Ion losses in expanded laser-produced plasma

Losses of charge carried by Ag ions emitted from a laser-produced plasma are measured up to a distance of 187 cm from the target. The plasma was generated by a high power iodine laser delivering the power density up to /spl sim/10/sup 15/ W/cm/sup 2/ on the target surface. Two ion collectors of different construction located coaxially were applied, which made the ion current measurement in the same direction and at two distances from the target simultaneously possible. The variation of the charge, /spl Delta/Q, of ions escaping the plasma at /spl sim/10/spl deg/ to the target normal with the distance, L, from the target was found to be of the form /spl Delta/Q/spl sim/L/sup -2/.