SU154952A1 - - Google Patents

Description

For photochemical processes, some optical devices often require point sources of light, which have a high stability of position, size and shape of sharply contoured light, uniform spot and uniform distribution of energy intensity in a wide solid angle with a large output of the most actinic ultraviolet radiation. Such sources are required, for example, when fixing the phosphor on the screen in the production of colored electro-radiation tubes, for the tanning of photosensitive varnish applied to the surface of metals, then treated in undescended (non-illuminated) places by chemical etching, etc.

The main disadvantage of the applied light sources (incandescent lamps, arc lamps with a zirconium cathode, dzgovy argon-tungsten lamps with a ball, a tungsten cathode, which are solid temperature emitters), is low brightness and very low output of ultraviolet radiation. Using for this purpose the brightest known constant sources of light — ultrahigh pressure lamps with an unsharply circumscribed channel of ionized plasma — is irrational because of the need in this case of using optical systems consisting of diaphragms and a projection lens (extremely expensive wide-angle quartz optics) low utilization of radiation.

In order to obtain a sharply defined light beam, it is proposed, in accordance with the invention, to perform a gas-discharge light source in the form of a plasma torch operating in a pulse discharge mode concentrated entirely in the cavity of the chamber.

No. 154952

In constructive terms, the proposed gas-discharge device is not fundamentally different from the above-mentioned plasma torch, which is a gas-discharge chamber with openings in the electrodes, one of which serves for the continuous supply of inert gas to the chamber, and the other for the exit of gas and radiation.

The increased brightness of the light source made on the basis of such a plasmatron, the dimensional stability and the position of the created nm light of the spot and the longer service life of such a source provide significant operational advantages compared to the known light sources. So, in particular, when using it for light tanning, the screens of colored cathode-ray tubes considerably shorten the process of chipping and reduce the quality of the screens.

FIG. 1 shows schematically the construction of the proposed light source in section; in fig. 2 is one of the possible variants of its switching scheme.

FIG. 1 the following designations are accepted: / and 2 — electrodes, 3 — cylindrical heat-resistant insulator, 4 — opening for exit of radiation, 5 — opening for blowing inert gas through chamber 6 formed by electrodes / and 2 and insulator 3. Inert gas, supplied to chamber 6, fills the volume bounded by electrodes / and 2 and insulator 5 and goes to hole 4 in electrode 2. Between electrodes 7 and 2 in chamber 6, a back arc fed by a rectifier 7 is ignited (Fig. 2). The high-power impulse discharge is accomplished by connecting the battery 8 for the duration of the pulse to the switching device 9 to the electrodes of the light source. At the moment the current passes through the light source, the plasma discharge fills the internal volume of the source. At high current pulses, the plasma temperature reaches significant values and produces intense ultraviolet radiation emitted through an opening in electrode 2. In the proposed source, there is no glass bottle between the discharge channel and the object of illumination that delays a significant part of the ultraviolet radiation that affects the life of the source zi with loss of transparency in the process. The advantage of the proposed source is also full stability of the light of the shell (the radiation leaves the strictly delineated contour of the hole in the electrode 2, filling the solid angle w). Since the intensity of the radiation emitted in this direction depends on the depth of the plasma layer in the same direction, the nature of the angular distribution of the radiation depends on the configuration of the internal volume of the chamber 6 and the electrodes / and 2.

Subject invention

A gas discharge light source with a sharply outlined light spot, characterized in that it is made in the form of a plasma torch (a discharge chamber with holes in the electrodes, one of which serves to continuously supply an inert gas to the chamber and radiation), operating in the mode of the imical series, concentrated entirely in the cavity of the chamber.