US3829732A

US3829732A - Gas-dynamic discharge light

Info

Publication number: US3829732A
Application number: US00296155A
Authority: US
Inventors: V Roldugin; V Sysun; J Basov
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-10-11
Filing date: 1972-10-10
Publication date: 1974-08-13
Anticipated expiration: 1991-08-13
Also published as: FR2156260A1; FR2156260B1; DE2249611A1; DD99692A1; IT966293B

Abstract

A gas-dynamic discharge light source comprising at least two discharge chambers made of a thermally stable dielectric material with light-reflecting properties, filled with a working medium, and linked together through the medium of an optically transparent tube, each discharge chamber having at one end a central electrode unit while positioned near the joint between each said discharge chamber and the optically transparent tube is an annular electrode unit coaxial with a respective central electrode unit; said optically transparent tube provided with a means for pre-ionization and transferring of at least part of the working medium therefrom into said discharge chambers through the electrode units; the working electrodes of said electrode units between which there flows working current initiating gasdischarge plasma and shock waves in said optically transparent tube are connected to control pulsed electric power storages.

Description

United States Patent 1191 Sysun et a1.

1 51 Aug. 13, 1974 1 GAS-DYNAMIC DISCHARGE LIGHT [76] lnventors: Viktor Viktorovich Sysun, korpus 707 kv. 71; Jury Georgievich Basov, korpus 309 kv. 32; Vladimir lvanovich Roldugin, korpus 347 kv. 34, all of Moscow Zelenograd, USSR.

22 Filed: Oct. 10,1972

1211 Appl. No.: 296,155

[30] Foreign Application Priority Data Oct. 11,1971 U.S.S.R ..1704150 52] US. Cl. 313/198, 313/216 [51] Int. Cl. H0lj 61/54 [58] Field of Search 313/188, 198,216

[56] References Cited UNITED STATES PATENTS 3,703,658 11/1972 Sysun et al 313/231 3,775,641 11/1973 Goldberg 313/198 Primary Examiner H. K. Saalbach Assistant Examiner-Darwin R Hostetter Attorney, Agent, or Firm-Holman & Stern 5 7 ABSTRACT A gas-dynamic discharge light source comprising at least two discharge chambers made of a thermally stable dielectric material with light-reflecting properties, filled with a working medium, and linked together through the medium of an optically transparent tube, each discharge chamber having at one end a central electrode unit while positioned near the joint between each said discharge chamber and the optically transparent tube is an annular electrode unit coaxial with a respective central electrode unit; said optically transparent tube provided with a means for pre-ionization and transferring of at least part of the working medium therefrom into said discharge chambers through the electrode units; the working electrodes of said electrode units between which there flows working current initiating gas-discharge plasma and shock waves in said optically transparent tube are connected to control pulsed electric power storages.

9 Claims, 5 Drawing Figures Z7 Z5 Z9- GAS-DYNAMIC DISCHARGE LIGHT The present invention is related to gas-dynamic impulse discharge devices, and more particularly to gasdynamic discharge light sources producing radiation within the optical range of wavelengths as a result of interaction of shock waves with flows of plasma.

Known in the art is a gas-discharge device producing radiation within the optical range of wavelengths at the expense of shock waves used for studying hightemperature plasma or as a light source.

Said device is made in the form of a T-type tube. The discharge chamber thereof is formed bythe cross-arm portion of said tube with two electrodes mounted at the opposite ends thereof between which a gaseous shock is produced. Shock waves and gas-discharge plasma enter the elongated tubular portion contacting the discharge chamber (shock-tube).

Also known in the art is a gas-dynamic discharge light source wherein two cylindrical discharge chambers are interconnected through the medium of an optically transparent tube for radiation yield. Said tube is coupled with the cylindrical discharge chambers made of a dielectric material.

Disadvantages of prior-art devices consist in a low efficiency of conversion of the electric energy delivered to the discharge into luminous radiation.

It is an object of the present invention to provide a light source without the above disadvantages.

The basic object of the invention is to provide a compact and dependable gas-dynamic discharge light source based on the principle of interaction between counter shock waves and flows of gas-discharge. plasma ensuring high efficiency of conversion of the applied electric energy into luminous radiation, permitting of obtaining flares of briefer duration and a uniform density of the radiation emerging from the luminous portion of the device with a more intensive radiation in the ultraviolet spectrum.

