1 Overview of Magnetic Measurements at Fermilab Magnet Test Facility Presented by J. DiMarco 26 September 2005 R. Carcagno, C. Ginsburg, H. Glass, D. Harding, M. Lamm, J. Nogiec, P. Schlabach, C. Sylvester, M. Tartaglia, J. Tompkins, G. Velev

20 September 2005IMMW-142 Not part of this talk LHC IR Quad measurements Alignment – Single Stretched Wire system Harmonics – tangential rotating coil TeVatron injection studies Tangential rotating coil, high speed data acquisition, (CERN) hall probe array Wide aperture quads for main injector Morgan coil harmonics, off-axis multipoles …our main activities in recent times

20 September 2005IMMW-143 Other activities at MTF… Unusual magnets/measurements VLHC In-situ field angle measurements of TeVatron ring (Kaiser coil) Curved magnets (Booster, EDWA) Pulsed magnets (ORBUMP) High frequency B-H measurements of ferrite bricks Magnet testing Future magnets Solenoid measurements Booster corrector measurements

20 September 2005IMMW-144 VLHC – “Transmission-line” Magnet Super-ferric dipole/gradient magnet design with single superconducting cable carrying ~100kA creating field for two counter-circulating beams Magnet would be 65 m long – tested prototype that was 1.5m Probe inserted from side – diameter 15mm, L=0.69m Probe body made of Vespel® polyimide –serves as bearing for rotation within support. Also is dimensionally stable – wound with tangential and bucking windings.

20 September 2005IMMW-145 VLHC Probe TAN has 30 turn Litz wire, bucking windings each have 3. TAN opening angle is 15 degrees. Probe mechanically registers to laminations for positioning in gradient field – need 0.05mm for 5 units strength accuracy Belt drive and encoder external to magnet MT-19 papers G. V. Velev, et al., “Field Quality Measurements of a 2-Tesla Transmission Line Magnet”, V. S. Kashikhin et al., “Test Results of a 2 Tesla Superconducting Transmission Line Magnet obtained with 102 Sensors Array of Hall Station”

20 September 2005IMMW-146 VLHC Testing

20 September 2005IMMW-147 VLHC Probe Data For this probe configuration we estimated measurement accuracy of 0.1 units through harmonic order 10 achievable at fields greater than 0.3 T (with 6m full-length probe). Field harmonics (in units at 10 mm) Harmonic orderInj. (0.1 T, 3.2kA)Collision (1.966 T, 87.5kA) b n inj a n inj b n col a n col n/an/a n/an/a n/an/a n/an/a

20 September 2005IMMW-148 Field angle within TeVatron The problem: Tevatron trying to improve luminosity – question of effect of errors in magnet rolls, both on tunnel supports and internal. Large rolls (2-3 mrad) in ‘broken anchor candidates’ (magnets in which internal supports appear to have degraded) observed during measurements of field angle. How many such magnets in ring? Do all behave this way? During Tev magnet fabrication, magnets had ‘yoke coil’ which served to set coarse alignment of coil to external yoke. Go back inside ring and try to make yoke coil measurements to investigate magnet rolls. Also try to tie in to historical record to see how much things have changed Portable system (PC/Labview, National Instruments A/D PCI card, power supply, WF generator) to take into tunnel. coil winding B ‘perfect alignment’  0 signal

20 September 2005IMMW-149 Broken Anchor Tests

20 September 2005IMMW-1410 Field Angle Within TeVatron Technique was straightforward – AC powering of magnet through voltage taps, sampling flux, current simultaneously, FFT decomposition. Resolution ~0.1 mrad. Entire ring measured once ‘cold’. Some portions re-measured ‘warm’. Data were difficult to sort through – things that could go wrong did (broken connectors, polarity issues, powering issues). Had to try to understand warm/cold changes – temperature at which yoke coil measurements were made, polarity issues, historical record (‘Kaiser’ vs. ‘Wilson’ style coils, errors in ‘traveler’, correspondence to ‘lift’ data, survey…) don’t care obviously OK obviously wrong angle (mrad) - tunnel angle (mrad) - legacy

