US3088052A - Pulse forming circuit - Google Patents

Pulse forming circuit Download PDF

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Publication number
US3088052A
US3088052A US104464A US10446461A US3088052A US 3088052 A US3088052 A US 3088052A US 104464 A US104464 A US 104464A US 10446461 A US10446461 A US 10446461A US 3088052 A US3088052 A US 3088052A
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United States
Prior art keywords
anode
current
pulse
voltage
tube
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Expired - Lifetime
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US104464A
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English (en)
Inventor
George L Clark
John J Hickey
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SPACE TECHNOLOGY LAB Inc
SPACE TECHNOLOGY LABORATORIES Inc
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SPACE TECHNOLOGY LAB Inc
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Priority to US104464A priority Critical patent/US3088052A/en
Priority to DES78216A priority patent/DE1155809B/de
Priority to CH338962A priority patent/CH405418A/fr
Priority to GB11277/62A priority patent/GB987268A/en
Priority to FR893074A priority patent/FR1319541A/fr
Application granted granted Critical
Publication of US3088052A publication Critical patent/US3088052A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K3/00—Circuits for generating electric pulses; Monostable, bistable or multistable circuits
    • H03K3/02—Generators characterised by the type of circuit or by the means used for producing pulses
    • H03K3/53—Generators characterised by the type of circuit or by the means used for producing pulses by the use of an energy-accumulating element discharged through the load by a switching device controlled by an external signal and not incorporating positive feedback
    • H03K3/55—Generators characterised by the type of circuit or by the means used for producing pulses by the use of an energy-accumulating element discharged through the load by a switching device controlled by an external signal and not incorporating positive feedback the switching device being a gas-filled tube having a control electrode

