FORMATION AND SURVIVAL OF H- AND C- IONS TRANSITING ULTRATHIN CARBON FOILS AT KEV ENERGIES

The fraction of negatively charged projectiles existing in a bulk foil and their neutralization at a foil's exit surface are characterized u sing exit charge-state distribution data for 1-30-keV/amu H and C that transit 1.1-mu g cm(-2) carbon foils. The equilibrium fraction of neg ative ions in the bulk foil is derived and is observed to decrease exp onentially with increasing projectile velocity.