vlhc design study technical aspectsg.w. foster aac may 2001 6 main dipole magnets main arc dipole...

G.W. Foster AAC May 2001 1

VLHC Design StudyTechnical Aspects

G.W. FosterMay ‘01


OUTLINE

• Stage 1 Magnets• Cryogenics (Stage 1 and Stage 2)• (PJL → Stage 2 Magnets & Synch Rad)• Stage 1 Subsystems• Beam Abort & Radiation Considerations


Transmission Line Magnet

• 2-in-1 warm iron warm bore superferric• alternating gradient (no quads)• 100kA Transmission Line• all-piping cryogenic system

230

660 REF.

SUPERCONDUCTINGTRANSMISSION LINE

100 kA RETURN BUS

CRYOPIPES

VACUUMCHAMBER

Support Tube /Vacuum Jacket


Corrector Region (every 135m)


VLHC-1 Magnet Summary

Magnet Type Bnom (T) Gnom (T/m) Lmag (m) Number ofelements

Notes

Gradient dipole (arc) 1.97 9.73 67.75 3136 Main Arc MagnetsGradient dipole (DS) 1.80 16.88 48.81 160 Dispersion SuppressorsStraight sect quads 70 4.8 - 6.8 464 Room temp. conventionalLow β quadrupoles 300 9.2 - 10.9 8 Supercond. IR QuadsSpecial dipoles 1.95 25 - 35 52 Separation, recombination,

and cross-overCorrectors Air-cooled Iron/Copper

Dipole (horiz.) 1.0 0.50 1648 Every “F” locationDipole (vert.) 1.0 0.50 1648 Every “D” locationQuadrupole 25 0.50 3296 Every F&D locationSextupole 1750 T/m2 0.80 3296 Every F&D location


Main Dipole MagnetsMain Arc Dipole Dispersion Suppressor

Magnet air gap in the orbit center 20 mm 22.26 mmBeam Pipe Inner Dimensions 18 mm x 28 mm (elliptical)Separation Between Beams 150 mmMagnet length 65.74 m 48.81 mHalf-cell length 135.5 m 101.6 mSagitta in Magnet 1.6 cm 0.6 cmGradient ± 4.73 %/cm ± 9.449%/cm

injection 0.1 T 0.09 TMagnetic field:maximum 1.966 T 1.766 Tinjection 20 mmGood field diameter

(< 0.02%): maximum 10 mmTransmission Line Design Current 100 kACurrent at 20 TeV 87.5 kAMagnetic field energy @100 kA 790 kJ (12 kJ/m) 473 kJ (10 kJ/m)Superconducting cable Braided NbTi with Braided Cu StabilizerSpecified Max. Temp of Conductor 6.5-6.7 KNominal Max Temp of Cryo System 6.0 KIron Core 1 mm Laminated low carbon Steel (AISI 1008 or better)


Why 65m Magnets?• Other Reasonable choices will work:

– 1/8 cell (38m), 1/2 Cell (135m)• Weight = 33 tons, similar to LHC = 35 tons• 65m Magnet can have lifting fixture

– pick magnet by 2 points, fixture fits in tunnel• All cables can be factory installed on 65m

– but not on shorter (1/8 cell) magnets• Tunnel labor for splicing ~$10M• Cryo load from splices ~10% of 4.5K load• Factory ~1.5x size for 2x length magnets


2-D Magnetic and Mechanical• Upper & Lower

half-cores welded together

• Gap spacer from nonmagnetic 316L

• 1 mm laminations• Holes in poles to

control saturation sextupole and gradient shift


B vs. Current

• 1.966 Tesla (=20 TeV) at 87.5 kA. • Transmission line design current is 100 kA.

0

0.5

1

1.5

2

0 20 40 60 80

I (kA)

B (

T)


Control of Saturation Sextupole

• Need correctors above ~1.8T• No loss of dynamic aperture at 1.966T

Effect of Slots on Saturation Sextupole(Field Shape change between 1.8T and 1.25T)

-25

-20

-15

-10

-5

0

5

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1

X (cm)

Diffe

renc

e in

Fie

ld S

hape

at 1

.8T

and

1.3T

(x 1

E4)

No Slots (Calculated)

With Slots (Calculated)With Slots (Measured) file:my0z1-00


Control of Gradient Shift

• Correctors sized to regulate tune and β up to design field of 1.966T.