Definitions

  • a principal object of this invention is to reduce both the rise and decay times of rectangular pulses.
  • a further object is to provide .a pulse forming circuit cap-able of generating rectangular voltage pulses having magnitudes of several hundred volts and rise and decay times of less than 3 nanoseconds.
  • the foregoing and other objects are realized 'according to the invention in a pulse forming circuit that utilizes a thynatron switching tube for controlling the discharge of current from two energy storage devices.
  • the electrodes of the thyratr-on are comprised of -a cathode, a control grid, a primary anode, and a secondary anode.
  • One of the energy storage devices comprises a capacitor connected to the secondary anode of the tube, while the other storage device comprises a delay line connected to the primary anode.
  • the discharge current from both devices flows through an output load resistor connected in the cathode cincuit.
  • a negative bias voltage on the control grid maintains the tube nonconducting, such that the delay line is charged to a moderately high positive potenti-al relative to the cathode and the capacitor is charged to a potential highly positive relative to both the primary anode and the cathode.
  • the tube is rendered conducting by applying a positive trigger pulse to the control grid.
  • the capacitor quickly discharges through the tube to produce a rapidly rising output pulse.
  • the secondary anode remains at a higher posit-ive potential than the primary anode, some of the ldischarge current ows into the primary anode circuit in a sense to add further charge to the delay line.
  • This charging current appears as la brie-f negative current pulse or wave that travels along the length of the delay line.
  • the delay line delivers a constant amplitude current to the load resistance, which appears as the main portion of the rectangular output pulse.
  • the output pulse terminates when both waves 'reach the primary anode, with the brief positive current wave reaching the primary anode slightly [ahead of the negative current wave .and serving to square up the trailing edge of the output pulse.
  • FIG. l is a schematic circuit of ⁇ one embodiment of the pulse for-ming circuit according to the invention.
  • RFIG. 2 is a graph showing certain voltage distributions in a thyratron tube.
  • FlGS. 3, 4, and 5 are graphs of waveforms useful in explaining the operation of the pulse forming circuit.
  • FIG. l shows one embodiment of the pulse forming circuit according to the invention.
  • the pulse forming circuit comprises a thyratron switching tube 10 which is preferably 4a tetrode, such as a type 2D2l.
  • the switching tube 10 includes .a cathode 12, la control electrode 14, a primary anode lr6 surrounded by the control electrode I14, and a secondary ⁇ anode 18 spaced from the control electrode 14. As depicted herein, the switching tube 10 is connected and ⁇ operated in a nonconventional manner.
  • control electrode @14 or the electrode which triggers the tube 10 into conduction, usually functions as a lshield electrode in conventional circuits, and the primary anode 16 usually is used to trigger the tube 10 into conduction.
  • the control electrode @14 or the electrode which triggers the tube 10 into conduction
  • the primary anode 16 usually is used to trigger the tube 10 into conduction.
  • a cathode load resistor Ztl is connected between the cathode 12 and ground.
  • the control electrode 14 is biased to a highly negative potential by connection through a grid bias .resistor 22 to a negative voltage source 24.
  • the bias on the control electrode 14 is in excess of the cutol bias of the switching tube 16.
  • the control electrode 14 is connected to a trigger pulse source 26 through a coupling capacitor 28, the source 26 providing a voltage pulse of suiiicient magnitude to overcome the bias on the control electrode 14 and thereby cause the tube 10 to switch into a conducting condition.
  • the primary anode 16 is maintained at a moderately high positive potential by connection through Ia r-st volt :age dropping resistor 30 to a primary anode voltage source 32.
  • a delay line 34 is also connected between the primary anode .16 and ground, and 'forms one discharge circuit.
  • the secondary anode '18 is maintained ⁇ at a relatively high positive potential by connection through a second yvoltage dropping resistor 36 to a secondary anode voltthe tube are realized when the bias source 24 is -75 volts, the primary anode source 32 is +800 volts, and the secondary anode source 38 is +1500 volts.
  • the operation of the pulse forming circuit will now be described.
  • the switching tube y10 is biased to a nonconduoting condition.
  • the trimmer capacitor 40 is charged to the full voltage of the secondary anode voltage source 38, and the delay line 34 -is charged to the full voltage of the primary anode voltage source 32.
  • the switching tube ⁇ 10 When a positive trigger pulse is applied to the control electrode 14 from the trigger pulse source 26, the switching tube ⁇ 10 is rendered conducting, such that current ows from the secondary anode 18 to the cathode 12, to provide a low resistance discharge path for the trimmer capacitor 40. When this occurs, the primary anode 16 is immersed in the positive column, a region of the switching tube 10 extending between the secondary anode 18 and an area A next adjacent to the cathode 12, as shown in FIG. 2. For purposes of this discussion, it is not necessary to refer to the control electrode 14, hence it is omitted from FIG. 2 for convenience.
  • FIG. 2 is a diagrammatic view and graph showing the voltage distribution in the space Ibet-Ween the cathode 1'2 and the secondary anode 18 of the switching tube 10
  • curve B represents the voltage distribution at the moment the tube 10 reaches full ionization
  • curve C represents the voltage a sh'ort time later. It is seen that at the time full ionization of the tube 10 is reached, the voltage rises sharply from zero voltage at the cathode 12 to a relatively high voltage approaching the maximum secondary anode voltage 18, at the area A next adjacent to the cathode 12.
  • the trimmer capacitor ⁇ 40 quickly discharges through two paths, current flowing in one path in the primary anode circuit, and in another path from the secondary anode 18 to the cathode 12 and through the load resistor 20.
  • the current flow in the second path, through the load resistor produces a sharply rising wavefront y42 in the ⁇ output current, as shown in FIG. 3(a).
  • the total trimmer capacitor discharge current is shown in FIG. 3(11) as a relatively large current pulse 44.
  • the cathode current is shown in FIG. 3(c) as a smaller magnitude current pulse 46 and the primary anode current is shown in FIG.
  • the direction of the primary anode current pulse 48 is shown negative because it is a charging current and it is assumed herein that a discharging current is positive.
  • the direction of ow of the initial primary anode current pulse 48 is such as to add further charge to the delay line 34. Hence, during the initial flow of the tube currents, the delay line 34 does not discharge but rather is briefly charged to a higher potential.
  • FIG. 4 shows these waves as they would appear at a fixed point along the delay line as the waves go by.
  • FIG. 4(a) shows the voltage e(t) as a function of time and
  • FIG. 4(b) shows the current i(t) as a function of time.
  • the voltage wave appears as a short positive going pulse 50 and the current wave appears as a short negative going pulse 52.
  • the current pulse 52 is negative because it is in a direction opposite that yof the discharge current of the delay line 34, which is considered as positive.
