CA1220287A - Apparatus and method for generating a plurality of electric discharges - Google Patents
Apparatus and method for generating a plurality of electric dischargesInfo
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- CA1220287A CA1220287A CA000415606A CA415606A CA1220287A CA 1220287 A CA1220287 A CA 1220287A CA 000415606 A CA000415606 A CA 000415606A CA 415606 A CA415606 A CA 415606A CA 1220287 A CA1220287 A CA 1220287A
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Abstract
ABSTRACT
A gas laser includes first and second electrodes defining a first discharge path and third and fourth electrodes defining a second discharge path alongside the first. A respective impedance is associated with any electrical connection between the electrodes and a common power supply. The electrodes are electrically arranged such that stable electric discharges which coalesce are generated between respective electrodes of the first and second sets. The invention obiates the necessity for a plurality of power supplies whilst maintaining the required stability of operation.
A gas laser includes first and second electrodes defining a first discharge path and third and fourth electrodes defining a second discharge path alongside the first. A respective impedance is associated with any electrical connection between the electrodes and a common power supply. The electrodes are electrically arranged such that stable electric discharges which coalesce are generated between respective electrodes of the first and second sets. The invention obiates the necessity for a plurality of power supplies whilst maintaining the required stability of operation.
Description
This invention relates to electric discharges. More particularly, ths invention relatas to ~as lasers wherein two or more discharges are arranged to occur adjacent to one another and to stabilization of the discharges between respective electrodes.
Various methods have been used to increase the volume of electric discharges, for example, magnetic fields have been used to rotate discharges between coaxial electrodes and offset the inherent tendency of an electric discharge to constrict due to thermal and electromagnetic effects so as to distribute the energy more uniformly in the space between the electrodes and reduce the power density at the interfaces of the discharge and the electrodes.
There is a mutual attraction between two electric discharges that exist alongside one another when current flows in the discharges are in the same direction and, if they are sufficiently close to one anothèr, the discharges coalesce. At the instant of coalescing, the discharges have a central merged portion and four root portions. Such nn arrangement has the advantage that the discharge is necessarily less concentra~ed in the vicinity of the electrodes and also the individual electrode currents are reduced for a given overall discharge current.
If the power for the respective discharges is provided from respective isolated power supplies it is possible to maintain such an arrangement, but the provision of separate power supplies can be disadvantageous.
Althou~h the possibility of generation of coalesced discharges has been known for many years, it is a technique that has not found industrial appl~cation. Indeed the normal approach has been to avoid the production of coalesced discharges by maintaining the discharges sufficiently far apart.
Furthermore, it has been accepted that in order to create a stable four root coalesced discharge, it is essential to have separate power supplies. For example, in an article entitled Multielectrode Arc Dischar~e in the Journal of Applied Spectroscopy, dated February 14, 1967, V.N. Apolitskii, when descri'oinga coalesced discharge, states that "the basic requirement is always separation of the power supplies which must not have a common point".
The necessity of usin~ separate power supplies when ~enerating coalesced discharges is a serious problem in practice since it raises the costs of the discharge apparatus and also makes the apparatus bulkier and more cumbersome to use.
J~
It is an object of the invention to provide a ~as laser and a method of enhancing the laser action by ~eneratin~ electric dischar~es that in certain respects overcomes at least some of the disadvanta~es described above.
It is another object of the invsntion to provide stabili7ation of two or more discharges extending between respective electrodes but coalescing intermediate their ends and ~enerated from a common power supply.
It is another object of the invention to provide a gas laser includin~ a dischar~e tube in which two or more stable dischar~es are generated simultaneously.
Thus, accordin~ to the invention, there is provided a ~as laser includin~ a discharge tube, optical path means for providing an optical path in the dischar~e tube, a power supply, a first set of at least two adjacent electrodes extendin~ into the dischar~e tube and a like number of first impedances each of which connects one electrode of the first set to one side of the power supply, and a second set of at least two adjacent electrodes spaced alon~ the optical path from the first set and extending into the dischar~e tube and a like number of second impedances each of which connects one electrode of the second set to an opposite side of the power supply, whereby stable electric glow disrhar~es which coalesce and extend along the optical path are ~enerated between the respective electrodes of the first and second sets to provide a stable volume of electric discharge in the optical path of the laser for excitin~ the laser.
