| 摘要 |
A voltage divider for high voltage vapor cooled leads for superconducting magnet systems. Power connections to large superconducting magnets often carry potentials in the range of 5 to 10 kilovolts. These leads penetrate the cryogenic cooling vessel surrounding the superconducting magnets. In order to avoid excessive heat leak paths that would be caused by conventional electrical insulation, the leads exiting the vessel pass through tubes cooled by boiling helium. Helium gas will break down at any distance in the potential exceeds about 2 kilovolts. Such a breakdown path exists since the vapor cooled lead is at very high potential and the helium source is at ground potential. The voltage divider provides a controlled gradient of the voltage so that no portion of the helium gas sees excessive potentials. The gas at high potential is directed through a series of conductive screens in a tube insulated from each other and connected by a resistive voltage divider. A grounded conductive sleeve surrounds the tube to limit the electric field to the space between the gradient screens. Thus, the system can operate at a high overall potential, with the potential between each pair of succeeding screens kept below the gas breakdown potential.
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