JPH0451996B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a pulse shaping circuit suitable for obtaining high voltage and large current rectangular wave pulses. For those requiring such pulses, e.g. CO ₂
There are lasers, excimer lasers, etc. this house,
CO ₂ lasers are mainly used for processing and welding, and excimer lasers are used for semiconductor annealing, optical etching, surface processing, photochemistry, uranium isotope enrichment, nuclear fusion, etc. Furthermore, it can also be used for testing high voltage and large current electrical elements.

Prior Art A conventional pulse shaping circuit of this type has, for example, a first pulse shaping circuit.
As shown in the figure, a high voltage is applied to capacitor C from the input side to temporarily accumulate charge in capacitor C, then switch S is closed and the charge accumulated in capacitor C is supplied to discharge gap G. By discharging the battery, the required pulse was obtained.
The capacitor C, regardless of whether it is a flat plate type or a coaxial type, uses a plastic such as mylar, epoxy or polyethylene, or a liquid such as ethylene glycol or water as a dielectric material. Also,
Ceramic capacitors are also known, but they use a ceramic capacitor with a general structure in which electrodes are attached to both opposing end faces of ceramic formed in a columnar or flat plate shape, and a plurality of the ceramic capacitors are connected to flat electrodes. The structure was such that they were connected in parallel between plates, etc.

Disadvantages of conventional technology However, in conventional pulse shaping circuits using plastic as a dielectric, the dielectric constant is low, resulting in high impedance and short pulse width, resulting in large current and long pulse circuits required for excimer lasers, etc. cannot be realized. When using ethylene glycol (εr ~ 40) or water (εr ~ 80), to obtain the same pulse width, it requires more than five times the length, and water has low insulation resistance, so DC The drawback was that voltage could not be applied. Furthermore, a circuit in which ceramic capacitors of normal structure are connected in parallel does not function as a pulse shaping circuit and does not function as a single capacitor.

OBJECTS OF THE INVENTION The present invention is capable of applying a fast rising high voltage and large current rectangular wave pulse for a relatively long time to a load with a very low impedance of, for example, 1Ω or less. Our objective is to provide a high-output pulse shaping circuit that is ideal for excitation of excimer lasers that require large current square wave pulses, testing of electrical switch elements, etc., and that is easy to miniaturize and highly practical. do.

Structure of the Present Invention In order to achieve the above object, a pulse shaping circuit according to the present invention includes a cylindrical dielectric ceramic having an inner circumferential electrode and an outer circumferential electrode formed on the entire surface of the inner circumference and the outer circumference, and The ends of the inner circumferential electrode and the outer circumferential electrode located on one end side in the axial direction of the body porcelain are used as pulse input ends, and the ends of the inner circumferential electrode and the outer circumferential electrode located on the other end side are used as pulse output ends, A pulse shaping circuit that outputs a pulse having a pulse width approximately proportional to the axial length of the dielectric ceramic from the pulse output terminal when a pulse is input to the pulse input terminal, wherein the dielectric ceramic is A plurality of electrodes are provided, each having substantially the same inner diameter and outer diameter, and arranged in the axial direction so that the inner electrodes and the outer electrodes are electrically connected to each other.

Embodiment FIG. 2 is a front sectional view of a pulse shaping circuit which is the basis of the present invention, and FIG. 3 is a side view thereof.
This embodiment has a structure in which an inner electrode 2 and an outer electrode 3 are formed on the inner and outer peripheral surfaces of a cylindrical dielectric ceramic 1 made of a suitable dielectric ceramic material, respectively. The electrodes 2 and 3 are typically deposited using techniques applied in the manufacture of ceramic capacitors, for example as baked-on silver electrodes.

This pulse shaping circuit operates between electrodes 2 and 3 at one end A in the axial direction as a pulse input terminal and between electrodes 2 and 3 at the other end B as a pulse output terminal. Here, impedance Z between input terminal A and output terminal B, pulse width τ at output terminal B, and capacitance C
Z=60(1/√)ln(r2/r1)Ω τ=2L√/v sec C=0.56εrL/ln(r2/r1)PF However, r1 is the dielectric and the inner diameter of the ceramic 1 r2 is the dielectric The outer diameter of the porcelain 1 is L, the length of the dielectric porcelain 1, εr is the relative dielectric constant of the dielectric porcelain 1, and v is the speed of light. As a concrete achievable value, let the dielectric constant εr of the dielectric ceramic 1 be εr=1200, and its shape be r1
= 9mm, r2 = 50mm, and L = 84cm, we obtain Z = 3Ω, τ = 194ns, and C = 28.6nF. That is, a long pulse with a pulse width τ=194 ns can be easily obtained. Further, the impedance Z is a low impedance of 3Ω. Moreover, by connecting a plurality of pulse shaping circuits having the above configuration in parallel, the value of impedance Z can be reduced in inverse proportion to the number of parallel connections. For example, if three pulse shaping circuits having the above configuration are connected in parallel, the impedance Z can be lowered to 1Ω. For this reason, for example, for a load with very low impedance of 1Ω or less,
It is possible to apply a fast-rising high voltage and large current square wave pulse for a relatively long time of about 200 ns, and it is an excimer laser excitation and electrical switch element that requires a high voltage and large current square wave pulse. This makes it possible to realize a compact pulse shaping circuit that is ideal for testing, etc.