Preferably, the impedances are each above a minimum value of the same order of masnitude as the impedance of the discharge path during stabi]i7ed operation.
In a further preferred embodiment, the first impedances are of substantially the same value and the second impedances are also of substantially the same value, and these values are preferably the same.
Impedance adjusting means are preferably provided for adjusting the discharge currents, such means desirably comprising means for adjusting the impedance of each of said first and second impedances (preferably equally).
The ~as laser is preferably a C02 ~as laser and the power supply is preferably a DC power supply.
Accordin~ to a further aspect of the invention, there is provided a method of enhancing laser action in the optical path of a ~as dischar~e laser by ~eneratinB two or more electric dischar~es extendin~ between respective :~2~a~'28~
electrodes but coalescing intermediate their ends in the optical path, the method including the following steps:
providing a first set of electrodes comprising two or more adjacent electrodes;
providing a second set of electrodes comprising two or more adjacent electrodes spaced along the optical path from the first set;
providing a separate impedance for each electrode;
connecting each electrode of the first set through a respective separate impedance to a common source of a first potential; and connecting each electrode of the second set through a respective separate impedance to a common source of a second potential;
the first and second set of electrodes being spatially arranged such that stable electric glow discharges which coalesce and extend along the optical path are generated between respective electrodes of the first ~nd second sets.
Preferably, one of the first and second potentials is earth potential and the discharges are preferably DC discharges.
By way of example, embodiments of the invention will now be described with reference to the accompanying drawings, in which:
Figure 1 is a schematic diagram of a gas laser embodying an electric discharge apparatus of the kind used in the invention;
Figure 2 shows the equivalent circuit for part of the apparatus of Fi~ure l;
Figure 3 is a schematic perspective view of an electrode configuration for use in a gas laser;
Figure 4 is a more detailed view of the arrangement shown in Figure 3; and Figure 5 is a schematic dia~ram of a ~as laser employing the electrode configuration shown in Figure 4.
Referring now to Figure 1, a power supply 12 consisting of an AC voltage supply 22, a bridge rectifier 32 and an inductive impedance XL2 is connected to terminals 42 and 52 of a gas laser, indicated schematically by reference 62.
The gas laser has a pair of anodes A12, A22 defining a first set of electrodes and a pair of cathodes K12, K22 defining a s~cond set of electrodes. Each anode A12, A22 is connected through a reSpectivQ rssistor R12, R22 to the terminal 42 and each cathode K12, K22 is connected through a respective rasistor R32, R42 to the terminal 52.
, - 3 -.~ 37 The voltaga generated by the power supply 12 is sufficient to create one discharge between the cathode Kl2 and anode Al2 and another dischar~e between the cathode R22 and anode A22. However, the separation of the dischar~es is sufficiently small that they interact and attract one another so that the discharge consists of a central region common to both dischar~es and peripheral regions adjacent to each electrode.
Fi~ure 2 shows the equivalent circuit for the dischar~e arrangement of Fi~ure 1. Resistance r is the resistance of the discharKe path common to both dischar~es while resistances rl2, r22, r32 and r42 are resistances of the dischar~e paths between the common dischar~e path and the resistors 12' 22' R32 and R42 reSpectively~
Because electric dischar~es ~enerally have a ne~ative dynamic resistance characteristic, that is as the current increases the resistance of the discharge decreases, the generation of two dischar~es from a common power supply is inherently unstable since an increase in the current in one discharge will tend to reduce the resistance of that discharge path tendin~ in turn to increase further the current through the discharge. As the current in one discharge increases so the current in the other discharge is reduced, since the currents ars derived from a common power supply, until all the current is carried in one discharge and the other discharge is extin~uished. Thus, the Yalue of the resistances rl2, r22, r32 and r42 dependent upon the current carried by the dischar~e.
The manner in which stability of the discharge is obtained can be understood by considerin~ the operation of the upper branches of the circuit shown in Fi~ure 2 and making the simplifying approximation that the junction of resistances rl2 and r22 is at constant potential.
