DIRECT DETERMINATION OF THE TEMPERATURE AND DENSITY OF GASEOUS ATOMIC-HYDROGEN AT LOW-TEMPERATURE BY ATOMIC-BEAM TECHNIQUES

We have measured the translational temperature of atomic hydrogen gas (H) in a cryogenic environment at T ≈ K. An atomic beam is formed; time of flight measurements are consistent with a maxwellian velocity distribution of 8.5 K. The flux of low velocity atoms is increased by ≈ 20 over that of the same source operated at room temperature. The low temperature density is estimated to be 3.4 × 1013 H/cm3. General considerations for transporting and cooling of a gas of H are given. © 1979.