operated by the jefferson science associates for the u.s. depart. of energy thomas jefferson...

Operated by the Jefferson Science Associates for the U.S. Depart. Of Energy

Thomas Jefferson National Accelerator Facility NuFact’06, UC Irvine, August 29, 2006.

Alex Bogacz, Dogbone RLA – Design Choices

Alex Bogacz

Dogbone configuration

orbit separation

simultaneous acceleration of both + - species

12.5 GeV Two-step-Dogbone RLA

Quadrupole focusing scheme – Triplet vs FODO lattices

multi-pass linac optics

‘droplette’ Arcs

matching to the Arcs

5 GeV Dogbone RLA (3.5 pass) – Complete lattice design, sensitivity studies

15 GeV Dogbone RLA (6.5 pass)?

Dogbone RLA – Design Choices




Simultaneous acceleration of both + species

E

E0

E0 + (n+½)E

orbit separation, energy difference between consecutive passes: 2E




12.5 GeV Two-step-Dogbone RLA

2 GeV to 5 GeV 5 GeV to 12.5 GeV

the same energy ratio for both dogbones:

2 GeV0.3 GeV

1 GeV/pass5 GeV

2 GeV/pass12.5 GeV

Ef

E0

= 2.5




Injection double-chicane

900

Wed Apr 26 00:28:03 2006 OptiM - MAIN: - D:\ISS_dogbone\Chicane\Chicane_dogleg.opt

30

0

2-2

BE

TA

_X

&Y

[m]

DIS

P_

X&

Y[m

]

BETA_X BETA_Y DISP_X DISP_Y




Initial beam emittance/acceptance after cooling at 273 MeV/c

Study IIb rmsA = (2.5)2

normalized emittance: x/y mmrad 4.8 30

longitudinal emittance: l

lp z/mc)

momentum spread: p/p

bunch length: z

mm

mm

27

0.07

176

150

0.17

442




Pre-accelerator different style cryo-modules

Short Medium Long

Number of periods 12 18 22

Total length of one period 3 m 5 m 8 m

Number of cavities per period

1 1 2

Number of cells per cavity 1 2 2

Cavity accelerating gradient 15 MV/m 15 MV/m 15 MV/m

Real-estate gradient 3.72 MV/m 4.47 MV/m 5.59 MV/m

Aperture in cavities (2a) 460 mm 460 mm 460 mm

Aperture in solenoids (2a) 460 mm 460 mm 460 mm

Solenoid length 1 m 1 m 1 m

Solenoid maximum field 1.5 T 1.9 T 3.9 T

460

1000

3000

200

1000 500

200 460

1500

5000

250

1000 500

500 500

460 1500

8000

1500 250

1000 500

500 500




Introduction of synchrotron motion in the initial part of the linac

0 100 200 3000

10

20

30

40

50

60

70

80

90

s[m]

RF

pha

se [

deg]

0 100 200 3000

1

2

s [m]

Syn

chro

tron

pha

se/2

PI

100 0 100

0.2

0

0.2

Phase [deg]

Dp/

p

0 50 100 150 200 250 3000

0.5

1

1.5

2

s [m]

Ene

rgy

[GeV

]

p/p=0.17or =93 (200MHz)




25-25 S [cm] View at the lattice end

20

0-2

00

dP

/P *

10

00

,

25-25 S [cm] View at the element 275

20

0-2

00

dP

/P *

10

00

,

Linear Pre-accelerator – Longitudinal dynamics

25-25 S [cm] View at the lattice beginning

20

0-2

00

dP

/P *

10

00

,

3020

Fri Dec 03 11:22:15 2004 OptiM - MAIN: - D:\Study 2A\PreLinac\Linac_sol.opt

25

0

30

-90

Be

tatr

on

siz

e X

&Y

[cm

]

An

gle

[de

g][

-90

,+9

0]

a b Angle[deg]




Symmetric ‘Dogbone’ RLA (3.5-pass) Scheme

Main Linac (2 GeV/pass)

3 ‘droplet’ Arcs based on periodic cells (900 betatron phase advance per cell)

Dogbone RLA - footprint

-5000

-3000

-1000

1000

3000

5000

-15000 -10000 -5000 0 5000 10000 15000 20000 25000 30000 35000

z [cm]

x [cm]




120

Mon Aug 28 23:06:16 2006 OptiM - MAIN: - D:\RLA explore\Cells\Triplet.opt

300

50

BE

TA_X

&Y

[m]

DIS

P_X

&Y

[m]

BETA_X BETA_Y DISP_X DISP_Y120

Mon Aug 28 23:09:19 2006 OptiM - MAIN: - D:\RLA explore\Cells\FODO.opt

30

0

50

BE

TA_

X&

Y[m

]

DIS

P_

X&

Y[m

]


FODO vs Triplet focusing structure

FODO Triplet

Advantages:

much weaker quads (~3 times)shorter quads (total)easier chromaticity correction

Advantages:

longer straight sectionssmaller vertical beta-functionuniform variation of betas and

dispersion

The same length

The same phase advance per cell (x= 900 = y)