If the stabilizing resistors R12 ant R22 are not employed so that Rl~ and R22 are zero, then with a symmetrical arran~ement of the electrodes the dischar~e paths represented by resistances rl2 and r~2 will be the same len~th and rl2 and r22 will be equal so that equal currents flow through each path. If, however, owin~ to a chan~e in, for example, a physical property of a dischar~e path, the resistance rl2 drops sli~htly, this will lead to an increase in current throueh the resistance rl2 which, in turn, will further reduce the resistance rl2 as a result of the ne~ative dynamic resistance of the dischar~e. As the resistance rl2 drops, so the current through 12~0~87 resistance r22 decreases and, accordingly, the resistance r22 increases.
Eventually, the discharge of resistance r22 is extinguished and all the current passes through the alternative discharge path.
On the other hand, with sufficiently large resistors R12 and R22 a drop in the resistance rl2 owing to a chanse in a physical property of the discharge path leads to an increase in current throu~h this discharge path but because of the resistor R12, the voltage across the discharge path is also reduced and the increase in current through resistance rl2 is limited. Any increase in the current through the resistance r12 produces an increased potential drop across the resistance R12 which overrides any reduction in the potential drop across resistance r12. Accordingly, the current remains distributed between the discharge paths of resistance rl2 and r22.
From the description above, it will be clear that it is necessary to provide a respective resistance for each electrode o~ the apparatus of Figure 1 in order to provide a stable discharge.
The inductive impedance XL2 operates to smooth the output of the rectifier 32 and also opposes changes in the discharge current thereby assisting in stabilization of the discharge.
In one particular example of the invention the anodes A12 and A22 were separated from each other by 10 mm, the cathodes K12 and R22 were separated ~rom each other by 10 mm, and the anodes were separated from the cathodes by 10 mm, with the cathodes K12 and K22 vertically below the anodes A12 and A22 rsspectively. Resistors R12, R22, R32 and R42 were each of reslstance 5J~.
With this arrangement an average rectified open circuit voltage of 110 v was applied across the terminals 4, 5 generatin~ a total discharge current of about lOA, with a discharge voltage o~ about 60 V.
Although in the described embodiment the power supply generates full wave rectified direct current, the dischar~e apparatus may be used with a constant voltage DC supply or with an AC supply.
It should be understood that additional anodes A32, A42 etc. with respective stabilizing resistors may be added in parallel with anodes A]2 and A22 and similarly additional cathodes with respective stabilizing resistors may be added in parallel with cathodes Kl~ and K22. It is not essential that the number of anodes and cathodes be the same: for example, four anodes and two cathodes could be provided.
PAT ~3393-1 ~2~2~t7 If it is desired to re~ulate the discharge current, then the resistors R12, R22, R32 and R42 may be made variable and connected to a common control which adjusts their resistance equally.
Figure 3 shows dia~rammatically the electrode arrangements which may be employed in a gas laser. The arrangement shown in Figure 3, which is for generating coalescing dischar~es, comprises a set of six anodes A31 arranged on radii of a circle symmetrically and equiangularly spaced and a set of six cathodes X31 arranged similarly on radii of another circle symmetrically and èquiangularly spaced.
Fi~ure 4 shows more practically the electrode arrangement described with reference to Figure 3 and also an electrical power supply circuit. A three phase supply is transformed to provide six separate alternating voltage supplies 113 which are each rectified by respective rectifiers 114. The positive output of each rectifier 114 is connected via a respective stabilizing impedance llS to a respective anode A31 and the negative output is connected via a respective stabilizing impedance llS to a respective cathode K31. Each anode and cathode pair connected to the same rectifier are located directly opposite to one another. The anodes are mounted on an insulating electrode holder 116 and similarly the cathodes are mounted on an insulating electrode holder 117.
Figure 5 shows schematically a C02 gas laser embodying the invention and employin~ the electrode arran~ement and power supply shown in Figures 3 and 4.
The laser has a discharge tube 118 surrounded by a cooling water jacket 119 with a water inlet 120 and water outlet 121. The cathode holder 117 is mounted at the end of the discharge tube adjacent the rear mirror and the anode h~lder 116 is mounted at the forward end. A rear mirror 122 together with adj-lsters 123 is connected via bellows 139 to an assembly head 124 which in turn is connected to the cathode holder 117. A front mirror~window 125 with adjusters 126 is similarly connected via bellows 127 to an assembly head 128 connected to the anode holder 116.
