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Lattice optimization for low charge Lattice optimization for low charge state heavy ion operation state heavy ion operation state heavy ion operation state heavy ion operation Collimation concepts for beam ions Collimation concepts for beam

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SLIDE 1

Lattice optimization for low charge Lattice optimization for low charge state heavy ion operation state heavy ion operation state heavy ion operation state heavy ion operation Collimation concepts for beam ions Collimation concepts for beam ions after a charge change after a charge change

CERN Collimator Workshop 3rd-5th Sep. 2007 Jens Stadlmann, FAIR Synchrotrons

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SLIDE 2

Contents Contents

  • Motivation: Heavy ions of intermediate charge states for the

FAIR project at the GSI FAIR project at the GSI

  • Benchmarking of different lattice concepts for SIS100
  • Conclusion

Conclusion

3rd-5th September

  • J. Stadlmann
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SLIDE 3

The Future Accelerator Facility - FAIR

SIS 100/300 UNILAC SIS18 HESR

Gain Factors

Super FRS CR

Primary beam intensiy : x 100 – 1000 Secondary beam intensiy : x 10000

Ion energy : x 15

NESR

Ion energy : x 15 New: cooled pbar beams (15 GeV) Special : intense cooled RIBs Parallel operation and time sharing 3rd-5th September

  • J. Stadlmann

p g

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SLIDE 4

Motivation: Beam Life Time in FAIR Synchrotrons

High intensity heavy ion beams require intermediate charge states High intensity, heavy ion beams require intermediate charge states

Dynamic Pressure Static Pressure

Life Time of U28+ is

significantly shorter than of U73+ Desorption Processes degenerate the residual gas pressure Life Time of U28+ depends strongly on the residual gas the residual gas pressure Beam losses increase with number of injected ions

3rd-5th September

  • J. Stadlmann

strongly on the residual gas pressure and gas components number of injected ions (vacuum instability)

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SLIDE 5

Residual Gas Pressure Dynamics

Fast variations (time scale ms) Slow variations (time scale s h) Fast variations (time scale ms) Slow variations (time scale s - h) up to two orders of magnitude

3rd-5th September

  • J. Stadlmann
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SLIDE 6

Short cycle time and short sequences

Main Issue: Vacuum Stabilization

SIS18: 10 T/s - SIS100: 4 T/s (high pulse power > new network connection)

High pumping power, optimized XHV spectrum

SIS18: NEG coating (local and distributed) g ( ) SIS100: Actively cooled magnet chambers 4.5 K

Localization of losses and control

increased pressure

  • f desorption gases

SIS18/SIS100: Desoprtion Scrapers

wedge collimator ion beam

SIS100: Optimized lattice structure

Low-desorption rate materials

D ti t d ERDA t

3rd-5th September

  • J. Stadlmann

Desorption rate and ERDA measurements Minimization of systematic (inital) losses

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SLIDE 7

Initial loss mechanisms Initial loss mechanisms

3rd-5th September

  • J. Stadlmann
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SLIDE 8

Special lattice layout to control the dynamic vaccum Special lattice layout to control the dynamic vaccum

Basic principles

  • The ions should not be lost at arbitrary positions.
  • The losses should be peaked in sections with

p p Peaked! The losses should be peaked in sections with sufficient space for a dedicated scraper system

  • The scrapers should not reduce the acceptance.
  • The circulating beam and the contaminants should

be clearly separated at the positions of the scrapers which requires a waist in the beam Separated! envelope and dispersive elements upstream.

  • Ideally all unwanted ions which are produced in the

downstream section after one scraper should be downstream section after one scraper should be able to be transported at least to the next

  • collimator. (High tune or increased aperture)

Acceptance!

3rd-5th September

  • J. Stadlmann
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SLIDE 9

New Lattice Design Concept for U28+

1. From all loss mechanisms, only charge change by

  • a
  • ss

ec a s s, o y c a ge c a ge by collisions with the residual gas atoms leads to loss within one lattice cell ! 2 Each lattice cell is designed as a charge separator The stripped“ beam ions (U29+) 2. Each lattice cell is designed as a charge separator. The „stripped beam ions (U ) are well separated from the reference beam. (The low dispersion function in the SIS100 arcs complicate this issue.) 3 The main lattice structure optimization criteria is the catching efficiency for U29+-ions 3. The main lattice structure optimization criteria is the catching efficiency for U ions. 4. The catching efficiency for U29- ions must be close to 100%. % ff 5. The 100 % catching efficiency must be achieved with scrapers at maximum distance from the beam edge. No acceptance reduction is caused by the catcher system.