This object is achieved in that the gas-dynamic discharge light source comprising at least two discharge chambers made of a thermally stable dielectric material with light-reflecting properties, filled with a working medium, interconnected through the medium of at least one optically transparent tube, provided with electrode units with working electrodes between which electric current is passed said current initiating gasdischarge plasma and shock waves in said tube, and connected to control pulsed electric power storages, has, according to the invention, electrode units in each discharge chamber made as a central electrode unit placed at one end of each dischargechamber and an annular electrode unit arranged coaxially with the central electrode unit near the joint between the latter and the optically transparent tube which is provided with a means for pre-ionization and transferring therefrom of at least part pf the working medium through said electrode units into said discharge chambers.

It is expedient that each discharge chamber be made in the form of a hollow truncated cone and enclosed in a metal housing of the shape which housing would reinforce the lateral sides of the chamber and be electrically connected to one of the electrode units, for example to the annular electrode unit.

Said discharge chambers may also be made in the form of hollow cylinders enclosed in a metal housing of the same shape and arranged with their open ends inside the common optically transparent tube at the opposite ends thereof.

It is advantageous to make each discharge chamber of a thermally stable ceramic material, selected from the group consisting of beryllium, aluminium or titanium oxides, while the optically transparent tube should be preferably made of fused quartz glass or polycrystalline alumina.

Each discharge chamber may as well me made of an optically transparent material to be coated with a layer of a material reflecting luminous radiation in a scattered or specular manner. In that case it is preferable, in the gas-dynamic discharge light source, that the means for pre-ionization and transferring of at least part of the working medium from the optically transparent tube into the discharge chambers in the course of operation of the device be made as auxiliary electrode units forming a supplementary discharge gap, mounted inside said optically transparent tube and separately connected to the control pulsed electric power storages initiating a discharge which starts prior to the discharge in the chambers and continues along with the latter. Besides, the means for pre-ionization and transferring of at least part of the working medium from the optically transparent tube into the discharge chambers may be also made in the form of a single auxiliary electrode introduced into said optically transparent tube and forming a supplementary discharge gap together with at least one electrode unit, for example the annular electrode unit. Recommended for use as the working medium filling the inner part of the device mixed with an inert gas are such elements as La, Li, Rb, Cs. K, Hg, Cd, Zn, TI and their halides.

The gas-dynamic impulse discharge light source according to the invention, more effectively uses the interaction between shock waves and flows of plasma. This enables the efficiency of conversion of the electric energy delivered to the discharge into luminous radiation to be increased as a result of decreasing dispersion of the energy expended by the gas-discharge plasma upon heating of the cold gas, as well as to more effectively utilize the radiation emerging from the zone of interaction between shock waves and between shock waves and flows of plasma.

The gas-dynamic impulse discharge light source is intended for obtaining recurring high intensity light flashes of short duration used mainly for optical excitation of active media, and most advantageously of organic dye solution lasers. The device may as advantageously be used in physicochemical research on pulsed photodissociation of gases and solutions, in luminoussignal equipment, etc.

The invention will now be explained in greater detail with reference to the embodiments thereof taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a partially cut front elevation of a gasdynamic discharge light source with tapered discharge chambers;

P16. 2 is a connection block diagram of the discharge device;

FIG. 3 is a partially cut front elevation of another embodiment of the device with cylindrical discharge chambers;

FIG. 4 is a longitudinal section of a gas-dynamic discharge light source with an auxiliary electrode unit in conjunction with a block diagram of its start-control devices;

FIG. shows an embodiment of the device with two auxiliary electrode units.

Referring now to FIG. 1 there is shown by illustration a gas-dynamic discharge light source 1 comprising two kindred discharge chambers 2 coupled with an optically transparent tube 3 made, for example, of fused quartz glass and intended for radiation yield. Said optically transparent tube 3 is provided at its opposing ends with expanded tapered portions 4 (with an angle of taper of 40) terminating in annular flanges 5 providing a leak-tight and mechanical connection of the optically transparent tube 3 with the discharge chambers 2.

Each discharge chamber 2 of the device is made in the form of a tapered body of revolution. The chamber 2 has at its base an annular flange 6 and is made of a thermally stable dielectric material with light-reflecting surfaces, such as beryllium oxide, alumina, etc. The chamber may also be made of fused quartz glass coated with a layer 7 of radiation-diffusing silica caked down to zero porosity.

Each discharge chamber 2 is linked to the optically transparent tube 3 through an annular electrode unit 8 mounted between said flange 6 at the base of the tapered chamber 2 and the flange 5 of the optically transparent tube 3. The electrode unit 8 is an asymmetric annular member made from molibdenum with a rounded inner surface serving as the'working surface of the electrode, while the top and bottom surfaces mate with the flanges 5 and 6. When mounting the annular electrode unit 8 between the flange 6 of the discharge chamber 2 and the flange 5 of the optically transparent tube 3, the gap therebetween is potted with a sealing compound 9.

