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Feb. 8 , `1927. C. G. SMITH ELECTRICAL APPARATUS Filed April 25. 1921 v A @j ïí/ ' .525' 'wé/9 ' 1,617,175 Patented Feb. 8, 1927. UNITED STATESV Pßfrlëur> 1,617,175 Fries. f CHARLES G. SMITH, 0F MEDFORD, MASSACHUSETTS, ASSIGNOR, BY MESNE ASSIGN MENTS, TO RAYTHEON MANUFACTURING COMPANY, 0F CAMBRIDGE, MASSACHU SETTS, A CORPORATION 0F MASSACHUSETTS. y ' ELECTRICAL ArPARATUs'. Application mea April 25, 1921. seriai Nn. 464,359. 5 The present invention relates to electrical form field introduced between any two elec apparatus and more particularly to appara trode surfaces immersed in a gas andsepa tus of the type disclosed inthe copending rated a distance apart approximating the applications of Smith, Serial No.' 415.536, order of magnitude of the mean free path filed October 8, 1920. and Serial No. 418,263, of electrons in such a gas whether the elec filed October 20, 1920. trode surfaces be plane or curved. As disclosed in the applications above rc 55 , The theory underlying the action of such 60 ferred to, it is possible to design and locate a tube is believed to be substantially as fol 10 electrodes immersed in a gas in- such a lows: In an apparatus of this character the> manner that gaseous conduction due to separation of the active surfaces of the elec ionization of the gas may not take place trodes approximates the order of magnitude even at high potential differences. This nor of the mean free path of the electrons, this 65 mal insulating state, however, may be `path varying in accordance with the char 15 20 changed to a conducting state by introduc acter of the gas employed and the pres ing a magnetic field in the space separating sure to which .this gas is subjected. The the electrodes., If the electrodes are in the employment of a magnetic field which is form of cylinders immersed in a gas with strongest at the outer cylindrical electrode 70 a radial electric field between the cylinders and weakest at the inner electrode substan and a magnetic field substantially parallel tially lengthens the path of electrons leav to the axes of the cylinders, then for a cer ing the outer electrode whenthe latter acts tain range of magnetic iield strength the as a cathode and shortens and constricts the tube will freely conduct with the outer cylin path of electrons leaving the inner electrode 75' 25 der at a negative potential but will insulate when' this latter electrode is acting as a against high potential differences when the4 cathode. In this manner the paths of elec inner cylinder is at a negative potential. It trons leaving the outer cylinder are suffi will be obvious to those skilled in the art ciently lengthened to insure cumulative that this form of tube is thus adapted for the ionization and consequent gaseous conduc rectification of alternating currents. . It has been discovered that the employ 30 ment of a non-uniform or space varying magnetic field in a tube of this character having cylindrical electrodes positioned with 30 tion and, on thel other hand, the paths of electrons leaving the cathode when the inner cylinder is negative are not sufiiciently long to produce cumulative ionization and gaseous conduction in the oppositeA direction. their axes coincident markedly increasesthe In the accompanying drawings illustrat recti?ying properties of the tube and permits ing the preferred form of the invention Fig. 35 rectification to take place over a consider able range of magnetic field .strength and a great range' of gas pressures within the tube. Such a tube may be caused to» rectiiy alter nating currents with either the inner or 40 1 represents a sectional elevation of a tube embodying the features of the invention; Fig. 2 is a simple circuit embodying the 90 tube; and Figs. 3 and 4 are partially dia grammatic views illustrating the approxi outer electrodes negative providing that the mate path which it is believed the electrons magnetic field is non-uniform and strongest follow when the tube is employed as a 95 adjacent the negative electrode. In the pre rectifier. ferred embodiment of the invention the tube . Referring to the illustrated embodiment is provided with concentric cylindrical elec of the invention it will be observed that the trodes and a space varying magnetic field bulb or tube 10 contains steel cylinders 12 with its strongest portion adjacent the outer and 13 separated by a small air gap and electrode and its weakest portion ~adjacent connected together by a sleevek 14 of co per 100 the inner electrode. This type of tube will or other non-magnetic material having eat rectify with permissible variations of mag radiation openings 16 formed therein. The 50 netic field strength and gas pressure ap outer electrode comprises a -short tube of proximating ten to one. molybdenum or other suitable electrode ma ' ' In its broadest conception the invention terial gripped within the cylinders 12 and 105 contemplates the employment of a non-uni'. 13, as indicated, opposite the openings 16. 1,611,175 The inner electrode comprises a copper tube 20 which may be spun onto a piece 22 of silica glass which is in turn held in proper relation to the steel cylinder 12 by a copper spacing member 24 spun thereon and pro and caused to return to the inner electrode or cathode from whence it started. Owing to the comparatively short distance which these electrons travel with respect to the length of travel of the electrons leaving the vided with annular flanges 26. The steel outer electrode it is a relatively simple cylinders are retained within the opposlte matter to cause rectification over a wide reduced ends of the bulb 10 by flexible hold range of pressures where the magnetic field ing rings 28 and 29. lThe inner and outer is varying in space and strongest adjacent 10 electrodes are respectively connected with the outer electrode. As a matter of act-ual leads 32 and 33 passing out of opposite ends fac-t it has been observed that tubes of this of the tube, the lead 32 being connected to character rectify successfully with gas presone end of the cylinder 12 and the lead 33 sures ranging from three-tenths of a milli being connected within the enlarged mouth meter to two-thousandths of a millimeter. 