Excitation system for a fast pulsed discharge

Excitation system for fast pulsed discharge with excitation by a highly homogeneous arc-free capacitor-discharge in a gas space between and defined by at least two electrodes of a laser chamber, the two electrodes being spaced from one another and extending parallel to the optical axis of the laser, and with first and second stripline capacitors for induction-free energy-storage and for contacting the laser electrodes and electrodes of a fast high-voltage switching gap associated therewith, respectively, includes a plurality of electrodes forming part of the first and the second stripline capacitors, a plurality of dielectric layers disposed between the capacitor electrodes, the dielectric layers and the capacitor electrodes extending substantially normally to the optical axis of the laser and being stacked substantially parallel to the optical axis of the laser in a capacitor stack, and laterally extending connecting lugs connecting the capacitor electrodes to the electrodes of the laser chamber.

The invention relates to an excitation system for a fast pulsed discharge, 
especially a high-energy laser of the TEA type, and more particularly with 
excitation by a highly homogeneous arc-free capacitor-discharge in a gas 
space between and defined by at least two electrodes of the laser chamber, 
the two electrodes being spaced from one another and extending parallel to 
the optical axis of the laser, and with first and second stripline 
capacitors for induction-free energy-storage and for contacting the laser 
electrodes and electrodes of a fast high-voltage switching gap associated 
therewith, respectively. 
Such an excitation system is fundamentally known (note "Applied Physics 
Letters", Vol. 10, No. 1, January 1967, pages 3 and 4, especially FIG. 1, 
hereinafter referred to as literature reference (1)). TEA lasers 
(transversely excited atmospheric pressure lasers), due to their high peak 
power and short pulse widths or durations have become particularly 
important. In these lasers, the laser gas which is under high pressure (50 
mbar to several bar) as compared to longitudinally excited gas lasers 
(HeNe-lasers), is excited by an homogeneous electric discharge with 
several kilovolts via two extended electrodes which are disposed opposite 
one another parallel to the optical axis (which is the direction of 
emission of the laser). 
Examples, of the laser type mentioned hereinabove are the CO.sub.2 -laser 
in the infrared region of the spectrum and, for visible spectrum and near 
UV, the N.sub.2 -laser and excimer lasers (for a definition of the excimer 
laser note, for example, "Physics Today", May 1978, pages 32 to 39 and, in 
particular, the lefthand and middle columns on page 32, hereinafter 
referred to as literature reference (2)). In TEA lasers, however, the 
initially homogeneous electric discharge has a tendency to degenerate into 
individual spark channels, which can result in an interruption of the 
laser emission and the destruction of the electrodes. For these reasons, 
it is necessary to operate TEA lasers with high-voltage pulses of large 
current and short half-amplitude width. Several systems are known from the 
scientific literature which meet these requirements (note, in addition to 
the two hereinaforecited literature refernces (1) and (2), also "physical 
Review Letters", Vol. 25, No. 8, pages 491 to 497 (3) and "Applied Physics 
Letters", Vol. 29, No. 11, 1976, pages 707 to 709 (4)). 
To obtain the necessary short rise times for the high-voltage pulses, 
capacitors with extremely small self-inductance and lead inductance must 
be used. For this purpose, stripline capacitors such as are shown in (1), 
are suited. The disadvantage of these capacitors is the specific capacity 
thereof. Lengthening the capacitor stripline brings with the desired 
increase in capacity, also an increase in inductance, which lowers the 
resonance frequency of the corresponding resonant circuit and thereby 
increases the rise times of the high-voltage pulse to an impermissible 
value. Thus, the electric energy which can be stored in the capacitors 
with a fixed voltage and can maximally be supplied to the laser gas, is 
limited to a relatively small value. In principle, the energy could be 
increased only by an increase of the voltage. Because of the insulation 
problems connected therewith, this approach, however, would lead to larger 
spacings between the voltage-carrying parts and thereby to an increase of 
the inductance, which could be compensated for only by a reduction of the 
effective capacity. In this connection, the employment of fast switches 
for high voltages makes the problem considerably more difficult. 
The invention of the instant application takes a different approach. It is 
an object thereof to provide an excitation system for a fast pulsed 
discharge wherein the energy content of the high-voltage pulse for a 
constant charging voltage is increased, for this purpose, the capacity of 
the capacitor is increased in such a manner that, the self-inductance of 
the capacitor and that of the leads to the laser can be reduced 
simultaneously. 