Alex Bogacz, Dogbone RLA – Design ChoicesTriplet - ‘flat focusing' linac profile

‘half pass’ , 2-3 GeV

1-pass, 3-5 GeV

mirror symmetry cond. (outn = in

n+1,and outn = -in

n+1, n - pass index)

Initial phase adv/cell 90 deg – constant quad grarients for the entire linac

phase adv. drops much faster in the horizontal plane

124.310

Mon Aug 28 23:31:09 2006 OptiM - MAIN: - D:\RLA explore\Dogbone_Triplet\flat\Linac05.opt

0.5

0P

HA

SE

_X

&Y

Q_X Q_Y

124.310


30

0

50

BE

TA_

X&

Y[m

]

DIS

P_

X&

Y[m

]


256.820


0.5

0P

HA

SE

_X

&Y

Q_X Q_Y

256.820


60

0

50

BE

TA

_X

&Y

[m]

DIS

P_

X&

Y[m

]




Alex Bogacz, Dogbone RLA – Design Choices Triplet - ‘flat focusing' linac profile

2-pass, 5-7 GeV

3-pass, 7-9 GeV


n+1,and outn = -in


256.820


0.5

0P

HA

SE

_X

&Y

Q_X Q_Y

256.820


12

00

50

BE

TA

_X

&Y

[m]

DIS

P_

X&

Y[m

]


256.820


0.5

0P

HA

SE

_X

&Y

Q_X Q_Y

256.820


12

00

50

BE

TA

_X

&Y

[m]

DIS

P_

X&

Y[m

]


phase adv. drops much faster in the horizontal plane

no phase adv. in the horizontal plane



Alex Bogacz, Dogbone RLA – Design ChoicesFODO - ‘flat focusing' linac profile

‘half pass’ , 2-3 GeV

1-pass, 3-5 GeV


n+1,and outn = -in


initial phase adv/cell 90 deg – fixed gradient in all cells

phase adv. drifting uniformly in both planes

122.150

Mon Aug 28 09:15:16 2006 OptiM - MAIN: - D:\RLA explore\Dogbone_FODO\flat\Linac05.opt

0.5

0P

HA

SE

_X

&Y

Q_X Q_Y

248.6510


0.5

0P

HA

SE

_X

&Y

Q_X Q_Y

248.6510


30

0

50

BE

TA

_X

&Y

[m]

DIS

P_

X&

Y[m

]


122.150


30

0

50

BE

TA_

X&

Y[m

]

DIS

P_

X&

Y[m

]




Alex Bogacz, Dogbone RLA – Design Choices FODO - ‘flat focusing' linac profile

2-pass, 5-7 GeV

3-pass, 7-9 GeV


n+1,and outn = -in


248.6510


0.5

0P

HA

SE

_X

&Y

Q_X Q_Y

248.6510


60

0

50

BE

TA_

X&

Y[m

]

DIS

P_

X&

Y[m

]


248.6510


0.5

0P

HA

SE

_X

&Y

Q_X Q_Y

248.6510


60

0

50

BE

TA

_X

&Y

[m]

DIS

P_

X&

Y[m

]




Alex Bogacz, Dogbone RLA – Design Choices FODO - ‘flat focusing' linac profile

4-pass, 9-11 GeV

5-pass, 11-13 GeV


n+1,and outn = -in


248.6510


0.5

0P

HA

SE

_X

&Y

Q_X Q_Y

248.6510


90

0

50

BE

TA

_X

&Y

[m]

DIS

P_

X&

Y[m

]


248.6510


0.5

0P

HA

SE

_X

&Y

Q_X Q_Y

248.6510


90

0

50

BE

TA

_X

&Y

[m]

DIS

P_

X&

Y[m

]




Alex Bogacz, Dogbone RLA – Design Choices ‘flat focusing' linac profile

6-pass, 13-15 GeV


n+1,and outn = -in


248.6510


0.5

0P

HA

SE

_X

&Y

Q_X Q_Y

248.6510


90

0

50

BE

TA_

X&

Y[m

]

DIS

P_

X&

Y[m

]





Phase slippage in the linac

avk

1

Ncavi

b k ib k i 1

Ebk i 1

b k ih

360

1

2

m

Ebk i

2

Ebk i h Ek

Ef0 Ea0

b7 0 0b5 0 0b3 0 0b1 0 0

b6 0 0b4 0 0b2 0 0b0 0 0Ebk 0 Eak mb k 0 0

i 0 Ncav 1hLlinac

Ncav

Ek

Eak 1 Eak

Llinac

j 0 8Ncav 80k 0 7Llinac 24000

0 1 104

2 104

20

0

20

s [m]

RF

pha

se [

deg]

0 1 104

2 104

3 104

0

5

10

s [m]

RF

pha

se [

deg]

1refi

b2 i 2refi

b3 i

E0 = 2 GeV E0 = 2 GeV




Arc 1 Layout

Arc dipoles

$Lb=150; => 150 cm$ang0=10.3283; => 10.328 deg$Nin=16; => 16$Nout=2; => 2$ang=(90+$ang0)/($Nin-2*$Nout); => 8.36 deg.#$Ang_out=$ang0+2*$Nout*$ang; => 43.77 deg.$Ang_in=2*$Nin*$ang; => 267.54 deg.