Gradient Shift vs. BWith and Without Slots in the Poles

-25

-20

-15

-10

-5

0

5

0 0.5 1 1.5 2 2.5B (Tesla)

Gra

dien

t (un

its @

1cm

) m

inus

Gra

d@1.

25Te

sla

Slots in Pole (Calculated)

No Slots (Calculated)

Measured with Slots file: my0z1-00


Transmission Line Design Requirements

• Enough NbTi to carry 100kA at 6.5K, 1T– (includes margin: TNOM= 6.0K, INOM=87.5kA)

• 2.5cm clear bore for He transport 9.5 km• Enough Cu to survive quench with τ = 1 sec• Withstand 35 Bar quench pressure• Conductor centered +/- 0.5mm• Low heat leak: < 50mW/m• Survive cooldown with ends constrained

⇒ Invar™ transmission line piping


Three Transmission Line Variants

BRAIDED CONDUCTOR(Drive and Current Return)

Drive Bus Return Bus Bus in Corr. Space

Cu/SC ratio in strand 1.8 1.8 1.3

Diameter (mm) 0.648 0.648 0.808

Cond. Type Braid Braid 9 Rutherford Cables

Number of strands 288 288 270

Cu Wire dia. (mm) 0.64 0.64 0.64

Number of wires 240 288 288

Inner Pipe ID .(mm) 25.3 36.8 36.8

Outer Pipe OD (mm) 38.1 47.1 50.1

Max working Pressure (bar) 40 40 40

RUTHERFORD CONDUCTOR(Corrector Region)


Operating Margin

Tm

ax =

6.1

K

Iop = 90 kA

0.7 K Margin

0

20

40

60

80

100

120

140

0 2 4 6 8Temperature (K )

Cur

rent

(kA

)

~ 0.7°K margin at design current of 87.5 kA~ 25kA margin at nominal peak temperature of 6.0 K

The design trades extra superconductor ($50M total) for simpler cryo ($110M)


What is most cost-effective Operating Temperature?Tradeoff: Refrigeration vs. Superconductor Costs

TOTAL(Cryo + SC)

Cryo System CostScaled by Carnot

NbTi Conductor

52,800 kA-mat 1 Tesla

DesignPoint

0

50

100

150

200

250

4 4.5 5 5.5 6 6.5 7 7.5 8 8.5

Peak Operating Temperature (deg K)

Cost

Com

pone

nt ($

M)


Mechanical Issues

• Gravitational Sag• Force and Stresses from adjusters• Gap Stability under magnetic forces• Cold-to-warm forces on spider• longitudinal forces, bellows, interconnects


Longitudinal Forces

• All pipes anchored to ground every 135m• Transmission line pipes are Invar• Other Cryo pipes have bellows• Vacuum jackets have anchors & bellows

every 135m• Designated break points for coolant accidents


Magnet Ends

• Dog-leg transmission line downwards to provide field-free region for correctors

• Handle large forces between conductors with cold-to-cold structural connection


Corrector Magnets • Dipole, quad, and 6-pole correctors every half-cell• Dipole correctors: full aperture scan @3 TeV• Quadrupole: corrects gradient shift at 1.96T• 6-pole: corrects saturation sextupole at 1.96T• correctors independently powered to correct for