15 formed in the lower end of the inner elec trode 20. The tube may be connected into’ appropriate form of circuitv where it may be desired for example to rectify an alternat ing current of five hundred volts or more. 20 The magnetic field' parallel to the axes 'of the electrodes may be conveniently intro duced by a permanent magnet 35 positioned approximately as shown and operating- in conjunction with the cylinders 12 and 13 of 25 30 35 40 It should be understood by those skilled in the art that the characteristic properties of a magnetic field having its strongest por S0 tion adjacent onefelectrode and becoming progressively weaker as the opposite elec trode is approached are capable of embodi ment in a wide range of constructions em ploying cooperating electrodes immersed in a gas, this type of magnetic field causing a tube to conduct when the electrode in the magnetic material to 'introduce a non-uni region of strongest magnetic field acts as' form magnetic field in the space separating a cathode and to insulate when the electrode the electrodes 18 and 20, this field being in the region of weakest magnetic field is weakest adjacent the surface of the inner acting` as a cathode. Y electrode 20 and becoming progressively In a generic sense, the term “hollow stronger as the outer electrode is approached. cathode” includes a cathode whose active Upon referrig to Fig. 2 a simple form of surface only partially surrounds a gaseous circuit embodying the tube as a rectifier is medium so that the medium immediately shown, this circuit conveniently comprising adjacent the active surface is more or less an input circuit indicated at 40 capable cf pocketed or confined. ' delivering alternating current to the pri A feature of the invention consists in that mary of a step-up transformer 42, the sec~ the field is stronger near the inner concave ondary of which is embodied in an output surface of cathode 13 than adjacent the circuit containing the tube whicl rectifies outer convex surface of the anode 20. the high voltage alternating current de~ I claim livered thereto. This output circuit may be 1. Gaseous conduction apparatus compris connected with any desired form of load ing a hollow cathode, an anode presented to circuit (not shown) to utilize the high the interior of the hollow cathode, means voltage current so rectified. for creating an electric field between the Upon referring to Figs. 3 and 4 it will be surfaces of the electrodes, and means for observed that the electrons leaving the outer introducing a non-uniform magnetic field in or negative terminal start in a region of the space separating the electrodes which is 90 100 llU strong magnetic field and _their path is ac strongest adjacent the cathode and becomes cordingly bent or curved quite rapidly. As progressively weaker as the anode is ap they continue to move toward the inner elec trode or anode, however, they pass into a proached. which the electron moves over a compara trode, means for creating an electric field in ‘ 2. Gaseous conduction apparatus compris region of less magnetic field and their path ing an electrode having a curved surface, a becomes straighter until it is substantially second electrode having a similarly curved parallel to the plane of the anode, alter surface on the convex side of the first elec tively long flat topped path adjacent the the space separating the curvedsurfaces of 60 65 anode, which form of path is ideal for pro the electrodes, and means for introducing a ducing positive ions near the anode which magnetic field in the space separating the drop to the cathode. On the other hand, electrodes which is stronger near the inner with the same character of magnetic field >surface of the concave electrode than adja 120 and with the inner electrode negative, elec- ` cent the outer surface of the convex elec 125 trons leavino‘ the cathode start off in a trode. straight pat lîtoward the anode or ,outer 3. An electrical apparatus comprising a electrode and then pass _into a region of gas filled tube, inner and outer cylindrical progressively stronger field where the elec electrodes received within the tube and lo tron is shortly bent back in a sharp curve cated with their axes substantially coinci 1,617,175 dent, means for creating an electric field in and meansfor impressing a space varying the space separating the electrodes, means magnetic field in t e region. for introduclng a magnetic field into the 7._A.n electrical apparatus comprising av annular space separating the electrodes, and gas filled receptacle, a pair of electrodes re cylinders of magnetic material positioned ceived therein and having opposing sur concentric with the electrodes and arranged faces separated by a distance which is short adjacent one of the electrodes to cause the and of the order of magnitude of the mean magnetic field to be non-uniform between .free path of electrons in the gas, means for the electrodes. -10 v - ` impressing a magnetic field between the ‘ 4. An electrical apparatus comprising a electrodes, and magnetic material placed ad~ gas filled tube, .an inner electrode member, , jacent one of the electrodes so that the mag an outer electrode .cylinder supported con netic field is strongest adjacent that-felec centrically with the inner electrode member, trode and becomes progressively weaker cylinders of magnetic material arranged 20 5'. An electrical apparatus comprising electrodes immersed in a gas and having op 25 toward the other electrode. , outside of _the outer electrode, and means for 8. Electrical apparatus comprising spaced lcreating a magnetic field which is intro-` electrodes with gas therebetween, the dis~ duced into the annular space between the vtance between the electrodes being of the electrodes by the cylinders of magnetic ma order of the mean free path of electrons in terial, the field being strongest adjacent the the gas, and means for producing, in said outer electrode andV becoming progressively space, a magnetic field which varies in in weaker toward the other electrode. tensity from one electrode toward the other electrode. » 50 - 9. Electrical apparatus comprising inner posing surf‘faces spaced apart a distance and outer electrodes with an annulai- dis which is short and comparable to the mean charge space therebetween, containing gas, free path of electrons in the gas, and means ' the distance between the electrodes being of for introducing a non-uniform magnetic the order of the mean free path of electrons field between the electrodes. in the gas, and means for producing a mag 6. An electrical apparatus comprising a im gas filled receptacle, means for creating an netic field which extendsl predominantly in the direction of the axis of said annular' electric field in a portion of the gaseous space and which varies in intensity radially region which is limited in the direction of the electric field to a length comparable to the mean free path of electrons in the gas, of the annular space. l CHARLES G. SMITH. (if)