Compensation of time varying fields in the Tevatron superconducting magnets

While the Tevatron is stored at 150 GeV for injection of protons during a colliding beam cycle, the sextupole fields in the Tevatron dipoles decay in a predictable manner. This decay has been further measured and compared with the behavior predicted by the theory of flux creep in the superconducting filaments of the magnet cable. A correction algorithm has been implemented which automatically adjusts the current output of function generators for the two orthogonal sextupole correction circuits. Results of the implementation are presented. The technique used has reduced the chromaticity drift while at 150 by an order of magnitude. Data taken during regular collider operations show a chromaticity spread at 1 h on the injection porch of the order of six units. These data also suggest an effect due to the fact that the prior ramp history is still present