The (110) crystal surface of Si was bombarded by slow highly charged ions (Pbq+，Arq+) and the secondary particle emission was measured for different incident angles. Comparing the relationship between the sputtering yield and the incident angle, channeling effect was suggested. The channeling effect in interaction of highly charged ions with Si causes the sputtering yield to depend strongly on kinetic energy. Highly charged ions can enhance sputtering yield at smaller incident angles. At incident angles from 40° to 50°, the higher the potential energy of highly charged ion, the greater the sputtering yield.

Energy loss of protons with energy 100 keV penetrating the partially ionized hydrogen plasma target was measured. The plasma target was created by electric discharge in the hydrogen gas, the state of the plasma target was diagnosed by using the laser interferometry method: the free electron density is up to 1016 cm-3, temperature is about 1-2 eV, and the plasma target may exist at the microsecond level. It is found that the energy loss of protons is closely related to the free electron density, and the energy loss data enable us to infer the value of the Coulomb logarithm (10.8) for the stopping power of the free electrons. This agrees well with the theoretical prediction which is 4.3 times higher than that given by the Bethe formula for neutral hydrogen, which is a little bigger than Hoffmann's result but much smaller than Jacoby's result. Comparing our result with Hoffmann's, the energy we used is only 100 keV, much lower than 1.4 MeV/u, and the low-energy regime we applied could be the cause of the increase in the enhancement factor. However, in the comparison between our result and the Jacoby's, the effective charge for protons is almost constant, unlike the Kr+ impact in wihch the enhanced ion charge state induces the giant enhancement factor. Compared to the gas target, the energy loss enhancement factor in plasma target is 2.9.