systematic & random errors in arc magnets


Orbit Corrector StrengthNumber of Magnet Moves vs. Time

to Maintain Closed Orbit Distortion at Flat-topWithin Various Tolerances

Perfect Closed Orbit

0.1 mm Peak COD

0.5 mm Peak COD

1.0 mm Peak COD

2.0 mm Peak COD

Corrector Bend 7.5 urad

B*L = 0.5 T-m at 20 TeV

0.25mm RMS Survey Err

1mrad Dipole Roll

dB/Bo = 3E-4

270m x 90 Degree Cells

1 H/V Corrector/halfcell

ATL const 5E-6

Circumference 225km

0

20

40

60

80

100

120

140

160

180

200

0 1 2 3 4 5 6 7 8 9 10

Years Since Initia l Insta lla tion

Num

ber

of M

agne

ts M

oved


Corrector SummaryCorrector type Horizontal

DipoleVerticalDipole

Quadru-pole

Sextupole

Quantity 1720 1720 3136 3136

Maximum magnet strength 1.0 T 1.0 T 25 T/m 1750 T/m²

Field quality, 18 mm diameter area, % 1.0 1.0 1.0 1.0

Effective magnet field length, m 0.5 0.5 0.5 0.8

Integrated field at r = 1 cm, T-m 0.5 0.5 0.125 0.14

Magnet core length, m 0.48 0.48 0.5 0.8

Current, A 25 25 1.0 1.0

Voltage, V 23 23 140 175

Power, W 600 600 150 200

Number of coils per magnet 1 1 4 6

Number of turns per coil 640 640 1240 633

Copper conductor diameter, mm 5 x 5 5 x 5 1 1

Copper weight, kg 250 250 40 50

Core weight, kg 300 220 30 50


IR Magnets for Stage 1• 300 T/m• 85mm aperture• 4.5K Nb3Sn• Synergy w/ LHC

upgrade quads• LHC-like layout• All other IR

magnets use warm iron


Straight Section Quads

• Warm magnets chosen for cost & integration• Fit side-by-side on 150mm beam centers


CRYOGENICS

• Stage 1: 6 Plants, each [email protected] equiv– 12 MW total wall power (17MW installed)– ~15% additional for SCRF option, IR’s etc.– Installed power 150% of nominal

• Stage 2: 12 Plants, each [email protected] equiv.– 85 MW total Wall Power (113 MW installed)– ~3.5x LHC


Split ColdboxRing Layout

40 km


Piping in Transmission Line Magnet

Vacuum Jacket(Aluminum Extrusion)

Transmission Line1.5" OD / 1.1" IDInvar + Cu + NbTi

Magnet Support Tube& Cryo Vacuum Jacket12" OD x 0.25" WallCarbon Steel

BeamPipes

Flow Return for FarTransmission Line(1st half-loop only)

Shield ReturnHeader 3" Invar tube

Shield Supply Header3" x 0.050" WallInvar Tube

Current Return Bus2.5" OD / 2.1" IDInvar + Cu + NbTi

70K40K

4.5K

6.5K

40-60K Shield Traces2 x 0.25" Invar Tubes

4.5K

Warm Iron

300K

Warm GasReturn Header6" PipeOn Tunnel Wall


4.5K-6K Supercritical Flow


40km Sector LayoutRefrigerator

Helium Pressure Relief Valves


Stage 1 Heat Loads

Primary 4.5K Secondary 40KSTATIC

Near LoopMechanical Supports, [mW/m] 53 670Superinsulation, [mW/m] 15 864

Far LoopMechanical Supports, [mW/m] 53 670Superinsulation, [mW/m] 13 864

DYNAMICBeam Loss, [mW/m] 2 1Superconductor Splice, [mW/m] 7 -


Transmission Line Cryostat

• Resist Vertical Decentering Force• Low Heat Leak


Stage 1 Ring Cryogenics Summary Shield

Near Loop Far Loop Near Loop Far Loop

Temp in [K] 4.50 4.52 5.44 5.40 37.00Press in [bar] 4.00 3.80 2.00 2.50 17.00Enthalpy in [J/g] 12.09 12.09 33.92 27.18 207.28Entropy in [J/(g*K)] 3.52 3.56 8.19 6.69 14.76Temp out [K] 5.57 5.39 5.80 5.54 70.00Press out [bar] 2.80 2.50 1.90 2.10 13.00Enthalpy out [J/g] 26.40 26.66 37.79 34.24 381.66Entropy out [J/(g*K)] 6.44 6.59 8.96 8.18 18.71Predicted heat load [W/m] 0.044 0.044 0.024 0.022 1.534Distance [m] 19400 19400 19400 19400 38800Design total heat [kW] 0.85 0.85 0.47 0.43 60Mass flow [g/sec] 60 59 120 60 341Design ideal power [kW] 103 107 27 53 345

