Superconducting bearing for borehole and survey gravimeters

Apparatus for stabilizing a levitated superconductive body, comprising:

• a. a hollow region of said body defined by an inner superconductive surface of said body, said hollow region extending along a first axis;
• b. means for generating a magnetic field within said hollow region, said magnetic field defining a bearing axis and tending to bring said first axis into coincidence with said bearing axis;
• and
• c. means located within said magnetic field for dissipating energy from changes in said magnetic field resulting from motion of said principal axis toward and away from coincidence with said bearing axis.

Apparatus for measuring force, comprising:

• a. a mass to be levitated, the mass comprising superconductive material;
• b. means for maintaining the mass at a temperature at which the mass is superconductive;
• c. means for generating a first magnetic field to levitate the mass along a vertical axis;
• d. means for detecting vertical position of the mass within the first magnetic field;
• and
• e. a bearing, comprising:
• i. an elongate member of superconductive material affixed to the mass and having a longitudinal axis;
• ii. means for generating a second magnetic field which tends to bring said longitudinal axis into coincidence with said vertical axis;
• iii. means for dissipating energy from changes in the second magnetic field resulting from motion of said longitudinal axis toward and away from coincidence with said vertical axis, wherein said energy dissipating means comprises at least one damping body of lossy conductive material located within said second magnetic field such that motion of said principal axis toward and away from coincidence with said bearing will induce eddy current in said damping body and thereby dampen said motion.

Apparatus for measuring force, comprising:

• a. a body to be levitated, the body comprising superconductive material;
• b. means for maintaining the body at a temperature at which the body is superconductive;
• c. means for generating a first magnetic field to levitate the body along a vertical axis;
• d. means for detecting vertical position of the body within the first magnetic field;
• and
• e. a bearing comprising;
• i. a hollow region of said body defined by an inner superconductive surface of said body, said hollow region extending along a principal axis;
• ii. means for generating a second magnetic field within said hollow region, said second magnetic field defining a bearing axis and tending to bring said principal axis into coincidence with said bearing axis;
• and
• iii. means located within said second magnetic field for dissipating energy from changes in the second magnetic field resulting from motion of said principal axis toward and away from coincidence with said bearing axis.