With the foregoing and other objects in view, there is provided, in 
accordance with the invention, an excitation system for fast pulsed 
discharge with excitation by a highly homogeneous arc-free 
capacitor-discharge in a gas space between and defined by at least two 
electrodes of a laser chamber, the two electrodes being spaced from one 
another and extending parallel to the optical axis of the laser, and with 
first and second stripline capacitors for low-induction energy-storage and 
for contacting the laser electrodes and electrodes of a fast high-voltage 
switching gap associated therewith, respectively, comprising a plurality 
of electrodes forming part of the first and the second stripline 
capacitors, a plurality of dielectric layers disposed between the 
capacitor electrodes, the dielectric layers and the capacitor electrodes 
extending substantially normally to the optical axis of the laser and 
being stacked substantially parallel to the optical axis of the laser in a 
capacitor stack, and laterally extending connecting lugs connecting the 
capacitor electrodes to the electrodes of the laser chamber. The 
advantages obtainable by the invention are in particular that the energy 
content of the high-voltage pulses is substantially increased in 
comparison with heretofore known excitation systems, with the charging 
voltage kept constant, without having to tolerate a corresponding rise of 
the self-inductance and therewith, an increase of the switching times 
resulting therefrom. The inductance per unit of capacity (H/F) even 
becomes smaller. The capacity of the first and the second individual 
stripline capacitors (smallest common capacity unit) as well as the number 
n of the stacks can be varied. It is furthermore possible to predetermine 
the inductance of the contacts of an individual electrode within certain 
ranges. All of these possible variations allow optimum adaptation or 
matching of the electric circuit formed by the system to the physical 
parameters of the gas discharge path, which is formed between the 
electrodes of the laser chamber. 
In accordance with another feature of the invention, the capacitor 
electrodes and the dielectric layers of the first and second stripline 
capacitors are structurally united, respectively, into a miniature common 
capacitance unit, n of such capacitance units, wherein n=1,2 . . . n-1, n, 
being joined together in stacking direction and parallel to the laser 
axis, respectively. 
In accordance with a further feature of the invention, mutually adjacent 
capacitance units are disposed, respectively, in stacking direction with 
the capacitor electrodes and dielectric layers thereof in a mirror-image 
manner relative to an imaginary symmetry plane extending normally to the 
laser axis between the capacitance units. 
In accordance with an added feature of the invention, the individual 
stripline capacitors and capacitance units, respectively, have a basic, 
substantially rectangular shape and the capacitor stack is somewhat 
parallelepipedal, the laser chamber and the connecting lugs associated 
therewith being disposed at a longitudinal side of the somewhat 
parallelepipedal stack. 
In accordance with an additional feature of the invention, the laser 
chamber and the fast high-voltage switching gap are disposed on opposite 
longitudinal sides of the capacitor stack, and a capacitor electrode, 
respectively, common to the first and the second stripline capacitor is 
disposed as a substantially hairpin-shaped folded band between respective 
other capacitor electrodes of the stripline capacitors so that one 
folded-band half thereof is disposed directly opposite the capacitor 
electrode connected between one of the electrodes of the laser chamber and 
one electrode of the switching gap, and the other folded-band half is 
disposed directly opposite the capacitor electrode connected to one of 
another electrode of the laser chamber and of the switching gap, the 
folded-band capacitor electrode being connected to one of the one 
electrode of the switching gap and the one electrode of the laser chamber. 
In accordance with yet another feature of the invention, the fast 
high-voltage switching gap is a substantially tubular spark gap having the 
electrodes thereof extending parallel to the axis of the laser, the 
substantially tubular spark gap being disposed on a side of the capacitor 
stack facing away from the laser chamber and being connected by the 
electrodes thereof to the laterally extending connecting lugs of the 
respective capacitor electrodes. 
In accordance with yet a further feature of the invention, the excitation 
system includes a Bluemlein circuit in which the first and the second 
stripline capacitors are connected for generating a laser excitation 
pulse. 
In accordance with an alternate feature of the invention, the excitation 
system includes a charge-transfer circuit in which the first and the 
second stripline capacitors are connected for generating a laser 
excitation pulse. 
In accordance with yet an added feature of the invention, the fast 
high-voltage switching gap is a substantially tubular spark gap, the 
substantially tubular spark gap being formed with electrode bores normal 
to the axis of the substantially tubular spark gap and distributed along 
the length of the spark gap, trigger pins being insulatingly received in 
the electrode bores and being energizable by a high-voltage ignition pulse 
applicable thereto. 
In accordance with yet an additional feature of the invention, the 
excitation system comprises a common switching capacitance having a 
high-voltage pole, a plurality of trigger capacitances, the trigger pins 
being connected via the trigger capacitances to the high-voltage pole of 
the common switching capacitance and on a side of the trigger capacitances 
connected to the trigger pins, the trigger capacitances being connected to 
one another and to ground potential via balancing impedances selected from 
high-resistivity resistances and inductances, one of a fast switching 
thyratron and a fast switching spark gap being connected in parallel with 
the common switching capacitance for releasing an ignition pulse. 
