JPH0135510B2 - - Google Patents

Description

[Detailed description of the invention]

The invention relates to a device for adapting a pulse forming network to the excitation circuit of a TE (transversely excited) high-energy laser device. This laser device is excited by an arc-free capacitor discharge as uniform as possible between at least two spaced apart laser electrodes in the gas space of the laser chamber, and consists of the following: ing. (a) A laser head with a laser electrode inside the laser chamber; the laser electrode extends parallel to the optical axis of the laser head and often extends its entire cross section in this direction. (b) at least one high speed high voltage switch; the switch allows high voltage pulses to be applied to the laser electrode through a pulse forming network; (c) Pulse forming network; this network includes a high voltage switch, first and second conductor capacitors associated with the laser head, and the equivalent inductance of the excitation circuit. This equivalent inductance is provided in particular by the self-inductance of the high-voltage switch, the laser head, the connecting wires and the strip conductor capacitor. One of the devices of this kind was the patent application published in 1981.
It is described in Publication No. 29387. A detailed description of TE (transverse excitation) lasers can also be found in this specification.
However, this does not take into account the equivalent inductance of the excitation circuit. TE lasers are also described in detail in this specification. Since this TE laser operates at a pressure of several bars within the laser chamber, it is now often called a TE laser rather than a TEA laser. It is assumed here that the high-energy laser device is equipped with a pre-ionization device. This device is a creeping discharge in West German Patent Application No. 3035702,
West German Patent Application No. 3035730 is a pre-ionization rod. Since this is well known, detailed explanation thereof will be omitted. The invention is based on the selection of an advantageous design of the pulse-forming network and the size of its circuit elements as excitation circuit. The excitation circuit here refers to both the pulse forming network, including the high speed high voltage switch, and the laser head. The problem that arises in the device that is the object of this invention is to keep the high speed high voltage switch load within certain limits so that its useful life is not too short, and to ensure that the rise time of the high voltage pulse applied to the laser head is one maximum. The goal is to ensure that the value is not exceeded. The purpose of this is to generate a discharge at the laser electrode as free as possible from arcing, in order to convert as large a portion of the energy stored in the pulse-forming network into optical energy as possible. The purpose of this invention is to improve the device for adapting the pulse forming network to the excitation circuit of a TE type high energy laser so that overloading of the high speed high voltage switch is avoided and the rise time of the high voltage pulse leading to the laser electrode is improved. is short enough so that a very favorable ratio between the high voltage energy utilized at the laser electrode and the energy introduced into the pulse forming network is achieved. This object is achieved by the configuration characterized in claim 1. Advantageous embodiments of the Bliumlein circuit on which this design is based are given in the claims 2 to 13. The object of the present invention is also achieved by the structure listed as the feature in claim 14. Advantageous embodiments thereof are indicated in the patent claims 15 and below. The present invention will be described in more detail with reference to the drawings showing various embodiments of the invention. Since TE lasers, such as excimer TE CO ₂ lasers, have found numerous potential applications in the technical and industrial fields, there is an increasing concern about the reliability and effective lifetime of these devices. There is. In principle, a TE laser device consists of a supply source and a control device, as well as a circulation system for the laser medium, a cooling circulation system for the laser head, a pulse forming network for energy storage, and high-speed, high-power switching elements (e.g. spark gap, thyratron or plasma switch). Extremely high requirements are placed on the switching elements necessary to operate a high-power TE laser, and it is necessary to keep these requirements as light as possible in order to maintain a long effective life and enable reliable operation. be. An advantageous example of a pulse-forming network (PFN) in the excitation circuit of a TE laser is the Briumlein circuit shown in FIG. The laser device consists of switch FK, laser chamber LK, impedance RK and PFN. This PFN consists of capacitors C _F and C _K and inductances L _F and L _K. This inductance includes the self-inductance of the switch, laser chamber, connecting lines and capacitors. The metal layer of capacitor C _F is 1,
2, that of C _K is shown as 3, 4, and the high voltage terminal is shown as HV. In order to achieve effective excitation of the laser gas in the laser chamber LK, the rise time of the voltage applied to the electrodes in the laser chamber must not exceed an experimentally determined maximum rise time _tr . Since the rise time is proportional to √ _F・_F , t _r > π√
L _F and C _F are required. Given C _F , this relationship determines the upper limit of L _F , and the maximum value of the current flowing through the switching element is

[Formula] (U _p : capacitor charging voltage). If the maximum rise time t _r is kept constant, the capacitance C _F is lowered to k・C _F (0.5≦k≦1), and therefore L _F is increased to L _F /k, the peak current of the switching element becomes

