A large octupole magnetic trap for research with atomic hydrogen

J. Ahokas , A. Semakin , J. Järvinen , O. Hanski , A. Laptiyenko , V. Dvornichenko , K. Salonen , Z. Burkley , P. Crivelli , A. Golovizin , V. Nesvizhevsky (1) , F. Nez (2) , P. Yzombard (2) , E. Widmann , S. Vasiliev

1 ILL - Institut Laue-Langevin
2 LKB [Collège de France] - Laboratoire Kastler Brossel

We describe the design and performance of a large magnetic trap for storage and cooling of atomic hydrogen (H). The trap operates in the vacuum space of a dilution refrigerator at a temperature of 1.5 K. Aiming at a large volume of the trap, we implemented the octupole configuration of linear currents (Ioffe bars) for the radial confinement, combined with two axial pinch coils and a 3 T solenoid for the cryogenic H dissociator. The octupole magnet consists of eight race-track segments, which are compressed toward each other with magnetic forces. This provides a mechanically stable and robust construction with a possibility of replacement or repair of each segment. A maximum trap depth of 0.54 K (0.8 T) was reached, corresponding to an effective volume of 0.5 l for hydrogen gas at 50 mK. This is an order of magnitude larger than ever used for trapping atoms.

Domaines: Physique Générale [physics.gen-ph]; Instrumentations et Détecteurs [physics.ins-det]

J. Ahokas, A. Semakin, J. Järvinen, O. Hanski, A. Laptiyenko, et al.. A large octupole magnetic trap for research with atomic hydrogen. Rev.Sci.Instrum., 2022, 93 (2), pp.023201. ⟨10.1063/5.0070037⟩. ⟨hal-03335411⟩