In accordance with another feature of the invention, n partial capacitor 
stacks encompass at least one respective capacitance unit of the capacitor 
stack, the fast high-voltage switching gap comprising n thyratrons 
connected in parallel with one another, a respective thyratron being 
operatively associated with a respective partial capacitor stack. 
In accordance with a further feature of the invention, mutually adjacent 
capacitance units are disposed, respectively, in stacking direction with 
the capacitor electrodes and dielectric layers thereof in a mirror-image 
manner relative to an imaginary symmetry plane extending normally to the 
laser axis between the capacitance units, each of the partial capacitor 
stacks, respectively, encompassing two of the capacitance units disposed 
in a mirror-image manner with respect to one another. 
In accordance with a further feature of the invention, the capacitor 
electrodes of the first and the second stripline capacitors are formed 
with a cutout for the laser chamber, the laser chamber being disposed, 
insulated for high-voltage, within the cutout, the fast high-voltage 
switching gap being disposed, on the other hand, at the outer periphery of 
the capacitor electrodes in parallel with the laser axis. 
In accordance with an added feature of the invention, the dielectric layers 
are formed of dielectric liquid, the capacitor electrodes being at the 
same potential and being united into metal plates immersed in the 
dielectric liquid. 
In accordance with an added feature of the invention, the dielectric liquid 
is chemically pure water. 
In accordance with alternative features of the invention, the laser is an 
excimer laser, a CO.sub.2 laser, a Cu-vapor laser or an N.sub.2 laser. 
In accordance with a further feature of the invention, the wall of at least 
one of the laser chamber and the high-voltage switching gap is formed of 
pure Al.sub.2 O.sub.3 ceramic having a purity of at least 95%. 
In accordance with a concomitant alternative feature of the invention, the 
excitation system is in combination with an electron beam gun or in 
combination with a Marx generator for generating high energy pulses 
therefor. 
Other features which are considered as characteristic for the invention are 
set forth in the appended claim. 
Although the invention is illustrated and described herein as embodied in 
an excitation system for a fast pulsed discharge, it is nevertheless not 
intended to be limited to the details shown, since various modifications 
and structural changes may be made therein without departing from the 
spirit of the invention and within the scope and range of equivalents of 
the claims.

Referring now to the drawing and first, particularly, to FIG. 1 thereof, 
there is shown a Bluemlein circuit symbolizing a laser chamber LK with two 
electrodes E.sub.L1 and E.sub.L2 and a fast high-voltage switching gap in 
the form of a spark gap F with two electrodes E.sub.F1 and E.sub.F2. The 
spark gap F with an external circuit yet to be described hereinafter 
serves for firing a gas discharge or for applying a high-voltage pulse 
between the electrodes E.sub.L1 and E.sub.L2. Shunted across the spark gap 
F is a first low-induction stripline capacitor C.sub.F, the electrodes 1 
and 2 of which are connected to the spark gap F via connecting lugs a1 and 
a2 which have as little inductance as possible. Connected in series with 
the laser chamber LK is a second low-inductance stripline capacitor 
C.sub.K, the two electrodes 2 and 3 of the capacitors C.sub.F and C.sub.K 
being connected to each other and to the high potential of a high-voltage 
source HV. On the side of ground potential, the electrodes E.sub.F1 and 
E.sub.L2 of the spark gap F and of the laser chamber LK, respectively, as 
well as the electrode 1 of the first capacitor C.sub.F are connected to 
each other and tied to ground potential. The electrode E.sub.L1 of the 
laser chamber Lk and the electrode 4 of the second capacitor C.sub.K, 
respectively, are connected to ground potential via a resistor which has a 
high resistance in comparison with that of the fired plasma. 
In FIG. 1A, the circuit diagram according to FIG. 1 is transposed into a 
three-dimensional or perspective view of a stripline capacitor 
arrangement, which is very similar to the illustration in FIG. 1 of the 
literature reference [1] or to that according to FIG. 1 of German 
Published Prosecuted Application (DE-AS) Ser. No. 21 35 109, the 
dielectric between the electrodes 1 and 2, on the one hand, and 3 and 4, 
on the other hand, is identified by reference character d. 
