SU512652A1 - Low pressure gas discharge device - Google Patents

Description

one

The present invention relates to cold cathode low pressure gas discharge devices.

Cold cathode gas discharge devices are known in which any of the electrodes, cathode or anode is hollow and contains at least an additional chamber located in the electrode cavity and connected with it through holes.

These devices have relatively large switching losses caused by a large voltage drop across them during the passage of a switching current pulse. The critical current, the transition to the arc in such devices, exceeds 1 ka. Moreover, even when switching large currents, at the beginning of the pulse, the glow discharge, characterized by a higher voltage drop than the arc discharge, is lit. This, in turn, leads to an increase in starting losses and to a distortion of the current pulse.

The aim of the invention is to reduce switching losses in cold cathode gas discharge devices.

This goal is achieved by the fact that on the walls inside the additional chamber there are elements made of dielectric material, on the surfaces of which at least partially a thin metal film is applied, which has electrical contact with the wall. The dielectric elements are expediently implemented in the form of ceramic rings, which, alternating with metal rings, form one of the walls of the additional chamber.

In order to reduce the critical current of the transition to the arc and reduce the time of development of the discharge, it is recommended to choose the transverse size of the cross-sectional chamber from 2 to 12 mm.

FIG. Figure 1 shows one of the variants of a gas discharge device in which the dielectric elements are made in the form of ceramic rings, a section; in fig. 2 - arrangement of metal and ceramic rings with a thin metal film applied on them; in fig. 3 is a diagram of an instrument in which dielectric elements are placed in an additional chamber.

formed by double walls in the end part, the cathode; in fig. 4 is a diagram of the device, in which the dielectric elements are placed in the bottom-hole chambers in the end wall of the cathode; in fig. 5 is a diagram of an instrument in which dielectric elements are placed in additional chambers, both in the cathode and in the anode.

The gas discharge device (Fig. 1) has a cylindrical ceramic body 1 in which the anode 2 and cathode 3 are placed in the form of glasses. In the cavity 4 of the cathode which performs the function of a starting chamber, a starting electrode is placed in the form of two disks 5 and 6 connected by metal oxy-columns 7. The starting chamber communicates with the gap 8 between the anode and cathode through the holes 9 in the end wall of the cathode. A cavity of an additional chamber 10 of an annular shape is formed by a cylindrical screen 11. In this screen there are openings B in the form of chips 12, with the help of which the opolite filament chamber is connected to the cavity 4. In the secondary chamber (see Fig. 2) stir, dielectric elements 13 in the form of rings of ceramics, for example, brand 22ХС. Rings 13 are separated from each other by m. Metal rings 14 and form together with it {the wall of the additional chamber. The outer surface of the dielectric rings 13 is supported by a metal ™ metallic 15 (shown in dotted lines), for example, from material of rings 14, which can be made of copper, stainless steel or another suitable metal or alloy. Mentioned chickpea plesha has electric. Contact with rings 14, which, in turn, contact with cathode 3. The device works as follows. The anode is connected to the positive pole of a commanded circuit, and the cathode is connected to the triple m.

A positive relative to the cathode discharge is applied to the starting electrode through the current limiting resistor, which excites a low-current glowing duty discharge inside the cavity. The device starts by supplying a starting impedance electrode of negative impedance, the amplitude of which must exceed the values of the burning voltage of the glow glow. In this case, electrons from the plasma of the duty discharge enter through the holes 9 into the gap 8, the breakdown of the latter and the device actuation, after which a low-voltage arc discharge is established in it. A significant role in the development of the arc discharge is played by a thin metallic.

