brookhaven science associates nsls-ii injection system t. shaftan nsls-ii accelerator systems...

BROOKHAVEN SCIENCE ASSOCIATES

NSLS-II Injection System

T. ShaftanNSLS-II Accelerator Systems

Advisory Committee

October 11, 2006


Contributors

• I. Pinayev, • J. Rose, • J. Skaritka,• R. Heese,• C. Stelmach,• S. Pjerov• S. Sharma,• L.H. Yu• T. Shaftan

• G. Ganetis,

• D. Hseuh,

• N. Tsoupas,

• W. Meng,

• J. Beebe-Wang,

• A. Luccio,

• D. Raparia

• D. Wang

• J. Safranek,• L. Emery,• W. Joho


Outline

• NSLS-II injection requirements• Considerations for injection system• Injection straight arrangement and

simulations• Low energy accelerator• Booster• Transport lines• Concluding remarks


Requirements for NSLS-II Injection

• High reliability• Reasonable fill speed• Low losses• Low power consumption

• Lifetime 3 hours (with 3rd HC)• Top-up

Stability of current <1 % Time between top-up injections

>1 min Bunch-to-bunch variations of

charge <20%

Ī

t

Īt

QI

t

Ib

bunch #


Ring parameters related to injectionParameter Value

Energy, GeV 3

Circulating current, A 0.5

Circumference, m 780

Revolution period, s 2.6

RF frequency, MHz (wavelength, m) 500(0.6)

Circulating charge, C 1.3

Total number of buckets 1300

Number of filled buckets 13004/51040

Charge per bucket, nC 1.25

Lifetime, hours 3

Interval between top-up cycles, min 1

Current variation between top-up cycles, % 0.55%

Charge variation between top-up cycles, nC 7.15


Injection ScenarioNM=20-100

Injected bunch train

#

Ring bunch pattern

t

t1st turn 2nd turn 3rd turn

Ib

kicker

• Many (~1000) bunches in the ring multi-bunch injection NM bunches in injected train Filling NM consecutive buckets in

the ring Sequentially shift injection timing

• 1 Hz repetition rate suffices with pulse train injection

• 1 minute between top-up cycles

• Kickers duration can be 2 turns long (5 sec) or even longer

• Considered in ALS top-up (10 bunches)


Injection straight design8 m

Fla

g

Fla

g

Fin

al

Septu

m

Kic

ker

1

Kic

ker

2

Kic

ker

3

Kic

ker

4

Quad

Quad

Stripline for transversefeedback

Stripline for transversefeedback

Ring Injection Kickers (4)

Field, T 0.193

Length, m 0.75

Angle, mrad 14.4

Current Amplitude, kA 5.34

Voltage, V 4500

Temporal shape 5 μsec ½ sine wave

Pre-septum magnet

Field, T 1.1

Length / Angle, m / mrad 0.75 / 83

Peak current/voltage, kA/kV 12/0.6

Pulse shape 100 μsec ½ sine wave

Final Injection Septum

Field, T 0.9

Length / Angle, m / mrad 0.5 / 45

Peak current/voltage, kA/kV 10/0.6

Pulse shape 60 μsec full sine waveI. Pinayev and R. Heese


Requirements on Ring Stay-Clear• Tracking is done with TRACY-2

• Tracking a set of particles corresponding to injected beam

• • Tracking for 500 turns

• Beam envelope is recorded at every ring turn on every element

• Tracking for 10, 50, 100 nm• • Black envelope: scaled septum

aperture for horizontal

• Scaled undulator gap for vertical

• Conclusion: stay-clear required for injection can be easily met

J. Rose, I. Pinayev and J. Bengtsson


NSLS-II injector

Linac200 MeV

Th. Gun100 keV

3 GeV


Low-energy accelerator• Specifications for NSLS-II linac:

• Energy 200 MeV, energy spread <0.5% RMS,

emittance ~100 nm at 200 MeV

• Defined by small vacuum chamber in the booster

• Soleil linac:

10 nC in 300 ns at 100 MeV Energy spread <0.5% RMS Emittance ~40 mm mrad Beam loading compensation

• Fits NSLS-II requirements• Turn-key system

Soleil linac

Measured bunch train along the linac

from: A. Setty et al., Commissioning of the 100 MEV …


Layout of 200 MeV linac

• 5 linac sections• 3 klystrons• With loss of one klystron: 177 MeV

J. Rose


Linac-to-booster Transport Line

• Length: 19 meters 2 dipoles, 8 quadrupoles, 4 correctors Energy spectrometer Safety shutter Flags, BPMs Loss monitors• Diagnostics set-up sufficient

for commissioning of the linac

fromlinac BQ

BQ

kicker

QD

1

QD

2

QD

3

QD

4QF

1

QF

2

QF

3

QF

4B1

trim

s

trim

s

trim

s

B2

trim

fromlinac BQ

BQ

kicker

QD

1

QD

2

QD

3

QD

4QF

1

QF

2

QF

3

QF

4B1

trim

s

trim

s

trim

s

B2

trim

I. Pinayev


Booster: design considerations

“Compact” booster “Same tunnel” boosterBuilding and shielding are very expensive

Higher cost for vacuum, diagnostics

Ability to commission booster in advance

OK, based on the SLS experience

Ability to service and troubleshoot without beam interruption

Lifetime is 3 hours Average hardware failure leads to stop anyway

“Conventional” design Higher beam quality, relaxed tolerances


Booster location

• Mounting on the ceiling

No expanding tunnel

No transport lines blocking tunnel pathway

No magnets above ring straights

No water-cooling for magnets

Cross-talks?


