Transcript
Page 1: Booster corrector measurement QA Phil Schlabach 1 May 2007 Proton Source Magnet Meeting

booster corrector measurement QA

Phil Schlabach1 May 2007

Proton Source Magnet Meeting

Page 2: Booster corrector measurement QA Phil Schlabach 1 May 2007 Proton Source Magnet Meeting

booster corrector measurement QA

• online QA– protect against bad measurements which are

not discovered until later– protect against bad magnets

• let’s assume for the moment there is an “offline” QA

– provide feedback during production measurements to

• “measurer”• “analyst”

Page 3: Booster corrector measurement QA Phil Schlabach 1 May 2007 Proton Source Magnet Meeting

measurement plan

• AC measurements with fixed coil array– excite each element individually with the

specified profile• other elements are connected to the PS, current

set to 0– excite all elements

Page 4: Booster corrector measurement QA Phil Schlabach 1 May 2007 Proton Source Magnet Meeting

booster corrector measurement QA

1. strength2. harmonics3. coupling• quality of the measurement

– 1, 2• quality of the magnet

– 1, 3

Page 5: Booster corrector measurement QA Phil Schlabach 1 May 2007 Proton Source Magnet Meeting

strength measurement

tolerances

compute a strength “error function”

=current_mon*TF_nom-measured_field

•apply tolerance band

Page 6: Booster corrector measurement QA Phil Schlabach 1 May 2007 Proton Source Magnet Meeting

harmonics

tolerances

1

1

1

1

max

max

)(

)(

0@

nN

mn refnx

nN

mn refny

RxAxB

RxBxB

y

monitor the field shape

•@y=0, By(x) probes Bn, Bx(x), An

•monitor min/max By(x), Bx(x), |x|<1.5”

•apply tolerance band

Page 7: Booster corrector measurement QA Phil Schlabach 1 May 2007 Proton Source Magnet Meeting

other

• centering, angles– see slides

• single vs. multi-element excitation– also slides

• should we monitor coil voltages, currents (or something)– coupling, regulation issues?

Page 8: Booster corrector measurement QA Phil Schlabach 1 May 2007 Proton Source Magnet Meeting

centering, angles

• so far, we have been looking at harmonics re-analyzed based the normal quadrupole center– this is difficult to do online as it links

information between “separate” measurements

– there are similar issues with the way we’ve done angles for certain cases

• this is better done offline

Page 9: Booster corrector measurement QA Phil Schlabach 1 May 2007 Proton Source Magnet Meeting

centering, angles (2)

• proposal: for online analysis leading to QA evaluation, analyze each measurement independently– centering, angle– monitor

• offsets• angles relative to expected angles• both should be small

• deviations will reveal both setup and/or coupling issues

Page 10: Booster corrector measurement QA Phil Schlabach 1 May 2007 Proton Source Magnet Meeting

centering, angles (3)• e.g.

– probe offset or rotated• will need some experience to know what to expect• mm for offset, few deg. for rotation?

– coupling• excitation of normal element skew

– shows up in the angle• excitation of (e.g.) sextupole dipole

– shows up in the centering offsets

• monitor in the same manner as strength error, field shape– plot x0, y0, , apply tolerances

• for any of this to be useful we will have to figure out how to deal with the field of the earth

Page 11: Booster corrector measurement QA Phil Schlabach 1 May 2007 Proton Source Magnet Meeting

single vs. multi-element excitation

• remarks so far deal with single element excitations

• multi-element excitations– one would have to choose an element for the

online analysis (e.g. analyze as “normal quad” by fiat)

– then try to devise a monitoring scheme– that’s as far as I’ve thought it out

Page 12: Booster corrector measurement QA Phil Schlabach 1 May 2007 Proton Source Magnet Meeting

list of variables

strength error strength-TFnom*I

field defect max/min of By(x), Bx(x) inteval of 1.5”

centering offsets field center for each element (except dipole)

angular offset field angle - nominal

Page 13: Booster corrector measurement QA Phil Schlabach 1 May 2007 Proton Source Magnet Meeting

post testing

• reanalysis, 2nd pass at magnet quality, and posting to repository

• trend analysis