Said tapered chamber 2 confining the discharge gap extends. at its vertex, into a cylindrical stem 10 mounted wherein is a central electrode 11 comprising a working electrode 12 made of tungsten and a hollow holder 13 sealed in the stem 10. The annular electrode unit 8 and the central electrode unit 11 with the working electrode 12 form the discharge gap.

The discharge chamber 2 is enclosed in a metal housing 14 made in the form of a truncated cone and acting as a current-carrying conductor.

The metal housing 14 is contigious to the layer 7 and is mechanically as well as electrically connected to the outer surface of the annular electrode unit 8. Mounted near the lesser base of the tapered chamber 2 are current supplying elements 15. To obtain selective radiation, used as the working medium filling the inner part of the device and mixed with an inert gas are such elements as Na, Li, K, Rb, Cs, Hg, Cd, Zn, Tl and their halides. For example, the gas-dynamic discharge light source 1 shown in FIG. 1 is filled with I-Ig.

Filled with xenon to a pressure of to 50 mm Hg, the gas-dynamic discharge light source 1 is connected into two independent low-inductance circuits l6 and 17 (FIG. 2) via controlled arresters l8 and 19 respectively operated by a two-channel sequential ignition unit 20 initiating discharge simultaneously in both discharge chambers 2. A duty-setting unit 21 allows for controlling the two-channel sequential ignition unit 20 and discharge initiation in the chambers 2 (FIG. I) in studying the process of interaction between shock waves and gas-discharge plasma, as well as in selecting the operating duty.

Both annular electrode units 8 are connected as an anode (or in a heteropolar manner). Discharge currents in both discharge gaps flow in directions opposite to those of the currents flowing through the metal housings 14 enveloping the chambers 2.

Referring to FIG. 3 there is shown another embodiment of the gas-dynamic discharge light source I wherein discharge chambers 22 are made in the form of hollow cylinders enclosed in cylindrical metal housings 23 (as distinct from those shown in FIG. 1) and disposed in expanded cylindrical portions 24 at the op posite ends of the optically transparent tube. Still another embodiment of the gas-dynamic discharge light source 1 shown in FIG. 4 includes the tapered discharge chamber 2 with the central electrode unit 11 plus an auxiliary electrode unit 25 with a working electrode 26 serving as the means for pre-ionization and transferring of the working medium from the optically transparent tube 3, the electrode 26 forming a supplementary discharge gap together with the annular electrode unit 8 of the discharge chamber 2 and connected, also together with the electrode unit 8, into the discharge circuit formed by three

capacitors

27, 28 and 29 arranged in a long line. To protect the elements of this circuit rated at a working voltage of up to 5 kV against main discharge surges in the chamber 2, a saturable-core reactor 30 is used. Discharge in the supplementary gap is initiated by means of an ignition unit 31. The low-inductance circuit (0.1 to 0.4 muH) comprises an electric power storage 32 constituted by a bank of capacitors charged by a rectifier 33. Thedischarge in the gap between the electrode units 8 and 11 is initiated by an arrester 34 operated by a sequential ignition unit 35. The arrester 34 is controlled by a phase-shifting stage 36.

Yet another embodiment of the gas-dynamic discharge light source 1 shown in FIG. 5 differs from that shown in FIG. 1 in that the optically transparent tube 3contains ameans for pre-ionization and transferring of the working medium therefrom comprising two auxiliary electrode units 37 and 38 wherebetween a preliminary discharge is initiated. In this case, connected to said auxiliary electrode units 37 and 38 is a bank of capacitors 39 arranged in a long line which is operated by an ignition unit 40 to initiate a discharge in the supplementary gap inside the optically transparent tube 3. The discharge chambers 2 are connected to an electric power storage 41 which is discharged in said chambers 2 when an ignition unit 42 operates. The initiation of discharge in the chambers 2 and in the gap formed by the electrode units 37 and 38 in the optically transparent tube 3 is effected by means of a phase-shifting stage 43.

Referring to FIGS. 1 and 2, as a discharge of short duration takes place, the resulting gas-dischargeplasma, simultaneously in both chambers 2, undergoes magnetic compression (under the effect of the magnetic field of the current flowing through the metal housing 14 toward the annular electrode unit 8) in a direction toward the longitudinal axis of the chamber 2. This phenomenon is caused by pinch-effect, radial compression starting near the working electrode 12 of the central electrode unit 11 of each discharge chamber 2 and gradually involving all the layers of plasma nearer to the surface of said electrode I2. Then, the heated pinched plasma flows over simultaneously from both discharge chambers 2 into the optically transparent tube 3 initiating powerful shock waves. In so doing,

photoionization of particles ahead of the powerful shock waves and flowing plasma which is conductive to faster mixing of the plasma with the gas heated under the effect of shock waves. When shock waves meet in the center of the optically transparent tube 3, this results in a highly intensive glow. The Zone of interaction between shock waves and between shock waves and flowing plasma is characterized in elevated brightness of continuous spectrum radiation.

