Compare options: Compare options: simulations recent historysimulations recent historyCompare options: Compare options: simulations recent historysimulations recent history

Cloud density near (r=1mm) beam (m-3) before bunch passage, values are taken at a cloud equilibrium density. Solenoids decrease the cloud density in DRIFT regions, where they are only effective. Compare options LowQ and LowQ+train gaps. All cases wiggler aperture 46mm.

Electron Cloud: need for mitigation

Outstanding Questions about key remedies:

1) Are thin film coatings effective to stably decrease SEY < 1.2 ? Is “conditioning” effective to stably decrease SEY < 1.2 ?

2) Fins: are fin-chambers viable to suppressing electron cloud in magnets ?

(resolve simulation discrepancy)

3) Clearing electrodes: is RF power load tolerable ? are impedance and HOM tolerable ?

ILC DAMPING RING R&D OBJECTIVES

2.2.3 Electron Cloud

2.2.3.1 Characterize electron-cloud build-upRequired for Baseline Priority: 12.2.3.2 Develop electron-cloud suppression techniquesRequired for Baseline Priority: 12.2.3.3 Develop modeling tools for e-cloud instabilitiesRequired for Baseline Priority: 1 2.2.3.4 Determine electron-cloud instability thresholdsRequired for Baseline Priority: 1

2.2.4 Ion Effects

2.2.4.1 Characterize ion effectsRequired for Baseline Priority: 1 2.2.4.2 Specify techniques for suppressing ion effectsRequired for Baseline Priority: 1

COLLECTIVE INSTABILITIES: PRIORITIES

4

Electron cloud issues: Milestones

1. Test clearing electrodes

(a) characterize impedance, HOM, power load

(b) machine studies

2. Test groove concepts

(a) characterize impedance, HOM, power load

(b) machine studies

3. Test coating techniques

(a) Secondary electron yield measurements

(b) machine studies

4. Characterize the electron cloud build up

5. Characterize the electron cloud instability

6. Integrated modeling: cloud, impedance, space charge..

Investigate alternative solutions

5

Ion issues: Milestones

1. Characterize ion effects

2. Specify techniques for suppressing ion effects

R&D MILENSTONES

TOWARDS A

TECHNICAL DESIGN REPORT TDR (2008)

7

Electron cloud issues: MilestonesTest clearing electrodes

(a) characterize impedance, HOM, power load

analytical estimates

simulate MAFIA, A. Krasnyhk, Cho Ng

simulate with VORPAL, V. Ivanov (?)

simulate, F. Caspers

(b) machine studiestest in HCX in a quadrupole or drift region, A. Molvik

test in ESA preliminary to PEPII installation, M. Pivi,

test in PEPII in bend chicane, M. Pivi

test in CESR in wiggler section, M. Palmer

test in KEKB arc section bend or wiggler section, Y. Suetsugu

test in LHC arc section bend section, F. Caspers

(c) develop diagnostic electron cloud diagnostic for test chambers, A. Molvik

electron cloud diagnostic for test chambers, R. Macek

8

Electron cloud issues: Milestones

Test groove concepts

(a) characterize impedance, HOM

K. Bane numerical estimation, G. Stupakov analytical

(b) machine studies

rectangular grooves drift SLAC, M. Pivi

triangular grooves in bend section SLAC, M.Pivi

triangular grooves in wiggler section CESR, M. Palmer

(c) develop diagnostic

electron cloud diagnostic for test chambers, A. Molvik

electron cloud diagnostic for test chambers, R. Macek

9

Electron cloud issues: Milestones

Test coating techniques and determine conditioning effectiveness

(a) Secondary electron yield measurements

measuring SEY, Y. Suetsugu

measuring SEY, R. Kirby

measuring SEY, (N. Hilleret)

(b) machine studies

installation of test chambers in KEKB Cu, TiN, NEG, Y. Suetsugu

SEY conditioning test in PEP-II, M. Pivi

Installation of chambers in CESR, M. Palmer

(c) manufacturing and diagnostics

building chambers for installations, S. Marks

10

Electron cloud issues: Investigators

Characterize the electron cloud build up

wiggler 3D simulations CLOUDLAND, L. Wang

wiggler 3D simulations WARP/POSINST, C. Celata

characterize ecloud in quadrupole, M. Pivi

characterize ecloud in quadrupole, C. Celata

fill pattern as possible mitigation, M. Venturini

compile e-cloud density over the machine, M. Pivi

optimize clearing electrode design, (Cornell)

optimize clearing electrode design, L. Wang

optimize clearing grooves design, W. Bruns

optimize clearing grooves design, L. Wang

optimize clearing grooves design, M. Venturini

11

Electron cloud issues: Milestones

Characterize the electron cloud instabilityCharacterize single-bunch instability PEHTS, K. Ohmi

Characterize single-bunch instability HEAD-TAIL, F. Zimmermann

Characterize single-bunch instability quasi-static QUICKPIC, P. Spentzouris

Characterize single-bunch instability in wiggler 3D WARP, C. Celata

Characterize single-bunch instability in lattice CMAD, M. Pivi

12

Electron cloud issues: Milestones

6. Integrated modelingCharacterize instability FRAMEWORK, P. Spentzouris

13

Electron cloud issues: Timescale

Test clearing electrodes

In PEP-II by 2007

In CESR by 2008

Test groove concepts

In PEP-II by 2007

In CESR by 2008

Test coating techniques

In KEKB, by 2007

In PEPII, by 2007

In CESR, by 2008

Characterize the electron cloud build up

Compile list of electron cloud density in ring by 2007

Characterize the electron cloud instability

by TDR

Integrated modeling

by TDR

14

Ion issues: Milestones

1. Characterize ion effects

to be discussed

2. Specify techniques for suppressing ion effects

to be discussed

15

Ion issues: Timescale

1. Characterize ion effects

by date …

2. Specify techniques for suppressing ion effects

by date …