Simulation of discharging dust grains by laser excitation of neutral atoms

We have simulated a method for changing the charge on dust grains in plasmas by exciting a small fraction of the neutral atoms into highly excited states. The atoms can be preferentially excited near a dust grain and quickly ionized by the hot electrons in the plasma. Because the neutral atom has low speed when it is excited, the resulting positive ion strikes the dust with nearly unit efficiency and the electron is repelled into the plasma. The rate for this process can be controlled by varying the state excited and/or the density of excited atoms. Thus, this mechanism gives a controllable method for varying the dust charge without substantially changing the other plasma properties. © 2010 American Institute of Physics. doi:10.1063/1.3500290