ABOUT THE CALCULATION OF THE NIS MATRIX'S MICRO COOLER FOR TARGETS WITH FROZEN NUCLEAR POLARIZATION OF HYDROGEN AND DEUTERIUM IN PARTICLE ACCELERATORS

Abstract

The paper deals with alternative cooling technologies for cryogenic targets with frozen polarization of hydrogen and deuterium nuclei. These targets are used on particle accelerators in experiments on the matter properties, and the results allow improving the fuel cryogenic targets in the implementation of inertial thermonuclear fusion. An important direction here is generation of spherical deuterium-tritium cryogenic targets. The creation of such cryogenic targets and optimization of their design requires large number of scientific experiments on particle accelerators. In accordance with conditions of the physical experiment two types of targets are used: a passive target (only for generation of secondary particles) and an active target (with built-in detector of secondary particles). An example of the active target may be a cryogenic ionization chamber where the extracted beam is used to study the temperature dependence of muonic catalysis of nuclear fusion in deuterium gas, hydrogen-deuterium and mixtures of deuteriumhydrogen. In order to cool cryogenic targets down to temperatures of 4.2–40 K helium refrigerators are used. However, a number of physical experiments especially for particles with large aperture angles require the usage of targets with frozen nuclear polarization. At the same time, the working temperature of the target is reduced to 100–300 mK. These temperatures are reachable in a continuous mode only in dilution refrigerators 3He- 4He. The discovery of the temperature reduction effect in the structures of the normal metal-insulator-superconductor (NIS) by tunneling of electrons through the junction (electron cooling) have led to active study of these devices in labs across the world not only as the active thermometer to measure the temperature in the region of < 300 mK but also as independent generators of cooling power. The main prospect of this direction is the creation of cooling devices on the basis of NIS matrix. In this paper we propose to use these devices with dilution refrigerators or separately in particle accelerators. It will minimize the size of the installation, reduce financial costs and enhance reliability during experiments. An example of a scheme of the accelerator with unit for the target cooling is provided. The paper in accordance with previously published results proposes the method for evaluative calculation of the number of NIS elements for cooler of targets with frozen nuclear polarization of hydrogen and deuterium.