Potential Energy Retention
In our calorimetric experiments we determine the absolute fraction of the retained potential energy of the highly charged ions. By using a calorimetric setup the increase of the target temperature is measured during the irradiation with multiple and highly charged ions. The retained energy of Arq+ (q=1 to 11) ions into the surface of Cu and Si is determined at kinetic energies between q*60 eV and q*200 eV. By extrapolation to zero kinetic energy the retained fraction of the potential energy is obtained.
For absolute calorimetric measurements a small resistive heater is used for the calibration of the calorimetric setup. Using the resistive heater a function between the temperature increase and the deposited electrical power of the heater is obtained. Assuming that the electrical power is equivalent to the retained power of the incident ions the retained power of the ions can obtained from the temperature increase.
The obtained retained potential energy of the different charge states of the argon ions is related to the total potential energy. The potential energy retention coefficient results as 0.8±0.2 and decreases weakly with increasing charge state. Complementarily, the fraction of potential energy emitted by the secondary electrons is determined. For multiple charged Arq+ ions it turns out that the energy missing in the bulk is totally emitted by the electrons. For higher charge states and higher masses of the ions (like Kr, Xe) we expect that this amount increase and energy emitted via x-ray become important.
|Fig. 1: Relative amount of potential energy deposited into the surface of Cu, n-Si, and p-Si, respectively.||Fig.2 Relative amount of potential energy emitted via secondary electrons from Cu, Si, and SiO2|