| 摘要 |
With this method, which uses a superconducting analog-digital (AD) converter, the signals are coupled via a flux transformer (1) into a SQUID SQ1 (2) arranged as a null detector, which maintains the magnetic flux in the SQUID SQ1 (2) constant by means of a negative feedback circuit (3). For this purpose, a negative feedback flux PHI 1 is coupled into the SQUID SQ1 (2) via a mutual inductance (M1), by a current I1 which is produced by a superconducting transformer (4) from a current I2 . This current in turn, after the critical current IC2 is reached, generates quantum leaps in a SQUID SQ2 (5) via a mutual inductance (M2). These are counted in a bidirectional counter (6) after being passed through an amplifier (7). The ratio of I1 to I2 is set by the superconducting transformer (4) and the mutual inductances (M1, M2) in such a manner that a variation delta I1, which corresponds for example to the current resolution of the SQUID SQ1 (2), is produced by a current variation DELTA I2, which in turn generates a flux quantum PHI o in the SQUID SQ2 (5). I1 is here much smaller than I2 and the ratio of I1 to I2 is set at a fixed level and remains constant in time. <IMAGE> |
