VERY PRELIMINARY - SUBJECT TO REVISION The table below summarizes the first degausssing tests on the little green quadrupole labeled OTF. These initial measurements were taken Wednesday evening, and are now being repeated, after better realigning of the coil. At maximal current 10.156 A, the GL was 4164.4 G. Current cycle Current measured GL before measurement (nominal 0) A A Gauss ------------------- ----------------- ----------- Run 1, before any ramp 0 0.18 8.72 ------------------- ----------------- ----------- (Run 8) +10 0.001 168.5 10 0.002 140.1 +5 0.001 101.4 5 0.002 99.2 4 0.002 80.9 2 0.002 39.0 1 0.002 34.6 0.5 -0.037 40.8 0.2 -0.013 29.8 0.1 -0.004 26.0 (Run 9) 0.001 12.0 0.05 -0.001 11.6 0.025 0.002 10.6 ------------------- ----------------- ----------- The first column shows the ramping treatment: e.g. the value 5 indicates a measurement after ramping first to +5 A (nominally) and then to -5A and then to 0. The value +10 there (and +5) indicates ameasurement taken after ramping to +10A (+5A) and then to 0, before the going to -10A (-5A) and back to 0 A for the next measurement. One sees that the scheme of ramping to ever smaller positive and negative currents does reduce the remaining field. Probably a better scheme might be to ramp to +x A, and then to e.g. -0.9x Ampere, and then to zero, to reduce the remnant field in less steps. I'll try that next. Cheers, >>>Achim