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Патент USA US3078428

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Feb. 19, 1963
Filed Jan. 23, 1961
FIG. 1.
FIG. 2
l.8-——-: I
1 I
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" atent ‘O
Patented Feb. 19, 1963
thousand volts (=18 kv.). This source connects through
inductor 2 to the anodes of both V1 and V2. The cath~
ode of diode V2 connects to the charging arti?cial trans
mission line generally indicated at 3 and composed of a
number of series-connected inductors 4 and shunt capaci
Charles Theodore, Los Angeles, Calif., assignor to Lmg
tors 5. In an illustrative embodiment the individual in
Temco Vought, Inc., Dallas, Tex., a corporation of
ductors of the transmission line have an inductance of
order of less than one microhenry and each capacitor
Filed Jan. 23, 1961, Ser. No. 84,126
of the order of ?ve one-hundredths of a
7 Claims. (Cl. 328--67)
10 microfarad. More sections of the line are normally em
ployed than have been shown, so that the total shunt
My invention relates to an electrical pulse type modu
capacitance is of the order of a half microfarad.
lator of high power capability and particularly to such a
A pulse transformer 6 has line 3 in series with the pri
device employing a high vacuum tube for current diver
mary 7 to ground, while secondary 8 is connected to the
The need for higher and higher power short pulse type 15 anode and the cathode of klystron V4, for the useful
pulsed energization thereof. Ignitron switch tube V3 is
modulators constantly increases as higher power oscilla
connected across line 3 and primary 7 (in series) and
tor vacuum tubes become available. In order to produce
serves to create a short across this circuit. This dis
pulses in the hundred megawatt class a gaseous switch
charges the line through the primary of the transformer
tube of the nature of an ignitron is required. While these
tubes have numerous advantages in handling high power, 20 and through the switch tube and so produces the modu
lating pulse.
it is necessary that the anode voltage of the same be With
Ignitron V3 is ignited by the application of a consider
held after a discharge for a period of the order of 150
able amount of power, such as two hundred amperes
microseconds in order that the switch tube may deionize.
at two hundred volts. This power is supplied between
The prior art, at lower power levels than I have
achieved, has been able to employ hydrogen thyratrons 25 terminal 11 and ground. Diode 12 is connected from
igniter electrode 10 to ground to prevent a reverse poten
to withhold the anode voltage from the switch tube in
tial upon the ignitor and possible damage thereto, as
order to accomplish deonization. It is not satisfactory
to attempt to operate hydrogen t-hyratrons in parallel in
The last, or gradient, grid of ignitron V3 is provided
order to obtain increased current-carrying capability and
single tubes to carry the current I require have not been 30 with a potential of the order of 10 kv. by the resistive
voltage divider composed of resistors 14 and 15. These
produced by man, and may not be producible.
are connected in series between ground and the anode
I have found that by employing a high vacuum diode
of V3, with the gradient grid connected to the junction
in place of the hydrogen thyratron and by adding a high
between the two resistors.
vacuum triode for diverting current from the diode for
The control grid of the ignitron is ?red by a pulse of
the period of time required for deionization of the switch 35
the order of 4 kv. and a current having an instantaneous
tube I have been able to increase the power capabilities
value of several amperes. This pulse is applied between
of a pulse type modulator almost without limit and to
terminal 16 and ground. The same pulse, at reduced
obtain long life from the essential elements of the modu
amplitude, is applied between terminal 17 and ground to
lator because of the high vacuum nature thereof.
Speci?cally, I provide a high power triode with the 40 the shield grid, which is seen to be connected directly to
terminal 1'7 .
anode thereof connected to the junction between the
A source of repetitive deionizing pulses 19 is connected
charging inductor and the anode of the diode and supply
to the grid of triode V1 through grid-current-limiting re
a positive pulse to the grid of the triode for the period
sistor 20, which has a resistance of the order of one
of time required for deionization of the switch tube. The
hundred ohms. The second terminal of source 19 is
triode drains off the current ?owing through the inductor
and maintains the voltage at the anode of the switch tube 45 connected to the cathode of the triode and also to termi
at essentially zero volts.
nal 21, which is connected to a negative power source of
An object of my invention is to provide a high power
line type modulator.
Another object is to provide a deionization facility for
the order of 2,000 volts.
a gaseous type switch tube.
Another object is to provide high vacuum means for
removing voltage from a gaseous tube to allow the lat
ter to deionize.
Another object is to provide a modulator circuit having
long life and high reliability.
Other objects will become apparent upon reading the
following detailed speci?cation and upon examining the
The above circuit operates as follows.
Assume that
ignitron V3 has completed discharging the transmission
50 line 3. A typical operation produces a 2.7 microsecond
pulse; as determined by the discharge time of the line.
The characteristic impedance of the line is a few ohms.
A typical repetition interval between pulses is of the order
of 2,700 microseconds. A deionization time of 150 micro~
seconds is characteristic of the ignitron with a large grid
bias, and for that period of time the voltage at the anode
of V3 should be zero.
