COOLING OF 2-DIMENSIONAL SPIN-POLARIZED ATOMIC-HYDROGEN

Two-dimensional polarized atomic hydrogen(H down arrow) was adsorbed o nto a liquid helium surface which was locally cooled much below the te mperature of the rest of a large sample cell. The steady state conditi on was obtained by introducing a constant H down arrow flux into the s ample cell. We measured a bulk density of H down arrow and the change of heat input due to the introduction of H down arrow flux into the sa mple cell as a function of the cold spot temperature for various sampl e cell temperatures and input flux. The cooling mechanism of two-dimen sional hydrogen was studied and the optimization condition to obtain K osterlitz-Thouless transition was investigated in this system.