It decreases to [formula]. Compared to the symmetric Briumlein circuit where C _F = C _K , the capacitor C _F
and C _K (in which case the inductance of the laser discharge gap and the ohmic resistor are placed in the circuit), resulting in an asymmetric Bryum line circuit, the range of values of k as C _F = kC _K
When 0.5≦k≦1, the characteristic resistance increases within an allowable range. It is also possible to make k less than 0.5, but in this case the characteristic resistance is It increases greatly due to the relationship between Such an asymmetric Bliumlein circuit significantly reduces the demands placed on the switching elements and has little influence on the properties of the actual laser excitation circuit. The present invention utilizes the above-mentioned knowledge in a high-speed pulse discharge excitation device that has already been proposed.
Figure 2 shows this device with some minor changes while retaining the fundamental advantages of PFN. metal layer 1,
The capacitor C _F constructed by 2 has an insulating layer thicker than that of the capacitor C _K , or has a smaller area, or uses a dielectric material with a lower dielectric constant. It is also possible to combine some of these changes. When water or other liquid is used as the dielectric as shown in FIG.
This is achieved by making the spacing between plates 1/1 and 2/3 larger than the spacing between plates 2/3 and 4/4.
These means may be combined. This device is not limited to liquid dielectrics, but can also use solid or pasty dielectrics. Measures corresponding to those described for solid dielectrics can also be adopted in the device shown in FIG. Corresponding measures are also taken when this device uses a liquid dielectric, particularly water. Its configuration is shown in FIG. This results in a compact device with high energy density. This extended device can also be operated as a charge transfer circuit, even if the plates are of equal area and equally spaced. A charge transfer type device is shown in FIG. Another embodiment is shown in FIG. 6 which provides the same advantages as described above. There is a potential difference HV between capacitor metal layers 1 and 2 and 3 and 4, and a voltage of 2×HV is applied between metal layers 4 and 1 when connected. Therefore, an insulating distance d _1,4 that is at least twice the insulating distance d _1,2 between the metal layers 1 and 2 must be placed between the two metal layers.
In this case, the capacitor C _F formed by metal layers 1 and 2
The capacitor C _K formed by the metal layers 3 and 4 has an area of
be less than or equal to the area of
Either the thickness of the insulating layer of C _F is made larger than or equal to that of C _K , or the dielectric constant of the insulating layer of C _F is made smaller than or equal to that of C _K. do. It is also possible to combine all or some of these measures. When a liquid dielectric material, particularly water, is used, the embodiment shown in FIG. 7 is obtained. Between metal layers 1 and 2/3 and 2/3
The insulation spacing between 3 and 4 is d, and the mutually facing metal layers 1 of adjacent capacitive units CE1 and CE2
The insulation spacing between and 4 is d _1,4 . Since the maximum voltage is 2×HV, d _1,4 must be 2d. In each capacitor, if the area of electrode plate 1 is chosen to be smaller than or equal to the area of electrode plates 2 and 3, or if the spacing between 1 and 2 is selected to be smaller than or equal to the spacing between 2 and 3, the desired effect can be achieved. is achieved. These means may be used in combination. For example, it has been revealed that the charge transfer circuit shown in FIG. 8 is advantageous for excitation of a CO ₂ laser. Capacitor C′ _F is charged to voltage U _O by high voltage power supply HV. Switch _FK For example, due to the closure of the thyratron, the capacitor C' _K , which had been placed at ground potential until then _, is charged at a charging voltage of 2
Charged to double the voltage. For charge transfer circuits
It is advantageous if C′ _K ≦C′ _F or C′ _K ≪C′ _F.
An example of realizing such a circuit while maintaining the advantages of PFN is shown in FIG. In this case metal layer 1',
The area of 2' is chosen to be less than or equal to the area of 3', 4', the thickness of the dielectric layer of capacitor C' _K is chosen to be greater than or equal to that of capacitor C' _F , capacitor C' _K The dielectric constant of the dielectric is chosen to be either smaller than or equal to that of the capacitor C′ _F. A combination of some of them may also be used. FIG. 10 shows a configuration example of a PFN for a charge transfer circuit. The metal layers placed at the same potential as in FIG. 9 are combined into one electrode plate as shown in FIG. The area of plate 1'/1' is plate 2',
3' and the area of plate 4'/4' is chosen to be smaller than or equal to it. Instead, plates 1'/1' and 2'/
The spacing between plates 2'/3' and 4'/4' may be chosen to be greater than or equal to the spacing between plates 2'/3' and 4'/4'. It is also possible to combine these two means. Another configuration example of the PFN is shown in FIG. This is also an expanded form. The area of plate 1'/1' is chosen to be less than or equal to the area of plates 3'/3' and 4'/4', or the spacing between 1'/1' and 2'/2' is 4'. The desired effect is achieved by choosing a distance greater than or equal to the distance between /4' and 3'/3' or by employing a combination of these measures. If a solid capacitor is used, the circuit shown in FIG. 12 can be constructed. In this device, metal layer 1'
and 2' are chosen to be less than or equal to the area of metal layers 3' and 4', or the spacing between 1' and 2' is chosen to be greater than or equal to the spacing between 3' and 4'. Alternatively, the dielectric constant between 1' and 2' is chosen to be less than or equal to the dielectric constant between 3' and 4'. Some or all of these may be combined. Depending on the current load tolerance limits of the components of the circuit, it is also possible to divide the capacitor stack into several subbanks, each subbank being assigned a different component.

