MAX IV magnets
Transcript of MAX IV magnets
MAX IV magnetsMartin Johansson, 29 Jan. 2016
Outline
● MAX IV overview
● the magnets
● how they were made
● some example results
● Located in Lund, Sweden.
● Facility dedicated to synchrotron radiation research. National Laboratory, hosted by Lund University, with ca 180 employees.
● Old MAX-lab located in Lund University campus (MAX I-III) was shut down Dec. 2015 and is currently being decommissioned.
The MAX IV Laboratory
Full energy linac, in operation since 2014.
1.5 GeV storage ring, installation in progress.
3 GeV storage ring, commissioning in progress since Aug. 2015.
Jan. 9th, 2015 photo: Perry Nordeng
Also, an identical copy ofthe 1.5 GeV ring has beenbuilt in Krakow, Poland. Thisfacility, named Solaris, is Poland’s new national synchrotron radiation lab.
klystron gallery
linac~300 mmax 3.4 GeV
The MAX IV accelerators
1.5 GeV ring96 mDBA lattice
3 GeV ring528 m7BA lattice
• Building construction began 2011
• Linac installation fall 2013 – spring 2014
• 3 GeV ring installation fall 2014 –spring 2015
• 1.5 GeV ring installation fall 2015 - …
11/12 achromats installed, awatingshutdown period for TR1 installation
● Through fall 2015:
3 GeV ring commissioning progress
beam in TR3
Aug 11
first turn
Aug 25
stored beam
0.1 mA
Sep 15
stacking
4 mA
Oct 08
first light
Nov 290 mA
Dec 18
Timeline copied from Pedro Fernandes Tavares’ Dec 2015 staff meeting presentation.
● Then, restart after Christmas/new year-shutdown,– 100 mA by end of 1st week
– Commissioning operation continues to cw5
– Shutdown for installation of 2 ID’s, cw6-10
– Then, resume commissioning…
● MAX IV overview
● the magnets
● how they were made
● some example results
the MAX IV 3 GeV ring magnets
U1 3d cad view with yokebottom and top halves transparent.
QFm1SFmQFm2
x ySD1
SD2 DIP
Key aspects:
● Relatively small magnet aperture of Ø25 mm.
●magnet block concept → integrated unit containing several consecutive magnet elements.
Magnet blocks in supplier’sassembly hall 2014.
Linac and 1.5 GeV ring magnets
● 1.5 GeV ring magnets = conceptually identical to 3 GeV
● Linac and transfer lines = various conventional magnet types
1.5 GeV magnet block at supplier’s fieldmapping bench 2014.
Linac quad and correctors
Bunch compressordipole
TR3 dipole
3 GeV ring lattice
● Each achromat consists of five unit cells and two matching cells.
● 20 achromats x 7 cells = 140 cells total
● achromat length = 26.4 m
● ring circumference = 26.4 x 20 = 528 m
● 0.33 nmrad bare lattice emittance.
● 1320 magnet elements
3 GeV ring achromat
3d cad assembly:
● Each lattice cell is realized as one mechanical unit containing all magnet elements.
M1
U1
U2
U3
U4
U5
M2
● Each unit consists of a bottom and a top yoke half, machined out of one solid iron block, 2.3-3.4 m long.
a MAX IV magnet block:
M1U1
U2U3
U4U5M2
• a U5 bottom half →
• ↓ an assembled U5
Oct. 10th, 2012 photo: Anna Olsson, Scanditronix Magnet AB
Sep. 27th, 2012 photo: Anna Olsson, Scanditronix Magnet AB
Magnet block features
● Dismountable at horizontal midplane.
● all yoke parts = Armco low carbon steel.
● Quad and corr pole tips mounted over the coil ends.
● 6pole and 8pole magnet halfs mounted into guiding slots in yoke block.
● Electrical and water connections located towards the storage ring inside.
M1 bottom and top halves in supplier’s assembly hall 2013.
Magnet block features
● The main structural parts of the magnet blocks are the yoke bottom and yoke top halves.
● Armco low carbon steel
● Dipole profile, and quad + corr. pole roots machined out of the block.
