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Патент USA US2405070

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July so, 1946.‘
L, TONKS Em
- 2,405,070
SQUARE WAVE PULSE GENERATING SYSTEM
Filed Feb. 23, 1942
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Inventors:
Lewi Tonks,
Milton Davis,
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Th ir' Attorney.
Patented July 30, 1946
2,405,070
UNITED STATES PATENT "OFFICE.
'
2,405,070
,
SQUARE WAVE PULSE GENERATING
SYSTEM
Lewi Tonks, Schenectady, and Milton Davis, Al
plaus, N. Y., assignors toGeneral Electric Com
pany, a corporation of New York 7
Application February 23, 1942, Serial No. 432,010
5 Claims. v (01. 250-37)
2
1
Our invention relates to pulse generating sys
tems, particularly to such systems employing
0 than the pulse provided by the latter system. In
accordance with our present invention this ob
ject is attained by the provision, in a system
spark gaps as switching mechanism, and the gen
eral object of the invention is to provide improved
systems of this character which produce pulses
such as disclosed in the above-mentioned appli
cation, of an auxiliary spark gap switching means
so'arranged as to terminate the transmission
at a relatively high rate, and operate at a high
charging voltage, and which supply a large value
of instantaneous power with a high order of pre
cision of sparking of the switch means proper.
In pulse generating systems for supplying in
line-formed pulse abruptly apredetermined rela
tively short interval of time after the initiation
of the pulse by the main spark gap switching
f means.
The novel features which are considered to be
characteristic of our invention are set forth with
stantaneous high power at a rapid rate which
have been proposed and used heretofore in an
extended range of applications, di?iculties have
been encountered in obtaining pulses of the re
quired power and repetition rate and at the same‘
time with the desired timing accuracy.
In‘v a copending application S. N. 432,009, ?led
February 23, 1942, and assigned to the same as,
particularity in the appended claims. Our in
vention itself, however, both as to its organiza
tion and method of operation together with fur
ther objects and advantages thereof may best be
understood ‘by reference to the following descrip
tion taken in connection with the accompanying
signee as the present application, a pulse gener
drawing wherein Fig. 1 is a diagrammatic repre
ating system" is described wherein these disad-I 29 sentation of a pulse generating system in which
our invention has been embodied, and Fig. 2
illustrates a voltage pulse produced in accordance
vantages are overcome by the provision of a pulse
generating apparatus in which a charged capac
itive storage element is connected to a load by
with our invention.
, ' '
In Fig. 1 the numeral 1 designates a capacitive
a spark gap assembly providing two spark gaps
in series, and in which a- predetermined initial 25 element adapted to be charged periodically from
an alternating current source through a trans
apportionment of the voltages across the two
former 2, a recti?er 3 and an inductance 4 shunt
gaps is changed or disturbed at the desired trig
edlbya resistor 5, and to be discharged during
gering instant thereby to cause breakdown of the
the reverse period of the current source through
spark gaps and to initiate the discharge, through
30 a load element such as a resistor 6, across which
the load, of a pulse from the storage element.
may be connected a desired output or utilization ’
An alternating current source is arranged to
circuit 1. For example, the pulses from the re
charge the storage element at each cycle through
sistor 6 may be supplied to radio apparatus or
a recti?er, and during the interva1 at each cycle
the like employed to transmit high-power signals,
when the voltage of the alternating current
source is reversed the spark gap switch means is 35 rapidly repeated, and accurately timed, and of
short duration. For illustrative purposes the uti
triggered thereby initiating the discharge of
lization circuit is shown herein as including a
the storage element through the load. The ca
magnetron upon the anode-cathode circuit of
pacitive storage element is of such character as
which the pulses from resistor 6 are impressed
to v‘produce a discharge pulse approaching a rec
tangular wave form and for this purpose is con 40 and which is connected to an antenna to trans
mit therefrom rapidly-repeated and short-dura
stituted by a section of a suitable transmission
tion pulses of intense microwave radiation utilized,
for example, in the detection of distant objects.
