Ion beam characteristics at the exit of the gas filled quadrupole

The paper presents experimental measurements of ion beam characteristics past the radiofrequency ion guide with collisional dampening. The measured emittance of 1.5 mm·deg at 35 eV ion energy matches theoretical expectations of ion dampening down to the thermal energy of surrounding gas. experimental evidences are presented that space charge is the predominant force factor driving ions along the ion guide. This explains additional heating of ion axial motion and matches the observed width of axial energy distribution around 0.4 eV.