Do ions heat up in the presheath, in the direction perpendicular to the flow? Results for a weakly collisional argon plasma

Summary form only given. Laser-induced fluorescence (LIF) measurements made with a diode laser have measured the transverse metastable ion velocity distribution function profile near a negatively biased plate in a low temperature (T_e < 1 eV), low pressure (p₀ < 1 mTorr) DC multidipole argon discharge plasma. Results indicate that the transverse temperature doubles as the ions transit the presheath. The metastable argon ions in the 3s²3p⁴(3P)3d ⁴F_7/2 state are found to be characterized by a Maxwellian temperature transverse to the direction normal to the plate. For a neutral pressure of 0.3 mTorr, the transverse temperature increases along the presheath from 0.026 eV in the bulk plasma to 0.058 eV at the presheath sheath boundary. This result is compared with the PIC code simulation results of Meige et al, and with the experimental results of Claire et al.