[Brief explanation of drawings]

Figure 1 is a wiring diagram of an excitation circuit that is the subject of this invention, Figure 2 is a configuration diagram of the excitation circuit in Figure 1, and Figure 3 is an excitation circuit using a liquid dielectric as a capacitor. 4, 5, 6, and 7 are mutually different configuration layout diagrams of the excitation circuit that is the subject of this invention, and FIG. 8 is an excitation circuit including a charge transfer circuit. 9 is a configuration diagram of the circuit in FIG. 8, FIG. 10 is a configuration diagram showing a modification of the device in FIG. 9, and FIG. 11 is a configuration diagram of the circuit in FIG.
FIG. 12 is a configuration diagram showing a second modification of the device shown in the figure, and FIG. 12 is a configuration layout diagram when a solid dielectric is used in the device of FIG. 11. HV...High voltage power supply, FK...High speed high power switch, LK...Laser chamber, C _F , C _K ...Strip conductor capacitor.

Claims (1)

[Scope of Claims] 1. A laser head with a laser electrode inside the laser chamber extending parallel to the optical axis of the laser head, and at least one high-speed high-voltage device applying high-voltage pulses to the laser electrode through a pulse-forming network. First and second conductor capacitors belonging to the switch, high voltage switch and laser head
High power consisting of C _F , C _K and a pulse-forming network with associated equivalent inductances L _F , L _K of the excitation circuit consisting of the high-voltage switch, the laser head, the connecting wire and the self-inductance of the strip capacitors. The excitation circuit of the laser device is a matching partner, and the pulse forming network (PEN) is of Bryumline circuit configuration, and at a given maximum rise time (t _R ) of the high voltage pulse produced at the laser electrode, the first The capacitance of the conductor capacitor C _F becomes smaller than the capacitance of the second strip conductor capacitor C _K by a coefficient k of 1 or less, and the equivalent inductance L _F connected in series with the strip conductor capacitor C _K has a corresponding coefficient. A TE-type high-energy laser excited by an arc-free capacitor discharge generated between at least two laser electrodes facing each other at an interval in a laser chamber, characterized in that the size increases by 1/k. A device for adapting a pulse forming network to an excitation circuit. The metal layers of the double-conductor capacitors C _F and C _K and the dielectric layer between them extend approximately perpendicular to the optical axis of the laser head, and these capacitors constitute a capacitor set stacked approximately parallel to the optical axis of the laser head, 2. Device according to claim 1, characterized in that it is connected within the pulse-forming network either directly or by a laterally drawn-out connection piece. 3. The device according to claim 1 or 2, wherein the value of the coefficient k is within the range of 0.5≦k≦1. 4. A patent characterized in that the thickness of the dielectric layer between metal layers 1 and 2 of the first conductor capacitor C _F is thicker than the thickness of the corresponding dielectric layer of the second article conductor capacitor C _K. Device according to one of claims 1 to 3. 5. A patent claim characterized in that the area (F _{F )} of the metal layers 1 and 2 of the Article 1 conductor capacitor C _F is smaller than the area F _K of the metal layer of the Article 2 conductor capacitor C K. Apparatus according to one of the ranges 1 to 4. 6 The dielectric constant (ε _F ) of the dielectric layer between metal layers 1 and 2 of the first conductor capacitor C _F is the second conductor capacitor.
6. Device according to claim 1, characterized in that the dielectric constant (ε _K ) is smaller than the corresponding dielectric constant (ε K ) of C _K . 7. The two capacitance units C _F and C _K adjacent to each other in the stacking direction of the capacitors are arranged in mirror symmetry with respect to a plane of symmetry perpendicular to the stacking direction. Device. 8. Claim 2, characterized in that the capacitor units C _F and C _K adjacent in the stacking direction are arranged in the same direction with the same orientation of their metal layers.
Apparatus described in section. 9. Device according to claim 7, characterized in that the capacitor set consisting of a single capacitive unit is provided with a liquid dielectric, in particular scientifically pure water or a paste-like dielectric. 10. Device according to claim 7 or 8, characterized in that the capacitor set comprises a dielectric of solid insulating material. 11 Double conductor capacitor in one capacitance unit
