Hi Paul, I completed the 'bipolar' measurements on the QE-072 Quadrupole you requested in your memo of Jan.4, 2006.[1] As usual, the results can be found on the web at http://www-group.slac.stanford.edu/met/MagMeas/MAGDATA/LCLS/quad/QE-072/ as indicated below. ------------------------------------------------------------------- The Integrated Strength (Int(Gdl)) values for the various currents can be found in that web site in the files strdat.ru etc. where refers to a set of measurements as follows: Item in Memo Description -------- --------------- ----------------------------------------- 2 Warm-up (>20 min at 100A) 3 Standardize(3x (ramp to 200, then 0))then 18,19 4 0-200A in 20A steps, 200-0A in 20A steps, 21 6 0 to -20A to -0 in 2A steps 'REVERSED CURRENT' 22 - One measurement at 0A, after powercycling PS 23 - " " " " -------- ------------ ----------------------------------------------- For the reverse polarity measurement, I had first switched the power cables at the power supply; which lead to a power surge due to unregulated PS; so I then repeated items 2,3,4 (and took run 19 then). Then, after run 19, I switched the cables at the magnet, and that worked. But it cannot be excluded, that the turning off the PS before switching cables led to a current surge (as I had learned from the degaussing business). Runs 18 and 19 have 0.02452 T and 0.02422 T as last measurements at ~0 A current (-2mA, +1 mA); Run 21, after power turn-off and on, starts with 0.01002 at ~ -1mA and ends with 0.00203 T at +1mA (If the starting value at 0 A had been the same, or close, I'd think there was no problem). So I powercycled once more, and took another measurement at 0A, r22 where it changes to 0.00031 T (at +1mA) (r22). Repeating this again, gives 0.00041 T (at +1mA) 9r23) If the crossing over 0A is a concern, perhaps another measurement would be to measure, as above, from 200 to 20 A, and then switch to a bipolar (+-20A) power supply which I have in the rack, and measure with that one from +20 to -20 in 2A steps. If you want that, I could do it Tuesday morning. [1]http://www-group.slac.stanford.edu/met/MagMeas/MAGDATA/LCLS/quad/QE-072/QE_meas2.doc Cheers, >>>Achim ------------------------------------------------------------------------- | Dr. Achim W. Weidemann E-mail: achim@SLAC.Stanford.edu | | ---------------------------------- Phone: 650-926-3391 | | Stanford Linear Accelerator Center Lab: 650-926-3756 | | Mail Stop 67 http:/www.slac.stanford.edu/~achim| | 2575 Sand Hill Road, Menlo Park, CA 94025 | -------------------------------------------------------------------------