  Eigenvalue spectrum has been a long term unsolved problem for plasma
physicists. In this paper, some numerical calculations are conducted about the
minimum eigenvalues of the linearized Rosenbluth collision operator and the
differential part of the whole operator. Similarities of the two operator lead
to further discussions about the differential operator. Completeness and
orthogonality are rigorously proved. Moreover, the continuum of the whole
operator is indicated.