The capacitive storage element l is constituted
line. The initial apportionment of the voltages
is disturbed or changed to initiate the discharge
by reducing, close to zero, the potential initially
impressed on one ‘of the conductive electrode
' by a section of transmission line of such char
acter that the discharge therefrom approximates
members which provide the two spark gaps. The
reducing of the potential close to zero is accom
a rectangular wave form.
plished ‘by pulsing positive the control electrode
section comprises a‘ plurality of condensers 8,
preferably at least live in number, connected in
of a space discharge device normally in cut-off
parallel, with one-side of each connected to a
common lead 9 and with the other sides of ad
condition connected to the electrode member, the
conduction periods of the space discharge device
being synchronized, through timing means which
may comprise a multivibrator, with the frequency
jacent condensers connected by inductances 10.
To discharge the storage element I through
the load 6 a main switching means is provided
comprising three spark gap members or conduc~
of the alternating current source which charges
the storage element.
‘
p
. .-
.
l
»
tive electrode members ll, 12, and I3 providing
In certain uses of the pulse generating system
above described it has been found to be highly
desirable'that the pulse discharge through. the
load from the capacitive storage means be of a
more nearly perfectly rectansular wave form.
The transmission line
two spark gaps i4 and I5 in series with the stor
age element l and the load 6. The voltages ini
tially impressed across the spark gaps I4 and I5
60
are preferably equally apportioned as by resistors
2,405,070
Q
4
It and IT connected respectively between member
tial voltages of the gaps. To assist in determin=
ing the instant of breakdown of the gaps 33 and
II connected to the capacitor element I and the
34 a‘ resistance 31 is connected in shunt with one
intermediate member I2, and between the inter
of the gaps. The length of the gaps is such that
mediate member l2 and member I3 connected to
the load 3. A capacitor I8 for balancing the dis 5 with resistance 31 disconnected, breakdown of the
gaps does not occur. To suppress undesired os
tributed capacity of member I2 is connected be,
' ci'llations during the sparking period which tend
tween members II and I2.
to occur in the circuit comprising the transmis
sion line I and the spark gaps I4, I5, 33 and 34,
23 of which is connected to the intermediate 10 a resistance v38 is" connected in series in the lat
spark gap member I2, and the cathode 2! of
ter circuit.
> In operation of the system illustrated in Fig.
which is connected to ground. To cause space
l, the transformer 2 charges the transmission line
discharge device I9 to become periodically con- }
section I once per cycle through recti?er 3 and
ducting, thereby to reduce periodically close to
zero the potential of spark gap member I2, a 15 inductance 4. After charging is complete and
during the interval when the voltage of trans
means is provided to impress a positive pulse upon
former 2 is reversed, the switching means con
the control electrode 22 of the latter space dis
stituted by the spark gap members or spark elec
charge device. For this purpose aninductance ‘
trode members II to I3 is triggered, thus apply
23 included in the anode circuit of a space dis
charge device 24 is provided which is connected 20 ing to the load 6 one-half of the voltage of the
charged transmission line I.
'
to the control electrode 22 of discharge device I3
In the absence of the auxiliary switch means
to supply the positive pulse thereto.
29 the pulse voltage after persisting for a prede
To initiate the supplying of the pulse from in
termined period at substantially its maximum
ductance 23 to the control electrode 22 of device
I9 and to synchronize this pulse with the fre 25 ‘value and then decreasing, would not then drop
from its maximum to its minimum value instant
quency of the above-mentioned alternating cur
The numeral I9 designates a space discharge
device, normally in cuto? condition, the anode
rent source, a space discharge device 25 of the
gas ?lled type arranged to operate in a usual
sweep circuit 26 is employed in connection with
ly but during a de?nite, even though relatively
short, time interval. The terminating or lagging
edge of the pulse wave form would therefore be
a multivibrator 21. Potentials are supplied to the 30 slightly sloped and the resulting wave would thus
approach but not attain a square‘ wave form.
control electrode of discharge device 35 from the
However, with the auxiliary switch members 33
alternating current source through a transform
to 32 connected into the system to provide the
or 23 to initiate periodic operation of this dis
spark gaps '33 and 34 in shunt with the load 6,
charge device and thereby to cause negative po
tentials in synchronism with the frequency of the 35’ the drop in pulse voltage occurs suddenly and the
“slight slope'of the lagging or terminating edge of
alternating current source to be impressed upon
the pulse wave form is therefore avoided.
an input electrode of the multivibrator.
