SU1521259A1 - Method of producing target for nuclear physics research - Google Patents

Abstract

This invention relates to accelerator technology. The purpose of the invention is to improve the operational characteristics of the target. The essence of the invention is to create a uniform lithium nitride layer on the substrate, which has good adhesion to the substrate, the thickness of which can be varied and controlled. This is provided by thermal vacuum spraying of a layer of metallic lithium onto the substrate of the required thickness and subsequent nitriding of this layer in a nitrogen atmosphere at a temperature of 110-140 ° C and a nitrogen leak rate of 1-100 cm / min. Targets made in this way are homogeneous, have large vacuum resistance and resistance to total irradiation ..

Description

The invention relates to accelerator technology, in particular, to targets for studying nuclear reactions on beams of accelerated ions and can be used to register neutrons using ionization chambers or semiconductor detectors.

The aim of the invention is to improve the performance of the target.

The invention is conveniently illustrated in three examples of the implementation of this technical solution.

In the first case, the whole process was carried out in a vacuum volume. The sputtering of metallic lithium was produced also; from a tantalum crucible spoon, heated by passing 150 A electric current through it. The substrate of the target is fixed to an annular

the mandrel of nickel was placed in an on: heated sample table at a distance of 30 mm from the crucible evaporating spoon, into which was placed a portion of metallic lithium. A polyp-xylenylene film with a thickness of 20 μg / cm was used as the substrate. After reaching a vacuum of 5-10 mm Hg. The heating of the sample table to 130 ° C was turned on. At this temperature. the substrate was heated for 1 h (for disinfection). After that, at the same substrate temperature (130 C), lithium metal was sprayed and a thin layer was formed on the substrate. Then, through the installation leak valve, nitrogen was fed under its cap at a flow rate of 50 cm / min to a pressure of 100 mm Hg, which occurred after a two-hour tie. Speed required

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Nitrogen leakage is ensured by establishing the experimentally found clearance value of the valve valve. After that, the heating of the sample table was stopped, and when it reached room temperature, the finished target was removed from under the hood and placed in a desiccator.

In the second case, a metal lithium was also sprayed, the same substrate was used. After heating the sample table, the substrate temperature was lowered to 11 for 1 h (by lowering the heating of the table) and the lithium metal was decomposed and nitrided at this temperature for 1 h to warm the substrate for degassing. The rate of nitrogen adsorption was set at f. Pressure 100 mm Hg. Art. came after 20 hours

In the third case, the same operations were performed in the same sequence. After degassing the substrate at a temperature of -130 ° C for I h, the temperature was increased, at which temperature lithium was sprayed and nitration was carried out on the substrate layer. The nitrogen inlet rate was 100 Daylenium 100 mmHg. Art. came in 15 minutes

Targets were fabricated in a wide range of thicknesses — I, from 20 μg / cm to 2 mg / cm.

The target nitite layer created in this way has a high uniformity; 4JO is determined by the homogeneity of the lithium metal layer, -. due to the fact that this layer is applied by thermo-vacuum spraying. In this case, the thickness of the lithium nitride layer is easily controlled by varying the thickness of the lithium metal layer to very small thicknesses. A delighted layer of lithium nitride (1 bond with the substrate due to molecular si

use of a sticky layer, which causes greater vacuum resistance and resistance to ion irradiation. The requirements for heat resistance and substrate thickness are minimal due to the low temperature of lithium metal evaporation in vacuum, which causes low thermal loads on the substrate during thermal vacuum sputtering of a lithium metal layer. It was established experimentally that at a temperature above 140 ° C, the destruction of the target layer in the process of nitriding occurs, apparently because of the mechanical effects that occur. strains due to the rapid course of the nitriding process, and at temperatures lower than 110 ° C, an insufficiently ductile microscopic layer forms, which is also easily destroyed. Experiments also showed that with a nitrogen leakage rate of more than 100 cm / min, nitriding proceeds very quickly, and an insufficient plastic layer is formed, easily destroyed (the target falls off). With a nitrogen leak rate of less than 1 cm / min, the time to manufacture the target is greatly increased: at a nitrogen leak rate of 10 cm / min, the nitriding time is 2 h, but at a leak rate less than 1 cm / min, it increases to 24 hours. economically impractical.

F o r M u l

the invention

The method of making a target for nuclear physics research, consisting in applying a layer of metallic lithium to the substrate by thermal vacuum deposition, is enough to produce, after filing, a target with the aim of improving the performance characteristics of the target. nitrogen. , deposition of the sprayed layer in the atmosphere; nitrogen at a temperature of P0-140 C and the rate of flow of nitrogen 1-100 cm / min

Claims (1)

Claim A method of manufacturing a target for nuclear physics research, which consists in applying a layer of metallic lithium to a substrate by thermal vacuum spraying, in that, in order to improve the performance of the target, the sprayed layer is nitrided in the atmosphere after spraying 'of nitrogen at a temperature of 110-140 ° C and • the rate of leakage of nitrogen 1-100 cm ⁵ / min.