Retention of ion implanted hydrogen, nitrogen and noble gases in lunar regolith simulant

We investigated if lunar regolith simulant JSC-1A can be "loaded" with hydrogen, nitrogen and the noble gases helium and argon in an attempt to simulate solar wind implanted particles (SWIP) by means of ion implantation. For that purpose we exposed specifically pretreated JSC-1A material to an energetic ion beam of 150 keV of these elements until their expected concentrations reached those reported for real lunar soil material (based on Apollo material). The ion implanted regolith simulant samples were then analyzed by thermogravimetric analysis-mass spectrometry (TGA-MS) for their gas release patterns. The samples showed that the noble gases helium and argon produce well traceable gas release patterns, whereas the proof of hydrogen release was not conclusive due to a dominant mass spectrometric signature of water. Likewise, implanted nitrogen could not be found in the mass spectrum indicating that chemical reactions may play a crucial role for the retention of these elements. The results show, that saturation of the chemical reaction sites of lunar regolith simulant has to be reached until release of these elements can be achieved. The results will be presented and discussed with regard to the gas retention, gas release patterns and compared to those reported for Apollo samples.