A ~as supply 129 is connected via bellows 130 to a gas inlet at the front of the discharge cavity and a vacuum pump 131 is connected via a control valve 132 and a bellows 133 to a gas outlet. A gas circulation path is also provided by a recirculating pump 134 and a heat exchanger 135. A reconstituting catalyst 136 is connected in a bypass of the main flow through which a fraction PAT 8393-l of the total gas flow passes.
Power is supplied to ths electrodes through a voltage regulator 137, a hi~h-volta~e transformer 138, rectifiers 114 and stabilizing impedances 115.
It should be understood that, as shown in Fi~ure 4, 5iX saparate rectifiers, each ~ith a respective stabilizin~ impedance, are connect~d to each electrode holder. However, it will also be understood from the description with reference to Figure 2 that a common rectifier could be employed.
In operation, discharges are generated between each pair of anodes and cathodes and these discharges coalesce along the len~th of the discharge tube.
In one particular example of the invention, the discharge cavity is of 1 m length and 100 mm diameter. With a volta~e between the slectrodes of ll~V a current of 150 mA is ~enerated in each discharge providing a total current of 0.9 A.
Various methods have been used to increase the volume of electric discharges, for example, magnetic fields have been used to rotate discharges between coaxial electrodes and offset the inherent tendency of an electric discharge to constrict due to thermal and electromagnetic effects so as to distribute the energy more uniformly in the space between the electrodes and reduce the power density at the interfaces of the discharge and the electrodes.
There is a mutual attraction between two electric discharges that exist alongside one another when current flows in the discharges are in the same direction and, if they are sufficiently close to one anothèr, the discharges coalesce. At the instant of coalescing, the discharges have a central merged portion and four root portions. Such nn arrangement has the advantage that the discharge is necessarily less concentra~ed in the vicinity of the electrodes and also the individual electrode currents are reduced for a given overall discharge current.
If the power for the respective discharges is provided from respective isolated power supplies it is possible to maintain such an arrangement, but the provision of separate power supplies can be disadvantageous.
Althou~h the possibility of generation of coalesced discharges has been known for many years, it is a technique that has not found industrial appl~cation. Indeed the normal approach has been to avoid the production of coalesced discharges by maintaining the discharges sufficiently far apart.
Furthermore, it has been accepted that in order to create a stable four root coalesced discharge, it is essential to have separate power supplies. For example, in an article entitled Multielectrode Arc Dischar~e in the Journal of Applied Spectroscopy, dated February 14, 1967, V.N. Apolitskii, when descri'oinga coalesced discharge, states that "the basic requirement is always separation of the power supplies which must not have a common point".
The necessity of usin~ separate power supplies when ~enerating coalesced discharges is a serious problem in practice since it raises the costs of the discharge apparatus and also makes the apparatus bulkier and more cumbersome to use.
J~
It is an object of the invention to provide a ~as laser and a method of enhancing the laser action by ~eneratin~ electric dischar~es that in certain respects overcomes at least some of the disadvanta~es described above.
It is another object of the invsntion to provide stabili7ation of two or more discharges extending between respective electrodes but coalescing intermediate their ends and ~enerated from a common power supply.
It is another object of the invention to provide a gas laser includin~ a dischar~e tube in which two or more stable dischar~es are generated simultaneously.
Thus, accordin~ to the invention, there is provided a ~as laser includin~ a discharge tube, optical path means for providing an optical path in the dischar~e tube, a power supply, a first set of at least two adjacent electrodes extendin~ into the dischar~e tube and a like number of first impedances each of which connects one electrode of the first set to one side of the power supply, and a second set of at least two adjacent electrodes spaced alon~ the optical path from the first set and extending into the dischar~e tube and a like number of second impedances each of which connects one electrode of the second set to an opposite side of the power supply, whereby stable electric glow disrhar~es which coalesce and extend along the optical path are ~enerated between the respective electrodes of the first and second sets to provide a stable volume of electric discharge in the optical path of the laser for excitin~ the laser.
Preferably, the impedances are each above a minimum value of the same order of masnitude as the impedance of the discharge path during stabi]i7ed operation.
In a further preferred embodiment, the first impedances are of substantially the same value and the second impedances are also of substantially the same value, and these values are preferably the same.