$BP=$PI*$Hr*$ang/(180*$Lb); => 6.537

kGauss

$Lring=227.3 m

footprint

-5000

-4000

-3000

-2000

-1000

0

1000

2000

3000

4000

5000

0 2000 4000 6000 8000 10000

z [cm]

x [cm]




Droplet Arc – Optics ‘Building Blocks’

900 phase advance/cell: inward and outward cells, missing dipole, empty cells

90

Fri Dec 03 13:23:10 2004 OptiM - MAIN: - D:\Study 2A\Droplette\A_out.opt

30

0

3-3

BE

TA

_X

&Y

[m]

DIS

P_

X&

Y[m

]BETA_X BETA_Y DISP_X DISP_Y 90

Fri Dec 03 13:24:34 2004 OptiM - MAIN: - D:\Study 2A\Droplette\A_out.opt

30

0

3-3

BE

TA_

X&

Y[m

]

DIS

P_

X&

Y[m

]


90

Fri Dec 03 13:27:09 2004 OptiM - MAIN: - D:\Study 2A\Droplette\L_out.opt

30

0

3-3

BE

TA_

X&

Y[m

]

DIS

P_

X&

Y[m

]

BETA_X BETA_Y DISP_X DISP_Y 4536

Fri Dec 16 13:01:21 2005 OptiM - MAIN: - D:\Study 2A\Droplette\SprTr.opt

30

0

3-3

BE

TA

_X

&Y

[m]

DIS

P_

X&

Y[m

]


footprint

-5000

-4000

-3000

-2000

-1000

0

1000

2000

3000

4000

5000

0 2000 4000 6000 8000 10000

z [cm]

x [cm]




237.30

Fri Jan 20 13:16:02 2006 OptiM - MAIN: - M:\acc_phys\bogacz\ISS_dogbone\Lattice\Arc1.opt

0.5

0P

HA

SE

_X

&Y

Q_X Q_Y

Arc 1 – Mirror-symmetric Optics

dipoles (2 per cell)

$Lb=150; => 150 cm$ang0=10.3283 deg

$ang=(90+$ang0)/($Nin-2*$Nout); =>

8.36 deg

$B=$PI*$Hr*$ang/(180*$Lb); => 6.537

kGauss

quadrupoles (triplet):L[cm] G[kG/cm] 68 -0.326125 0.328 68 -0.326

16 cells2 cells 2 cells

(out = in ,and out = -in , matched to the linacs)

237.30

Fri Jan 20 13:12:52 2006 OptiM - MAIN: - M:\acc_phys\bogacz\ISS_dogbone\Lattice\Arc1.opt

30

0

3-3

BE

TA

_X

&Y

[m]

DIS

P_

X&

Y[m

]


$Nout=2, need minimum of 3 triplets to match 6 Twiss parameters




Straight-Arc Periodic transition

1170

Wed Nov 30 01:22:41 2005 OptiM - MAIN: - D:\ELIC\Figure-8\tran.opt

20

0

0.2

5-0

.25

BE

TA

_X

&Y

[m]

DIS

P_

X&

Y[m

]


Triplet

FODO

1080

Wed Dec 07 10:30:44 2005 OptiM - MAIN: - D:\ELIC\Figure-8\FODO\low_emitt\spr_in.opt

30

0

2-2

BE

TA

_X

&Y

[m]

DIS

P_

X&

Y[m

]





15 GeV Dogbone RLA (6.5 pass)

energy ratio:

2 GeV0.3 GeV

Ef

E0

= 7.5

2 GeV/pass15 GeV




Beam Separation Switchyard

footprint

0

20

40

60

80

100

0 50 100 150 200 250 300 350 400 450 500

z [cm]

x [cm]

5 GeV9 GeV

13 GeV




Summary

‘Dogbone’ RLA – preferred configuration better orbir separation for higher passes

offers symmetric solution for simultaneous acceleration of + and -

FODO lattice more favorable (compared to the triplet) to

accommodate large number of passesuniform phase advance decrease in both planes

smaller variation of Twiss function – easier match to the Arcs

Proposed 12.5 GeV two-step-dogbone RLA (30 mm rad

acceptance)

3.5 pass 5 GeV Dogbone (triplet lattices) – error sensitivity studiesMagnet misalignment error analysis (DIMAD Monte Carlo on the above

lattice) shows quite manageable level of orbit distortion for ~1 mm

level of magnet misalignment error.

Great focusing errors tolerance for the presented lattice 1% of Arc-to-

Arc betatron mismatch limit sets the quadrupole field spec at 0.2%

Aggressive 15 GeV dogbone RLA

operated by the jefferson science associates for the u.s. depart. of energy thomas jefferson...

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