This is brought about according to my invention by
accompanying drawing, in which are set forth by way of
illustration and example certain embodiments of my 60 applying a pulse of 150 microsecond duration to the grid
of triode V1, to allow the same to pass current. This is
shown in FIG. 2 as pulse 25. This pulse starts at time
FIG. 1 shows a schematic diagram of my invention,
To. The typical duration thereof may be 150 micro
seconds, as for the type of apparatus herein described.
FIG. 2 shows certain waveforms explanatory thereof.
This duration may be varied greatly as desired for other
In FIG. 1 V1 is a high vacuum triode characteristic
of my invention. Similarly, V2 is a high vacuum diode. 65 apparatus by altering the time constants of the circuit
within source 19.
V3 is typically an ignitron; that is, a high power mercury
It will be recalled that the potential of the cathode of
vapor tube having a pool of metallic mercury for a cath
tube V1 is 2,000 volts negative. Thus the resting potential
ode. V4 is illustrative of an electronic load, such as a
of 2,500 volts negative for the grid of V1 is su?icient to
high power klystron.
High voltage source 1 is typically one supplying elec 70 'cut that tube off during all periods of time except when
tric power of the order of ten amperes at eighteen-'
pulse 25 is present.‘ Pulse 25 has a positive'polarity’ and
\ smears
ment connections are conventional according to high
power and high voltage practice and have not been shown.
an amplitude of 700 volts. This causes the grid of triode
V1 to go 200 volts positive with respect to the cathode
and thus to cause the tube to act essentially as a short
circuit from the anode of diode V2 to the 2,000 volt
The duration of the deionizing pulse may, of course,
have any desired duration, depending upon the speci?c re
quirement in this regard of switch tube V3.
negative supply, or signal ground.
Still other detailed modi?cations in the characteristics
High voltage source 1 operates continuously and so 5
of the circuit elements, aspects of circuit connections and
current starts to build up through inductor 2 and triode
alteration of the coactive relation between the elements
V1. This is shown as the ramp function 26, which is the
may be taken without departing from the scope of my
anode-cathode current of triode V1, in FIG. 2. In a
representative apparatus, in which a Machlett 7003 triode 1 invention.
Having thus fully described my invention and the
is employed, this current reaches 1.8 amperes by the
manner in which it is to be practiced, I claim:
time the rear of pulse 25 is reached.
1. In an electrical modulator having pulse-forming
The charged potential of ignitron V3 is twice that of
means, and ionizable means for the actuation of said
high voltage supply I; i.c. it is 36 kv. When the line is
y pulse-forming means;
discharged at time To, this potential drops to zero. Be
deionizing means comprising
cause of the bypass type of short of V3 the voltage drop
a single vacuum tube means connected to said ioniz
across inductor 2 makes up all of the potential of high
able means,
voltage source 1 and the potential of the anode and of
control means to cause a ?ow of electrical energy in
the gradient grid of V3 adjacent thereto is zero. This
said vacuum tube means from said ionizable means,
is shown in the lowest waveform of FIG. 2, at 27.
for longer than the duration of the pulse formed by
Upon the conclusion of the 156 microsecond interval, 20
said pulse-forming means, to thereby remove an
triode V1 becomes non-conducting and transmission line
ionizing potential from said ionizable means.
3 starts to charge through inductor 2 and diode V2. How
2. In a pulse modulator having electrical delay pulse
ever, the ionization within ignitron V3 has disappeared
and although a positive potential be applied to the anode N) U_ forming means, with an ionizable shorting tube connected
of that tube it will not conduct until triggered by a posi
the deionizing time of said shorting tube being in ex
tive pulse on the control grid, etc., to repeat the cycle
cess of the duration of the modulating pulse formed
heretofore sketched. The potential at the anode of V3
by said modulator;
increases according to a cosine function, as graphed in
means to deionize said shorting tube comprising only
P16. 2. At the end of this increase shown, the potential
one vacuum tube having a current-flow electrode
has reached the full 36 kv. for this embodiment and the 30
connected to said shorting tube,
line remains charged until the next triggering pulse, which
means to cause current ?ow in said vacuum tube for
at 2,700 microseconds from the prior pulse, is a rela
‘at least the duration of said deionization time to re
tively long time away.
In the use of ignitron V3 it is necessary that the igniter 35
pulse precede the general trigger pulse and the 150 micro
move voltage from said shorting tube by conducting
a current flow from said shorting tube.