Magnets ShieldPredicted heat load [kW] 2.6 60Heat uncertainty factor [-] 1.25 1.25Design Heat Load [kW] 3.2 74Design mass flow [g/sec] 120 348Design ideal power [kW] 291 3454.5 K equiv design power [kW] 4.43 5.26Efficiency (fraction Carnot) [-] 0.28 0.28Nominal operating power [kW] 1039 1233Overcapacity factor [-] 1.3 1.3Installed operating power (kW) 1351 1603

Operating wall plug power for one sector (MW) 2.0Installed wall plug power for cryogenics for one sector (MW) 3.0Operating wall plug power for cryogenics for entire accelerator (MW) 11.8Installed wall plug power for cryogenics for entire accelerator (MW) 17.7

MagnetsTransmission Line Current Return Bus

IR’s and RF add ~10kW to

on-site load.

(May cover this with CHL since Tevatron is not

ramping)


Stage 2 Cryogenics

dQdQ fQ

Tom Peterson19 March 2001High Field VLHC cell flow concept with S. Zlobin electrical scheme

5.5 K, 1.8 bar helium return and quench header

Quench and cooldown valveShield and beam screen flow valve

80 K, 20 bar helium thermal shield supply and beam screen supply

110 K, 17 bar helium shield return flow and transfer line shield

4 IPS (11 cm) pipe

5 IPS (14 cm) pipe

6 IPS (17 cm) pipe

One 270 meter cell

Transfer line

D D D D D DD D

4.5 K, 4 bar magnet helium flow

Magnet cryostat1.5 inch (3.8 cm) tube

D D D D D D

80 K to 90 K thermal shield

90 K to 110 K beam screens

C C C

Four 25 kA bus in 4 IPS (11 cm) helium pipe

Jumper connections

Dipole bus and coil leads

Defocussing quad bus and coil leadsFocussing quad bus and coil leads

Spool LargeSpool

Spool

300 K, 1.2 bar helium gas return Relief and cooldown valve

6 IPS (17 cm) pipe

26 inch (66 cm) OD transfer line vacuum shell

D D D

Pipe includes 4.5 K, 4 bar helium flow parallel to magnet flow

(Include vacuum breaks)

36 inch (92 cm) magnet cryostat vacuum shell


Stage 2 Cryogenics SummaryShield supply Shield return pipepipe Thermal shield Beam screen and thermal shield Magnet cold mass(in transfer line) (magnet) (two beams) (transfer line)

Temp in (K) 77.00 77.61 87.58 77.61 4.5Press in (bar) 20.0 19.4 19.3 18.1 4.0Temp out (K) 77.61 87.58 106.58 108.82 5.5Press out (bar) 19.4 19.3 18.1 17.7 1.8

Predicted heat load (W/m) 0.1 4.2 10.0 2.2 0.83Heat uncertainty factor 1.25 1.25 1.00 1.25 1.25Design heat load (W/m) 0.13 5.25 10.00 2.75 1.04Distance (m) 9700.0 9700.0 7824.0 9700.0 9700.0Design total heat (kW) 1.2 50.9 78.2 26.7 10.1Design mass flow (g/s) 1104.0 13.6 6.8 1104.0 422.7

Design ideal power (kW) 10.4 137.5 194.5 63.0 647.34.5 K equiv design power (kW) 0.2 2.1 3.0 1.0 9.9

Efficiency (fraction Carnot) 0.30 0.30 0.30 0.30 0.30Efficiency in Watts/Watt (W/W) 28.7 9.0 8.3 7.9 214.4Nominal operating power (kW) 34.8 458.2 648.5 210.1 2157.6

Overcapacity factor 1.30 1.30 1.30 1.30 1.30Installed operating power (kW) 45.2 595.7 843.0 273.1 2804.8

Percent of power 1.0% 12.6% 17.9% 5.8% 59.4%

Total installed operating power for one 10 km string (MW) 4.7Total installed 4.5 K equivalent power for one 10 km string (kW) 21.2

Number of above "strings" in accelerator 24Operating wall plug power for cryogenics for entire accelerator (MW) 85.7Installed wall plug power for cryogenics for entire accelerator (MW) 113.3Installed 4.5 K equivalent power for entire accelerator (kW) 508.9Installed number of LHC system equivalents 3.5


Radiofrequency Systems(Sergey Belomestnykh)

