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Energy Removal from a Superconducting Solenoid

IP.com Disclosure Number: IPCOM000095530D
Original Publication Date: 1964-Feb-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 24K

Publishing Venue

IBM

Related People

Dowley, MW: AUTHOR

Abstract

An oscillatory circuit absorbs the energy from a large solenoid 11 disposed in a superconducting environment in a cryostat 12. Such occurs in the event solenoid 11 undergoes a transition to the resistive state. The oscillatory circuit has a capacitor 13 and a diode 14. These are, during normal superconducting operation of solenoid 11, bypassed by contacts 16a of a high-speed relay 16. Relay 16 is operated when detecting device 17, including a current transformer in the solenoid circuit, detects a decrease in the current to the solenoid 11. Relay 16 is fast acting (700 microseconds) and has high power handling capacity (18 kva) to insert capacitor 13 and diode 14 in circuit with solenoid 11.

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Energy Removal from a Superconducting Solenoid

An oscillatory circuit absorbs the energy from a large solenoid 11 disposed in a superconducting environment in a cryostat 12. Such occurs in the event solenoid 11 undergoes a transition to the resistive state. The oscillatory circuit has a capacitor 13 and a diode 14. These are, during normal superconducting operation of solenoid 11, bypassed by contacts 16a of a high-speed relay 16. Relay 16 is operated when detecting device 17, including a current transformer in the solenoid circuit, detects a decrease in the current to the solenoid 11. Relay 16 is fast acting (700 microseconds) and has high power handling capacity (18 kva) to insert capacitor 13 and diode 14 in circuit with solenoid 11.

The energy (1/2 LI/2/) in solenoid 11 oscillates into capacitor 13 in a time , where L is the inductance of solenoid 11 and C is the capacitance of capacitor
13. At the end of this time, the current in L is zero, and the energy in capacitor 13 is 1J2 CV , which is approximately equal to 1/2 LI/2/, provided the time 2~LC is much less than the time for the natural decay for the current. Diode 14 prevents further oscillation of the current so that the energy is essentially absorbed in capacitor 13 to prevent damage to the winding of solenoid 11 or loss of liquid helium in the cryostat.

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