2 m heat pipe-cryogenic targets for COSY-TOF experiment

A liquid hydrogen/deuterium target is used in COSY external experiments. For the TOF and WASA applications at COSY, a 2.0 m long, 7 mm diameter heat pipe (HP) has been developed and tested under filling conditions of 9.45 l at 228 mbar with the four gases H2, D2, N2 and CH4. The cooling down times are 107, 200, 54 and 38 mins, respectively, from 300 K until working conditions have been achieved. The target liquid is produced at a cooled condenser and guided through a central tube assisted by gravitation into the target cell. The characteristics at steady-state operating conditions were measured for H2, N2 and CH4 as the working fluids. The effect of the operating temperature and the heat loads on the effective thermal conductivity and the liquid mass in the heat pipe was investigated.