15Jan04 AC Booster Meas Status – J. DiMarco 1

Ac booster magnet measurements with an indexed rotating coil

Alternate technique to SSWIntegrate signal at fixed angle from t1 to t2

Index by fixed angle, repeatFourier analyze results

Extract bn(t2)-bn(t1), an(t2)-an(t1)t1, t2 correspond to I1, I2

If bn(t1), an(t1)=0, this gives the usual results, instead get the change in multipole coefficients up the ramp

15Jan04 AC Booster Meas Status – J. DiMarco 2

Ac booster magnet measurements with an indexed rotating coil

more detailsRecord analog bucked tan winding or summed (series connected) Morgan coil windings (analog bucking for free)

Use DVMs with external triggering and script to record winding voltage and magnet current

Synchronize first external trigger to cycle current and record “n” triggers up the rampcycle current synchronization imperative

15Jan04 AC Booster Meas Status – J. DiMarco 3

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15Jan04 AC Booster Meas Status – J. DiMarco 10

Booster AC measurements with SW

SW gradient fixtures mounted on SSW stages, translated across aperture with

AC measurements at each position.

Simultaneously sample current, gradient, and bucked gradient changes due to

ramping (use 3 similar devices 3458’s or PDI’s (internal triggering with external

sync from power supply)).

Normalize the measure flux changes in bucked (i.e. moving–fixed) combination

with the (fixed) gradient flux change (obtain change in gradient normalized by

reference gradient).

Assemble normalized ∆flux vs x-position “snap-shot” at each current (might also

normalize to current change) – fit to extract field coefficients during each snap-

shot.

Stationary fixtures could be mounted near center so that gradient would be

bucked as well as dipole. In principle bucking should be very good.

15Jan04 AC Booster Meas Status – J. DiMarco 11

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15Jan04 AC Booster Meas Status – J. DiMarco 14

Flux in reference gradient winding (DataAcq)

Flux in moving winding

Bucked flux (moving – ref) (DataAcq)

Bucked flux normalized to ref. grad (calculated)

Harmonics

mDWLRIbIB )()( 1

0

...2)()()( 22

01

0 +− mm xDWLRIbBDWL

RIbIB

...2)()( 22

0 +mxDWLRIbIB

D distance between loops,

W is width of loops

...2)()(

1

2 +xIbRIb

15Jan04 AC Booster Meas Status – J. DiMarco 15

SW gradient probe

2 pairs of sw-grad fixtures: one mounted on stages, the other fixed near magnet center

SW gradient fixtures mounted on stages are translated across aperture: AC measurements at each position.

Simultaneously sample current, gradient, and bucked gradient changes due to ramping (use 3 similar devices 3458’s or PDI’s (internal triggering with external sync from power supply)).

Gauge blocks 2, 5mm distance (D), rods are 3mm width (W). Minimize D,W to reduce harmonics error termsMaximize D,W to reduce errors terms from differences in W’s

Sapphire rods have diameters same to <1µm. Ceramic gauge blocks also with sub-micron dimensional accuracy. Still may need to calibrate againstDC measurement…

15Jan04 AC Booster Meas Status – J. DiMarco 16

Status

Indexed rotating coil completed and assembled in D10 at E4R.

Data acquisition has started.

SW-grad fixtures completed (including mounting on stages).

Power supply runs in voltage regulation mode for AC meas.

Current is obtained from Holec transductor; consecutive cycles

may not have same timing of synch trigger. Trigger module with

adjustable threshold and delay being used to try to match

current start cycle to cycle.

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200.

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