Magnetic Trapping and Cooling of Atomic Hydrogen.

O.J. Luiten, H. G. C. Werij, M. W. Reynolds +3 more

Luiten, O.J., Werij, H.G.C., Reynolds, M.W. +3 more

Tom W. Hijmans, O.J. Luiten, Irwan D. Setija +1 more

We describe the prospects for optical cooling of magnetically trapped atomic hydrogen. We analyze the performance of an optical system currently under development in our laboratory and present calculations for the optical cooling rate. We conclude that by using optical techniques hydrogen can be cooled to below 10 mK while the density is simultaneously boosted to approximately 1014 cm−3. The same system can be used for thermometry down to temperatures well into the microkelvin regime.

В. Ф. Ежов, E. K. Izrailov, G. B. Krygin +2 more

A new method for cooling atomic hydrogen down to 100 µK or below is suggested. The method exploits the unique properties of atomic hydrogen, which are the following: atomic hydrogen does not condense at temperatures as low as 20 µK and cannot be heated by IR radiation in the absence of atom-wall collisions. Therefore, the most efficient and well-known gas cooling technique can be employed, namely, the adiabatic expansion of the volume occupied by the gas (this approach is used in a gas-expansion machine). It is suggested to adiabatically expand the volume of a magnetic trap containing atomic hydrogen.

Jook T. M. Walraven, Raymond Van Roijen, Tom W. Hijmans

Makoto Yamashita, Masato Koashi, T. Mukai +2 more

We study the evaporative cooling of magnetically trapped atomic hydrogen on the basis of the kinetic theory of a Bose gas. The dynamics of trapped atoms is described by the coupled differential equations, considering both the evaporation and dipolar spin relaxation processes. The numerical time-evolution calculations quantitatively agree with the recent experiment of Bose-Einstein condensation with atomic hydrogen. It is demonstrated that the balance between evaporative cooling and heating due to dipolar relaxation limits the number of condensates to $9\ifmmode\times\else\texttimes\fi{}{10}^{8}$ and the corresponding condensate fraction to a small value of 4% as observed experimentally.