RU2733786C1 - Device for discharge excitation in pulse-periodic gas laser - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: invention relates to the technique of pulsed gas lasers operating on mixtures with high pressure. Improvement consists in using flat electrodes installed in the chamber across the gas flow, at that at least one electrode is divided into sections isolated from each other, and pulse voltage for each of electrodes of section is supplied from separate source of pulses or through individual key. It is proposed to use powerful transistors as switches. Thus, disclosed device for exciting a discharge in a pulse-periodic laser enables to maintain stability and uniformity of plasma discharge, and also to simplify design solutions for implementation of electrodes and power supply circuits of discharge medium. Besides, it becomes possible to use complicated methods of discharge monitoring.

EFFECT: technical result is possibility of maintaining homogeneous plasma in active volume of laser with transverse gas pumping.

1 cl, 1 dwg

Description

The invention relates to the technique of pulsed gas lasers operating on mixtures with high pressure.

In a gas-discharge laser, to obtain a sufficiently high gain, a considerable length of the active medium is often required. In a laser with transverse gas circulation, to obtain a volume discharge that fills the active medium of the laser along its entire length (along the entire cross section of the gas chamber along the optical axis), it is necessary to use extended electrodes.

When using extended electrodes to obtain an electric discharge in a gas, a number of difficulties arise in maintaining the stability and uniformity of the plasma medium of the discharge. The main problem is the high probability of developing an unstable discharge, in which streamers are formed that short-circuit the electrodes.

In this regard, it is required to use special design solutions concerning the design of the cell and the choice of the laser power supply circuit. The discharge stability can be increased by using electrodes with a special profile.

Known device "Device for exciting a discharge of atmospheric pressure in a gas laser", in which it is proposed to use electrodes, the working section of which has an Ernst profile (RF patent 2195753, IPC H01S 3/097, published on 27.12.2002).

The disadvantage of this technical solution is the complexity of the manufacture of electrodes, in particular the observance of such parameters as the radius of curvature of the curvature of the electrode and the length of the working section of the electrode.

Known devices for exciting a discharge in a pulsed gas laser, containing, in addition to the main electrodes, also additional electrodes. Predionization is carried out due to the occurrence of a low-current discharge between the additional electrode, which is isolated from the gas discharge, and one of the main electrodes. A thin layer of ionized gas is formed along the entire surface of the electrode, and electrons uniformly distributed in a thin layer of gas become sources of a powerful rapidly developing diffuse main discharge (RF patent 1840807, IPC H01S 3/09, published on 10.12.2010).

The disadvantage of the device lies in the strict requirements for the thoroughness of the execution of the main elements of the cell design.

A device is known in which the uniformity of the discharge distribution over the active medium of the laser is achieved by ignition along the main electrodes of a plurality of macrochannels of increased electron density. In fact, this method does not provide a uniform volumetric discharge, but a uniform arrangement of discharge inhomogeneities (macrochannels) along the electrode (RF patent 2321119, IPC H01S 3/097, published 03/27/2008).

The disadvantage of this method is the need to ensure the ignition rate of the discharge is not less than dj / dt≥6 × 10 ¹¹ A / cm ² , which creates structural difficulties in the manufacture of a discharge circuit corresponding to the current density required to maintain the discharge ignition rate.

In power supply circuits of repetitively pulsed lasers, thyratrons are usually used to obtain high-power short pulses. A device is known where the laser contains a pulsed power supply circuit with a storage capacity and a switch in the form of a thyratron. When developing a laser, an attempt was made to obtain the highest possible pulse repetition rate of 10 ns duration (RF patent 2249282, IPC H01S 3/038, published on March 27, 2005).

The disadvantage of such a power supply circuit is that the achieved pulse repetition rate does not exceed 2000 Hz, which is clearly insufficient for some types of gas-discharge lasers.

The closest analogue is a device, the electrode system in the gas-discharge chamber of which contains a sectioned anode and a cathode for creating a stationary discharge in a transverse gas flow. The electrode system consists of a sectioned cathode and anode loaded with ballast resistors. The anode sections are made in the form of thin plates, and the cathode sections are made of needles or pins. This device was used as a prototype (RF patent 2370924, IPC Н05Н 1/24, published on 20.10.2009).

The disadvantage of the prototype is the way to power the electrodes by using a single generator. This requires supplying such a circuit with powerful switches that have ineffective frequency characteristics.

The purpose of the proposed device is to organize the discharge by improving the design of the electrodes, simplifying the design of the cuvette, and eliminating the drawbacks of previous developments associated with the obvious design difficulties and inhomogeneities of the active medium of a laser with a transverse gas flow configuration.

In the proposed device, the cell for high-pressure pulsed gas lasers with a transverse discharge contains two flat parallel electrodes of the main discharge - the cathode and the anode. In this case, at least one of the electrodes consists of sections isolated from each other. Moreover, the pulse voltage supplying the discharge is supplied to each of the electrode sections through a separate switch. The technical result is to increase the stability of the discharge and ensure the possibility of scaling the laser.

In the proposed device for organizing the discharge, in contrast to the prototype, in order to simplify manufacture, it was decided to use flat electrodes instead of the thin plates and needles proposed in the prototype. In addition, it is proposed to change the way the camera electrodes are supplied. In the prototype, a pulsed supply voltage is supplied to the electrode sections through ballast resistors from a single generator. In our proposed method, the voltage for each section of the electrode is supplied from a separate generator. This will allow using less powerful switch switches in the generator and facilitate their temperature regime. In addition, less powerful switches tend to have better frequency characteristics than powerful counterparts. The ability to control the torque and duration of each section enables the use of sophisticated discharge control methods.

The technical result of the invention is to increase the stability of the discharge and thereby ensure the possibility of scaling the laser by increasing the volume of the active medium.

The technical result is achieved due to the fact that the known gas-discharge chamber has been improved to create a low-temperature nonequilibrium plasma at atmospheric pressure, containing an electrode system of pin cathodes and anode sections with a gas flow in the interelectrode gap. The improvement consists in the fact that flat electrodes are used, installed in the chamber transverse to the gas flow, while at least one electrode is divided into sections, isolated from each other, and a pulse voltage is applied to each of the electrodes of the section from a separate pulse source, or through an individual key. It is proposed to use powerful transistors as keys.

The essence of the proposed device is illustrated by a drawing (Fig. 1), which shows a general diagram of the proposed organization of the discharge. High-voltage pulses from the GI 1 - GI N generators are fed to sections C 1 - C N of the electrode E1, separated from each other by insulating inserts I. Each section of the electrode is electrically connected to a separate generator. The duration and repetition rate of the pulses of the generators GI 1 - GI N are set by the generator of the master pulses of the MO. GI pulse generators are powered from a power supply source. The amplitude of the pulse at the output of the GI pulse generator is determined by the value of the output voltage of the MT power supply. The gas flow is pumped in the interelectrode gap formed by the electrodes A1 and A2.

Thus, the proposed device for exciting the discharge allows you to maintain the stability and uniformity of the plasma discharge, as well as to simplify the design solutions for the implementation of electrodes and the power supply circuit of the discharge medium. In addition, it becomes possible to use sophisticated methods of monitoring the discharge.

Claims (1)

Discharge excitation device in a gas discharge chamber, the electrode system of which consists of flat electrodes installed in the chamber transverse to the gas flow in the interelectrode gap, characterized in that at least one electrode is divided into sections, isolated from each other, and a pulse voltage is applied to each section from a separate source of impulses or through an individual key.

Images