Effect of damping resistance on voltage versus flux relation of a dc SQUID with large inductance and critical current

Journal Article · Thu Feb 28 23:00:00 EST 1985 · J. Appl. Phys.; (United States)

DOI:https://doi.org/10.1063/1.334439· OSTI ID:6015519

Enpuku, K; Sueoka, K; Yoshida, K; Irie, F

The effect of a damping resistance on the relation between a voltage V and a magnetic flux Phi of a dc SQUID is studied theoretically for the case with a large SQUID parameter ..beta../sub L/ = 2LI/sub 0//Phi/sub 0/ , where L is a loop inductance, I/sub 0/ is a critical current, and Phi/sub 0/ is the flux quantum. An approximate analytical expression for the V-Phi relation is obtained by replacing the Josephson junctions with ac current generators. It is shown that the V-Phi relation becomes almost independent of the value of ..beta../sub L/ in the case of large damping. As a result, the conversion efficiency dV/dPhi is not degraded even for large ..beta../sub L/ , as is not the case with a conventional SQUID without the damping resistance. This result indicates the possibility to use the SQUID with large ..beta../sub L/ for the improvement of the coupling between the SQUID and the input coil without the degradation of the conversion efficiency. Effect of the capacitance is also studied. It is shown that the effect of the capacitance becomes remarkable for the case of ..beta../sub c/> or approx. =0.4 , where ..beta../sub c/ is the McCumber parameter; for example, at ..beta../sub c/ = 1 the conversion efficiency becomes about 30% of that at ..beta../sub c/ = 0 . These analytical results are in good agreement with numerical-simulation ones.

• Research Organization: Department of Electronics, Kyushu University 36, Fukuoka 812, Japan
• OSTI ID: 6015519
• Journal Information: J. Appl. Phys.; (United States), Journal Name: J. Appl. Phys.; (United States) Vol. 57:5; ISSN JAPIA
• Country of Publication: United States
• Language: English

Related Subjects

420201* -- Engineering-- Cryogenic Equipment & Devices
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ANALYTICAL SOLUTION
COUPLING
DAMPING
EFFICIENCY
ELECTRIC CONDUCTIVITY
ELECTRIC POTENTIAL
ELECTRICAL PROPERTIES
ELECTRONIC EQUIPMENT
EQUIPMENT
FLUXMETERS
JOSEPHSON JUNCTIONS
JUNCTIONS
MAGNETIC FLUX
MEASURING INSTRUMENTS
MICROWAVE EQUIPMENT
PHYSICAL PROPERTIES
SQUID DEVICES
SUPERCONDUCTING DEVICES
SUPERCONDUCTING JUNCTIONS