The operation of the circuit according to FIGS. 1 and 1A is as follows. The 
capacitors C.sub.F and C.sub.K are charged to the high voltage HV. The 
laser chamber LK is connected via the high-resistance resistor R.sub.K to 
ground potential. After the switch F is closed (spark gap fired), a high 
voltage builds up between the electrodes of the laser chamber LK, and a 
voltage breakdown occurs, the laser gas being excited to emission. Besides 
spark gaps F, thyratrons can also be considered as suitable high-voltage 
switching gaps. The invention proceeds from the excitation system for fast 
pulsed gas discharges shown in FIGS. 1 and 1A, which is constructed as a 
high-energy laser of the TEA type. The excitation within the laser chamber 
LK occurs due to a capacitor discharge, which is as homogeneous as 
possible and without arc, between the two electrodes E.sub.L1 and E.sub.L2 
which extend parallel to the optical axis o of the laser LK and are 
disposed spaced from and opposite each other. The first and second 
stripline capacitors C.sub.F and C.sub.K serve for providing 
low-inductance energy storage and for making contact with the laser 
electrodes E.sub.L1 and E.sub.L2 and the associated high-voltage switching 
gap F with the electrodes E.sub.F1 and E.sub.F2, which effects the 
application of a high-voltage pulse to the laser electrodes. 
In a first embodiment of the invention of the instant application shown in 
FIGS. 2 and 3, in contrast to the conventional construction of FIG. 1A, 
the electrodes 1 to 4 of the first and second stripline capacitors C.sub.F 
and C.sub.K and the dielectric layers d therebetween extend substantially 
normally to the optical axis o of the laser LK. Furthermore, the 
electrodes 1 to 4 are stacked substantially parallel to the optical axis o 
of the laser LK to form a capacitor stack and are connected to the 
electrodes E.sub.L1 and E.sub.L2 of the laser chamber LK by laterally 
outwardly extending connecting lugs generally identified by reference 
character f. The stripline capacitors C.sub.F and C.sub.K are thus tilted 
or tipped 90.degree. to the optical axis o of the laser LK; thereby, n 
smallest common capacitance units C.sub.F,K can be stacked parallel to the 
laser axis and can be contacted serially at the laser chamber LK, where 
n=1,2 . . . n-1,n. The laser chamber LK and the fast high-voltage 
switching gap, referred to hereinafter, in brief, as the switching gap F, 
are shown only diagrammatically as tubular structures in comparison with 
the presentation in FIG. 3; a simple structural embodiment is shown in 
perspective view in FIG. 3. The switching gap F may be a multi-channel 
spark gap with electrodes E.sub.F1, E.sub.F2 correspondingly extending 
parallel to the laser chamber and the laser axis; this switching gap F can 
be realized, however, also by fast-switching thyratrons, as is explained 
hereinafter. By comparing FIGS. 1, 1A and FIG. 2, it is found that the 
excitation system according to FIG. 2 is likewise based on a Bluemlein 
circuit. Accordingly, the electrodes of the first and second stripline 
capacitor C.sub.F and C.sub.K are identified by the same reference 
characters 1, 2, 3, 4 as in FIG. 1. The dielectric layers d are disposed 
between the electrodes 1, 2 and 3, 4, respectively, which are at different 
high-voltage potentials during operation. In the space between the two 
capacity units C.sub.F,K, the electrodes 4, 4 and 2, 3 could also be 
combined structurally into a single electrode, since they are at the same 
potential (they are both connected to the same electrode E.sub.L1 of the 
laser chamber LK). An integrated construction of the electrodes 4, 4 and 
2, 3 is taken into consideration especially if a liquid dielectric e.g. 
chemically pure water, is used. This variation is explained hereinafter in 
connection with FIG. 11. 
In particular, the electrode 1 of the stripline capacitor C.sub.F in FIG. 2 
makes contact with the electrode E.sub.F1 of the switching gap and with 
the electrode E.sub.L2 of the laser chamber LK, and it is preferably at 
ground potential. The electrode 2 of the stripline capacitor C.sub.F makes 
contact with the electrode E.sub.F2 of the switching gap F and with the 
electrode 3 of the stripline capacitor C.sub.K and is preferably at high 
potential, namely, that of the high-voltage source HV. The electrode 4 of 
the capacitor C.sub.K is connected to the electrode E.sub.L1 of the laser 
chamber LK, which is connected via a large resistance R.sub.K or an 
inductance to the electrode E.sub.L2, which is preferably at ground 
potential. As mentioned, these structures or arrangements can be provided 
n-times parallel to each other at the laser chamber LK and the switching 
gap F, the electrodes lying in planes normal to the laser axis o. 