Stage 1 Stage 2Acceleration Storage Acceleration Storage

Beam current 190 mA 68.9 mABeam energy 0.9 – 20 TeV 20 TeV 10 – 87.5 TeV 87.5 TeV

Acceleration time 1000 sec 2000 secAcceleration per turn 14.8 MV 39.4 – 18.15 MV

Acceleration power (2 beams) 5.62 MW 4.134 MWSynch. rad. loss per turn 0.03 MeV 12.37 MeV

Total s.r. power (2 beams) 13 kW 2.1 MWRevolution frequency 1286.5 Hz

Bunch length, rms 142 mm 66 mm 81.9 mm 33.7 mmSynchrotron tune 0.00845 0.00179 .00280 .00189

Synchrotron frequency 10.87 Hz 2.30 Hz 3.60 Hz 2.43 HzBunch frequency 53.1 MHz

Number of buckets 41280Bunch spacing 5.646 m, 18.8 ns

RF harmonic number 288960RF frequency (7×53.1) 371.7 MHz

RF wavelength 80.65 cmRF voltage 50 MV 50 MV 50 MV 200 MV

Accelerating gradient 7.75 MV/mVoltage per cavity 3.125 MV

R/Q 89 OhmQ factor at 8 MV/m 2×109

Number of cavities 32 (16+16) 128 (64+64)Cavities per cryostat 4RF cavity wall losses 55 W

Cryostat static heat leak 60 WTotal cryogenic heat load 2.24 kW 8.96 kWBeam power per cavity 176 kW 0.406 kW 42.4 kW peak 16.4 kW

Number of 500 kW klystrons 16 (8+8) 16 (8+8)Number of cavities per klystron 2 8

• Either Warm Copper or SC RF systems are possible

• Superconducting RF chosen for Design Study

• Need to integrate coalescing cavities (if needed).


Ramp Optimization - Stage 2 Ramp for High Field Ring

0

5

10

15

20

25

30

35

40

45

50

0 500 1000 1500 2000 2500

Ramp Time (sec)

Pow

er S

uppl

y Cu

rren

t(kA)

, Po

wer

Sup

ply

Tota

l Vol

tage

(kV)

,RF

Ram

ping

Vol

tage

(MV/

turn

)or

Pow

er P

er S

exta

nt (M

W)

RF accelerating MV/Turn

PS Pow er per Sextant (MW)

PS Voltage (kV total)

PS Current (kA)

Voltage Limitedfor first 35% of Ramp

Magnet Power Limited for rest of Ramp.

Stage 1 is always

RF Limited


Power Supplies, Quench Protection,and Current Leads - Stage 1

TransmissionLine Power

Supply

IR QuadrupolePower Supplies

(sect 5.1.4)

Straight sectionWarm MagnetPower Supplies

CorrectorMagnets

(warm copper)Number 1 2 16 approx. 12,000Location FNAL at Experiments Straights Quad locationsVoltage per supply 62 10V typ. 1000V typ. 100 TypCurrent per supply 100kA 25kA 200A typ 2A typRamping MVA (tot) 6.2 MVA 1 MVA - -DC Power (total) 0.4 MW 0.6 MW 7.4 MW 2.1 MWLCW Consumption - - 150 liters/sec (air cooled)Quench Detection 1 Circuit at PS 2 circuits/quad - -Quench Protection Dumps @ 20km 4 heaters/quad - -SC Current leads 100kA-pair 60kA-pair - -

Peak RampingSupply Power 17.7 MW

Total Power SupplyPower in Collision 10.5 MW


100kA MAIN DIPOLE POWER SUPPLY

• Single Supply on-site at FNAL• Above or Underground?• 6.2 MVA ~1/6 of Main Injector• +/-62V ramps magnets in 1000 secs• Actually 2 supplies in series:

1) +/-62V Ramping Supply (SCR)2) +2.5V Precision Holding Supply


• 12-phase SCR Bridge• 2 Quadrant Operation• Parallel 8.5kA modules similar to FMI

RAMPING POWER SUPPLY


HOLDING POWER SUPPLY

• +2.5V Single Quadrant Operation• Overcomes Series Drops in busswork,

SC leads, Splices, and SCR Bypass Switch• 2 KHz Switching supply• Parallel ten 10kA modules• Stagger Phasing of modules to reduce ripple• Synchronize to Revolution Frequency to

eliminate emittance growth from noise


100kA Power Supply and Current Leads


100kA Power Supply Assembly for MP6 String Test


Stability Against Quenches From Beam Losses

• Full shower development and energy deposition calculated (Mokhov).

