DD225883A3 - CIRCUIT ARRANGEMENT FOR TURNING GAS LASERS AND GAS LASER AMPLIFIERS - Google Patents

Abstract

The invention relates to a circuit arrangement for igniting gas lasers and gas laser amplifiers with a plurality of coupled discharge paths, in particular CO2 lasers which are operated with axial direct current discharge, preferably with multiple convolution resonator arrangements. The aim of the invention is to develop a circuit arrangement to the ends of gas lasers of the type mentioned, which ensures a high degree of security with optimally reduced Baulaenge of the laser with low technical complexity and low Stoeranfaelligkeit. According to the invention, this is achieved with a circuit arrangement using a controlled by thyristors Hochspannungsnetzgeraetes with downstream rectification and Glaettung the high voltage delivered by the laser capacitor is first charged after the start of the Glaettungskondensator to a value that is still below the Zuendspannung to be ended discharge lines , Then subsequently the Zuendwinkel for the thyristors is briefly reduced to zero, so that a steep Zuendspannungsimpuls results at the output, which covers the Zuendspannungsbereich all involved Teilentladungsstrecken within a very short time and thus ends the laser safely. Subsequently, the required discharge current is set via the thyristors, provided that all partial discharge paths are closed, otherwise the supply voltage is switched off again immediately.

Description

Title of the invention

Circuit arrangement for igniting gas lasers and gas laser amplifiers

Field of application of the invention

The invention relates to a circuit arrangement for igniting gas lasers and gas laser amplifiers with a plurality of coupled gas discharge paths, in particular COp lasers, which are operated with axial direct current discharge, preferably with multiple convolution resonator arrangements and two opposite discharge paths whose cathodes are at ground potential and their anodes have a small distance from each other.

Characteristic of the known technical solutions

For reliable ignition of the discharge paths of gas lasers which are operated with gas mixtures, an ignition voltage must be applied to the individual tubes and the discharge path _; which is generally about two to three times greater than the burning voltage required to maintain the gas discharge. Here, the ignition voltage and also the burning voltage range of the geometry of the discharge paths , the gas mixture and

Depending on the gas pressure, gas mixtures with favorable laser properties are usually relatively difficult to ignite. "In order to avoid such ignition difficulties, it is generally worked with a Zündspannungsimpuls relatively high voltage. For this purpose, it is known, for example, for generating this ignition voltage pulse to switch an auxiliary power supply low power to the actual power supply in series. In Einschaltmoment.wird the .Spannung of the auxiliary power supply is increased, upon ignition of the laser and the resulting load breaks the voltage of the auxiliary power supply together and the actual power supply takes over a corresponding diode circuit, the power supply. The adjustment of the discharge current is carried out high-voltage side via triodes, This variant is technically complicated, among other disadvantages.

In high-voltage power supplies controlled by thyristors, the high ignition voltage can be generated by short-term reduction of the firing angle of the thyristors. Both variants' is contrary as a particular disadvantage _; that the sufficiently smooth DC voltage required for continuous operation of the laser or the smoothing capacitors used counteract the generation of a sufficiently steep ignition pulse, because the smoothing capacitors charge according to an e-function and the voltage rise rate decreases with increasing charging due to different factors due to ignite at different voltages, the ignition takes place due to the relatively flattened course of the ignition pulse with a time delay, so that at low anode distances of opposing discharge distances ignition difficulties may occur such _i that at a sufficiently large time offset between the anodes involved a potential difference in height the difference between operating and burning voltage arises, which lead to a gas discharge between the anodes and thereby considerably beschä the laser can do. This phenomenon

is to be avoided with the previously known means only with certainty, if the respective anodes are arranged sufficiently far away from each other ^ what u. a, especially with regard to the required _? shortest possible length of such laser brings significant disadvantages.

In order described to avoid difficult lighting, and has also been proposed to introduce the individual gas components of the gas mixture used in each case one by one in the discharge paths to be which first started with the gas component _", which can be ignited at _leichtesten; thereafter mix in the further gas constituents so _? That the discharge is maintained until the mixture at normal working pressure the required 'mixing ratio has (DE-OS 31 13 591).