FIG. 4 shows an embodiment of the pulse shaping circuit according to the present invention. The feature of this embodiment is that a plurality of cylindrical dielectric ceramics 1 having substantially the same shape with electrodes 2 and 3 formed on the inner and outer peripheries are prepared, and each dielectric ceramic 1, 1, . . . The circumferential electrodes 2 and the outer circumferential electrodes 3 are arranged in the axial direction so as to be electrically conductive with each other.

As is clear from the above formula τ=2L√/v,
The pulse width τ is proportional to the length L of the dielectric ceramic 1 constituting the pulse shaping circuit. Therefore, by adjusting the length L of the dielectric ceramic 1, the pulse width τ
can also be adjusted. For example, if a longer pulse width τ is required, the length L of the dielectric ceramic 1 may be increased. However, in FIGS. 2 and 3, since a single piece of dielectric ceramic 1 is used, there is a limit to the length that can be manufactured due to manufacturing technology, and there are cases where the required length cannot be obtained. be. In the case of the embodiment shown in FIG. 4, a plurality of cylindrical dielectric ceramics 1 having approximately the same shape are prepared, and each dielectric ceramic 1,
... are arranged in the axial direction so that the inner circumferential electrodes 2 and the outer circumferential electrodes 3 are electrically conductive, so the length of one dielectric porcelain can be shortened, resulting in technical difficulties in manufacturing. By solving the problem and appropriately selecting the number of dielectric ceramics 1, 1,...
By adjusting the substantial length L of the pulse shaping circuit, the pulse width τ can be freely and easily controlled.

FIG. 5 is a diagram showing a more specific embodiment of the composite structure pulse shaping circuit shown in FIG. 4. In this embodiment, each of the dielectric ceramics 1, 1, . This is prevented by an insulating resin coating 4. The dielectric ceramics 1, 1, . . . are axially aligned and integrated with a resilient metal pipe 5 commonly passed through their inner diameters. The metal pipe 5 is provided with elasticity by inserting a crack 51 into its thick wall part. With such a structure, the metal pipe 5 can be closely fitted into the inner diameter of the dielectric ceramics 1, 1, ... and elastically contacted with the inner circumferential electrode 2 without causing damage or the like. Can be done.

The outer peripheral surfaces of the dielectric porcelains 1, 1, . The respective outer peripheral electrodes 3 of No. 1, . . . are electrically connected to each other.

Furthermore, in order to improve electrical insulation, a heat-shrinkable insulating tube 7 is placed over the metal mesh 6, and the entire structure is housed within an insulating housing 8. The area around the pulse shaping circuit in the insulating housing 8 is filled with insulating oil, insulating gas, silicone rubber, etc. to prevent creeping dielectric breakdown. However, if the voltage is low, the insulating housing 8 may be omitted.

FIG. 6 is a diagram showing an example in which the pulse shaping circuit according to the present invention is used in a rare gas-halide excimer laser generator. In the figure, R is the input resistance, C
is the capacitor, SG1 is the spark gap, PFL
is a pulse shaping circuit according to the present invention shown in FIGS. 2 to 5, SG2 is a rail gap, and A is a rare gas
It is a halide excimer laser tube. In the pulse shaping circuit PFL, the inner electrode 2 on the input terminal A side is connected to the spark gap SG1, and the outer electrode 3 is connected to the capacitor C.
At the same time, the inner circumferential electrode 2 on the output end (R) side is connected to the rail gap SG2, and the outer circumferential electrode 3 is connected to the electrode of the rare gas-halide excimer laser tube A.

In the above rare gas-halide excimer laser generator, high pressure is supplied through the input resistor R,
After charging capacitor C, spark gap
Close SG1 and pulse charge the pulse shaping circuit PFL. When the pulse charging voltage of the pulse shaping circuit PFL reaches a certain value and the rail gap SG2 closes, the voltage wave reciprocates inside the pulse shaping circuit PFL,
A square wave pulse is applied to the rare gas-halide excimer laser tube A to generate an excimer laser in the ultraviolet range.

Next, an embodiment will be described in which a pulse shaping circuit PFL with εr=1200 r1=9 mm r2=50 mm L=84 cm is used in this rare gas-halide excimer laser generator. In this case, in one pulse shaping circuit PFL, Z=3Ω, τ=194ns, and C=28.6nF. In this example, the rare gas-5
Three pulse shaping circuits are installed in consideration of impedance matching with the ride excimer laser tube A.
PFLs were connected in parallel. Therefore, for the entire pulse shaping circuit, Z=1Ω, τ=194ns, and C=86nF.

