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Патент USA US2409955

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0a, 22,1946.
9
H, T, RA‘MSAY
'
2,409,955
GAS FILLED ELECTRIC RECTIFIER
Filed March 13, 1943
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Patented Get. 22, 1946
2,409,955
UNITED STATES PATENT OFFICE
2,409,955
GAS-FILLED ELECTRIC RECTIFIER
Henry Thomas Ramsay, Hatch End, England,
assignor to The General Electric Company
Limited, London, England
-
Application March 13, 1943, Serial No. 479,121
In Great Britain March 13, 1942
6 Claims.
1
This invention relates to electrical apparatus
of the type comprising a recti?er of the kind hav
ing a thermionic cathode, an anode, a shield
forming part at least of a labyrinth separating
the cathode from the anode, an auxiliary elec
trode, and a gas or vapour (e. g. mercury) ?ll
ing the space between the said members, the ar
(Cl. 315-340)
2 .
mercury pressure, the arrangement of the elec
trodes, and the voltages applied to them, at least
over a certain range. It is sometimes desirable
that the interval should be‘ very short, for ex
ample 1 micro-second; then the discharge dur
ing the interval is apt to damage the cathode,
especially when it is activated and of the form
rangement being such that, when the auxiliary
described with reference to the drawing accom
electrode is at cathode potential a discharge be
panyin'g the said British Speci?cation No. 541,919.
tween cathode and anode cannot start under any 10 An object of this invention is to provide means
voltage normally applied between them, but when
the auxiliary electrode is made positive to the
cathode, so as to' produce‘ an ion-forming dis
charge between the auxiliary electrode and the
cathode, the main discharge starts between cath
ode and anode.
Recti?ers of the said kind are
described in British Patent Speci?cation No.
541,919 and in U. S. patent application Serial No.
466,651 ?led November 23, 1942. It is to be un
derstood that the auxiliary electrode may be a
substantial part of the shield (as in the speci?ca
tion of the said application), or it may be so small
that it has practically no effect in shielding the
cathode from the anode (as in the said British
Speci?cation No. 541,919) .
The term “labyrinth” implies that the starting
of an ion-forming discharge from the cathode is
for mitigating this damage in these circumstances.
This object can be attained by producing, by
means of a discharge, ionization‘ in the neigh
bourhood of the cathode before the application
between the cathode and the control electrode
of the voltage that starts the main discharge
between the‘ cathode and the anode. This ioniza
tion must not, of course, itself enable the main
discharge to start; this condition can be ful?lled
by causing the preliminary discharge that ,pro
duces the said ionization .to pass between the
cathode and another auxiliary electrode, differ
ent from‘ the aforesaid auxiliary electrode and
wholly on the cathode side of the said shield, or
between the cathode‘ and part of the shield‘itself,
which part is then to be regarded as another
auxiliary electrode. The‘ same result can some
substantially independent of the potential dif
times be produced by causing to pass between the
ference between anode and cathode. A necessary
cathode and the ?rst-mentioned auxiliary elec
condition for such independence is that no 30 trode a preliminary discharge carrying a current
straight line can be drawn from anode to cathode
too small to enable the main discharge to‘start;
that does not intersect a conductor that is nega
but no advantage of this‘ alternative is known.
tive to the anode during the starting period. A
The preliminary discharge may pass continu»
straight line passing through an aperture
a
ously during the Whole operation of the appa
grid is not to be‘ held to intersect the grid. But
‘ ratus, or during the whole period, between suc
this condition is’ not suiiicient. A su?icient con
cessive mam discharges. But it is often ‘more
dition is that, if the anode and cathode potential
convenient to apply between the cathode and
is held constant and the control electrode is
the other auxiliary electrode‘ a pulse of voltage
made progressively more positive to the cathode,
immediately preceding that applied between the
the potential of the control electrode at which
cathode and ?rstauxiliary electrode to start the
an ion-forming discharge ?rst occurs (evidenced
main discharge; such a pulse will generally last
by a very sharp rise in the current between con
longer than the pulse that starts the main dise
trol electrode and cathode) is substantially in
charge, but will occupy only a small fraction of
dependent of the anode-cathode potential. ‘This
the period between main discharges.
proves that the anode and control grid do not
Embodiments of the invention will be described
co-operate in the starting of the ?rst ion-form
with reference to the accompanying drawing, in
ing discharge. The anode potential is effective
which Figs. 1 and 3 show respectively relevant
only in converting this ?rst discharge into a dis
parts of two'diiierent forins'of the improved recti
charge between anode and cathode in virtue of
?er in axial section, together with certain circuit
the‘introduction of ions into the labyrinth.