Booster parametersParameter NSLS-II SLS

Energy range [GeV] 0.2 – 3.0 0.1 – 2.4

Circumference,[ m] 780 270

Emittance [nm] 11.5 9

Repetition rate [Hz] 1 3

Radiation loss per turn [keV] 500 233

RF frequency [MHz] 500 500

Magnet power [kW] 75.3 150

RF voltage [MV] 1.0 0.5

RF acceptance [%] 1 0.43

Beam current [mA] 3 1

Momentum compaction 5.7·10-4 5·10-3

Tunes [x / y] 19.19 / 10.73 12.41 / 8.38

Chromaticity [x/y] –21.7 / –21.7 –15 / –12

Damping times [ms] (x / y / E) 22 / 31 / 19 11 / 19 / 14


Booster lattice

Dynamic Aperture

• Modified NSLS booster lattice

• 60 combined function dipoles

• 90+6 quadrupoles

• 15+15 sextupoles

• 60 X-Y correctors

• 75 BMPs for orbit correction, rms orbit < 1mm

• Dipole field 0.7 T at 3 GeV

• Large dynamic aperture

• Negligible eddy current effect at 1Hz


Booster magnets• Magnets are located above

storage ring

• Use of air-cooled coils

• Small size of vacuum chamber small magnet size and weight

• Small power consumption

• Relaxed tolerances on magnet alignment and field errors

• Simple design of support hangers

• Quadrupoles and sextupoles: standard and compact design


Booster Magnet Power Supplies and RF• In series circuits:

B-PS – 60 dipoles Q1-PS – 60 quadrupoles Q2-PS – 30 quadrupoles SF-PS – 15 sextupoles SD-PS – 15 sextupoles

• Separate circuits:

60 horizontal trims 60 vertical trims 3 x 2 quadrupole trims

• All power supplies can operate at 1 Hz

• Programmable ramping profiles

• Synchronization from line voltage

G. Ganetis

J. Rose• RF voltage ramps to 1 MV • Energy acceptance 1% at 3 GeV• Total RF power 37 kW• Single 5-cell PETRA cavity• Capable of delivering 1.5 MV• IOT transmitter 80 kW at 500 MHz


1.E-09

1.E-08

1.E-07

1.E-06

0 2 4 6 8 10 12 14 16 18 20 22 24 26

Longitudinal Distance (m)

Pre

ssur

e (T

orr)

q(t) = 1e-10 Torr.l/ sec.cm̂ 2

η = 1e-3 mol/ photon

I e = 3 mA

P

S (P) = 30 l/ s

Pavg = 1.5e-7 Torr

S (P) = 100 l/ s

Pavg = 1.3e-7 Torr

P PP

DD

D

P

Booster vacuum• Target average value 1E-7

• Gas-scattering losses throughout energy ramp 0.5%

• Vacuum chamber provides with > 10xRMS beam sizes in both planes

• 2 sizes of vacuum chamber: 20x30mm2 in dipoles 25x40mm2 in dispersive

straights

• 5 pumps per superperiod = 150 pumps total

• Pumps in RF and injection/extraction straights

D. Hseuh


Booster-to-Storage ring Transport Line• Consists of 3 parts

– Horizontal achromat– Vertical dogleg– Horizontal achromat

• Doublets for optimizing -functions without disturbing -functions

• Maintain small beam size along the transport line

• Magnets / diagnostics: 4 dipoles, 17 quadrupoles, 6 trims, 6 BPMs, 6 flags, 2 ICTs

C. Stelmach, S. Pjerov


Concluding Remarks• We designed reliable and robust NSLS-II injection

system

• Conceptual design of NSLS-II injector Linac will be purchased, turn-key + some R&D? “Same tunnel” booster Transport lines: sufficient diagnostics for step-by step

commissioning• Storage ring:

Sufficient dynamic aperture for injection Sufficient stay-clear for injection Injection kicker system will be purchased, turn-key

• Future work: Optimization of injector design/cost tracking in realistic scenario, injection tolerances Consider Lambertson septum

brookhaven science associates nsls-ii injection system t. shaftan nsls-ii accelerator systems...

Documents

ring bunch

injection scenariomany

injection systemt

heesering injection

injected bunch train

als topup

length angle

pulse shape60 sec