October 27, 2020 - Magnetic field mapping and characterization meeting
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Hardware:
* Use new SCE 20A/75V PS for measurements. This is the same type of PS that will be used for oparations * DC power will install new SCE PS in magnet test ~10/29/20 * Software will provide EPICS controls and hysteresis ramp loops * Label and wire coil leads to ensure positive current produces positive B field per convention * PS limits for Hysteresis curve: 20A at 1A/s, but measurements done at +/- 19.9A
Field mapping:
* Hall probe step size 2 mm * On axis values z=[-25,25] cm * Background: measure z=[-30,30] cm. First run the probe in this range w/o the magnet. Then place the magnet for measurements and do a full map at 0 A after hysteresis at 0A . Finally subtract from each value. * Off axis values: limited by 15 mm diameter nickel endplates hole and 6 mm square hall probe. Measure z=[-25,25] cm once at 18A and as far as these limitations allow in +X,-X,+Y,-Y and record X,Y positions for comparing with models. * Measure at +/-19.9A, +/- 15A, +/- 10A, +/-5A and 0A.
CED field map
* EPICS hysteresis cycle ending at +19.9 A. Measure B(I) at center of magnet at 19.9A, then decrement by 0.9A to 19A, then 1 A increments until -19 A reached. Final reading -19.9A. All without further hysteresis loops. Finally, set to zero A and EPICS hysteresis cycle.
Other measurements:
* V vs I resistance and inductance.