Considerable importance is then ascribed to the low-inductance contact 
between the stripline capacitor plates and the electrodes. The perspective 
view according to FIG. 3, which simultaneously provides a cross-sectional 
view, shows that the plate 1 of the capacitor C.sub.F makes contact with 
the electrode E.sub.F1 surrounding the switching gap F by means of two 
lugs f1. This electrode E.sub.F1 has a somewhat E-shaped cross section 
with two outer legs e11 and e11 and a middle leg e12. A highly 
temperature- and corrosion-resistant high-grade steel alloy, such as 
tunsten alloy, especially, is used as material for the electrode E.sub.F1, 
E.sub.F2 of the switching gap F. For the electrodes of the laser chamber, 
halogen-resistant metals such as high-grade steel or aluminum, for 
example, are used. All those wall portions of the switching gap F and the 
laser chamber LK, which are not formed by electrode material, are 
connected to each other and to the electrodes by temperature-stable, UV 
radiation-resistant plastic material, such as PVDF (polyvinylidene 
fluoride), for example, or a high-purity Al.sub.2 O.sub.3 ceramic so that, 
in the interior of the switching gap F and the laser chamber LK, the gas 
mixture contained therein can be kept at the desired pressure (as a rule 
between 50 mbar up to several bar). The hereinafore-mentioned insulating 
wall portions are identified in FIG. 3 by reference character w.sub.F for 
the switching gap F and by w.sub.L for the laser chamber LK. The 
individual plates or foils for the dielectric d protrude, in the 
respective edge zones, beyond the electrodes 1, 2, 3, 4, as is illustrated 
by the contour of the capacitor stack K, so that leakage or flashover 
paths in the outer or edge region are avoided. While the electrode 1 of 
the capacitor C.sub.F in FIG. 3 is shown by a solid outline, electrode 2 
within the lines 1 is indicated by a broken line sequence 2; it is 
connected by a lug F2 to the electrode E.sub.F2 of the spark chamber F. 
This electrode E.sub.F2 is connected to the wall part w.sub.F. As to the 
contacts, attention must be given to the fact that they are made with an 
inductance which is as small as possible and, as far as possible, bifilar. 
The capacitor electrode 4 is indicated in FIG. 3 by a dot-dash line; it 
makes contact via the connecting lug f4 with the electrode E.sub.L1 of 
the laser chamber LK which is connected to the wall part w.sub.L. The 
other electrode E.sub.L2 of the laser chamber LK has, as a mirror image of 
the switching gap F, likewise an approximately E-shaped cross section with 
two outer electrode legs e21, e21 and a middle leg e22, forming the 
electrode E.sub.L2 proper and disposed opposite and spaced from the 
counterelectrode E.sub.L1. The two electrode legs e21, e21 make contact 
with the plates of the capacitor C.sub.F via the two lugs f1. Instead of 
the double-lug contact f1, f1 for the electrode E.sub.F1 of the switching 
gap F and the electrode E.sub.L2 of the laser chamber LK, a single-lug 
contact could also be provided in the inner region shifted in the laser 
axis relative to the lugs f2, f4, however, the contact shown has 
especially low inductance and has largely oppositely directed loops and is 
therefore bifilar, as can be visualized from the course of the pulse 
currents during the discharge process in the switching gap and in the 
laser chamber. 
As can be seen in FIG. 2, the electrodes 2, 3 of the capacitors C.sub.F and 
C.sub.K are conductively connected to each other via a wide lug 23; 
instead of this wide connecting lug 23, the electrodes 2, 3, as mentioned 
hereinbefore, could also be made as one piece and brought into the form 
thereof shown in FIG. 2 by bending. The electrodes 2, 3 could also, 
however, be formed of a single metal sheet or plate. When constructing the 
capacitor stack, care should be taken that the electrodes 2, 3 and 1 are 
insulated for high voltage from the electrode E.sub.L1 and the electrodes 
2, 3 and 4 similarly from the electrode E.sub.L2, as is indicated by the 
dielectric d. It may further be of advantage to place the entire capacitor 
stack in an oil tank or in a water tank (as explained hereinafter). 
As is further shown in FIG. 2, respective adjacent capacity units C.sub.F,K 
are arranged in direction of the stack, with the electrodes 1, 2, 3 and 4 
and the dielectric layers d thereof mirror-symmetrical with respect to a 
symmetry plate s,s imagined as extending normally to the laser axis 
between the two capacity units C.sub.F,K. As mentioned hereinbefore, only 
n=2 capacity units C.sub.F,K are shown in FIG. 2; if one imagines two 
further capacity units i.e. a total of n=4, as being in FIG. 2, then the 
third and the fourth capacity unit C.sub.F,K would likewise be arranged 
mirror-symmetrically with respect to each other. It follows therefrom that 
the electrodes 4,4, which are statically and dynamically at the same 
potential, are opposite each other, so that no high-voltage insulation is 
necessary between these two electrodes 4,4. 