3. In a high power pulse modulator having an elec
trical delay line for forming a modulating pulse and a
switch tube having an anode, said anode connected to
will be formed in the mercury pool of the ignitron brie?y
in advance of need. This is standard practice for this tube 4 O said ‘delay line, in which the deionization time of said
switchtube is in excess of the duration of said modulat
and so is not illustrated. The pulse for the ignitor enters
second pulse from source 19 (i.e., precede To) by 40
This is so that electron-emissive points
my apparatus at terminal 11, as has been described.
ing pulse; deionizing means comprising a single high
My system is relatively lossless, in that the energy
stored in inductor 2. during the 150i microsecond interval
vacuum tube connected to the anode circuit of said switch
tube, pulse means connected to said high vacuum tube
is later returned to the line capacitors 5 as useful charg 45 to cause a current flow in said high vacuum tube for the
duration of said deionization time to remove ionizing
ing current after the 150 microsecond period has expired.
potentials from said switch tube by current conduction
It will be understood that my invention can be carried
from said anode circuit for the period of said deioniza
out in a number of embodiments. However, I have em
tion time.
ployed a GE. 5233 ignitron for V3 and a thermionic
4. In an electrical modulator having pulse-forming
high vacuum diode for V2.
means, inductive charging means, and ionizable discharg
In one alternate embodiment, diode V2 is omitted and
ing means connected to said pulse-forming means; de
the former terminals thereof are connected by a wire.
For this simpli?cation the operating frequency (pulse
ionizing means comprising a vacuum tube having an
anode, a grid and a cathode, said anode connected to the
repetition rate) must be nearly the same as the resonant
junction between said inductive charging means and said
pulse-forming means, pulse means connected to said grid
charging period. This charging period is determined by
the inductance of inductor 2 and the total network (line)
capacitance. The latter is of the order of'a half micro
farad and the former is 1.5 henries for an operating fre
quency of 360 pulses per second, which may be con
sidered typical.
to cause a current ?ow in said vacuum tube for the dura
Not only do my hard tubes and circuit provide means
for operating at very high powers that would otherwise
tion of the deionization time of said ionizable discharging
means, to remove the ionizing voltage at said inductive
charging means from said ionizable discharging means
for the duration of said deionization time.
5. In an apparatus having a load,
pulse-forming means connected to said load,
not be attainable, but these provide apparatus of long life
and stable operation at any power level.
Other alternate arrangements are also possible. All of 65
the circuit to the right of V3 in FIG. 1 may have any con
ionizable means connected to said pulse-forming means
to actuate the same,
?guration and serve any purpose as long as a high power
means to deionize said ionizable means comprising
a vacuum tube having electrodes,
pulse is required, there is a charge type of energy build~
up and, of course, deionization protection to V3 is re
quired. In the embodiment described the amplitude of 70
the pulses out of secondary 8 of transformer 6 is 300
It will be understood that the several tubes shown in
FIG. 1 are preferably water cooled in high power em
bodiments, but, this has not beenwshown. Also, the ?la
and reactive means connected to said pulse-forming
a current-passing electrode thereof connected only to
said pulse-forming means and to said reactive means,
enabling means connected to another of said electrodes
of said vacuum tube to cause said current-passing
electrode to pass current,
said enabling means operative for an interval of time
su?iciently long to allow deionization of said ioniza
and a high vacuum diode connected in series between a
ble means.
positive voltage electrical energy supply and said line for
6. In a modulator having a load,
a transmission line,
means connecting said line to said load,
charging said line; means to deionize said switch tube
comprising, a high vacuum high power triode vacuum
5 tube having an anode, a grid and a cathode, said anode
an ionizab'le switch tube connected to said line to peri
odically discharge the same upon ionization of said
connected to the junction between said inductor and said
diode, a source of deionizing pulses having a duration at
least an order of magnitude of time interval longer than
switch tube,
the duration of the discharge pulse of said line through
and inductive means and thermionic means connected
between an electrical energy supply and said line for 10 said switch tube, the grid of said triode connected to said
the energization of said line;
source of deionizin-g pulses through a current-limiting
resistor, and the cathode of said triode connected to a
means to deionize said switch tube comprising a triode
negative voltage electrical energy supply, said triode con
vacuum tube having an anode, electron control
stituted and connected to bypass said charging current
means, and a cathode,
said anode directly connected to said inductive means 15 ?owing through said inductor in response to said deioniz
ing pulses for an interval of time suf?ciently long to allow
and to said thermionic means,
deionization of said switch tube, and not to bypass cur
a source of deionizing pulses,
rent at other times.
said electron control means connected to said source
of deionizing pulses,
said triode connected to bypass said electrical energy
energization ?owing through said inductive means in
response to said deionizing pulses to allow deioniza
tion of said switch tube.
7. In a high power modulator having a load, an in 25
ductance-capacitance transmission line, a pulse trans
former connecting said line to said load, a multiple grid
References Cited in the ?le of this patent
2,43 8,962
Burlingame et al. ______ __ Apr. 6, 1948
Van Dorsten __________ __ Dec. 6, 1949
Pulse Generators, by Glasoe and Lebacoz (1948), Mc
Graw-Hill Book Co., Inc. (vol. V of Radiation Lab.
metallic vapor switch tube connected to said line to
periodically discharge the same upon the actuation of 30 Series).
said switch tube by a modulating pulse, and an inductor
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