ler magnets major r&d effort

April 27, 2006 LARP LBL Meeting Henryk Piekarz

SC Magnetsat Fermilab

LER Magnets Major R&D Effort

The new injection scheme shows only the path from SPS to LER to LHC

There are 2 distinct sets of magnets:

1. Arc magnets covering ~ 26 km of accelerator circumference

2. LER to LHC transfer line magnets covering total of ~ 1 km of beam path

The VLHC low field magnet is proposedas the base magnet for the LER arc.

The LER-LHC transfer line magnets areviewed as new initiative in magnet design.



VLHC & LER Magnet Count

FNAL

Fermilab cluster:Injection, Extraction,RF, Two Detectors

Typical Stage 1Surface Facility forCryogenics (1 of 6)

Far ClusterLF -> HF Transfer

and Collimation Ring OrientationArbitrary

Stage 1

Required for Stage 2

VLHC: - 233 km accelerator ring - ~ 3200 main arc dipoles - ~ 466 km continued length of transmission line superconductor

LER: - ~27 km accelerator ring - 1232 main arc dipoles - ~ 54 km continued length of transmission line superconductor



Base Magnet of the LER Accelerator

LER Main Arc Dipole Magnet • Magnet cross-section area: 26 cm (height) x 24 cm (width) Pole gap: 20 mm (?)• 1.6 Tesla field (nominal operation) (1.99 T for VLHC)• 0.6 Tesla (beam injection) (0.2 T for VLHC)• Alternating gradient: 12 m (64 m)• 20 mm magnet pole gap ( 25 mm ??)• Energized by 55 kA (87 kA for VLHC), single turn superconductor line• Coolant – supercritical helium (4.2 K, 3 bar, 60 g/s) • Warm beam pipe vacuum system- ante-chambers required

We propose that LER is based on theVLHC low field, combined function dipole magnet



LER Magnet Location in the LHC Tunnel

It fits easily in the space above the LHC magnet

-Vertical distance between LHC and LER beams: 1350 mm

-The holding brackets and the magnets can be installed without disturbing the LHC operations

-The 4 K, 3 bar LHe can be tapped at convenient locations from the QRL line providing 1700 g/s flow



LER Arc Dipole Magnet in LHC Tunnel

Normal tunnel area Area with cryogenic feed tower



VLHC Magnet and B-field Measuring Instrumentation

Magnet view (tangential coil side) Magnet view (Hall station side)



Magnetic Measurements

Gueorgui Velev, TUA07PO02

Probe: 15.2 mm dia. x 754.1 mm longVespel (polyimide) used to form the probe (winding support) and bearings.

Field Harmonics measured to:order 10 at 1.966 Tesla (collisions),and order 6 at 0.1 Tesla (injection)



Magnetic Measurements

Quadrupole component is as designed; ~ -415 units, both atinjection and full field 1.966 T.

102 element Hall Probe confirmsthe +/- 4% gradient.

Sextupole component very small;~ few units, and no change frominjection to the full field 1.966 T.

The b4 – b10, and the a4 – a10 also << 4 units, or << 0.04%.

LER magnet operates at 1.6 T !!



Principle of the LER-LHC Beam Transfer

After the LER ring filling is complete, the pulsing magnets are turned off as soon as the last proton bunch passed through them.



Principle of LER-LHC beam transfer

Cryogenic support for fast pulsing magnets must sustain long-termoperations at 0.45 TeV, and a 100 second long ramping to 1.5 TeV



LER-LHC Transfer Line Boundaries

- Total length of ½ straight section: 260 m- Available free space between D1 and Q7: 176.5 m - To reproduce the LHC optics the LER-LHC transfer line magnets must reach the LER

level of 1100 mm at the D2 LHC dipole (approximately 65 m from the end-face of D1)- A 336 T-m bending power is required to lift a 1.5 TeV beam by 1100 mm above the

LHC nominal beam level, or on average ~5 T magnets are required for a 65 m beam path

- For comparison, to bypass detectors by ~ 40 m in the straight sections of 260 m the transfer line magnets of ~50 T field would be needed



LER-LHC Transfer Line Option 1No re-arrangementof LHC, D1 magnet.

4 vertical bendspreceded by a horizontal bend toprovide enough separation in thefirst pair of vertical dipole magnets forthe “cc” and “cw” LER beams.

Three sets of fast pulsing magnets

are needed!



LER-LHC Transfer Line Option 2

LHC D1 magnet ismoved a bit (or shortened) to make a space for a (5

m?) LER single bore dipole magnet.

Only one set of fastPulsing magnets isneeded!



An Example of Possible Vertical Bend Magnet Arrangement



LER-LHC Transfer Line Magnets

In order to accomplish the LER-LHC beam transfer the beam line must consists primarily of three type of dipole magnets:

- 2 T range, normal conducting, fast pulsing, single bore dipole to

enforce the LER beam circulation in the LHC

- 2 T range, normal conducting, single bore dipole operating with

the LHC LER beam pipe separation of no less than 75 mm (40 mm beam pipe and ~ 30 mm for the magnet yoke)

- 7-8 T, superconducting, two-bore, 1m long vertical dipole to pass

the LER beam through most of the 1.35 m vertical separation



Fast Pulsing Magnets

- For 3 microseconds current decay time, L < 1 uH, so the magnet length is typically < 1 m, and the conductor spacing 40-60 mm.- For B field in 2 T range, the conductor current is in the range of 100 kA.- Magnet operating < 25 K (lowest resistance of Cu) is the only option.

From Martin N. Wilson,Superconducting Magnets,ISBN 0 19 854810 9 (Pbk), 1997



Fast Pulsing LER-LHC Transfer Line Magnets

Horizontal bend of both LER beams. Vertical bend of the LER beams,B-field shaped by laminations, B-field shaped by conductors,conductors are LHe cooled. conductors are LHe cooled.

40 mm gap, 1.5 T max @ 90 kAPulsed or continual operation

60 mm gap, 2.0 T max @ 67 kA pulsed or continual operation. CERN operated WC 0.6 T magnet @ 29 kA



LER-LHC Transfer Line Magnets

A vertically bending magnet –for horizontally separated LERand LHC beams.

Continual or fast pulsing operations.

Laminations are used to contain

magnetic flux, and to minimize fringe field at the LHC beam.



Fast Pulsing Magnet Power Supply

For I = 90 kA and L =1 uH of the magnet system, the voltage drop is 30 kV at

3 microsecond of current decay time. Lowering the operating temperature of the power supply switcher cells to 25 K will eliminate need for the HTS leads.



LER Major Magnet R&D for FY07

1. Dipole, 2T range, single bore (30-50 mm), 0.8 m long, dc, 3 microsecond turn-off time, LHe cooled condcutors: (a) magnetic field shaped by conductor (b) magnetic field shaped by Silicon Steel tape core

Goal for FY07: magnetic and mechanical/cryo design

2. A 100 kA dc power supply with 3 microsecond turn-off time: (a) switcher cells operating below 100 K, possibly down to 25 K (b) fast transformer/heater to turn-off the current (c) superconducting dump resistor to expend

magnetic energy

Goal for FY07: research and preliminary design



LER Major Magnet R&D for FY07

3. Two-bore (40 mm), high field (7-8 T) vertically bending magnet:

set of short (0.8m) 12-15 magnets arranged into a single cryostat

Goal for FY07: magnetic and mechanical/cryo design

4. VLHC combined function magnet, 1.6 T, 25 and 30 mm gaps:

Goal for FY07: magnetic design

ler magnets major r&d effort

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