FIG. 3 shows that the base area of the individual stripline capacitors 
C.sub.F, C.sub.K and of the capacity units C.sub.F,K, respectively, is 
substantially rectangular and, accordingly, the capacitor stack K is 
somewhat prismatic, and that the laser chamber LK and the corresponding 
connecting lugs f1, f1; f4 are arranged on an elongated side 11 of the 
prism. The switching gap F and the associated electrodes E.sub.F1, 
E.sub.F2 and connecting lugs f1, f1; f2 are then advantageously arranged 
on the other elongated side 12. 
When the two FIGS. 2 and 3, which represent a preferred embodiment, are 
viewed together, it is apparent that the laser chamber LK and the fast 
high-voltage switching gap F realized in this case as an extended spark 
gap are disposed on the opposite elongated sides 11 and 12 of the 
capacitor stack K, and an electrode 2, 3 common to the first and the 
second stripline capacitor C.sub.F, C.sub.K is disposed as a folded band 
or ribbon bent somewhat hairpin-like between the other two electrodes 1 
and 4 of the stripline capacitors C.sub.F and C.sub.K in such a manner 
that the one folded-band half 2 is directly opposite the electrode 1 which 
is connected between a respective electrode E.sub.L2 of the laser chamber 
LK and a respective electrode E.sub.F1 of the switching gap F. The other 
(second) folded-band half 3 is directly opposite the electrode 4, which is 
connected to the second electrode E.sub.L1 of the laser chamber LK, the 
folded-band or ribbon electrode 2, 3 being connected by the folded-band 
half 2 thereof to the second electrode E.sub.F2 of the switching gap F. In 
the embodiment illustrated in FIGS. 2 and 3, the laser chamber LK and the 
spark chamber F are of substantially tubular construction with a 
rectangular outer cross section. A detailed description of the laser 
chamber, for instance, the preionization device, is dispensed with herein, 
since it is not required for an understanding of the invention. 
A second embodiment of the invention is shown in FIG. 5 and is based upon a 
charge-transfer circuit which serves as a circuit for generating the laser 
excitation pulses. The corresponding circuit diagram, which is per se 
within the state of the art, is shown in FIG. 4. For a better 
understanding of the operating of this circuit shown in the diagram of 
FIG. 4, it has been transposed in FIG. 4A into a three-dimensional or 
perspective view of a stripline arrangement. The capacitor electrodes are 
identified by the same reference characters in FIGS. 4, 4A and 5 as in 
FIGS. 1, 1A and 2 but with the addition of a prime. On the other hand, the 
reference characters identifying the laser chamber LK, the switching gap F 
(in this case again constructed as a spark gap), and the first and second 
stripline capacitors C.sub.F and C.sub.K remain exactly the same. It is 
seen from FIGS. 4, 4A that , in this circuit, the second stripline 
capacitor C.sub.K is connected in parallel with the electrodes E.sub.L1, 
E.sub.L2 of the laser chamber LK; that a high resistance R.sub.F (instead 
of which an inductance L could also be used) is connected in parallel with 
the capacitor C.sub.K ; and that the series circuit formed of the first 
stripline capacitor C.sub.F and the switching gap F is connected in 
parallel with the resistor R.sub.F, the high-voltage source HV being 
connected to the two electrodes E.sub.F1, F.sub.F2 of the switching gap F, 
the high potential of the high-voltage source HV to the electrode E.sub.F1 
and the ground potential thereof to the electrode E.sub.F2. This circuit 
operates so that, if the spark gap F is fired via the capacitor C.sub.F, 
the capacitor C.sub.K is charged up, the latter, in turn, feeding the 
electric energy into the laser chamber LK. 
By comparing FIGS. 5 and 2, it can be found that the spatial arrangement of 
the excitation system in FIG. 5 is effected in a manner similar to that of 
FIG. 2. A detailed description of this second embodiment of FIGS. 4, 4A 
and 5, as well as a perspective view thereof corresponding to that of FIG. 
3 for the first embodiment of FIGS. 1, 1A and 2 are therefore dispensed 
with. In particular, the arrangement in FIG. 5 is also provided so that 
the laser chamber LK and the switching gap F are disposed on opposite 
elongated sides of the capacitor stack K, and an electrode 2', 3' common 
to the first and the second stripline capacitors C.sub.F and C.sub.K, 
respectively, is disposed as a folded-band or ribbon, bent somewhat 
hairpin-like between the other two electrodes 1', 4' in such a manner that 
one folded-band half 2' lies directly opposite the electrode 1' which is 
connected between a respective electrode E.sub.L1 of the laser chamber LK 
and a respective electrode E.sub.F2 of the switching gap F. The second 
folded-band or ribbon half 3', on the other hand, lies directly opposite 
the electrode 4' which is connected to the second electrode E.sub.F1 of 
the switching gap F, the entire folded-band or ribbon electrode 2', 3' 
being connected to the second electrode E.sub.L2 of the laser chamber LK. 
