FNAL 8 GeV SC linac / HINS linac Beam Dynamics Jean-Paul Carneiro FNAL Accelerator Physics Center

FNAL 8 GeV SC linac / HINS linac Beam Dynamics

Jean-Paul CarneiroFNAL Accelerator Physics Center

Peter N. Ostroumov, Brahim MustaphaANL

March 13th , 2009

Jean-Paul Carneiro Meeting on HINS Beam Dynamics & Diagnostics, FNAL, March 13h, 2009

HINS / FNAL 8 GeV SC Linacs

▪ FNAL 8 GeV SC linac : 1.56E14 protons per cycle in the MI (~45 mA) 10 Hz, 1 msec, 2 MW at 8 GeV

▪ HINS linac

~ 35 m, ~ 60 MeV

~16 m~10 MeV

~140 m~420 MeV

~670 m~8 GeV

~60 m~120 MeV

325 MHz 1300 MHz

~1.7 km~8 GeV


Content

■ Lattice design of the FNAL 8 GeV linac • Design recipes for high-intensity linacs [ Design and optimization of the FNAL 8 GeV lattice performed with TRACK by P. Ostroumov at ANL and

benchmarked with ASTRA (DESY) by J.-P. Carneiro at FNAL ]

■ TRACK H-minus stripping simulations (gas, blackbody, EM force) • FNAL 8 GeV linac @ 2 MW

■ Work in Progress • New PTRACK (Parallel TRACK) simulations (865 M particles) (PTRACK runs on parallel on BlueGene Supercomputer @ ANL)

• Implementation of diagnostic drifts in the HINS linac lattice


Lattice sections of the FNAL 8 GeV linac

SectionNo.

SectionName

Wout(MeV)

CavitiesNo.

FocusingType

PeriodNo.

Lf(m)

z(m)

1 CH 10 16 S1R 16 0.49- 0.75 17

2 SSR1 32 18 S1R 18 0.75 31.4

3 SSR2 124 33 S2R 18 1.6 61.0

4 TSR 421 42 FRDR 21 3.8 142.2

5 S-ILC 1223 56 F2RD2R 14 6.1 226.7

6 ILC1 2445 63 F4RD3R 9 12.2 336.5

7 ILC2 8000 224 F8RD8R 14 24.2 678.1

Total 8000 452 110 ~678


Design Recipes for High-Intensity Linacs (F. Gerigk, Space Charge and Beam Halo in Proton Linacs, 2003)

■ The zero current phase advance of transverse and longitudinal oscillations should be kept below 90° per focusing period to avoid parametrically-excited instabilities at high current

■ The transverse and longitudinal wavenumbers kx0, ky0, kz0 must change adiabatically along the linac. This feature minimizes the potential for mismatches and helps assure a current independent lattice.

f

LL

f

TT L

kL

k 00

00 ,

Phase advance

Focusing Period Length■ Avoid the n=1 parametric resonance between the transverse and longitudinal motion. It can be avoided by proper choice of operational tunes in the Kapchinskiy stability diagram.

■ Avoid strong space charge resonances by selecting stable areas in the Hofmann’s stability chart

■ Provide proper matching in the lattice transitions to avoid appreciable halo formation and emittance increase


Trans. and Long. Phase Advances (Zero Current) per Focusing Period

■ Transverse and longitudinal oscillations are kept below 90° in most of the focusing periods


Wavenumber(s) along the linac (Zero Current)

■ kT0, kL0 adiabatic despite of many lattice transitions with different types of focusing and inter-cryostat spaces, cavity TTF.

Kapchinskiy stability diagram (Zero Current)(I. M. Kapchinskiy, Theory of resonance linear accelerators, 1985)

O=TRACK x=ASTRA


20

2

3

)sin()(

12 cm

eEL smfs

n=1 parametric resonance


Trans. & Long. Tune depression along the linac (45 mA)

■ Moderate Trans. & Long. tune depression along the linac

Tune depression :Wavenumber with SC

Wavenumber without SC


Hofmann’s Chart for the FNAL 8 GeV linac 45 mA

■ Avoid strong space-charge resonances


RMS emittance growth along the FNAL 8 GeV linac at 45 mA

■ Main contribution from– MEBT, irregular lattice– Inter-cryostat drift space

• Beam diagnostics– Lattice transition

• Increase of focusing length

– Long focusing periods in the S-ILC section

– Beam matching is good but not perfect

■ Emittance growth is low and

acceptable for the HINS PD


Blackbody H-minus Stripping Simulations with TRACK

• H stripping now in the beam dynamics simulation code TRACK (residual gas, black-body radiation, magnetic field)

• Simulation on Fermi Grid (1E6 × 100 runs = statistics on 1E8 particles)

1 W/m limit

Transfer line @ 300 K Transfer line @ 150 K


PTRACK simulations of the FNAL RFQ at 45 mA (BlueGene, ANL)

• 1M

• 10M

• 100M

• 865M32768 processors ~ 5H30


Beam Envelopes Beam Emittances

PTRACK Error simulations of the FNAL 8 GeV linac at 45 mA (100 seeds, 10M each, 4096 processors, ~1H30, BlueGene, ANL)

■ RF errors: all misalignments, 1 deg and 1%, rms Beam Losses (W/m)

PTRACK Error simulations of the FNAL 8 GeV linac at 45 mA (100 seeds, 10M each, 4096 processors, 1H30, BlueGene, ANL)


1 W/m limit

MEBT – Option 1: StriplinesWS (+100)

Tor (+100) Tor (+100)

WS (+100)800?

Strip (0) Strip (0)Strip (0)

Strip (0)

200

HINS lattice with drifts (V. Scarpine / 19-FEB-09)



Comparison HINS lattice with drifts @ 45 mA / Project X @ 45 mA(Implementation of drifts in HINS lattice = Work in Progress)

Trans. Emittance looks OK Long. Emittance needs more tuning

Conclusion

■ New concept of pulsed H-minus/proton linac design has been developed– Fully SC above 10 MeV– Cost-effective design of the SC linac can provide acceptable beam quality for

peak current ~45 mA

■ H-minus stripping simulations now available with PTRACK ■ Work in progress

• High-statistics simulations of machine errors (100E6 × 100 = statistics on 1E10) show acceptable <0.1 W/m losses

• Implementation of drifts in HINS lattice looks OK• Optimization of the lattice in high energy section• Include realistic LLRF model into parallel TRACK


FNAL 8 GeV SC linac / HINS linac Beam Dynamics Jean-Paul Carneiro FNAL Accelerator Physics Center

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