● Cross section size = 350 x 128 mm
● Lengths = 2299 mm (M1, M2), 2418 mm (U1, U2, U4, U5), 3356 mm (U3)
● Weights = ~450 kg (M1, M2), ~490 kg (U1,…), ~620 kg (U3)
U4/U5 yoke bottom half at subsupplier’s 3D CMM, 2012.
• M1/M2 DIPm soft end reduces thermal load to the long straight.
more magnet block detailsM1 with DIPm bottom coil and pole face strip hidden
• Top half aligned to bottom half by 3 guiding blocks on bottom + top outer reference surfaces.
• Field clamps reduce the dipole fringe field distribution sensitivity to coil shape.
field clamp
soft end
guide blocks
guide block
Inside the 3 GeV ring tunnel
2015 photo: Simon C. Leemann
M1 U1 U2 U3U4
U5
concrete support stands
magnet cabling
magnet cooling water hoses
Inside the 3 GeV ring tunnel
2015 photo: Simon C. Leemann
magnet cooling water hoses
vacuum cooling water hoses
bpm cabling
U1U2U3U4
concrete support stands
3 GeV ring magnet block layout
● The 3 GeV ring lattice has two cell types, unit cells and matching cells.
● -MC is mirror image of MC.
● UC1 and UC2 have identical magnet lengths and distances between elements, but different strengths for quads and one sextupole.
● -UC1 and -UC2 are mirror images of UC1 and UC2.
● UC3 is symmetric around its center, with layout identical to other UC.
3 GeV ring magnet block layout
… correspondingly, there are two basic magnet block layouts, shown here in 3d cad, bottom halves view from top,
● U2, U3, U4, U5 and M2 are identical/mirror of U1 and M1.
x y OXX OXY OYYQFend QDend DIPm SDendxM1:
QFm1 QFm2SFm y x SD1 SD2DIPU1:
Lattice magnet element lengths in mm:
● U2, U3, U4, U5 and M2 are identical/mirror of U1 and M1.
100100
3 GeV ring magnet block layout
x y OXX OXY OYYQFend QDend DIPm SDendxM1:
QFm1 QFm2SFm y x SD1 SD2DIPU1:
100 100250 250
100100100150 150
12 slices, total = 1.5°
12 slices, total = 3°
2d simulations made from cross sections exported from the magnet block 3d cad models:
+ SFm, SD, SDend (Ø25 mm), OYY (Ø36 mm), x/y (g = 25 mm).
3 GeV ring magnet elements
DIP: -0.524 T, 8.607 T/m DIPm: -0.524 T, 8.622 T/mg=28 mm at x=0
QF: -40.34 T/mQFm: -37.79 T/mQDend: 25.10 T/mQFend: -36.59 T/mØ25 mm
SFi: -2069 T/m2
Sfo: -1742 T/m2
Ø25 mm
OXY: -65060 T/m3
OXX: 32394 T/m3
Ø25 mm
design procedure
● 2D simulations were performed using FEMM for all magnet elements.
● 3D simulations were performed using Radia for dipoles and quads as standalone magnets, ie no 3D simulations of the full magnet blocks.
● The dipole was evaluated, and represented in the lattice, as consisting of 12 longitudinal slices.
● Lattice and magnet design were iterated against each other.
21/19
Ø25 mm aperture
• Was required from the lattice design, since…
• the pole aperture has a direct influence on lattice compactness,
o by defining minimum distance between elements
o and by defining minimum lengths for quads, 6poles, ...
• The aperture also has an indirect influence on lattice compactness through coil design, in that the required NI is proportional to g for dipoles, r2 for quads, r3 for 6poles, ... making it easer to fit the coil ends longitudinally.
• For the MAX IV 3 GeV ring design, the enabling factor for Ø25 mm magnet aperture is the choice of NEG-coated copper vacuum chambers throughout the achromats.
Ø25 mm aperture
… by defining minimum distance between elements?
• Rule of thumb used for MAX IV: min. distance ≈ one pole gap
• If shorter, fringe fields overlap, destroying field quality.