The auxiliary switching means 29 functions in
The pulse rate of the multivibrator is thus syn~
the following manner. The gaps 33 and 34 are of
chronized, by connection to circuit 26, with the
predetermined frequency. The output circuit of 40 such length that they do not break down in the
the multivibrator is in turn connected to the con
trol electrode of space discharge device 24 to
absence of means to change or disturb the initial
apportionment of the voltage impressed there
across by the charged line I. But when a suit
able impedance, resistance 31, is connected in
impress short pulses at this frequency upon the
latter electrode. Danger of overloading of the
anode circuit of device 23, which is liable to oc 45 shunt with one of the latter gaps a progressive
unbalance of voltages thereacross occurs which
cur unless the current-passing interval, or inter
causes the gap to break down or ?re during the
val during which current is traversing inductance
pulse interval itself and at a predetermined short
23, is maintained at a small fraction of the total
time interval after the initiation thereof. The
time period of each pulse, is avoided since our
rent-passing intervals of the required short dura 50 sudden breakdown of the gaps 33 and 34 causes
the pulse voltage to drop abruptly from its maxi
tion in device 24 are obtained corresponding'to
mum to its minimum value. The pulse being thus
the short pulses readily obtainable from the multi
terminated abruptly, the lagging edge of the wave
vibrator and impressed upon the control electrode
form is effectively clipped, and the resulting volt
of the device 24.
In accordance with our present invention an 55 age pulse is of the substantially exactly rectangu
auxiliary switching means, indicated generally by
the numeral 29, is provided to cooperate with the
lar wave form illustrated bythe curve of Fig. '2.
The resistance 38 serves to damp out the oscil
lation which tends to be set up, in the circuit
above-described main switching means and its
comprising storage element I and the spark gaps
associated charging and timing elements in pro
ducing a pulse of improved wave form. The 00 54, I5, 33 and 34, as a result of the short-circuit
ing of load 6. The energy still stored in element I
switching means 29 comprises three auxiliary
when the gaps 33 and 34 ?re must be dissipated
spark gap members or conductive electrode mem
in some manner and if no element such as resist—
bers 39, 3I and 32 similar respectively to the
ance 38 is provided for this purpose a large part
members II, I2 and I3 which are disclosed and
described in the above mentioned application, 65 of the energy goes into the spark, and the intense
oscillation in the storage element and spark cir
S. N. 432,009. The members 39 to 32 provide aux
cuit above mentioned interferes with the func
iliary spark gaps 33 and 34 in shunt with the load
tioning of the circuits of the multivibrator 21
resistor 6. The auxiliary spark gap members may
included in the triggering or spark initiation pore
be of smaller diameter than that of the main
spark gap members II to I3 and the length of 70 tion of the system. The damping resistance 38
e?ectively prevents this interference.
the gaps 33 and 34 may be less than that of the
In a practical application of our present inven
main gaps I4 and I5. The gaps 33 and 34 are
preferably equal in length and are shunted re
tion the charging circuit was powered from a 400
spectively by equal impedances constituted by
cycle alternating current source, "A pulse of 125
capacitances 35 and 36 for apportioning the ini 75 amperes at 32 kilovolts which had a duration of
‘2,405,070
5
6
approximately one microsecond repeated 400
times per second, and of a substantially improved
wave form as shown in Fig. 2, closely approxi
mating the desired square wave form, was applied
to the load 6. The value of resistance 38 ranged
from 12.5 to 50 ohms. The value of load resist
of said pulse to cause said voltage to drop abruptly
whereby said voltage pulse becomes of substan
tially exactly rectangular wave form.
ance 6 was 250 ohms; capacitors 35 and 36 were
.pulse at the initiation thereof rising abruptly
of approximately 15 micromicrofarads each; the
value of resistance 31 was 25,000 ohms; the spark
from its minimum to its maximum value, then re
from said maximum to said minimum value
2. The combination with means to produce a
voltage pulse across a load, the voltage of said
maining at maximum for a short time interval,
gap members 30 to 32 were one inch in diameter 10 and thereafter dropping to its' minimum value
and were provided, as in the main spark members
during a relatively short time interval, of means
H to l3, with airblast means (not shown) to re
to cause said voltage to drop to said minimum
move ionization products from the gaps after
value abruptly a predetermined time interval
?ring.
after said initiation whereby said voltage pulse
It Was found, as the charging voltage was ?rst
becomes of substantially exactly rectangular wave
applied at a relatively low value and then in
spark gap members providing two spark gaps in
creased, that the spark gaps “! and I5 of the
series, the pair being in shunt with said load and
main switching means ?rst ?red alone giving,
means to change the apportionment of the volt
across load 6, the usual pulse having a wave form
ages between said gaps.