  • the duration of the pulse of current -52 lasts as long as the primary anode 16 remains at a potential below that of the positive column in the tube 10. However, as the tube 10 draws current, the secondary anode 18 potential quickly falls ⁇ by an amount determined by the discharge of capacitor 40, bringing the potential of the positive column down with it and below the potential of the primary anode 16, as shown in curve C of FIG. 2. When this occurs, the current flowing in the primary anode circuit reverses direction, thereby terminating the negative current pulse 52 (FIG. 4) and initiating a discharge of the voltage in the delay line 34 through the primary anode circuit.
  • the discharge in the primary anode circuit path gives rise to a negative going voltage wave 54 and a positive going current /wave S6 which travel down the delay line immediately behind the positive voltage wave 50 and the negative current wave 52 previously sent down the line 34.
  • the combined voltage wave 58 traveling down the line away from the primary anode 16 is a positive pulse 50 followed by a negative step 54
  • the combined current wave 60 is a negative pulse 52 followed by a positive step 56.
  • the negative voltage step 54 drops the voltage on the delay line 34 to one half of its initial value E, or to E/2.
  • the positive current step ⁇ 56 raises the current in the delay line 34 to a value I.
  • the total primary anode current has the form shown in the left half lof FIG. 3(e), and the output current, as well as the output voltage, has the form shown in the left half of IFIG. 3(a).
  • the traveling voltage and current waves 58 and 60 reach the end of the delay line 34 the voltage wave 58 is reflected in phase and the current wave 60 is reflected out of vthe phase with the incident waves.
  • the reflected voltage wave 58' appears as a positive pulse 50 leading a negative step 54'
  • the reflected current Wave 60 appears as a positive pulse 52' leading a negative step 56.
  • the traveling waves 58 and 60' reach the primary anode 16 again, the traveling waves terminate, the delay line 34 is fully discharged, and the output current and voltage waves terminate.
  • the effect of the initial traveling current pulse '52, upon termination, is to add a positive component ⁇ 61S to the output current pulse which tends to square up the trailing edge of the output pulse, as shown in FIG. 3(a).
  • the traveling current pulse ⁇ 52 is shown in FIG. 3(e) as a negative pulse in the leading edge of the total primary anode current waveform and as a positive pulse in the trailing edge thereof.
  • the rise time can likewise be reduced to less than 3 nanoseconds.
  • the fast discharge is enhanced by utilizing as the control electrode 14 which controls the ionization, the electrode that is conventionally used as a shield electrode.
  • the close proximity ⁇ of one portion of the control electrode 14 to the cathode y12 permits greater control over the ionization and results in shorter ionization times with consequent fast discharge of the trimmer capacitor 40.
  • Typical operating values for the circuit of FIG. l are as rfollows:
  • Resistor 20 ohms said primary anode; a second charging circuit in- ⁇ Resistor 36 -..megohms 10 Capacitor 40 micromicrofarads 4-30 Resis-tor 30 megohms ⁇ 10 Source 32 volts 800 Source 38 do 1500 Capacitor 28 micromicrofarads 100 Resistor 22 kilohms 10 Source 24 volts -75 Delay line 34 2 feet of RG-SS/U cable In one operative embodiment constructed with the above circuit values, rectangular pulses of 350 volts in magnitude were generated having rise and decay times less than 3 nanoseconds.
  • the value of the trimmer capacitor 40 can be varied to produce a desired waveform.
  • the capacitance may be made relatively large to produce a steep rise at the expense of overshoot in the pulse, or it may be made relatively small to produce a substantially flat waveform at the expense of longer rise time.
  • FIG. 5 shows variations in the shape of the output waveform with variations in the value of the trimmer capacitor 40. Typically, the output waveform may have a duration of l0 nanoseconds.
  • FIG. 5(a) shows a typical uncompensated waveform, that is, one resulting from Zero trimmer capacitance.
  • FIG. 5(b) shows a typical properly compensated waveform resulting from the proper value of trimmer capacitance.
  • FIG. 5(c) shows an overcompensated Waveform resulting from too high a value of trimmer capacitance.
  • a pulse forming circuit comprising: a thyratron switching tube including a cathode, a control grid, a primary anode, and a secondary anode; a load resistor connected in series with said tube; a first charging circuit including a first energy storage device connected to said primary anode; a second charging circuit including a second energy storage device connected to said secondary anode; said charging circuits including means for simultaneously charging said second energy storage device to an initial voltage greater than the voltage on said iirst energy storage device; means for maintaining said tube normally nonconductingwhereby both of said energy storage devices are fully charged to their initial voltages, and means for switching said tube into a conducting condition to provide a common discharge path for both of said energy storage devices through said load resistor.
  • a pulse forming circuit according to claim l wherein said first charging circuit includes a first voltage source of given magnitude, and said second charging circuit includes a voltage source that is greater in magnitude than said first voltage source.
  • a pulse forming circuit comprising: a thyratron switching tube including a cathode, a control grid, a primary anode, and a secondary anode; a load resistor connected in series with said tube; a iirst charging circuit including a first energy storage device connected to cluding a second energy storage device connected to said secondary anode, said load resistor being out of both of said charging circuits; said charging circuits including means for simultaneously charging said second energy storage device to an initial voltage greater than the voltage on said first energy storage device; means for applying a negative bias on said control grid that is greater than the negative cutoi potential thereof to maintain said tube normally nonconducting, whereby both of said energy storage devices are fully charged to their initial voltages; and means for switching said tube into a conducting condition to provide a common discharge path for both of said energy storage devices through said load resistor.
  • a pulse forming circuit comprising: a thyratron switch-ing tube including a cathode, a control grid, a primary anode, and a secondary anode; a load resistor connected in series with said tube; a first charging circuit including a delay line, a first resistor, and a tirst voltage source connected in series, with said primary anode connected to the junction between sa-id rst resistor and said delay line; a second charging circuit including a capacitor, a second resistor and a second voltage source connected in series, with said second anode connected to the junction between said second resistor and said capacitor; said charging circuits including means for simultaneously charging said capacitor to an initial voltage greater than the voltage on said delay line; means for maintaining said tube normally nonconducting, whereby said capacitor and said delay line are fully charged to their intial voltages and means for switching said tube into a conducting condition to provide a common discharge path for said capacitor and said delay line through said load resistor.
  • a pulse forming circuit comprising:
  • a thyratron switching tube including a cathode, a control grid, a primary anode, and a secondary anode mounted in that order in a common electron path;
  • a pulse forming circuit comprising:
  • a thyratron tube including, a cathode, a control grid, a primary anode and a secondary anode mounted in that order in a common electron stream path,
  • first source means for applying a posit-ive potential on said primary anode
  • second source means for applying to said secondary anode a positive potential that is substantially larger than potential on said primary anode
  • said capacitor and delay line being initially charged to the potentials of said first and second sources respectively, when said tube is nonconducting