• We are at this limit in M1 and M2:
• U1-5 are more relaxed, 75 mm between SF and adjacent QF.
100100
x y OXX OXY OYYQFend QDend DIPm SDendxM1:
100 100250 250
25 mm 25 mm
Ø25 mm aperture
… by defining minimum lengths for focusing elements?
• Assuming a fixed max pole tip field, Bpt, max quad gradient = Bpt/pole r
• We have chosen max Bpt ≈ 0.5 T, which keeps the whole pole face in the linear region of the iron B(H) curve. Resulting max G ≈ 40 T/m.
• Our quads are at this strength, so with larger pole radius, they would have needed to be longer.
• Our strongest sextupoles have ca 0.3 T at the pole tip…
• max Bpt ≈ 0.5 T is quite conservative. It allows us to have a mechanically simple quad design with upright standing pole roots, and racetrack coil. There are no tapered coils in any of our magnets.
Ø25 mm aperture
● A negative aspect is that with smaller pole gap, the relative strength of random field errors due to manufacturing tolerances increase, since the tolerances are fixed, constituting a larger fraction of the pole gap.
● A positive side effect of small aperture is that the powerconsumption goes down. MAX IV 3 GeV ring magnets total ~300 kW.
The magnet block concept
Does is have an impact on compactness?
• In principle no.
• Practically, maybe in how close you dare to place adjacentcoils. But that can just as well be handled through appropriatespec. and QA.
MAX IV choice was made for,
• Vibration stability.
• Ease of installation.
• The magnet block being an alignment concept which is totallyoutsourced to industry.
● MAX IV overview
● the magnets
● how they were made
● some example results
Specification and procurement
• Production sourced as build to print-contracts for fully assembled and tested magnet blocks, with MAX-lab providing technical specifications and full sets of manufacturing drawings.
• Suppliers responsible for mechanical tolerances, ±20 µm for the yoke bottom and top blocks (2.3-3.4 m long), and for performing field measurements according to MAX-lab spec.
• MAX-lab responsible for magnetic field properties!
• Contracts signed Sept 2011:• Danfysik A/S, Taastrup, Denmark: M1, M2 and U3 = 60 magnet
block units.
• Scanditronix Magnet AB, Vislanda, Sweden: U1, U2, U4 and U5 = 80 magnet block units.
Specification and procurement
● 3D CMM reports for mechanical tolerances for all 140x2=280 yokebottom/top halves, and for all quad pole tips, 6pole/8pole yokes, etc..
● 3D CMM reports for yoke top halves includes measurement ofalignment target locations.
● Specified field measurements for all 140 magnet blocks,
– Hall probe:• Dipole field map at nom. I
• Dipole field map at nom. I + pole face strips at max I
• Quadrupole single transverse lines at nom. I
– Rotating coil:• Quads/6poles/8poles/corr at I = 0, 100, 0 %
• 6poles/8poles trim coils at max I for each connection mode
– extended with more current levels and repeatability tests for every10th magnet blocks.
Expected challenges
• Meeting the ±20 µm mechanical tolerances.
• Performing Hall mapping with the same level of positioningaccuracy.
• Solving rotating coil meas access while also meeting specifiedaccuracy.
• And doing all this with required production pace!
Outcome
Machining – meeting the tolerances,
• The two magnet suppliers subcontracted machining of the large yoke bottom/top halves to three different CNC machiningcompanies, • Required extra visits to these companies at intervals in the early
stage, and in depth review of 3d CMM tolerance verification.
• But no hands on problem solving in how to perform the machining. Our conclusion: ±20 µm is a tolerance level that canbe met without needing a key person at the accelerator lab togo into the details of how to perform the machining.
• Required continuous monitoring from us to keep pace.
Outcome
Field measurement,
• Both suppliers chose to procureboth new Hall mapping benches, and new rotating coil systems,• Necessitated by meeting the
specified accuracy, and/or keepingtheir previous existing measurement equipment availablefor other customers during the MAX IV production phase.
• Also, rotating coil mechanicallayout necessitated by our magnet block concept.
• Establishing the measurementprocedures according to specrequired both in depth review and hands on problem solving from our side.
