In Section 1, we describe how the creation of quasiparticles by current flo
w through a normal-insulator-superconductor (NIS) junction degrades the coo
ling performance of the junction. Degradation occurs due to the absorption
of recombination phonons in the normal electrode and due to a reduction in
the cooling power. In Section 2, we describe how vibrations from a pulse tu
be mechanical cooler affect X-ray measurements performed with a superconduc
ting tunnel junction. (C) 2000 Published by Elsevier Science B.V. All right
s reserved.