Everything stated hereinbefore with respect to the first embodiment of 
FIGS. 1, 1A and 2 as to the number n of the capacity units C.sub.F,K and 
as to the mirror-symmetrical arrangement applies also to this second 
embodiment of FIGS. 4, 4A and 5. 
Of considerable importance for the excitation system of the first and the 
second embodiments and those described hereinafter is the fast 
high-voltage switching gap F, for which, for example, fast individual 
spark gaps or fast thyratrons, which are well know per se from the 
scientific and technical literature, are suitable. The excitation system 
according to the invention, however, additionally provides ways of 
reducing considerably the inductance of the switching gap as compared to 
that of an individual spark gap or an individual thyratron, so that the 
extremely short switching times which are required are assured. A measure 
or feature which is effective in that sense is shown schematically in FIG. 
6. In this regard, several or, generally, n individual spark gaps of the 
switching gap F are connected in parallel with each other. The undivided 
counterelectrode is identified as E.sub.F2 in FIG. 6 and the electrode as 
a whole as E.sub.F1. However, the latter has many small electrodes 
E.sub.F11, E.sub.F12 and so forth. For this purpose, n holes b are formed 
in the electrode wall w.sub.F1 located one behind the other i.e. serially, 
in the longitudinal direction p of the switching gap F. A trigger pin T of 
suitable material (high-grade steel, tungsten), insulated by insulating 
bushings i, is screwed into each of the holes b, so that the trigger pins 
T are insulated from the wall w.sub.F1 against high voltage. The 
individual electrodes E.sub.F11, E.sub.F12 and so forth, therefore, form 
collar-shaped regions in the wall w.sub.F1 which, in its entirety, 
represents the electrode E.sub.F1. During operating of the switching gap 
F, a high-voltage pulse of short rise or buildup time is applied to each 
of the trigger pins T, so that a breakdown from the trigger pin to the 
electrode E.sub.F1 and to the respective subelectrode E.sub.F11, 
E.sub.F12, respectively, and to the counterelectrode E.sub.F2 occurs. Due 
to this triggered predischarge, the gas space of the switching gap is 
pre-ionized and the main discharge from E.sub.F1 to the counterelectrode 
E.sub.F2 is released suddenly, whereby the switching gap E.sub.F1. . . 
E.sub.F2 becomes conducting. 
The high-voltage pulse which fires the switching gap according to FIG. 6, 
is generated by the circuit shown in FIG. 7. The trigger pins T, in the 
latter circuit, are connected via respective trigger capacities C.sub.S to 
the high-voltage pole of a common switching capacity C.sub.T and are 
connected on the trigger-side thereof via compensating or balancing 
resistors (or inductances) R.sub.T to each other and to ground potential. 
Parallel to the switching capacity C.sub.T, there is connected, for 
example, a fast-switching thyratron or a spark gap for releasing the 
firing pulses. Also, the counterelectrode E.sub.F2 of the switching gap F 
is connected to ground potential. The broken line in FIG. 7 indicates that 
a multiplicity of the T-C.sub.S -R.sub.T branches may be provided in 
addition to the three illustrated ones. The trigger pins T are at the same 
potential through the inductances or high resistances R.sub.T. The 
capacitors C.sub.S and C.sub.T are charged up to high voltages. By firing 
the thyratron Thy or the spark gap, a high-voltage pulse with steep rise 
or build-up is applied to the trigger pins T, which leads to uniform spark 
development at all of the trigger pins T and the opposing electrode 
E.sub.F2 and, thereby, to uniform firing and volume-wise discharge of the 
entire switching gap F. 
Another possibility for associating a switching gap F having low inductance 
with the laser LK is to connect n thyratrons in parallel. All thyratrons 
must be addressed for this purpose, simultaneously, by a suitable firing 
pulse. A third embodiment of the invention according to FIG. 8 shows, in a 
greatly simplified manner, in a view corresponding to those of FIGS. 2 and 
5, the construction of a laser, in a Bluemlein circuit with n thyratrons 
(of which only two are shown), as the switching gap. Respectively, n' 
capacitors C.sub.F and C.sub.K (n' being an integral multiple of n) are 
combined in a capacitor stack C.sub.F,K' which is, respectively, switched 
by a thyratron. The respective anodes and cathodes of the thyratrons can 
be connected to each other conductively via resistors or via inductances 
(not shown). Otherwise, the arrangement corresponds to that of FIG. 2, for 
which reason elements which are analogous to those of FIG. 2 are 
identified by the same reference characters. The capacitor substacks 
C.sub.F,K' respectively, encompass two capacity units C.sub.F,K according 
to FIG. 2 (n'=2n). Depending upon the capacity of the stripline capacitors 
C.sub.F,K and, therefore, depending upon the switching power, a respective 
thyratron could also be assigned to each capacity unit C.sub.F,K (note 
FIG. 2). In FIGS. 9 and 10, a fourth embodiment of an excitation system is 
shown in presentation analogous to that of FIGS. 2 and 3, which is 
likewise based upon a Bluemlein circuit. Among other things, this 
arrangement affords the accommodation of a greater number of capacitor 
plates of the capacitors C.sub.F and C.sub.K per stack length i.e. a 
greater number in comparison with the embodiment of FIGS. 2 and 3. The 
first and second stripline capacitors C.sub.F and C.sub.K are thus 
accommodated on plates indentified as a whole by reference numeral 5, each 
thereof being formed with cutouts 5.1 for passing therethrough the laser 
chamber LK insulated for high voltage. The chamber for the fast 
high-voltage switching gap F is arranged in FIGS. 9 and 10 at the outer 
periphery on the left-hand side and at the longitudinal side of the 
capacitor stack at the left-hand side of the Figures, respectively, 
disposed axially parallel to the laser. 