the terminating or lagging edge of which was 20
3. The combination with means to produce a
slightly sloped. As a particular charging voltage
voltage pulse across a load, the value of said volt
was passed, however, the spark gaps 33 and 34 of
age at the termination of said pulse dropping
the auxiliary switching means began to ?re ir
from its maximum to its minimum during a short
regularly in a transition range and then regu;
time interval, of means to terminate said pulse
larly, clipping the lagging edge of the pulse to 25 abruptly comprising three spark gap members
give the desired substantially rectangular form
providing two spark gaps in series, the pair being
illustrated in Fig. 2. Further increase of charg
in shunt with said load, and means to change the
ing voltage shortened the pulse duration until the
apportionment of the voltages between said gaps
limit of the main gaps l4 and I5 was reached.
comprising a resistance in shunt with one of said
The voltage at which clipping began, as well as
gaps.
the pulse duration at a given voltage, was con
4. The combination with a capacitive device
trollable by suitable variation of resistance 31 and
adapted to produce a voltage pulse approaching
capacitances 35 and 36, and variation of the
a rectangular wave form, a load, switch means
length of gaps 33 and 34.
adapted to connect said device to said load pro—
The system illustrated in Fig. 1 embodying our 35 viding two spark gaps in series with said device
invention has been described as powered from
and said load, and means to change suddenly the
an alternating current source, However, instead
of the alternating current source a direct current
apportionment of the voltages between said spark
gaps to initiate the discharge of said pulse
source may be employed to charge the capacitive
through said load, of means to short circuit said
storage element I as described in the above-men 40 load a predetermined short interval of time after
tioned copending application, S. N. 432,009,
said initiation of said pulse discharge to cause
and in this case the multivibrator 21, together
abrupt termination of said pulse thereby to pro
with any initial or primary timing device con
duce a pulse approaching substantially closer
nected thereto, may be utilized as a timing means
than said ?rst-named pulse to an exactly rec
to control the positive pulsing of the control
tangular wave form, said last-named means com
electrode of the space discharge device 24. Fur
prising auxiliary switch means providing two
ther, instead of changing the initial apportion
spark gaps in series, the pair being in shunt with
ment of the voltages across the main spark gaps
said load, two capacitances connected respective
l4 and 15 by reducing close to zero the initial po
ly in shunt with said last named spark gaps, and
tential on spark gap member l2, the change may 50 means including a resistance in shunt with one
be accomplished, as described in the above-men
of said last-named spark gaps to change progres
tioned copending application, by impressing a
sively the apportionment of the voltages there
voltage pulse on member 5 from the inductance
between.
23, arranged to be raversed periodically by cur
In combination, a capacitive device adapted
rent from the space discharge device 24 having a 55 to 5.produce
a voltage pulse approaching a rectan
pulse timing means associated therewith which
gular wave form, a load, switch means adapted to
may include the multivibrator 21 together with
connect said device to said load providing two
any primary or initial timing device associated
main spark gaps in series with said device and
therewith.
said load, means to change suddenly the appor
Our invention has been described herein in a 60 tionment of the voltages between said gaps to in
particular embodiment for purposes of illustra
itiate the discharge of said pulse through said
tion. It is to be understood, however, that the
load, means to short circuit said load a short in
invention is susceptible of various changes and
terval after said initiation comprising auxiliary
modi?cations and that by the appended claims
switch means providing two auxiliary spark gaps
we intend to cover any such modi?cations as fall
in series, the pair being in shunt with said load,
within the true spirit and scope of our invention.
means to change the apportionment of the volt
What we claim as new and desire to secure by
ages between said auxiliary spark gaps, an oscil
Letters Patent of the United States, is:
lator circuit comprising said capacitive device
1. The combination with means to produce
and said main and auxiliary spark gaps, and a re
across a load a voltage pulse approaching rec 70
sistance
connected in series in said circuit to
tangular wave form, the voltage of said pulse
damp oscillation therein tending to occur upon
dropping from its maximum to its minimum value
sparking in said gaps.
during a relatively short time interval, of spark
LEWI TONKS.
gap switching means to short circuit said load a
predetermined time interval after the initiation 76
MILTON DAVIS.
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