Secondary electron emission from Au, Mo, and CuBe by high-charge-number laser-produced metal ions

The secondary electron emission coefficient γ for gas-covered Au, Mo, and CuBe surfaces was determined in the energy range 0.3–22.4 keV for incident ions as follows: H+, C+ 1 → 6, Al+ 1 → 10, Cu+ 1 → 9, Ta+ 1 → 3. Energetic highly charged ions produced by a Nd laser beam focused on solid targets in vacuum were allowed to impinge on a metal target. The electrons ejected were collected and the current measured. Potential ejection is dominant over kinetic ejection in this energy range. The Parilis-Kishinevskii theory of secondary electron emission, based primarily on ionization of metal target atoms with subsequent recombination through an internal Auger process, and the present experimental results for low charge numbers (n ≤ 3e) and high mass (A ≥ 27) are only in qualitative agreement. For high charge numbers (n ≥ 4e) or low mass (A ≤ 12), there is no agreement.