode, a control electrode and an anode, and another anode adapted to be coupled to said frequency determining element to receive electrons therefrom at periodic intervals, said control electrode and said anodes being so constructed and arranged that the capacitance between said anodes is of substantially the same magnitude as the capacitance between said control electrode and said another anode.

3. An electron coupled oscillator comprising a frequency determining element including a cathode, a helical control electrode encompassing said cathode, and a perforate anode encompassing said control electrode, and a second anode encompassing said perforate anode, said control electrode and said anodes being so constructed and arranged that the capacitance between said anodes is of the same order of magnitude as the capacitance between said control electrode and said second anode.

4. An electron discharge device comprising a cathode and an anode constituting elements of an oscillator system, and an output electrode in said device and spaced from said anode a distance of the order of one-half wave-length of the frequency of said oscillator system.

5. An electron discharge device comprising a cathode, a control electrode and an anode constituting elements of an oscillator system, said anode being disposed in immediate proximity to said cathode so that at the resonant frequency of said system the electron transit time between said cathode and said anode is substantially negligible, and an output electrode in said device and spaced from said anode a distance such that the transit time between said anode and said output electrode is of the order of one-half period of said resonant frequency.

6. An electron discharge device comprising a cathode, a control electrode encompassing said cathode, a perforate anode encompassing said control electrode, said cathode, control electrode and perforate anode constituting elements of an oscillator system, and an output anode outside of said perforate anode, in said device and said perforate anode being disposed in such proximity to said cathode that the electron transit time between said cathode and said perforate anode is substantially negligible, and said output anode being so disposed relatively remote from said perforate anode that the electron transit time between said anodes is of the order of one half the period of the frequency of said oscillator system.

ARTHUR L. SAMUEL.

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