  • 6. The ionization beam losses on cold and NEG coated surfaces shall be minimized.

Minimum additional load for the UHV and the cryogenic system.

3rd-5th September

  • J. Stadlmann

Minimum additional load for the UHV and the cryogenic system.

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SLIDE 10

Comparison of Scraper Efficiency

ηcoll = Ncoll/Ntotal at injection energy at injection energy

High charge scraping effcienc as High charge scraping effciency was reached by lattice (cell) optimization. Many lattice structures have been compared compared.

Strahlsim -> Talk by C. Omet

3rd-5th September

  • J. Stadlmann
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SLIDE 11

Comparison of scraper efficiency of all studied lattices

SIS 100 Design I: Lattice Choice and Optimization

Vergleich alle Lattices

95% 100%

CDR (TR_DFD_4Dipole3.0Grad2.0T_08_Ausgelagert) TR_DFD_3Dipole2.9Grad2.0T_09 TR_DFD_3Dipole3.0Grad2.0T_09_Aus TR DFD 3Dipole3.0Grad2.0T 10 Ausgelagert

Comparison of scraper efficiency of all studied lattices

85% 90% 95%

TR_DFD_3Dipole3.0Grad2.0T_10_Ausgelagert TR_FDF_3Dipole2.9Grad2.0T_09 TR_FDF_3Dipole3.0Grad2.0T_09_Ausgelagert TR_FDF_3Dipole3.0Grad2.0T_10_Ausgelagert DOFO_2Dipole3.0Grad2.0T_17 DP_DF_2Dipole3.0Grad2.0T_13_Tune DP_DF_2Dipole3.0Grad2.0T_13_Ausgelagert DP_DF_2Dipole3.0Grad2.0T_13_Aus_Tune DP_DF_2Dipole3.0Grad2.0T_14 DP_DF_2Dipole3.0Grad2.0T_14_Tune DP DF 2Di l 3 0G d2 0T 14 A l t

75% 80%

limationseffizienz

DP_DF_2Dipole3.0Grad2.0T_14_Ausgelagert DP_DF_2Dipole3.0Grad2.0T_14_Aus_Tune DP_DF_2Dipole3.0Grad2.0T_15 DP_DF_2Dipole3.0Grad2.0T_15_Ausgelagert DP_DF_2Dipole3.0Grad2.0T_15_Aus_Tune DP_DF_2Dipole3.0Grad2.0T_15_Aus_T2 DP_DF_2Dipole3.3Grad1.9T_13_Ausgelagert DP_DF_2Dipole3.3Grad2.0T_13 DP_DF_2Dipole3.3Grad2.0T_13_Ausgelagert DP DF 2Dipole3.3Grad2.0T 14

65% 70%

Koll

_ _ p _ DP_DF_2Dipole3.3Grad2.0T_14_Ausgelagert DP_DF_3Dipole2.7Grad2.0T_11_Ausgelagert DP_DF_3Dipole2.9Grad2.0T_11 DP_DF_3Dipole2.9Grad2.0T_12 DP_DF_3Dipole3.0Grad1.9T_11_Ausgelagert DP_DF_3Dipole3.0Grad2.0T_11_Ausgelagert DP_DF_3Dipole3.0Grad2.0T_12_Ausgelagert DP_DF_3Dipole3.3Grad2.0T_11 DP_DF_3Dipole3.3Grad2.0T_12 DP FD 2Dipole3 0Grad2 0T 15

55% 60% 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2

Abstand von Strahlachse / n*R(k v Verteilung)

DP_FD_2Dipole3.0Grad2.0T_15 DP_DF_2Dipole3.0Grad2.0T_16_Aus_11/2_Tune DP_DF_2Dipole3.0Grad2.0T_16_Aus_11/2 DP_DF_2Dipole3.0Grad2.0T_16_Aus_11/2_19_17 DP_DF_2Dipole3.0Grad2.0T_16_Aus_11/2_28_16 DP_DF_2Dipole3.0Grad2.0T_16_Aus_11/2_28_20

3rd-5th September

  • J. Stadlmann

Abstand von Strahlachse / n*R(k-v-Verteilung)

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SLIDE 12

SIS100 design II, the chosen structure SIS100 design II, the chosen structure

DF doublet lattice

good

A waist after the dispersive elements.