Impedance adjusting means are preferably provided for adjusting the discharge currents, such means desirably comprising means for adjusting the impedance of each of said first and second impedances (preferably equally).
The ~as laser is preferably a C02 ~as laser and the power supply is preferably a DC power supply.
Accordin~ to a further aspect of the invention, there is provided a method of enhancing laser action in the optical path of a ~as dischar~e laser by ~eneratinB two or more electric dischar~es extendin~ between respective :~2~a~'28~
electrodes but coalescing intermediate their ends in the optical path, the method including the following steps:
providing a first set of electrodes comprising two or more adjacent electrodes;
providing a second set of electrodes comprising two or more adjacent electrodes spaced along the optical path from the first set;
providing a separate impedance for each electrode;
connecting each electrode of the first set through a respective separate impedance to a common source of a first potential; and connecting each electrode of the second set through a respective separate impedance to a common source of a second potential;
the first and second set of electrodes being spatially arranged such that stable electric glow discharges which coalesce and extend along the optical path are generated between respective electrodes of the first ~nd second sets.
Preferably, one of the first and second potentials is earth potential and the discharges are preferably DC discharges.
By way of example, embodiments of the invention will now be described with reference to the accompanying drawings, in which:
Figure 1 is a schematic diagram of a gas laser embodying an electric discharge apparatus of the kind used in the invention;
Figure 2 shows the equivalent circuit for part of the apparatus of Fi~ure l;
Figure 3 is a schematic perspective view of an electrode configuration for use in a gas laser;
Figure 4 is a more detailed view of the arrangement shown in Figure 3; and Figure 5 is a schematic dia~ram of a ~as laser employing the electrode configuration shown in Figure 4.
Referring now to Figure 1, a power supply 12 consisting of an AC voltage supply 22, a bridge rectifier 32 and an inductive impedance XL2 is connected to terminals 42 and 52 of a gas laser, indicated schematically by reference 62.
The gas laser has a pair of anodes A12, A22 defining a first set of electrodes and a pair of cathodes K12, K22 defining a s~cond set of electrodes. Each anode A12, A22 is connected through a reSpectivQ rssistor R12, R22 to the terminal 42 and each cathode K12, K22 is connected through a respective rasistor R32, R42 to the terminal 52.
, - 3 -.~ 37 The voltaga generated by the power supply 12 is sufficient to create one discharge between the cathode Kl2 and anode Al2 and another dischar~e between the cathode R22 and anode A22. However, the separation of the dischar~es is sufficiently small that they interact and attract one another so that the discharge consists of a central region common to both dischar~es and peripheral regions adjacent to each electrode.
Fi~ure 2 shows the equivalent circuit for the dischar~e arrangement of Fi~ure 1. Resistance r is the resistance of the discharKe path common to both dischar~es while resistances rl2, r22, r32 and r42 are resistances of the dischar~e paths between the common dischar~e path and the resistors 12' 22' R32 and R42 reSpectively~
Because electric dischar~es ~enerally have a ne~ative dynamic resistance characteristic, that is as the current increases the resistance of the discharge decreases, the generation of two dischar~es from a common power supply is inherently unstable since an increase in the current in one discharge will tend to reduce the resistance of that discharge path tendin~ in turn to increase further the current through the discharge. As the current in one discharge increases so the current in the other discharge is reduced, since the currents ars derived from a common power supply, until all the current is carried in one discharge and the other discharge is extin~uished. Thus, the Yalue of the resistances rl2, r22, r32 and r42 dependent upon the current carried by the dischar~e.
The manner in which stability of the discharge is obtained can be understood by considerin~ the operation of the upper branches of the circuit shown in Fi~ure 2 and making the simplifying approximation that the junction of resistances rl2 and r22 is at constant potential.
If the stabilizing resistors R12 ant R22 are not employed so that Rl~ and R22 are zero, then with a symmetrical arran~ement of the electrodes the dischar~e paths represented by resistances rl2 and r~2 will be the same len~th and rl2 and r22 will be equal so that equal currents flow through each path. If, however, owin~ to a chan~e in, for example, a physical property of a dischar~e path, the resistance rl2 drops sli~htly, this will lead to an increase in current throueh the resistance rl2 which, in turn, will further reduce the resistance rl2 as a result of the ne~ative dynamic resistance of the dischar~e. As the resistance rl2 drops, so the current through 12~0~87 resistance r22 decreases and, accordingly, the resistance r22 increases.