In FIG. 10, the electrode of the capacitors C.sub.F and C.sub.K at 
high-voltage potential is represented by a solid line 2, 3. The electrodes 
1 and 4 which lie directly opposite this electrode 2, 3, with the 
dielectric d interposed, are represented by broken lines in FIG. 10. The 
insulating layers of the laser chamber LK and of the switching gap F are 
identified by reference character i; they serve for insulating the 
electrodes E.sub.L1 and E.sub.L2 of the laser chamber and the electrodes 
E.sub.F1, E.sub.F2 of the switching gap F from those electrodes of the 
capacitors C.sub.F and C.sub.K which are not at the same potential. 
Otherwise, those parts in FIGS. 9 and 10 which have the same functions as 
corresponding parts in FIGS. 2 and 3 are identified by the same reference 
characters. As is evident, the laser chamber LK extends somewhat centered 
through the capacitor stack K. Here, too, the illustrated rectangular 
cross section and the prismatic shape of the capacitor stack K, 
respectively, are particularly advantageous from the point of view of high 
packing density and manufacturable construction; it is possible, however, 
to select cross-sectional shapes deviating from the rectangular shape i.e. 
squares, ellipses or approximately circular shapes, if this appears 
advantageous in view of the specific application. 
The embodiment of the invention according to FIGS. 9 and 10 can also be 
realized as a charge transfer circuit instead of by a Bluemlein circuit. 
With respect to the fast high-voltage switching gap F, the same remarks 
apply which appear hereinbefore in connection with the first three 
embodiments of the invention. 
In FIG. 11, an embodiment of the invention similar to that of FIG. 2 is 
shown, which affords a further increase of the energy density by providing 
that water be used as the dielectric layer d'. In this case, the 
electrodes 1/1, 2/3 and 4/4, which had up to now been constructed 
individually, are, respectively, combined into one plate. 
Corrosion-resistant high-grade steel is preferably used as the plate 
material. Since water retains its high insulation ability only for a few 
microseconds, the high-volltage d-c voltage source HV is replaced by a 
pulse-charging device. The pulse width or duration of the charging pulse 
must be small in comparison with the time which the high voltage would 
require for a breakdown through the water insulation path, and must be 
large in comparison with the discharge time of the entire excitation 
system. In particular, the capacitor C.sub.F, C.sub.K is briefly charged 
by the pulse-charging method i.e. less than 10 .mu.s, prior to the firing 
of the switching gap. Otherwise, the arrangement is logically the same as 
that according to FIGS. 2 and 3. The particular advantages of the 
construction according to FIG. 11 are, apart from the higher dielectric 
constant or E-value, the possibility of more intensive cooling (water 
cooling), higher energy density and the self-healing properties of the 
water dielectric. 
In a preferred embodiment, the illustrated excitation systems operate as 
high-energy excimer lasers, since the excimer lasers specifically ensure a 
high radiation yield with respect to the excitation energy. As mentioned 
hereinbefore, the excimer laser is described in detail, for example, in 
literature reference (2) so that it is unnecessary to explain its 
operation and its gas composition further in the instant application. The 
use of the excitation system for CO.sub.2 -, Cu-vapor or N.sub.2 lasers is 
also within the scope of the invention since, whereby, the spectrum of the 
laser radiation can be varied i.e. differently colored laser light in the 
visible range as well as invisible (UV and infrared) laser light can be 
generated. 
In addition, the excitation system according to the invention is highly 
suitable, because of the high energy density thereof, for applying 
high-energy high-voltage pulses to two electrodes, especially for the 
purpose of generating high-energy pulses in electron beam guns or in Marx 
generators.