1. Fast negative ion thermometer for 3He superfluids
- Author
-
K. K. Nummila, L. Skrbek, J. T. Simola, and J. S. Korhonen
- Subjects
Materials science ,Time constant ,General Physics and Astronomy ,chemistry.chemical_element ,Ion ,Magnetic field ,Superfluidity ,Nuclear magnetic resonance ,chemistry ,Thermometer ,Electric field ,Helium-3 ,General Materials Science ,Atomic physics ,Helium - Abstract
A thermometer based on the temperature dependence of the negative ion mobility in superfluid 3 He is described. The device can be used for monitoring the temperature of an open geometry sample of 3 He in the range 0.4 ≲ T / T c ≤ 1. The ion thermometer is most sensitive immediately below T c , in the Ginzburg-Landau region; above T ≈ 0.95 T c a resolution of 0.1 μK can be achieved. The measuring technique provides an on-line display of the relative mobility, μ ( T )/ μ ( T c ), and the ions probe the temperature of the 3 He sample directly, which leads to a short time constant τ versus T / T c is insensitive to the external magnetic field and the pressure of the sample. Only a low electric field, E ≲ 10 V cm −1 , with essentially no homogeneity requirements is needed. Parasitic heating due to the flow of ions is of the order of 1 pW.
- Published
- 1987