elements, represented diagrammatically, and N
‘In apparatus of the type hereinbefore speci?ed
Fig. 2 is a sectional plan‘ on the line 2-2 in
there is a ?nite interval between the application
Fig. 1.
of (a positive voltage to the auxiliary electrode and
Referring‘ to Figs. 1 and 2, I’ is the cathode, 2
the development of the full‘ discharge between‘
the anode, and‘ 3 is a hollow metal cylinder sur
anode and. cathode. The interval depends on the 55 rounding the cathode. Leads IA and [B for
2,409,955
heating current connect to the ends of the cathode
and a lead IC to the centre of the cathode.
These three leads pass through insulating bush
ings in the base of the cylinder 3. The auxiliary
electrode is made up of a hollow metal cylinder
4 round the inner end of the anode and a plate
5 covering but spaced from the end of a tube‘
6 projecting from the apertured base of the
cylinder 4 into an aperture in the top of the
cylinder 3. The parts 4, 5 and 6 are electrically
connected together and are maintained normally
negative to the cathode by a source of E. M. F.
‘I acting through a choke 8 and a lead It].
The
plate 5 is the main operative element of the lab
yrinth: it shields the cathode completely from a
?eld due to the potential difference between anode
and cathode.
The cylinder 3 is insulated from the parts
4, 5 and 6 and is connected to the central cathode
lead IC through a pulse-generator 9'. A pulse 20
generator 9 is connected between the cathode and
4
of one or more parts interposed between said
cathode and said anode so as to provide a laby
rinth capable of rendering the starting of a dis
charge between said cathode and said anode sub
stantially independent of the potential difference
between said cathode and said ‘anode and an
auxiliary starting electrode separate from said
cathode and said anode, means for periodically
rendering said auxiliary electrode positive with
respect to said cathode so as to produce between
said cathode and said auxiliary electrode an ion
forming discharge capable of enabling the main
discharge between said cathode and said anode
to start, and means for producing by a prelim
inary discharge ionization in the neighbourhood
of said cathode during the period immediately
preceding such application to said auxiliary elec
trode of the voltage that starts the main dis
charge.
’
2. An electrical circuit arrangement compris
ing a thermionic gas-?lled recti?er including a
thermionic cathode, an anode, and separate from
the lead In.
said cathode and said anode an electrode system
In‘ order to produce the preliminary discharge,
constituting a labyrinth capable of rendering the
the pulse-generator 9’ applies a Voltage pulse to
the cylinder 3 positive with respect to the cathode, 25 starting of an ion-forming discharge from‘said
cathode substantially independent of the poten
lasting say 80 micro-seconds and immediately
preceding the application of a positive starting
tial difference between said cathode and said an
ode, means for periodically rendering one part of
pulse applied to the auxiliary electrode 4, 5, 6 by
said electrode system positive with respect to,
the pulse-generator 9. The choke 8 prevents
short circuiting of this pulse. An ion-forming 30 said cathode so as to produce between said cath
ode and said part an ion-forming discharge capa
discharge is thus started between cathode and
auxiliary electrode. The ions produced by this
discharge enable the main discharge to flow
round the edge of the plate 5 and through the
tube 6. When the discharge has been extin
guished by reduction of the anode potential, the
auxiliary electrode is negative and collects the
residual positive ions. The example shown may
be so arranged that the preliminary discharge
ble of enabling the main discharge ‘between said‘
cathode and said anode to start, and means for
rendering another part of said electrode system
positive with respect to said cathode so as to pro
duce by a preliminary discharge ionization in
the neighbourhood of said cathode immediately
preceding such application of starting voltage to
said one part of the electrode system.
3. An electrical circuit arrangement compris
current to the cylinder 3 is about 2 amps, and, 40
ing a thermionic gas-?lled recti?er including a
when the auxiliary electrode 4, 5, 6 is pulsed
about 100 volts positive with respect to the oath
thermionic cathode, an anode, and separate from
ode, a main discharge carrying about 100 amperes
said cathode and said anode an electrode system
constituting av labyrinth capable of rendering the
(limited by the anode-cathode circuit) will then
start within about 1 micro-second of the appli 45 starting of an ion-forming discharge from said
cation of the starting pulse.