Although this form of ignition does not require an excessive ignition voltage pulse as when igniting the already optimized gas mixture, because the ignition voltage for the most easily ignited gas can sometimes even be below the normal burning voltage of aspired gas mixture, it is, however, experience extremely time consuming. A particular disadvantage of this solution is that the laser can not be switched on and off within short time intervals.

Object of the invention

The aim of the invention is to develop a circuit arrangement for igniting gas lasers and gas laser amplifiers of the type mentionedj which ensures high ignition safety with optimally shortened overall length of the laser with low technical complexity and low susceptibility.

  4 Presentation of the essence of the invention

The invention has for its object to solve the contradiction between the integrating effect of the smoothing capacitors and the required for a reliable ignition of the laser steep voltage increase of all participating partial discharge routes with a relatively low technical effort> that a high ignition safety with optimally shortened length of the laser is guaranteed.

According to the invention, this object is achieved with a circuit arrangement for igniting gas lasers and gas laser amplifiers of the type mentioned using a high-voltage transformer controlled by thyristors with downstream two-way rectification and smoothing of the pulsating DC voltage by means of smoothing capacitors by preloading the smoothing capacitors to a voltage whose value is determined by the Zündwinkeleinstellung the thyristors using a corresponding control voltage and which is still below the ignition voltage of the individual partial discharge paths of the laser and the subsequent ignition of the laser by briefly reducing the firing angle of the thyristors to zero with the aid of a needle as a pulse trained control voltage pulse synchronous with the zero crossing of the sine wave voltage of the network Thus, the smoothing capacitors load with a steep in the initial phase The increase continues and there is a short-term, over the ignition. Voltage of the individual partial discharge sections lying voltage pulse, which covers the ignition voltage range of all involved partial discharge paths due to its steep rising edge within a very short time and thus ignites the laser in all partial discharge paths with high reliability. The firing angle of the thyristors in turn, in a conventional manner with the help of a corresponding Control voltage set to a value corresponding to the respective required discharge current for the laser

embodiment

The invention will be explained in more detail below using an exemplary embodiment.

In the accompanying drawing, Figure-1 shows the circuit arrangement according to the invention.

1 has a thyristor 1 with a pulse lock 2, which is operated on the input side with a sinusoidal AC voltage and the output side operates a high-voltage transformer 3. This high-voltage transformer 3 is followed by a two-way rectification 4 j whose output voltage is smoothed by smoothing capacitor 4 to the extent required and the connected to the parallel partial discharge paths 5-1. ··· 5 η is applied. The ignition process according to the invention will be described with reference to the circuit arrangement shown first in the arrangement of the associated modules and subsequently in their temporal or circuit-related interaction in more detail The circuit consists of the following modules:

- A timer 6, _# of a diode D 1 a resistor

R 1 is a capacitor C.1 connected in series and a parallel to the capacitor C 1 lying relay K 1 and that via the opener of the switch S, d, h. is supplied with locked pulse lock 2 of the Thyristorstellers 1 with voltage;

- A synchronization element 7, which is supplied from the thyristor 1 with synchronization pulses and in which the synchronization pulses with closed normally open K 1-1 of the relay K 1 through a resistor R 2 to ground while they open with open closer K 1.1. via a resistor R 3 to the base of the transistor T 1 which operates as an inverter;

a differentiating member 8 _; from a capacitor C 2 and

a resistor R 5, with the aid of which the synchronization pulses negated by the transistor T 1 are differentiated and forwarded via a diode D 2 ^ which allows only positive needle pulses to pass;

a bistable multivibrator 9 which is controlled via the differentiating element 8 and which is reset to the low state via the normally closed contact of the switch-on switch S and the resistor R 10;

- A circuit part 10 ,. which is controlled by the bistable multivibrator and which serves to generate the control voltage described below:

, U-StI with a resistor R 8 the adjustment resistor .R 9 and a diode D 4,. U-St2 with a "capacitor C 3 and U-St3 with the adjustment resistors R 6 and R Ί _} where the capacitor C 3 is parallel to the resistor R 6 and the tap of R 7 and both voltages U-St2 and U-St3 be guided via the diode D 3 to the control input "12 of the Thyristorstellers 1 while the control voltage U-StI via the diode D 4 is applied to the control input 12 and

