The negative ion yields φ (H-)and the neutral atom yields φ (H) of 0.6, 0.9, 1.2, 1.6 and1.8 MeV H+ projectiles traversing various carbon foils have been measured. The experimental re-sults showed that neither φ (H-) nor φ (H) varies with the dwell time td at the same energy. φ (H) islarger than φ (H-) by about 3-4 orders of magnitude. The charge exchanging between H+ ionsand carbon foils was analyzed. It can be seen that the charge exchange is the most basic proc-ess.The experience formula of σc/σ/has been gotten.
