  The WKB-approximation for the Bogoliubov-equations of the quasi-particle
excitations in Bose-gases with condensate is worked out in the case of
spherically symmetric trap potentials on the basis of the resulting
quantization rule. The excitation spectrum is calculated numerically and also
analytically in certain limiting cases. It is found that the energy levels of a
Bohr-Sommerfeld type quantization may be considerably shifted when the
classical turning point gets close to the surface of the condensate.

Condensed Matter