Characterization of CD₂ targets for a ³He Polarimeter

In light of the rapid advancements in the field of nuclear fusion and thedevelopment of new reactor concepts, the topics of target design and fusion fuel arebecoming increasingly important. To this end, the Jülich Research Center (FZJ)has been conducting research for some time on the concept of “polarized fusion”,which is the optimization of fusion processes through the use of polarized fuels.Start-ups such as Artemis Tagetra GmbH are developing experimental targets forthis purpose, e.g. for ³He polarimeters. The goal of this work was to evaluate thequality of a series of deuterated polyethylene films. In addition, a method forproducing hydrogen deuteride (HD) is presented, which is intended to be used as asubstitute for deuterium tritide (DT) in corresponding polarization experiments.Rutherford backscattering spectroscopy was used to examine the quality andthickness of the films. Furthermore, the deuterium concentration in the solidtargets was determined by comparing the detector signals. Both investigationswere conducted using a deuteron beam with an energy of 5 to 9 MeV at thetandem accelerator at the University of Cologne.The HD, on the other hand, was produced at the IKP-2 at the FZJ using ahydrogen generator and a mixture of H₂O and D₂O. The concentrations of all themolecules produced were measured using a quadrupole mass spectrometer.The results showed that the thickness of the different CD₂ targets range from26.6 ± 0.8 μm to 70.2 ± 1.5 μm, in contrast to the previously expected range of20 μm to 80 μm. Furthermore, tritium ejectiles from the fusion reactions weredetected, confirming the target’s functionality. The deuterium concentrations inthe targets were determined to be approximately 50%, with the exception ofTarget B, whose concentration was already known to be approximately 100%. Ananomaly was observed in Target D, which exhibited a relative deuteriumconcentration of 67.8 ± 2.3%, even though semi-deuterated powder was used in itsfabrication.As expected, a concentration of just under 50% was achieved during theproduction of the HD gas, while H₂ and D₂ each reached approximately 25%. Therequired D₂O concentration for maximizing HD production was determined to bein the range between 84.8% and 87.3%. This provides a method for producing HDin sufficient quantities for further purification and use in spin-polarizationexperiments.