NLC - The Next Linear Collider Project Oct 01 MAC James T Volk October 2001 MAC meeting Magnet Systems for the NLC James T Volk October 26, 2001

NLC - The Next Linear Collider Project Permanent Magnet Team J DiMarco, A Drozhdin, D Finley, V Kashikhin, N Solyak V Tsvetkov, J Volk Fermilab J Alonso, Jing-Young Jung, (K Robinson). R Schleuter LBNL Cherrill Spencer, Carl Rago SLAC Oct 01 MAC James T Volk

NLC - The Next Linear Collider Project Magnet Measurement Stretched Wire at Fermilab –X and Y stages Stretched wire at SLAC –X stage only Rotating Coil at SLAC –Two 50 turn coils able to buck out quad signal and get harmonics Tested systems with permanent magnet at constant temperature Oct 01 MAC James T Volk

NLC - The Next Linear Collider Project Stability of Center Measurements Fermilab 0.5  m Oct 01 MAC James T Volk

NLC - The Next Linear Collider Project 18 hours Oct 01 MAC James T Volk Stability of Rotating Coil SLAC

NLC - The Next Linear Collider Project Measurement Upgrades Fermilab could upgrade stretched wire stages for 120 k$ This would improve center measurements to better than 0.5 micron SLAC is upgrading to both X&Y stages with 0.5 micron accuracy. Oct 01 MAC James T Volk

NLC - The Next Linear Collider Project Permanent Magnet Types Wedge Magnet Corner Tuner Oct 01 MAC James T Volk Pole Pole magnet Tuning rod Wedge magnet Tuning Rod Pole magnet Pole

NLC - The Next Linear Collider Project Corner Tuner Y Center Vs. YGdl Oct 01 MAC James T Volk

NLC - The Next Linear Collider Project Wedge Data Oct 01 MAC James T Volk

NLC - The Next Linear Collider Project Permanent Magnet Types Sliding Shunt Rotating Quad Magnets Pole Sliding Shunt Fixed Rotating Oct 01 MAC James T Volk

NLC - The Next Linear Collider Project Sliding Shunt Data Oct 01 MAC James T Volk

NLC - The Next Linear Collider Project Counter Rotating Quad Oct 01 MAC James T Volk Intergal Gradient

NLC - The Next Linear Collider Project Electrical Corrector Coils By adding electrical corrector coils to any of these magnets center stability can be held to under one micron 1 amp can correct center shift by 20 micrometers Advantage is small power supply and cables No LCW

NLC - The Next Linear Collider Project Prototype Electromagnetic NLC Linac Quadrupole, Under Test Synflex Water Hoses DC Power LeadModified Motor Quick Disconnect Recessed Core Belt C1006 Solid Steel Modular Core, mm long Potted Coil, 21 Turns Thermocouple Thermal Switch 1/4” Round,Seamless Cu Tubing, Monolithic Coil Lead

NLC - The Next Linear Collider Project Results Oct 01 MAC James T Volk

NLC - The Next Linear Collider Project Center Shift Studies For the Wedge magnet PANDIRA was used to model the center shift One of the four rods was move from the balanced position along and across the field in steps of inches A change in the field near the center of the quad of 0.7 Gauss equals a 1 micrometer shift in the center Shift of the rod along the field has the biggest effect

NLC - The Next Linear Collider Project Shifting a Tuning Rod Oct 01 MAC James T Volk Along the Field Across the Field Three other rods remain fixed

NLC - The Next Linear Collider Project Center shift due to tuner rod wobble 1 micron center shift Oct 01 MAC James T Volk

NLC - The Next Linear Collider Project Emitance Growth A Drozhdin and N Solyak at Fermi have been modeling emmitance growth Section of LINAC from 10 to 20 GeV 32 quads all of same strength Start by assuming perfect quad no higher harmonics or skew moments Counter rotate single quad Then counter rotate pair (Focussing and Defocusing) quad Will add random skew quadrupole moment of  1 x Oct 01 MAC James T Volk

NLC - The Next Linear Collider Project Horizontal size for quad with no correction Oct 01 MAC James T Volk

NLC - The Next Linear Collider Project Horizontal size growth with correction Oct 01 MAC James T Volk

NLC - The Next Linear Collider Project Vertical size no correction Oct 01 MAC James T Volk

NLC - The Next Linear Collider Project Vertical size with correction Oct 01 MAC James T Volk

NLC - The Next Linear Collider Project Phase Space Plots Permanent magnet Electro magnet No Correction Corrected Oct 01 MAC James T Volk

NLC - The Next Linear Collider Project Beam Size with and without correction Oct 01 MAC James T Volk

NLC - The Next Linear Collider Project Beam growth By rotating a focussing and defocusing quad in opposite directions at the same time the beam growth remains small. Oct 01 MAC James T Volk