cathode substantially independent of the poten
-
Fig. 3 shows a modi?cation in which the pre
tial di?erence between said cathode and said an
ode, said electrode system comprising a ?rst aux
liminary discharge passes between the cathode
and part of the shield itself. The numerals I, 2,
iliary electrode, and a second auxiliary electrode
3, 5, 9 and 9’ represent parts corresponding to 50 disposed nearer to said cathode than is said ?rst.
those similarly denoted in Fig. 1. The shield is
auxiliary electrode, means for periodically ren
constituted by the cylinder 3, an inner tube 3A
dering said ?rst auxiliary electrode positive with
surrounding the cathode, and the plate 5. The
respect to said cathode so as to produce between
said cathode and said ?rst auxiliary electrode
centre point of the cathode is connected to the
cylinder 3, and through this to the plate 5. A lead 55 an ion-forming discharge capable of enabling the
main discharge between said cathode and.‘ said
IilA,‘connected to the cathode by the pulseegen
erator 9, enters the cylinder by a bush“ and
anode to start, and means for renderingsaid
second auxiliary electrode positivewith respect to ,
leaves it by a bush 12; where it is within the
cylinder it is surrounded by a quartz tube 13'
said cathode so as to produce by a preliminary
discharge ionization in the neighbourhood of said
which shields it from the cathode. The upper
cathode immediately precedingsuch application
endof the lead IBA projects from the top of the
of starting voltage to said ?rst auxiliary'elec
case and forms the control electrode M. The
inner tube 3A is insulated'from the cylinder '3 and '
connected thereto and to the centre point of the
cathode through ‘the pulse-generator 9’. The
preliminary ionization in the neighbourhood of
the cathode is established by application of a
positive pulse to the tube 3A by the pulse-genera~
trode.
.
v
i
,
.
4. An electrical circuit arrangement comprise
ing a thermionic gas-?lled recti?er including a
thermionic cathode, an anode, a shield forming
at least part of a labyrinth separating said cath
ode from said anode, a ?rst auxiliary electrode
constituting at least a substantial part of said
tor 9', immediately preceding the application of
the starting pulse to the auxiliary electrode lit 70 shield anda second auxiliary electrode on the
cathode side of said shield, means for periodically
by the pulse-generator 9._
'
rendering said ?rst auxiliary electrode positive
with respect to said cathode so as to produce be
1. An electrical circuit arrangement compris
ing a thermionic gas-?lled recti?er having a
tween said cathode and said ?rst auxiliary elec
thermionic cathode, an anode, ashield consisting 75, trode‘an ion-forming discharge capable of__ en
Iclaim:
'
,
2,409,955
5
6
abling the main discharge between said cathode
for rendering said second auxiliary electrode pos
and said anode to start, and means for rendering
said second auxiliary electrode positive with re
spect to said cathode so as to produce by a pre
itive with respect to said cathode so as to produce
by a preliminary discharge ionization in the
neighbourhood of said cathode immediately pre
liminary discharge ionization in the neighbour
hood of said cathode immediately preceding such
ceding such application of starting voltage to
said ?rst auxiliary electrode.
6. An electrical circuit arrangement compris
application of starting voltage to said ?rst aux
iliary electrode.
ing a thermionic gas-?lled recti?er including a
5. An electrical circuit arrangement compris
thermionic cathode, an anode, a shield disposed
ing a thermionic gas-?lled recti?er including a
between said cathode and said anode and provid
ing a labyrinth separating said cathode from said
thermionic cathode, an anode, a ?rst auxiliary
electrode having an apertured diaphragm dis
anode, an auxiliary electrode 50 positioned that a
starting discharge occurring between said auxil
posed between said cathode and said anode and
also having a ba?‘le covering but spaced from the
iary electrode and said cathode will produce ions
aperture in said diaphragm, a second‘ auxiliary 15 in said labyrinth, means for periodically render
electrode in the form of a hollow metal cylinder
ing said auxiliary electrode positive with respect
disposed around said cathode and having an
to said cathode so as to produce said starting dis-.
apertured cap at its end nearer said anode, means
charge, and means for rendering part of said
for periodically rendering said ?rst auxiliary
shield positive with respect to said cathode so as
electrode positive with respect to said cathode so 20 to produce by a preliminary discharge ionization
as to produce between said cathode and said ?rst
in the neighbourhood of said cathode immedi
auxiliary electrode an ion-forming discharge ca
ately preceding such application of starting volt
pable of enabling the main discharge between
said cathode and said anode to start, and means
age to said auxiliary electrode.
_
HENRY THOMAS RAMSAY.
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