3rd-5th September

  • J. Stadlmann
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SLIDE 13

SIS100 design III SIS100 design III

Problematic: FODO structure

good bad g bad

One half cell is ok, next one is bad.

3rd-5th September

  • J. Stadlmann
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SLIDE 14

SIS100 design IV SIS100 design IV

Not optimal: triplet structure

good bad

Would work, if all dispersive elements are in the first half of the cell

3rd-5th September

  • J. Stadlmann

the first half of the cell.

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SLIDE 15

SIS100 design V: Special lattice SIS100 design V: Special lattice

The doublet structure with high

Results and influence of better transmission

The doublet structure with high momentum acceptance delivers best

  • results. An unwanted particle just

missing one collimator is "stored" missing one collimator is stored and can be collimated later.

Comparison Lattices Structures for SIS100 100,0% 95,0% 97,5% CDR (Triplett) FODO Dublett Speichermode Dublett

ciency

90,0% 92,5% Speichermode Dublett

mation effic

85,0% 87,5% 1 1,1 1,2 1,3 1,4 1,5 1,6 1,7 1,8 1,9 2 2,1

collim

3rd-5th September

  • J. Stadlmann

distance from beam edge [x/beam radius]

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SLIDE 16

Problem 1: Multiple Ionisation Problem 1: Multiple Ionisation p

R Olsen et al HIF04

Ave

SIS18 LEAR

  • R. Olsen et.al., HIF04

SIS100 injection energy SIS18 injection energy

erage num

experimental P = 3.67x10-11 P = 2.87x10-11 H2 – 81.87 % H2 – 83.18 %

SIS100 injection energy

mber of p

2

8 8 % CH4 – 11.86 % CO – 3.02 % Ar – 3.25 %

2

83 8 % He – 2.36 % CH4 – 10.38 % CO – 1.73 % N2 – 1.38 % Ar 0 97 %

  • proj. loss

Ar – 0.97 %

electrons E [MeV/u] s M lti l i i ti d th i ffi i

  • A. Smolyakov

3rd-5th September

  • J. Stadlmann

Cross section interpolation

Multiple ionization reduces the scraping efficiency The total number of multiple ionized particles is low

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SLIDE 17

Problem 2: Different working points

The scraping efficiency depends slightly on the tune.

3rd-5th September

  • J. Stadlmann
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SLIDE 18

Problem 3: Behaviour of lighter ions

The scraper system is optimized for heavy ions. Lighter ions miss the scraper and are dumped in the beam pipe.

3rd-5th September

  • J. Stadlmann

The loss rate of light ions is low, since the cross sections are lower (will be calculated).

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SLIDE 19

80.

SIS100 scraper position

[mm] 8

  • x[mm].. +x[

path length [mm]

  • 80.

Envelopes at maximum acceptance show the position of the cathersnot interacting with the stored beam.

3rd-5th September

  • J. Stadlmann
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SLIDE 20

Beta Beam loss in existing PS Beta Beam loss in existing PS

Heβ beam Neβ beam

3rd-5th September

  • J. Stadlmann
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SLIDE 21

Beta beam loss in an possible new PS Beta beam loss in an possible new PS

Heβ beam Neβ beam

3rd-5th September

  • J. Stadlmann
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SLIDE 22

Conclusion and Outlook Conclusion and Outlook

W f d SIS100 l tti t f FAIR h i

  • We found a SIS100 lattice concept for FAIR heavy ion
  • peration which limits the charge exchange induced

losses to a dedicated scraper system losses to a dedicated scraper system

  • No ions are lost on cold surfaces during U28+ Operation
  • The scraper system does not limit the machine's
  • The scraper system does not limit the machine s

acceptance

  • Basic principles of peaked loss distribution can be applied

Basic principles of peaked loss distribution can be applied to other problems (Beta beams at CERN)

  • Studies for light ions and fragments passing the scrapers

have to be done

3rd-5th September

  • J. Stadlmann