NLC - The Next Linear Collider Project SUMMARY of LBL/SLAC DESIGN WORK on DR MAGNETS I. Damping Ring Transport Line Dipole : 2 cm gap, B(gap)= 14.43KG, L=0.6m Both Ferrite and NdFeB (“Neo”) bricks with iron poles and core were tried.. End effect and effect of temperature compensating material were both accounted for in the 2-D PANDIRA models. Resulting models: Ferrite magnet (86”) is much taller than Neo magnet (16.26”). Relaxing field strength by 10 % and increasing effective length by 10 % => magnet height smaller: Ferrite magnet: 28 % height reduction, 26 % PM volume reduction Neo magnet: 10 % height reduction, 4 % PM volume reduction Neo magnet: compact, small dimensions. If radiation were not a potential problem, Neo magnet would be preferred. Gradient Dipole for Main Damping Rings: 4cm gap at center, B(gap)=12KG Has to be an electromagnet. Tight field variation requirements. Grad=660.5 G/cm By shimming pole tip, the field variation along x direction meets the requirement. But not yet found the pole tip shape to meet the tolerance in y direction Oct 01 MAC James T Volk

NLC - The Next Linear Collider Project III. Main Damping Ring quadrupoles modeled as permanent magnets Ferrite and Neo bricks with iron poles and core and rotating rod tuners have been tried. End effect and effect of temperature compensating material were both accounted for in the 2-D PANDIRA models. Outer iron core is circular: Ferrite quad (R=16.4”) is larger than Neo quad (R=6.1”). Tuning rod is used to create +/- 10 % variation in integrated strength. Torque for turning the tuning rods is very high in Ferrite quad. To estimate loss of B(pole tip) thro’ end effect: 3-D TOSCA model been made. From TOSCA calcs: adding steel end plate near magnet does not reduce the end effect. Same DR quads been modeled in POISSON as electromagnets The magnet radius: 10” for 2 cm pole tip magnet and 9.8” for 3 cm pole tip magnet. Temperature rise in the coil: 13.6 o C for 2 cm pole tip and 13.7 o C for 3 cm pole tip SUMMARY of LBL/SLAC DESIGN WORK on DR MAGNETS Oct 01 MAC James T Volk

NLC - The Next Linear Collider Project DR Quads Magnet Comparison Oct 01 MAC James T Volk

NLC - The Next Linear Collider Project Radiation Damage Investigations started about 1980 by several groups Many different particles n, p,  Both Sm Cobalt and ND Iron were tested All experiments used free bricks Wide variety of results everything from no change to reversal of the field direction. Roughly Sm Cobalt ok up to 10 9 rads ND Iron 10 7 rads Higher the coercivity the better Table next slide give a summary Oct 01 MAC James T Volk

NLC - The Next Linear Collider Project Radiation Damage Luna et al. NIM 1989 Oct 01 MAC James T Volk

NLC - The Next Linear Collider Project Radiation Damage No real consistent data Heating a local area can cause domain to flip Internal demagnetizing fields can speed this up  M/M goes as Volume of grain/ Volume of sample Need to know grain size and manufacturing process Higher Coercivity the better Learn from Undulator experience Need to test real magnet with real load line Under real exposure conditions Oct 01 MAC James T Volk

NLC - The Next Linear Collider Project Time Decay Data Fermilab has 4+ years experience with Ferrite No degradation seen in 8 GeV transferline –750 meter long –45 dipoles, 65 gradient, 9 quadrupoles Log(time) decay well measured from RGF005-1 Expect that Sm Cobalt and Nd Iron will have similar decay Need to determine decay constants for both materials Oct 01 MAC James T Volk

NLC - The Next Linear Collider Project RGF005-1 Data Oct 01 MAC James T Volk

NLC - The Next Linear Collider Project Fermilab Recycler Ring 5th largest storage ring 8 GeV fixed energy antiproton storage All ferrite 60,000 bricks ( 25.4 x x mm) 400 gradient magnet 100 quadrupoles Magnets built in 1997 and 98 Oct 01 MAC James T Volk

NLC - The Next Linear Collider Project Recycler Tune Numbers Difference Measured Design (MAD) VERT.HORIZ. Magnets are stable after 3 years Oct 01 MAC James T Volk

NLC - The Next Linear Collider Project Summary In 2 years we have produced 4 styles of permanent magnet quadrupoles Both SLAC and Fermi have measurement systems good enough for testing and plans to improve them The counter rotating quads meet the requirements Two other (wedge and sliding shunt) can meet requirements with some more effort Emmittance growth in counter rotating quads is no problem if pairs of quads are rotated simultaneously Oct 01 MAC James T Volk

NLC - The Next Linear Collider Project Summary Possible application of PM in Damping rings Radiation damage needs more testing but we believe it can be resolved Stability and aging issues need to be tested Good indications from the FNAL Recycler that this is not a problem There is a good working relationship between the labs We continue to make steady progress on these issues Able to make realistic cost estimates Oct 01 MAC James T Volk