The metal layers 2 and 3 common to C _F and C _K are spread out without overlapping, and the capacitor set has a cut in the center extending in the stacking direction for the laser head LK, and the laser head is inserted into this cut. 11. The device according to claim 2, or one of claims 7 to 10, characterized in that it is provided insulated and that the high voltage switch FK is provided on the outer peripheral surface of the capacitor set. 12 Double conductor capacitor in one capacitance unit
For the high-speed high-voltage switch FK, in which the metal layers 2' and 3' common to C' _F and C' _K are spread out without being overlapped, and the capacitor set is housed inside one tube.
The patent claim is characterized in that a cut extending in the stacking direction is provided in the center, a high-speed high-voltage switch is insulated and provided inside the cut, and a laser head LK is provided on the outer peripheral surface of the capacitor set. Apparatus according to one of the ranges 7 to 10. 13. A compact structure for a capacitor set in which water is used as a dielectric material, characterized in that the equipotential metal layers of capacitor units adjacent in the stacking direction are combined into a common metal layer. An apparatus according to claim 7. 14 a laser head with a laser electrode inside the laser chamber extending parallel to the optical axis of the laser head; at least one high-speed high-voltage switch applying high-voltage pulses to the laser electrode through a pulse-forming network; the associated equivalent inductance L _{F ′} of the excitation circuit consisting of the first and second conductor capacitors C′ _F , C′ _K belonging to the laser head, and the self-inductance of the high-voltage switch, the laser head, the connecting line and the conductor wire capacitors; , L _K ′, the pulse forming network is a charge transfer circuit including a strip conductor capacitor, and the strip conductor capacitor is connected to its metal layer. and a dielectric layer therebetween extending approximately perpendicular to the optical axis of the laser head to form a set of capacitors stacked approximately parallel to this optical axis;
The first conductor capacitor C′ _K , which belongs to the laser head, and the second conductor capacitor C′ _F , which belongs to the high-voltage switch, are connected to each other directly or through laterally projecting connection pieces inside the pulse-forming network.
metal layer area (F _K , F _F ), dielectric layer thickness (d _K ,
d _F ) and permittivity (ε _K , ε _F ) satisfy at least one of the following relationships, (a) F _K ≦F _F ; (b) d _K ≧d _F ; (c) ε _K ≦ε _F Therefore, the arc-free capacitor discharge occurring between at least two opposing laser electrodes in the laser chamber is characterized by the following relationship: ε _K・F _K /d _K ≦ε _F・F _F /d _F TE excited by
A device for adapting pulse-forming circuitry to the excitation circuit of type high-energy laser devices. 15 A patent characterized in that two capacitance units C _F , C _K or C′ _F , C′ _K adjacent to each other in the stacking direction of the capacitors are arranged in mirror symmetry with respect to a plane of symmetry perpendicular to the stacking direction. Apparatus according to claim 14. 16. Claim 14, characterized in that the capacitor units C _F , C _K or C' _F , C' _K adjacent in the stacking direction are arranged in the same direction with the same orientation of their metal layers. Device. 17. Device according to claim 15 or 16, characterized in that the capacitor set consisting of a single capacitive unit is provided with a liquid dielectric, in particular chemically pure water or a paste-like dielectric. 18. Device according to claim 15 or 16, characterized in that the capacitor set comprises a dielectric of solid insulating material. 19 Double conductor capacitor in one capacitance unit
When the metal layers 2 and 3 common to C _F and C _K are spread out without being overlapped, the capacitor set has a cut in the center part extending in the stacking direction for the laser head LK, and the laser head 19. The device according to claim 15, wherein the high voltage switch FK is provided on the outer peripheral surface of the capacitor set. 20 Double conductor capacitor of one capacitance unit
The metal layers 2', 3' common to C' _F , C' _K are spread out without being superimposed, and a capacitor set is stacked in the center for a fast high-voltage switch FK housed inside one tube. Equipped with cuts extending in the direction,
According to one of claims 14 to 18, the high-speed high-voltage switch is provided insulated within this cut, and the laser head LK is provided on the outer peripheral surface of the capacitor set. equipment. 21. A compact structure for a capacitor set that uses water as a dielectric, characterized in that the equipotential metal layers of capacitor units adjacent in the stacking direction are combined into a common metal layer. An apparatus according to claim 15.