Download Feb. 8 , `1927.

Feb. 8 , `1927.
C. G. SMITH
ELECTRICAL APPARATUS
Filed April 25. 1921
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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.
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ELECTRICAL ArPARATUs'.
Application mea April 25, 1921. seriai Nn. 464,359.
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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
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, 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
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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
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mal insulating state, however, may be `path varying in accordance with the char
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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'
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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
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ment of a non-uniform or space varying
magnetic field in a tube of this character
having cylindrical electrodes positioned with
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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
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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
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netic field strength and gas pressure ap
outer electrode comprises a -short tube of
proximating ten to one.
molybdenum or other suitable electrode ma
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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
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35
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It should be understood by those skilled
in the art that the characteristic properties
of a magnetic field having its strongest por
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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.
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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.
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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
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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
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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
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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
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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.
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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
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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.
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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.
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CHARLES G. SMITH.
(if)