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NLC January Video conference. Status of Permanent Quadrupoles James T Volk January 18, 2001. NLC Quad Specifications. Corner tuner Rods rotate to adjust field. Rotating tuning rods. Permanent magnets. Pole. Wedge Quad Rods rotate to adjust field. Rotating magnets. Wedge Magnets. Pole.

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Nlc january video conference
NLC January Video conference

Status of Permanent Quadrupoles

James T Volk

January 18, 2001

Nlc january video conference

Corner tunerRods rotate to adjust field

Rotating tuning rods

Permanent magnets


Nlc january video conference

Wedge QuadRods rotate to adjust field

Rotating magnets

Wedge Magnets


Nlc january video conference

SSW and Wedge Quad

Wire stages

Nlc january video conference

Gradient ((measured-average)/average)*10000

FWHM 3 units

Nlc january video conference

Center StabilityDifference between 5 successive measurements

FWHM 2 microns

Nlc january video conference

Calculated vs.Measured Field

  • PANDIRA predicts 0.62 Tesla at 0.005 m for 0.202 m

  • This is 25.05 Tesla

  • SSW measures 21.02 Tesla

  • 16% lower than predicted

  • Br and Hci in calculation needs to be adjusted

Nlc january video conference


  • Close to desired field 16 % low

  • Have 20% tunable range

  • Need to measure Center stability during adjustment

  • The FNAL test stand is capable of these measurements

  • New wedge tuner design in drafting magnet material on order

  • Increase the amount of magnet material by 15% increased predicted field by 25%

Status of permanent wedge magnet measurements at slac jan 2001 pg 1 2
Status of permanent “wedge” magnet measurements at SLAC, Jan 2001,pg 1/2

  • Tuner rods much harder to rotate than expected

    • Chain drive mechanism was modified but still one rod rotated by 6 - 8 degrees more than other 3, so resorted to no chains, rotate each rod by hand and clamp in place with special plate. If we have the rod starting positions correct, then we have the rotated the 4 tuners through the same angle to 0.37 degrees – corresponds to  1m

    • Concern- does rotating one at a time introduce some magnetic hysteresis effects?

  • Only measuring X co-ord with a stretched wire system

    • not the highest resolution linear stages

    • measuring set-up is not thermally stablilized

    • thermal noise is significant (signals are very small)

    • precision of each measurement is 3-4 microns

  • Nevertheless we’ve measured the X center

    • at various tuner rod angles, corresponding to different G.dl

Status of permanent wedge magnet measurements at slac jan 2001 pg 2 2
Status of permanent “wedge” magnet measurements at SLAC, Jan 2001,pg 2/2

  • X magnetic center observed to shift by up to 37m when strength is changed by rotating tuner rods. The larger the rotation the larger the x, 114  20% strength change 37um

  • Several things could be causing these shifts, so not a final measurement, e.g. whole magnet moves as exert much force to rotate rods; stretched wire set-up maybe temp sensitive; rod starting angle wrong.

  • Improvements being made to improve precision:

    • highest res linear stages about to be refurbished by Newport Corp

    • thermal noise being reduced; thermal stability to be improved

    • modify fitting routine

  • From electromagnet measurements we know rotating coil’s precision in x/y is 0.02-0.2 m and is very stable so rotating coil’s length being extended so it can measure the permanent magnet prototypes

  • Second wedge magnet being assembled with less stiff tuner rods

Nlc january video conference

Sliding Shunt Jan 2001

Nlc january video conference

Shunt Quad Test Jan 2001

  • Gradient 101.7 Tesla\meter

  • Maximum field 32.96 Tesla

  • Minimum Field 28.50 Tesla

  • 13.5% change

  • Center Shift ~ 15 microns

  • From Max field to Min field

  • New design in works improve sliding bearings

Nlc january video conference

Rotational quad Jan 2001

Permanent magnets

Rotating quad
Rotating Quad Jan 2001

  • Parts are in the shop

  • Expect to have a magnet by March

Nlc january video conference

Issues to test Jan 2001

  • Center Stability

  • Strength

  • Repeatability in Tuning

  • Speed of Gradient Change

  • Radiation Hardness

Conclusions Jan 2001

  • There are three prototype permanent magnet quads

  • Two more on their way

  • Two test stands SLAC and FNAL capable of doing measurements

  • Both SLAC and Fermilab agree to better than 1 part in 10,000 on strength

  • Will start rigorous test of stability

  • Will chose “best” model this year