20 September 2005IMMW-1411 TeV align conclusions After fixing all “known” polarity problems 33 magnets fail 2 mrad cut 11 remain after further review 5 mrad largest difference Not much evidence for large field misalignments based on Kaiser coil measurements no 2 nd population, only a tail ~1% of magnets |  angle| 2-5 mrad magnets identified as suspicious from lift data show only slightly larger |  angle| than others  Angle (mrad)  tunnel-legacy 2 mrad

20 September 2005IMMW-1412 Curved magnets Two programs addressed in similar way DC measurements of Booster magnets (combined function (gradient, 6p) magnets with 27mm sagitta over 3m) - including scan across aperture. EDWA magnets: (43mm sagitta over 3m) Use (straight) tangential probe + hardware supports to follow curvature and keep probe center on tangent of arc. Also measured strength with stretched wire

20 September 2005IMMW-1413 Coordinate system R Beam Axis R-h h R´ x = d x X position of coil in coordinate frame of Beam Axis is given by s(z): Coil is tangent to beam axis at its center z Can correct for geometry effects – acts as feed-down correction – turns out pretty small (0.5% of harmonics value) True for stretched wire measurements of strength as well.

20 September 2005IMMW-1414 Curved magnets – DC Booster

20 September 2005IMMW-1415 Curved magnets – DC Booster 1m long, BNL-built ‘mole’ (SSC vintage) – 25mm diameter. Internal piezo- electric drive, encoder.

20 September 2005IMMW-1416 Curved magnets – EDWA 25cm long ceramic coil, 1in. diameter tangential coil. Plate fabricated to mount along edge of pole face and provide track for probe carriage. Carriage rolls to different positions keeping probe tangent to arc. Flexible coupling so external drive can be applied at all positions.

20 September 2005IMMW-1417 New OrBump magnets H- beam from the Linac is injected into the Fermilab Booster using a DC septum magnet and four pulsed magnets that cause a local orbit-bump (hence the name Orbump). The role of the DC Septum magnet is to bend the incoming H- beam parallel to the circulating beam. The first two Orbump magnets combine the two beams, after which they pass through a stripping foil. The last two Orbump magnets restore the circulating orbit to its normal position. Circulating Beam Injected Beam H- Stripping Orb1Orb2 Orb3 Orb4 Foil The plan is to replace the Orbump magnets with new ones having improved cooling for increased pulse operations. Magnets run with repetition rate of 10kHz, but pulse from 0 to full field (15kA) in few  s

20 September 2005IMMW-1418 B-H Brick testing for OrBump High flux density Ni-Zn CMD10 ferrite material – needed to measure its high frequency characteristics (Bs at high freq) PXI DAQ Oven Power Supplies Cap. Banks and IGBT switches DAQ GUI B-H TEST STAND Brick Frame for production testing Brick Size: 2” x 3.125” x 13.25”

20 September 2005IMMW-1419 B-H testing hardware IGBT control: NI PXI-6602 Counter/Timer Module Faster DAQ card: NI PXI 5122 High Speed Digitizer 2 Channels Up to 100 MS/s 14-bit

20 September 2005IMMW-1420 B-H data Hysteresis Curves for 10 kHz Bipolar and 10 kHz Unipolar measurements

20 September 2005IMMW-1421 OrBump magnet measurements

20 September 2005IMMW-1422 OrBump magnet measurements Stationary “Morgan coil” probe (dedicated winding for each harmonic order) External indexing head rotating probe to each of 32 angles. At each angle, high-speed data acquisition (same as used for brick testing) measuring flux and current during capacitor discharge cycles. Current pulses only to about 300A with capacitor bank

20 September 2005IMMW-1423 OrBump data Dipole and quad ‘ok’, sextupole has large noise (still can see large change wrt shim)

20 September 2005IMMW-1424 OrBump data Raw sextupole ‘snapshot’ is complex (analysis still in progress …)

20 September 2005IMMW-1425 Other near future projects… Solenoid magnets for Proton Driver (3D Hall probe measurements of strength/axis, SSW measurements of axis) 15Hz AC measurements of corrector magnets for Booster (development of dedicated AC system (perhaps with simultaneous sampling of all angles))