When the auxiliary electrode units 37 and 38 (FIG. 5) or the auxiliary electrode unit 25 and the annular electrode unit (FIG. 4) are connected into the discharge circuit forming a long line and comprising the bank of capacitors 39, superimposed on the electric pulse with a duration of 100 to 400 msec shaped in the supplementary discharge gap is a pulse of briefer duration to 50 msec) shaped by the low-inductance storage 32 or 41 (FIGS. 4 and 5) of the electric energy which l0 to times exceeds that of the auxiliary discharge. The discharge in the supplementary gap is conductive to increasing gas density in the discharge chamber 2 (or 22), as well as to increasing the velocity of shock waves as they move in the optically transparent tube 3 through the ionized gas with a density lower than it was before pre-ionization. These factors conduce to increase the temperature of the ionized gas of radiation fluxes and to intensify the process of uniform filling of the optically transparent tube 3 with emitting plasma.

What is claimed is:

1. A gas-dynamic discharge light source comprising at least two discharge chambers made of a thermally stable dielectric material with light-reflecting properties and filled with a working medium; at least one optically transparent tube linked together said discharge chambers; at least two central electrode units with working electrodes each placed at one end of a respective said discharge chamber; at least two annual electrode units with working electrodes each positioned near the joint between a respective discharge chamber and said optically transparent tube coaxially with a respective said central electrode unit; a means for preionization and transferring of at least part of the working medium from said optically transparent tube into said discharge chambers through said electrode units which means is housed in said optically transparent tube; control pulsed electric power storages connected to said working electrodes of said electrode units.

2. A gas-dynamic discharge light source as claimed in claim 1 wherein each said discharge chamber is made in. the form of a hollow truncated cone.

3. A gas-dynamic discharge light source as claimed in claim 1 wherein each said discharge chamber is enclosed in a metal housing of the same shape which housing reinforces the side walls of said discharge chamber and is electrically connected to one of said electrone units, for example to said annular electrode unit.

4. A gas-dynamic discharge light source as claimed in claim 1 wherein said discharge chambers are made in the form of hollow cylinders, enclosed each in a metal housing of the same shape, and arranged with their open ends inside a common optically transparent tube at the opposite ends thereof.

5. A gas-dynamic discharge light source as claimed in claim 1 wherein each discharge chamber is made of a thermally stable ceramic material, selected from the group consisting of beryllium, aluminium, or titanium oxides, and the optically transparent tube is made of fused quartz glass or polycrystalline alumina.

6. A gas-dynamic discharge light source as claimed in claim 1 wherein each said discharge chamber is made of an optically transparent material and coated with a layer of a material reflecting luminous radiation in a scattered or specular manner.

7. A gas-dynamic discharges light source as claimed in claim 1 wherein said means for pre-ionization and transferring of at least part of the working medium from said optically transparent tube into the discharge chambers in the course of operation is made as auxiliary electrode units forming a supplementary discharge gap, mounted inside said optically transparent tube, and separately connected to control pulsed electric power storages initiating a discharge which starts prior to a discharge in said discharge chambers and continuous along with the latter.

8. A gas-dynamic discharge light source as claimed in claim 1 wherein said means for pre-ionization and transferring of at least part of the working matter into the discharge chambers is made as a single auxiliary electrode introduced into said optically transparent tube, connected to said control pulsed electric power storage, and forms a supplementary discharge gap together with at least one said electrode unit, for example the annular electrode unit.

9. A gas-dynamic discharge light source as claimed in claim 1 wherein the working medium filling the inner part of the device comprises an inert gas mixed with at least one element selected from the group consisting of Na, Li, K, Rb, Hg, Cd, Zn, Tl and other halides.

Claims

1. A gas-dynamic discharge light source comprising at least two discharge chambers made of a thermally stable dielectric material with light-reflecting properties and filled with a working medium; at least one optically transparent tube linked together said discharge chambers; at least two central electrode units with working electrodes each placed at one end of a respective said discharge chamber; at least two annual electrode units with working electrodes each positioned near the joint between a respective discharge chamber and said optically transparent tube coaxially with a respective said central electrode unit; a means for pre-ionization and transferring of at least part of the working medium from said optically transparent tube into said discharge chambers through said electrode units which means is housed in said optically transparent tube; control pulsed electric power storages connected to said working electrodes of said electrode units.

2. A gas-dynamic discharge light source as claimed in claim 1 wherein each said discharge chamber is made in the form of a hollow truncated cone.