• Warm iron design can tolerate ~20x more beam loss than conventional cold-bore magnet, probably more.

Beam Loss Points


Magnetic EnergyDump System - Stage 1

• 10kJ/m stored energy in magnet requires active energy dump.

• 2 GJ Stage 1 vs. 10 GJ LHC • When quench detected, current diverted to

series dump resistor to extract magnetic energy.

• 1 second dump time reasonable.• Practical limit +/-3kV to ground


VLHC Magnetic EnergyDump System

• Requires dump resistors and switches to be spaced ~20km.

0.06 Ohm

0.06 H

Quench Cell 20km Long

MagnetString

Dump Switchand Resistor


Advantages of Superconducting Dump Switch

• Zero Power Dissipation.• Small heat leak (safety leads).• Easy to re-cool by venting He into warm gas

return.• No LCW.• Small quench trigger power ~1kJ.• Can be spaced far from utilities.


Transmission Line Current 100 kAMagnetic Stored Energy @100kA 10 kJ/meter, 2100 MJ/ringMagnet Inductance at low field 3uH/m 600mH/ringEnergy Dump Time Constant 1 second

Peak Voltage To Ground during Dump ± 3 kVI2t during dump 5 x 109 Amp2SecondsPeak Temperature of Conductor During Quench 250KPeak Pressure of Helium During Quench 35 BarPressure relief during quench Every 2 cells (500m)

Effective Copper Cross Section of Conductor 3cm2

Quench Detection Threshold 1 VoltQuench Detection Method (primary) Analog bucking with midpoint of current return busQuench Detection Method (backup) Deviation from V=LdI/dt at power supply

terminals

Energy Dump Resistance 60 mΩ per location,Dump Switch Locations at cryoplants and midpoint of arc (20km spacing)Dump Switches Quenched superconducting cables 65m longSuperconducting Dump Switch Conductor 1:1 CuNi:NbTi “Switch Wire”Cryogenic Dump Resistor Thermal Mass 65m long x 20cm2 Thick Wall Invar pipeFinal Dump Temperature after Dump from 100kA 325KLHe Required for recovery after Dump from 100kA 1600 liters (less if shield flow used for pre-cooling)

Table 5.2.2.3 - Stage 1 Quench Detection and ProtectionParameters


Power Dissipation and LCW Summary - Stage 1Heat Load Total Loads Total kW LCW Flow (l/min)

Resistive Magnets 188 4480 3200

Power Supply Cooling 22 500 600

RF Klystrons 16 3760 6400

RF Loads & Recirculators 16 5600 4500

Beam Stop 1 500 600

On-Site

Straight

Sections

Total (on-site) 227 14840 15300

Resistive Magnets 176 3320 3500

Power Supply Cooling 9 550 600

Beam Collimation - 40 50

Far Side

Straight

SectionsTotal (far side) 185 3910 4150

LCW Systems Total 412 18750 19150


LCW System (FNAL Site)

PowerSupply

RFKlystron

Utility Straight

CryoBend

PowerSupply

IR1 Straight

CryoBend

CrossOver

CryoBend

Pump From Tunnel to Surface

IR2 Straight

CryoBend

PowerSupply

RFKlystron

Utility Straight

BeamDump

Main Ring Ponds and LCW System

3 km 3 km

Comparable to MI-60 LCW System of Fermilab Main Injector


ARC INSTRUMENTATION• Electronics

modules each half-cell ~135m

• Shielded Coffin• Minimizes

Cables• Average Power

in Tunnel ~15W/m

• Mostly correctors

R 72 in

Ø6in

Electronics Module

Ø12.00in


Local Electronics Modules


Cabling Pre-Installed on MagnetELECTRONICS MODULE AT EACH ARC HALF-CELL (135m


Power Distribution In Tunnel

1kV DC 100 kW

AC from Surface

RedundantBulk DC Suppliesin Walk-In AlcoveEvery 10 km

Control

CorrectorMagnets(6-8 total.)