- A circuit part for ignition 11 with inserted into the cathode branches of all discharge paths 5-1- ... 5-n measuring resistors R 11 ... Rm and parallel to these measuring resistors relay K 11 ... Km, whose associated opener K 11.1. ... K m.1 are connected in parallel and on the one hand via the opener K 11 of the relay K 1 are connected to the Zündimpulssperre 2 and on the other hand against ground in series with a timing relay K 2, the opener K 2.1 arranged in the Zündimpulssperre 2 is.

The circuit arrangement is designed so that the timer 6 is disconnected from the supply voltage with actuation of the power button S and the associated cancellation of Zündimpulsssperre 2. In this case, the relay K 1 remains for a time dependent on the capacitance of the capacitor C 1

room still dressed. Thus, on the one hand derived from the thyristor 1 synchronization pulses on the normally open K 1.1 grounded and on the other hand, the supply voltage UV through the resistor R 8, the tap of the adjustment resistor R 9 and the diode D 4 to the control input 12 of the Thyristorstellers 1 and the thyristors are driven with the control voltage U-StI set via the adjusting resistor R 9 or the ignition angle resulting therefrom, and the smoothing capacitor C 4 is charged with the resulting output voltage. After appropriate discharge of the capacitor C 1, the relay K 1 drops off delayed. the opener K 1.2 closes and thus switches on the ignition control, while with the opening of the closer K 1 1 the next synchronization pulse precisely with the zero crossing of the line input voltage drives the transistor T 1 whose output signal differs from the downstream differentiating element 8 and to the input of the bistable multivibrator 9 is placed. As a result, the bistable multivibrator 9 switches from the L to the Η state and outputs a higher output voltage at its output. This corresponds to the value of the control voltage U-St2-This sudden voltage change is first passed fully through the capacitor C 3 and the diode D 3 (in the form of a needle pulse) to the control input 12 of the Thyristorstellers 1, so that the thyristors are fully open (firing angle d = 0) As a result, a steep ignition voltage pulse is emitted at the output, which sweeps over the ignition voltage range of all involved discharge paths (5.1 ··· 5.n) within a very short time and thus ignites the laser with high reliability. With the charging of the capacitor C 3, this blocks the output from the multivibrator DC voltage (H potential) and set using the adjustment resistors R 6 and R 7 control voltage U-St3 is applied via the diode D 3 to the control input 12 of the Thyristorstellers 1, , In order for the thyristors are driven with a firing angle at the output of the required discharge current through the discharge paths 5-1. 5 η. The prerequisite for this is that all discharges

dung stretch 5.1 - · - are ignited 5-n, so that all the measurement resistors R 11 .., R m drops a corresponding voltage which drives the respective associated relay K 11 ... Km _i so that all openers K 11.1 ... K m.1 to be opened. If, however, one of the discharge sections 5.1... 5-n is not ignited, the associated relay K 11... Km is not actuated, and the associated normally closed contact K 11 1... K m.1 remains closed, so that after Expiry of an adjustable time, the relay K 2 attracts, the corresponding opener K 2.1 opens _; so that the Zündimpulssperre locks again and thus ultimately turns off the high voltage.

Claims (1)

J3T invention claim Circuit arrangement for igniting gas lasers and gas laser amplifiers having a plurality of coupled partial discharge paths., Which are operated with axial DC discharge, preferably with multiple convolution resonator arrangements and two opposite partial discharge paths _; their cathodes are at ground potential and their anodes have a small distance from each other ₇ using a high-voltage transformer controlled on the primary side via thyristors with downstream two-way rectification and smoothing of the pulsating DC voltage by means of smoothing capacitors _; characterized by the precharging of the smoothing capacitors to a voltage below the value of the ignition voltage of the individual partial discharge paths and the subsequent in a known manner 'carried out ignition of the laser by briefly reducing the firing angle of the thyristors to the value of zero synchronously with the zero crossing of the sine wave voltage of the network. For this a sheet drawing