Rotating axis
Outcome
• In addition to the expected challenges, the total workload wasalso challenging for the suppliers. Project meetings wererequired at monthly, bi-weekly, or at times even weeklyinterval.
• A positive outcome was that during the project we did not sacrifice any performance requirements!
Production timeline
2011 Sept. Contracts signed
2012 spring start of yoke machining
2012 Sept. 1st yokes approved
2012 fall 1st magnets assembled
2012/2013 fall/winter field measurement systems operational
2013 fall coming into series production phase…
Production statistics from suppliers weekly status reports,
• Yoke machining pace = 1-2 yoke halves/week average
• Field meas pace = 1 Hall and 1 rot. coil /day possible
• Production series completed summer 2014
Series production phase
Danfysik M1, M2 and U3: Scanditronix Magnet U1, U2, U4 and U5:
0
10
20
30
40
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60
yoke machining
assembled
rotating coil
Hall probe
delivered to MAX IV
0
10
20
30
40
50
60
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80
yoke machining
assembled
rotating coil
Hall probe
delivered to MAX IV
● MAX IV overview
● the magnets
● how they were made
● some example results
3 GeV ring magnet field meas. results
U1,2,4,5 quads spread in strengthby rotating coil (160 magnets):
• max-min ≈ 0.7 % total
• or ≈ 0.5-0.6 % amonginner/outer
• Expected from mech. tolerance±25 µm at r = 12.5 mm: ± 0.4 %
0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
mai
n t
erm
, (ab
s(sc
ale
d)-
no
m)/
no
m [
%]
outer QFm
inner QFm
outer QF
inner QF
3 GeV ring magnet field meas. results
U1,2,4,5 SD sextupoles spread in strength by rotating coil (160 magnets):
• max-min ≈ 1.4 % total
• or ≈ 1.2 % among inner/outer
• Expected from mech. tolerance±25 µm at r = 12.5 mm: ± 0.6 %
-0,2
0
0,2
0,4
0,6
0,8
1
1,2
1,4
1,6
mai
n t
erm
, (ab
s(sc
ale
d)-
no
m)/
no
m [
%]
inner SXD
outer SXD
Examples indicate that spread in strengths agree with expected.
3 GeV ring magnet field meas. results
M1,2 OXX/OXY octupoles spreadin strength by rotating coil (80 magnets):
• max-min ≈ 1.2 % total
• No difference in averagestrength between OXX and OXY.
• Expected from mech. tolerance±25 µm at r = 12.5 mm: ± 0.8 %
0
0,2
0,4
0,6
0,8
1
1,2
1,4
mai
n t
erm
, (ab
s(sc
ale
d)-
no
m)/
no
m [
%]
OXX
OXY
3 GeV ring magnet field meas. results
U1,2,4,5 DIP spread in integratedgradient by Hall probe (80 magnets):
• max-min ≈ 0.5 %, similar toquads.
-0,1
0
0,1
0,2
0,3
0,4
0,5
0,6
intB
', (a
bs(
scal
ed
)-n
om
)/n
om
[%
]
DIP pfs=0 U1,2,4,5
Field quality example, rotating coil measured higher order harmonic content for 10 quads:
• Expected from mech. tolerance ±25 µm at r = 12.5 mm: 10-15 1E-4 error terms in 2d simulations of different “worst case” displacements of poles.