RedundantDC-DCConvertersIn LocalElectronicsModulesEvery 135m

1kV DC 100 kW

Redundant 1kV DC Feeder Looping Ring

250W

1400W


Beam Vacuum System(Turner, Pivi, Kennedy)


Vacuum System

• Aluminum Extrusion is placed inside magnet core after bakeout and magnet test

• Vertically pre-loaded against laminations

• No in situ bakeout.


Beam Lifetime During Vacuum Cleanup

0 20 40 60 80 1000

50

100

150

200

250

300

350

400

450

500

proton proton lifetime τpp

beam gas-scattering lifetime τg

Beam lifetime τb

Life

time

(hrs

)

Time (hrs)

~200-hour vacuum lifetime

after 5 stores


Beam Pipe Apertures

20mm

Ø20mm

22mm

Ø50mmØ46mm Ø23 mm

40mm

Ø40mm

10mm20mm

28mm30mm

18mm

20mm

28mm

30mm

18mm20mm

28mm30mm

18mm20mm

QUADRUPOLEor Quad Corrector

ARC DIPOLEor Horiz. Corrector ( F location)

ARC DIPOLE ( D location)

Vertical Corrector ( D location)

STRAIGHT SECTION BEAM PIPE

SEXTUPOLE CORRECTOR(F & D Locations)

INJECTION LAMBERTSON LARGE APERTURE QUADNEAR INJECTION LAMBERTSON


BPM SYSTEM

• Button Style Pickups

• ~ 5 m cable to readout electronics

• Either AM/PM conversion or Log Amps OK

Beam Position MonitorX & Y, “Button” style

Calibration can be verified in situwith independent quad correctors


BLM SYSTEM

• Mission-Critical• Redundant:

– Two full-length BLMs per magnet

– Read-out at alternate halfcell locations

• Maintenance-Free Design


Once-per-Turn Instrumentation

FUNCTION Occurances Readout Frequency CommentsTune Measurement a few/ring 10 Hz Use Arc Module DSP’s for FFT?Beam Current Toroids 1/ring Also on injection linesSampled Bunch Display 1/ring 1 Hz Fast Bunch Integrator 1/ring 1 Hz Synchrotron Light Monitor 1/ring 1 Hz Ion Profile Monitor 2/ring .1 Hz Small beam size may be challengingFlying Wires 1/ring ~few per store

• Can be mostly copied from Tevatron/MI systems• Easily fit into Warm Utility Straight Sections


Beam Damper (Lambertson/Marriner)

D D D D D D D DF F F F F F F

KickerPickup KickerPickup

9ns PulseStretcher

Strip LinePickup Cable

Driver

270m Foam Coax Line

PA Kicker

90° Betatron Phase Advance between Pickup & Kicker


Radiation and Beam Abort

• Beam energy can liquefy 400 liters of SS(LHC beams can only liquefy 50 liters)

• Three Qualitatively New Features:1) Beam Sweeper failure will damage dump

⇒ sacrificial plug upstream of dump.2) Beam Sweeper failure will melt hole in

window ⇒ close gate valve.3) Beam Cleaner Secondary Collimators

Must be Water Cooled ⇒ do it.


Beam Abort

X-Y Sweeper Magnet

Sacrificial Absorber (for Sweeper Failure)

Spiral Sweep on Graphite Absorber Block

Lambertson

Beam Window

Aluminum, Steel, & Cement Sarcaphagus

Kicker

300m 3000 m

Circulating Beam

• Under normal circumstances the extracted beam beam is swept in a spiral pattern to spread the energy across the graphite dump.

• If the sweeper magnet fails, the beam travels straight ahead into a sacrificial graphite rod which takes the damage and must be replaced. Beam window also fails.


Beam Collimation System(Drozhdin)

• Purpose-Built System works nearly perfectly

• 20kW power in secondary collimators (→ LCW)


Worst-Case Beam Accident• 2.8 GJ ~ 8x LHC Beam Energy (400 liters SS)

vlhc design study technical aspectsg.w. foster aac may 2001 6 main dipole magnets main arc dipole...

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