Since the coefficient of secondary emission of the film is significantly larger than that of ma. cathode material, discharge current density

This film will be higher than to other areas of the cathode. On the other hand, the critical glow-to-arc current for thin films is substantially less than for a massive metal cathode. Therefore, the discharge will turn into an arc form with relatively small currents. The increased resistance of the film, which should have an electric contact with the electrode, also contributes to the transfer of the discharge into the arc form, as the discharge current passes through it, the film heats up, which facilitates the development of cathode spots that quickly transfer to metal rings 14. And; burns at the junction of the metal rings 14 and the dielectric rings 13, that is, the burning point of the cathode spot is strictly fixed. At this stage of the development of the arc discharge, as shown by the experiments performed, a significant value is the fact that the dielectric elements with a metal film are placed in an additional chamber. If the transverse size of the additional chamber (between the cylindrical screen 11 and the open surface of dielectric cavities., Lets 13 with the imprinted on it) is chosen in the range from 2 to 12 mm with hydrogen pressure from 3 to 0.6 torr, compared to other transverse dimensions of the chamber 10, this leads, firstly, to a decrease in the critical arc transition current by two to three times, secondly, to a significant increase in arc stability even at low currents and, thirdly, to a certain decrease in the voltage drop on the instrument during switching and current pulse.

The dielectric element 13 can be placed in an additional chamber 10 of a gas discharge device, which is formed by a perforated partition in the end part of the cathode, facing the anode 2, and an additional wall 16 (Fig. 3). The advantage of such a device is a simpler design and somewhat smaller dimensions and weight (than with the device of FIG. 1). The dielectric elements 13 can be placed in additional chambers 10, which are holes that expand towards the cathode in a thick partition 17. This design variant (Fig. 4) is expedient to use when switching impulse currents of large amplitude and duration.

Claims (2)

It is possible, along with dielectric elements 13 placed in an additional chamber 10 of the cathode, the presence of the same dielectric elements in the form of rings, which are located in the additional chamber 10 of the anode 2 formed in the cavity of the anode 4 using a cylindrical screen 11 (Fig. 5). As in the cathode, the dielectric rings 13 are separated by metal rings 14 and form the wall of the additional chamber 1O. The anodic chamber, as well as the cathode, is connected with the gap between the cathode and the anode by means of the holes 9. The gas-discharge side-arm structure can be used for switching AC pulses, for example, when a capacitor discharges into an inductive load. The operation of this device is basically similar to the operation of the device described above (Fig. 1), except for the fact that when the switching current polarity is reversed, the cathode spot alternately occurs either in one chamber 1O or in another. As a result, the voltage drop across the device is of little value when current flows in both the forward and reverse directions. Experiments have shown that a convenient way of applying a metal film to the dielectric elements with the properties necessary for obtaining a positive effect is to excite a pulsed glow discharge in the cathode strip. To do this, a fully manufactured and tested device is connected as a switching device to the circuit of a high-power pulse modulator and put into operation. Initially, the voltage drop across the switch will be relatively high. However, after a thin metal film having contact with the cathode is in at least one place on the surface of dielectric elements due to the sputtering of the cathode material under the influence of a glowing discharge, the discharge turns into an arc shape with a small voltage drop. After that, the training can be stopped and the device is ready for use. It should be noted that this manufacturing method is not the only one possible. It can be made by other methods, for example, by vacuum sputtering, however, the method of sputtering the cathode material in the glow discharge is the most convenient and efficient. During operation of the device during arc burning, on the one hand, the film is destroyed at random in the place where the arc is burning, and, on the other hand, the film is deposited on those places of dielectric elements that are currently directly charged do not touch. Experiments have shown that when the surface of dielectric elements, available to the impact of a discharge, is substantially larger than the area occupied by the discharge, then in a wide range of currents, when a film breaks down in one place of dielectric elements, it is sprayed in an adjacent place and thus, promoting the ignition of a low-voltage stable discharge, are maintained when the device is operated for a long time. The main advantage of the proposed device in comparison with the known ones is that its design allows realizing an arc discharge characterized by a low burning voltage and, consequently, a low level of losses, at much lower switching currents. Claim 1. A low-pressure gas discharge device comprising a cold cathode and an anode, wherein at least one of the electrodes, for example, a cathode, is hollow and provided with at least one additional chamber located in the cavity of the electrode and the openings associated with it, characterized in that, in order to reduce switching losses, dielectric elements with a metal film deposited on them and in electrical contact with the wall are located on the chamber walls. 2. The apparatus according to claim 1, characterized in that the wall of the additional chamber is made in the form of alternating metal and dielectric rings with a metal film applied on their inner surface. 8 Oe (Pu & .f /four (iez.2 to Phi. ФКЬА I rj - / 4 five