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Optimum Operating Temperatures

IP.com Disclosure Number: IPCOM000097213D
Original Publication Date: 1962-Jul-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 26K

Publishing Venue

IBM

Related People

Lentz, JJ: AUTHOR

Abstract

Cryogenic circuitry is generally designed in the form of loop circuits which have first and second current paths connected between a current source and a current collector. Each current path includes at least one gating element and one control element. The loop circuit is in one state when current is in the first current path and in the second state when current is in the second current path. Each time the loop circuit changes state, a certain amount of power is dissipated in the gating elements as heat. The amount of power (heat) dissipated by a particular gating element is related to the inductance L of the associated loop circuit. It is also related to the frequency at which the loop circuit changes state.

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Optimum Operating Temperatures

Cryogenic circuitry is generally designed in the form of loop circuits which have first and second current paths connected between a current source and a current collector. Each current path includes at least one gating element and one control element. The loop circuit is in one state when current is in the first current path and in the second state when current is in the second current path. Each time the loop circuit changes state, a certain amount of power is dissipated in the gating elements as heat. The amount of power (heat) dissipated by a particular gating element is related to the inductance L of the associated loop circuit. It is also related to the frequency at which the loop circuit changes state.

The amount of current needed in the control element associated with the gating element in order to change the state of the gating element is dependent upon the temperature of the gating element. As the temperature of the gating element decreases, a greater amount of current is needed to change the state of the gate. Each particular superconducting material has a certain critical temperature above which it always remains resistive.

Each of the temperatures now referred to is expressed in a normalized form. The temperatures are expressed as a ratio of a temperature to the critical temperature of the particular material. The initial temperature of a gating element,
i.e., the temperature of the bath in which the circuit is operated...