3 GeV ring magnet field meas. results
-10,0
-8,0
-6,0
-4,0
-2,0
0,0
2,0
4,0
6,0
3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
@r=
10
mm
, Bn
[1
E-4
]
n
U2-19
U2-18
U1-19
U1-18
U1-17
U5-19
U1-20
U2-20
U5-20
U5-16-8,0
-6,0
-4,0
-2,0
0,0
2,0
4,0
6,0
8,0
3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
@r=
10
mm
, An
[1
E-4
]
n
U2-19
U2-18
U1-19
U1-18
U1-17
U5-19
U1-20
U2-20
U5-20
U5-16
3 GeV ring magnet field meas. results
Rotating coil meas, magneticcenter offsets to rotating axis by harmonic content feed down:
same, subtracting linear fits, shows relative alignment of 4 magnet elements over 675 mm:
-0,1
-0,08
-0,06
-0,04
-0,02
0
0,02
0,04
0,06
0,08
0,1
0 500 1000 1500 2000 2500dx
[mm
]
z [mm]
M1-16
M1-18
M1-19
M1-20
M1-15
M1-17
QDend
OXY
QFendOXX
-0,1
-0,08
-0,06
-0,04
-0,02
0
0,02
0,04
0,06
0,08
0,1
0 500 1000 1500 2000 2500
rela
tive
dx
[mm
]
z [mm]
M1-16
M1-18
M1-19
M1-20
M1-15
M1-17
Qdend OXY QFend OXX
elements
length[mm]
eval. [pcs]
rel. align
min [µm]
max [µm]
RMS [µm]
M1,2 4 675 39/40 dx -10 12 3
dy -27 20 9
U1,2,4,5 3 400 79/80 dx -16 12 4
dy -24 30 6
U3 4 928 20/20 dx -10 13 5
dy -41 29 18
3 GeV ring magnet field meas. results
Relative alignment within magnet blocks, statistics for 39 pcsM1/M2, 79 pcs U1,2,4,5, and 20 pcs U3:
• dy includes rotating shaft sag.
• MAX IV DDR requirement = 25 µm RMS with 2σ cut-off.
• Our conclusion: rotating coil measurements indicate that MAX IV magnet block alignment concept works!
0
5
10
15
20
25
30
-0,04 -0,03 -0,02 -0,01 0,00 0,01 0,02 0,03 0,04
no
of
mag
ne
ts
relative dx [mm]
M1,M2
3 GeV ring commissioning- from the magnet perspective:
lattice correctors
Aug 11 beam in TR3
Aug 25 first turn nominal 0
many turns nominal manually tuned
Sep 15 stored beam 0.1 mA nominal -||-
Oct 8 stacking 4 mA QFE, QDE adj. -||-
meas. bpm-offsets LOCO -> all Q adj, to differentvalues in different achromats.
kicker changed from 3.5 to 1.7 µs
Dec 18 90 mA -||- SOFB
• nominal = current set values calculated from the suppliers field measurements.
• Conclusion, from the magnet perspective, is that alignment and fieldmeasurements accuracy was OK!
Thank you for your attention!
Extra slides …
3 GeV ring magnet block features
● 3d cad view from top of U1 magnet block bottom half with vacuum chamber in place:
● Vacuum chamber bolted to magnet block at bpm and two support brackets.
● Vacuum chamber cooling and signal connections located towards outer side.
3 GeV ring magnet block features
● 3d cad view from outer side of M1 magnet block with vacuum chamber in place, on concrete support stand:
3 GeV ring magnet block features
● U1 magnet block with plastic cover removed; view from inner side, where cooling and electrical connections are located:
● Water cooling circuits are separate for bottom and top halves.
● Electrical connections across the midplane has to be disconnected when dismounting top half – bus bars/external cables for main coils and plug in contacts for corr, trim and thermoswitches.
top half cooling water inlet
bottom half cooling water inlet
top half cooling water outlet
bottom half cooling water outlet
QFm1 terminals QFm2 terminals
SFm terminals
DIP main coil & pfs terminals
shunt boardSD1 terminals SD2 terminals
trim coils and corrector plug-in contacts
Interlock D-sub contacts
… so, one pole gap distance between consecutive elements, doesit work?
• Compare QFend and QDend harmonic content:
• These two elements see different iron surroundings, differencein n=4 could come from this …
• … but this difference is negligible. Ie, our data data indicatesthat in this case one pole gap distance is sufficient.
-10
-8
-6
-4
-2
0
2
3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
@r=
10
mm
, har
mo
nic
co
nte
nt
[1E
-4]
n
QDend production series average
normal
skew
Distance between magnets?
-10
-8
-6
-4
-2
0
2
3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
@r=
10
mm
, har
mo
nic
co
nte
nt
[1E
-4]
n
QFend production series average
normal
skew