Abstract: Disclosed is a method and apparatus which can detect progress of degradation of a sodium-sulfur cell and predict possibility of final breakdown of the cell in a very near future before such a final breakdown of the cell actually occurs. The method and apparatus for diagnosing the presence or absence of an abnormal state in the sodium-sulfur cell, containing a porous electrical conductive material impregnated with molten sulfur or sodium polysulfide as its positive electrode reactant and containing sodium as its negative electrode reactant, comprises observing the operating voltage of the cell during charging and discharging so as to detect occurrence of a minute ripple in the operating voltage, and, when the amplitude of the ripple and the frequency of occurrence of the ripple increases as a result of repeated cycles of charging and discharging, deciding that degradation of the cell has progressed to an extent that final breakdown of the cell will occur in a very near future.

Abstract: A turbomolecular vacuum pump having stator blades disposed in a multistage fashion within a casing in an axial direction thereof, and rotor blades which are located between respectively adjacent stator blades and are mounted on an outer periphery of a rotor situated centrally of the casing. A motor rotor is fixed to a rotating member which is formed of the rotor having the rotor blades fixed to the outer periphery, and a motor stator opposite to the motor rotor is arranged so as to construct a drive mechanism for the rotating member. The rotating member is supported at a lower portion thereof by a pivot-type plane bearing, and a magnetic bearing is arranged in such a manner so as to oppose a lower end of the rotor and a supporting member for the rotating member.