Authors: A. Bürgi, M. Oetliker, P. Bochsler, J. Geiss, and M.A. Coplan
Reference: J. Appl. Phys. 68 (1990) 2547-2554.
Abstract:
In order to calibrate a time-of-flight mass spectrometer which is to be
flown in the solar wind we have investigated the charge exchange
properties of low-energy ions in thin carbon foils. We have used
incident ions of He, C, N, O, Ne, and Ar with energies in the range
0.5-2 keV/nucleon to measure charge-state distribution, residual
energy, and angular distribution after transmission through thin (1-6
mu g/cm2) carbon foils. Within such foils an equilibrium between
ionization and recombination of the projectile is rapidly established
and, consequently, the charge state of the emerging particle depends
essentially on its residual velocity. A comparison of the charge
exchange properties of 22 Ne with 20 Ne demonstrates that indeed the
velocity (and not the energy) of the emerging particle determines its
final charge. Comparing properties of different elements one observes
an indication of an electron shell effect. Predictions for the energy
loss of ions within the carbon foils made with the trim code [J. F.
Ziegler, computer code trim-88 (IBM-Research, Yorktown, NY, 1987)] are
in good agreement with the experimental results presented in this
paper. Journal of Applied Physics is copyrighted by The American
Institute of Physics.