SUPERCONDUCTING UNCLOSED SHIELDS IN HIGH ENERGY PHYSICS

This paper presents the experimental and theoretical results of studying the unclosed shields made from LTS (low temperature superconductor) and HTS (high temperature superconductor) materials to obtain a homogeneous magnetic field in solenoids. There is a comparison of LTS and HTS shields, the construction peculiarities are described. HTS shield was proposed to obtain the required magnetic field homogeneity (about 10 ) in the 6 meters length solenoid of the electron cooling section which will be installed in the heavy ion collider of the NICA project (JINR, Russia). INTRODUCTION The main requirement at the development of the electron cooling system for charged-particle beams of the NICA collider is to form a highly homogeneous magnetic field [1,2]. At the same time the electron cooling system solenoid will be multisectional with a magnetic field up to 0.2 T. Generation of a highly homogeneous magnetic field using unclosed superconducting shields is the most promising direction to solve this problem. It is known that low-temperature superconductors can be used for these purposes [3,4,5]. Still, the need of cooling to the liquid helium temperature (4.2 K) forms a major disadvantage of the shield and raises exploitation costs. For this reason the idea of an HTS shield, which works under 77K, is even more attractive. This paper presents the comparison between conventional LTS shields and HTS shields requiring a fundamentally different winding technology, their construction peculiarities are described as well. It also contains data on characteristic homogeneity of magnetic fields which appear in HTS shield in the gap between two magnetic dipoles.