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US104464A 1961-04-20 1961-04-20 Pulse forming circuit Expired - Lifetime US3088052A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
US104464A US3088052A (en) 1961-04-20 1961-04-20 Pulse forming circuit
DES78216A DE1155809B (de) 1961-04-20 1962-02-26 Elektrische Schaltung zur Formung flankensteiler Impulse
CH338962A CH405418A (fr) 1961-04-20 1962-03-22 Générateur d'impulsions
GB11277/62A GB987268A (en) 1961-04-20 1962-03-23 Improvements in or relating to pulse forming circuits
FR893074A FR1319541A (fr) 1961-04-20 1962-04-02 Perfectionnements apportés aux générateurs d'impulsions

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Application Number Priority Date Filing Date Title
US104464A US3088052A (en) 1961-04-20 1961-04-20 Pulse forming circuit

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US3088052A true US3088052A (en) 1963-04-30

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US104464A Expired - Lifetime US3088052A (en) 1961-04-20 1961-04-20 Pulse forming circuit

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US (1) US3088052A (fr)
CH (1) CH405418A (fr)
DE (1) DE1155809B (fr)
GB (1) GB987268A (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3509567A (en) * 1967-08-25 1970-04-28 Nat Res Dev Solid state radar
US20050204819A1 (en) * 2004-03-17 2005-09-22 Taylor Steven C Ultrasonic pulser-receiver

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2487923A (en) * 1947-06-24 1949-11-15 English Electric Co Ltd Electric circuits, comprinsing electric discharge devices

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1015544B (de) * 1952-12-13 1957-09-12 Siemens Ag Gittergesteuertes gas- oder dampfgefuelltes Entladungsgefaess

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2487923A (en) * 1947-06-24 1949-11-15 English Electric Co Ltd Electric circuits, comprinsing electric discharge devices

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3509567A (en) * 1967-08-25 1970-04-28 Nat Res Dev Solid state radar
US20050204819A1 (en) * 2004-03-17 2005-09-22 Taylor Steven C Ultrasonic pulser-receiver
US7104131B2 (en) * 2004-03-17 2006-09-12 Battelle Energy Alliance, Llc Ultrasonic pulser-receiver
WO2007030085A3 (fr) * 2004-03-17 2009-04-16 Battelle Energy Alliance Llc Recepteur/generateur d'impulsions ultrasonore

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Publication number Publication date
GB987268A (en) 1965-03-24
DE1155809B (de) 1963-10-17
CH405418A (fr) 1966-01-15

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