Electron-Ion Recombination at 10 K

This work is focused on recombination processes in low temperature plasma down to 10 K. When reaching this low temperature in atomic gases, Collisional Radiative Recombination (CRR) where extra electron carries off energy, is dominant. A few accomplished CRR experiments do not follow theoretical predictions of very strong negative dependence. We propose to study transition from dissociative and radiative recombination to CRR at cryogenic temperatures. For this study we are constructing electron-ion trap. Electrons will be trapped in combination of electrostatic and magnetic field (magnetic-mirror like). Ions will be trapped in 3D potential minimum in the middle of the trap formed by space charge of trapped electrons. The trapped electrons and ions will be cooled by collisions with helium buffer gas. From the decay of the ion density recombination rate coefficient will be obtained. PIC calculation is used to model trapping and cooling of electron-ion plasma, FEMM program is used to model magnetic field in trap. Trap is currently under construction, first problem, that will be studied with trap (in year 2009) is state selective (ortho/para) recombination of H3, which could not been measured by any other technique yet (low temperature, low pressure).