Eventually, the discharge of resistance r22 is extinguished and all the current passes through the alternative discharge path.
On the other hand, with sufficiently large resistors R12 and R22 a drop in the resistance rl2 owing to a chanse in a physical property of the discharge path leads to an increase in current throu~h this discharge path but because of the resistor R12, the voltage across the discharge path is also reduced and the increase in current through resistance rl2 is limited. Any increase in the current through the resistance r12 produces an increased potential drop across the resistance R12 which overrides any reduction in the potential drop across resistance r12. Accordingly, the current remains distributed between the discharge paths of resistance rl2 and r22.
From the description above, it will be clear that it is necessary to provide a respective resistance for each electrode o~ the apparatus of Figure 1 in order to provide a stable discharge.
The inductive impedance XL2 operates to smooth the output of the rectifier 32 and also opposes changes in the discharge current thereby assisting in stabilization of the discharge.
In one particular example of the invention the anodes A12 and A22 were separated from each other by 10 mm, the cathodes K12 and R22 were separated ~rom each other by 10 mm, and the anodes were separated from the cathodes by 10 mm, with the cathodes K12 and K22 vertically below the anodes A12 and A22 rsspectively. Resistors R12, R22, R32 and R42 were each of reslstance 5J~.
With this arrangement an average rectified open circuit voltage of 110 v was applied across the terminals 4, 5 generatin~ a total discharge current of about lOA, with a discharge voltage o~ about 60 V.
Although in the described embodiment the power supply generates full wave rectified direct current, the dischar~e apparatus may be used with a constant voltage DC supply or with an AC supply.
It should be understood that additional anodes A32, A42 etc. with respective stabilizing resistors may be added in parallel with anodes A]2 and A22 and similarly additional cathodes with respective stabilizing resistors may be added in parallel with cathodes Kl~ and K22. It is not essential that the number of anodes and cathodes be the same: for example, four anodes and two cathodes could be provided.
PAT ~3393-1 ~2~2~t7 If it is desired to re~ulate the discharge current, then the resistors R12, R22, R32 and R42 may be made variable and connected to a common control which adjusts their resistance equally.
Figure 3 shows dia~rammatically the electrode arrangements which may be employed in a gas laser. The arrangement shown in Figure 3, which is for generating coalescing dischar~es, comprises a set of six anodes A31 arranged on radii of a circle symmetrically and equiangularly spaced and a set of six cathodes X31 arranged similarly on radii of another circle symmetrically and èquiangularly spaced.
Fi~ure 4 shows more practically the electrode arrangement described with reference to Figure 3 and also an electrical power supply circuit. A three phase supply is transformed to provide six separate alternating voltage supplies 113 which are each rectified by respective rectifiers 114. The positive output of each rectifier 114 is connected via a respective stabilizing impedance llS to a respective anode A31 and the negative output is connected via a respective stabilizing impedance llS to a respective cathode K31. Each anode and cathode pair connected to the same rectifier are located directly opposite to one another. The anodes are mounted on an insulating electrode holder 116 and similarly the cathodes are mounted on an insulating electrode holder 117.
Figure 5 shows schematically a C02 gas laser embodying the invention and employin~ the electrode arran~ement and power supply shown in Figures 3 and 4.
The laser has a discharge tube 118 surrounded by a cooling water jacket 119 with a water inlet 120 and water outlet 121. The cathode holder 117 is mounted at the end of the discharge tube adjacent the rear mirror and the anode h~lder 116 is mounted at the forward end. A rear mirror 122 together with adj-lsters 123 is connected via bellows 139 to an assembly head 124 which in turn is connected to the cathode holder 117. A front mirror~window 125 with adjusters 126 is similarly connected via bellows 127 to an assembly head 128 connected to the anode holder 116.
A ~as supply 129 is connected via bellows 130 to a gas inlet at the front of the discharge cavity and a vacuum pump 131 is connected via a control valve 132 and a bellows 133 to a gas outlet. A gas circulation path is also provided by a recirculating pump 134 and a heat exchanger 135. A reconstituting catalyst 136 is connected in a bypass of the main flow through which a fraction PAT 8393-l of the total gas flow passes.
