Monday, October 6, 2008

SQUID

It consists of a ring of superconducting material with two side arms Aand B. P and Q are the Josephson junctions (insulating layers) of
different thickness. Let p and q represent the phase differencebetween the input current and output current while passing through theinsulator junctions P and Q respectively. In the absence of magneticfield, these two phases are equal. i.e. p = q = 0.When a magnetic field is applied, the phase difference between thereunited currents is directly proportional to the magnetic flux passing through the ring. It can be shown that total current comingout of the ring, I = 2I0 sin0 cos(e/hc)This expression indicates that the output current varies with theapplied magnetic flux and shows oscillations.SOUID is used as a very sensitive magnetometer which can measure veryweak magnetic fields of the order of 10-13 Tesla.

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