FIG. 7 is a voltage waveform diagram in the above embodiment, and FIG.
The figure is also a current waveform diagram, and FIG. 9 is a laser waveform diagram. First, as shown in Figure 7, the voltage changes from infinity to 1Ω when the laser discharges.
Since the voltage drops rapidly below, there is a steep peak at first, and then a constant voltage corresponding to the pulse width τ = 194 ns of the pulse shaping circuit PFL is obtained. Regarding the current, as shown in Figure 8, the pulse width τ of the pulse shaping circuit PFL is
A nearly square wave was obtained for 194 ns, and a current of approximately 80 KA was obtained with a rise time of 20 ns. As for the laser, as shown in FIG. 9, a pulse width of about 150 ns was obtained, corresponding to the pulse width τ=194 ns.

Conventionally, in rare gas-halide excimer lasers, in order to obtain high output with a pulse width of 100ns or more,
A planar pulse shaping circuit with water as the dielectric was used, but using this circuit required a length of 3.3 m to obtain a pulse width of 200 ns. In contrast,
According to the present invention, as explained in the above embodiment, a pulse shaping circuit having a pulse width of approximately 200 ns can be realized using dielectric ceramic having a total length L of 85 cm and an outer diameter r2 of 50 mm. This makes the device significantly smaller and simpler. Moreover, since a water circulation device and a deionization device are not required, the entire device can be significantly downsized.

Effects of the present invention As described above, according to the present invention, the following effects can be obtained.

(a) Since a cylindrical dielectric ceramic is used, and one end in the axial direction is used as a pulse input end and the other end is used as a pulse output end, the impedance is low, for example, excitation of an excimer laser with a low impedance load of 1Ω or less, A pulse shaping circuit suitable for testing electrical switch elements can be provided.

(b) Since cylindrical dielectric ceramic is used, it is possible to provide a pulse shaping circuit suitable for rectangular wave pulse shaping of high voltage and large current, and suitable for excitation of excimer lasers, testing of electrical switch elements, etc.

(c) One axial end of the cylindrical dielectric ceramic is the pulse input end, the other end is the pulse output end, and when a pulse is input to the pulse input end, the axial length of the dielectric ceramic from the pulse output end. Since a pulse having a pulse width approximately proportional to is outputted, a pulse having a relatively long pulse width determined by the axial length of the dielectric ceramic can be outputted. Therefore, it is possible to provide a pulse shaping circuit suitable for excimer laser excitation, testing of electrical switch elements, etc., which require relatively long rectangular wave pulses.

(d) A plurality of dielectric ceramics are provided, each having substantially the same inner diameter and outer diameter, and arranged in the axial direction so that the inner circumferential electrodes and the outer circumferential electrodes are electrically conductive. By selecting the number of dielectric ceramics, it is possible to provide a pulse shaping circuit in which the pulse width can be freely and easily controlled.

[Brief explanation of the drawing]

Fig. 1 is an electrical circuit connection diagram of a conventional pulse shaping circuit, Fig. 2 is a front sectional view of the pulse shaping circuit which is the basis of the present invention, Fig. 3 is a side view thereof, and Fig. 4 is the invention of the present invention. 5 is a front sectional view of another embodiment of the pulse shaping circuit according to the present invention, FIG. 5 is a front sectional view of yet another embodiment, and FIG. 6 is a rare gas-halide excimer using the pulse shaping circuit according to the present invention Electric circuit connection diagram of laser generator,
FIG. 7 is a voltage waveform diagram obtained by the rare gas-halide excimer laser generator of FIG. 6, FIG. 8 is a current waveform diagram, and FIG. 9 is a laser waveform diagram. 1... Dielectric ceramic, 2... Electrode, 3... Electrode.

Claims (1)

[Scope of Claims] 1. A cylindrical dielectric ceramic having an inner circumferential electrode and an outer circumferential electrode formed on the entire surface of the inner circumference and the outer circumference, and the inner circumference located on one end side in the axial direction of the dielectric ceramic. The ends of the circumferential electrode and the outer circumference electrode are used as pulse input ends, and the ends of the inner circumference electrode and the outer circumference electrode located on the other end side are used as pulse output ends, and when a pulse is input to the pulse input end, the A pulse shaping circuit that outputs a pulse having a pulse width approximately proportional to the axial length of the dielectric ceramic from a pulse output end, wherein a plurality of the dielectric ceramics are provided, each having substantially the same inner diameter. What is claimed is: 1. A pulse shaping circuit having dimensions and external dimensions, and wherein the inner circumferential electrodes and the outer circumferential electrodes are arranged in the axial direction so as to be electrically conductive with each other. 2. Each of the dielectric ceramics is connected by an elastic metal pipe passed through the inner diameter part,
2. The pulse shaping circuit according to claim 1, wherein the inner peripheral electrode is electrically connected through the metal pipe. 3. The pulse shaping circuit according to claim 2, wherein the metal pipe has a split along the axial direction, and is imparted with elasticity by the split. 4. Wrapping a metal mesh around the outer periphery of the dielectric porcelain,
The pulse shaping circuit according to claim 1, 2, or 3, wherein each of the outer electrodes is electrically connected by the metal net.