Power is supplied to ths electrodes through a voltage regulator 137, a hi~h-volta~e transformer 138, rectifiers 114 and stabilizing impedances 115.
It should be understood that, as shown in Fi~ure 4, 5iX saparate rectifiers, each ~ith a respective stabilizin~ impedance, are connect~d to each electrode holder. However, it will also be understood from the description with reference to Figure 2 that a common rectifier could be employed.
In operation, discharges are generated between each pair of anodes and cathodes and these discharges coalesce along the len~th of the discharge tube.
In one particular example of the invention, the discharge cavity is of 1 m length and 100 mm diameter. With a volta~e between the slectrodes of ll~V a current of 150 mA is ~enerated in each discharge providing a total current of 0.9 A.
Claims (12)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A gas laser including a discharge tube, optical path means for providing an optical path in the discharge tube, a power supply, a first set of at least two adjacent electrodes extending into the discharge tube and a like number of first impedances each of which connects one electrode of the first set to one side of the power supply, and a second set of at least two adjacent elec-trodes spaced along the optical path from the first set and extending into the discharge tube and a like number of second impedances each of which connects one electrode of the second set to an opposite side of the power supply, whereby stable electric glow discharges which coalesce and extend along the optical path are generated between the respective electrodes of the first and second sets to provide a stable volume of electric discharge in the optical path of the laser for exciting the laser.
2. A gas laser as claimed in claim 1 in which the impedances are each above a minimum value of the same order of magnitude as the impedance of the discharge path during stabilized operation.
3. A gas laser as claimed in claim 1 in which the first impedances are of substantially the same value and the second impedances are also of substantially the same value.
4. A gas laser as claimed in claim 3 in which the value of the first impedances are the same as the value of the second impedances.
5. A gas laser as claimed in claim 1 including impedance adjusting means for adjusting the discharge currents.
6. A gas laser as claimed in claim 5 in which the adjusting means comprises means for adjusting the imped-ance of each of said first and second impedances.
7. A gas laser as claimed in claim 6 in which the adjusting means is arranged to adjust the impedance of each of the first impedances and each of the second impedances equally.
8. A gas laser as claimed in claim 1 in which the laser is a CO2 gas laser.
9. A gas laser as claimed in claim 1 in which the power supply is a DC power supply.
10. A method of enhancing laser action in the optical path of a gas discharge laser by generating two or more electric discharges extending between respective elec-trodes but coalescing intermediate their ends in the optical path, the method including the following steps:
providing a first set of electrodes comprising two or more adjacent electrodes, providing a second set of electrodes comprising two or more adjacent electrodes spaced along the optical path from the first set, providing a separate impedance for each electrode, connecting each electrode of the first set through a respective separate impedance to a common source of a first potential, and connecting each electrode of the second set through a respective separate impedance to a common source of a second potential, the first and second set of electrodes being spatially arranged such that stable electric glow dis-charges which coalesce and extend along the optical path are generated between respective electrodes of the first and second sets.
providing a first set of electrodes comprising two or more adjacent electrodes, providing a second set of electrodes comprising two or more adjacent electrodes spaced along the optical path from the first set, providing a separate impedance for each electrode, connecting each electrode of the first set through a respective separate impedance to a common source of a first potential, and connecting each electrode of the second set through a respective separate impedance to a common source of a second potential, the first and second set of electrodes being spatially arranged such that stable electric glow dis-charges which coalesce and extend along the optical path are generated between respective electrodes of the first and second sets.
11. A method as claimed in claim 10 in which one of the first and second potentials is earth potential.
12. A method as claimed in claim 10 or 11 in which the discharges are DC discharges.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000415606A CA1220287A (en) | 1982-11-15 | 1982-11-15 | Apparatus and method for generating a plurality of electric discharges |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000415606A CA1220287A (en) | 1982-11-15 | 1982-11-15 | Apparatus and method for generating a plurality of electric discharges |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1220287A true CA1220287A (en) | 1987-04-07 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000415606A Expired CA1220287A (en) | 1982-11-15 | 1982-11-15 | Apparatus and method for generating a plurality of electric discharges |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1220287A (en) |
-
1982
- 1982-11-15 CA CA000415606A patent/CA1220287A/en not_active Expired
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