Collimation in the ILC BDS Carl Beard ASTeC Daresbury Laboratory People Requirement Recent Successes...

Collimation in the ILC BDS

Carl Beard

ASTeC Daresbury Laboratory

•People

•Requirement

•Recent Successes

•Future Aims

Carl Beard – Cockcroft SAC Meeting 23rd – 24th November 2006

People

Task Leader – Nigel Watson (B’ham) Damage Studies

L. Fernandez (ASTeC), A.Bungau (Manc) R. Barlow (Manc) G. Elwood (RAL), J. Greenhaulgh (RAL).

Wakefield Simulation and TDR C. Beard (ASTeC), J. Smith (Lanc), R. Jones (Manc), R.Carter

(Lanc), S Jamison (ASTeC), P Corlett (ASTeC)… I. Zagorodnov (DESY), M.Kärkkäinen, W.Müller, T.Weiland (TEMF)

Beam Tests (T-480 Experiment) Frank Jackson…plus most of the above SLAC ESA Team – Steven Malloy, Mike Woods…


Need for Collimation

Reduce the background levels in the detector, by removing halo particles built up over the long linac.

Machine Protection, in the event of a beam miss-steer.

Collimators are introduced, as a result of this the change in impedance has detrimental effects to the beam quality.

The collimators have to be robust to withstand the full impact of several ILC Bunches.

Design / optimisation of spoiler jaws (geometry and materials) for wakefield

and beam damage performance


Development of Advanced EM modelling methods Benchmarking of wakefield calculations against

experiments SLAC ESA beam test / data analysis RF bench tests (training/code comparisons)

Tracking simulations with best models of wakefields Simulations of beam damage to spoilers Material studies using beam test

Submitted 7 papers at EPAC, several EUROTeV reports/memos

Objectives


Collimator Parameter and Beam Parameters

Beam Energy, GeV 250, 500

Material Cu, Ti, C

Penetration (mm) 2 to 10

e- Particles/bunch 2 x 1010

Copper

Fracture temperature ~200 °C (473 K)

Melting temperature 1085 °C (1357.77 K)


Collimator Proposals

0.3 Xo of Ti alloy each side, central graphite part (blue).

0.6 Xo of Ti alloy leading taper (gold), graphite (blue), 1 mm thick layer of Ti alloy

Ti/C

2 mm, 10mm

250, 500 GeV e-


Cu+Graphite spoiler

∆T [K]; 250 GeV e- ∆T [K]; 500 GeV e-

2 mm from top 465 K 860 K

10 mm from top 440 K 870 K

Difference -5% 1%

Fracture temp.

Melting temp.

Carbon zones Cu zones

500 GeV:σx = 79.5 µm, σy= 6.36 µm

250 GeV:

σx = 111 µm, σy= 9 µm


Ti / Graphite Spoiler

∆Tmax = 575 K per a bunch of 2E10 e- at 500 GeV

σx = 79.5 µm, σy= 6.36 µm

270 K

405 K

540 K

2 mm deep from top

Ti alloy and graphite spoiler

400 K

Temperature data in the left only valid the Ti-alloy material. Top increase of temp. in the graphite ~400 K. Dash box: graphite region.

[L.Fernandez, ASTeC]


Fluka Benchmark

0

100

200

300

400

500

600

700

0.5 1 1.5 2 2.5 3

Incident e-/um^2 (+/- 2 sigma)x10^7

Mel

ted

area

(um

^2)

Measurements courtesy of SLAC, Marc Ross et al.

Fluka Prediction of beam Damage (Evaporated material not considered

Measurements of Beam damage crater in cooper on the FFTB.


Damage Studies

Beam tests are being planned to benchmark the Fluka/Geant Simulations No electron beam is available with sufficient intensity Or probability to hit the same point due to beam jitter.

Dynamic Simulations in ANSYS are being studied in support of the FLUKA/GEANT Simulations


Wakefield Analysis

Analytical Formula

Simulation Bench Tests (TDR)

Tests with Beam

Instant solution for only simple geometry

Real life measurements, slow turnaround time for measurements

Good indicator – poor resolution

Fast Results – Limited by Resolution/ confidence


Simulation and Wire tests

Current TDR and TDT measurements are limited to 10 ps Pulse lengths.

TDR and TDT are being used to measure the Impedance of a vessel and its loss factor

Loss Parameter

-1.5

-1

-0.5

0

0.5

1

1.5

2

2.5

1E-09 1.2E-09 1.4E-09 1.6E-09 1.8E-09 2E-09 2.2E-09

Time (s)

Vo

lts

Launch Pulse

Transmitted Signal


Achieving a 1 ps Pulse (In development)


MAFIA Simulations

y = 0.5856x3 - 1E-14x2 + 0.4088x - 1E-13

-8

-6

-4

-2

0

2

4

6

8

-2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5

Beam Off set (mm)

Kic

k F

ac

tor

(V/p

C/m

m)

0.5mm Bunch

Poly. (0.5mm Bunch)

-15

-10

-5

0

5

10

15

0 0.001 0.002 0.003 0.004 0.005 0.006

Distance Z (mm)

Wakep

ote

nti

al (V

/pC

)

500 micron bunch

2mm offset

1.2mm offset

0.8mm offset

0.4mm offset


Limitations / Advances

Limiting the simulations to short structures or only sufficient resolution for >>300 um bunch length.

A new technique is being applied to allow full structures to be simulated with substantially higher resolution

MAFIA/HFSS

GDFIDL / ECHO 2 &3D


Beam Tests in ESA

Simple Shapes to allow benchmarking with Calculations/Code Geometric Wakefields Resistive Wall Wakefields Surface Roughness

=/2rad

r=3.8mm4

335mrad

r=1.4mm3

335mrad

r=1.4mm2

=335mrad

r=1.9mm1

Beam viewSide viewSlot

=/2rad

r=3.8mm4

335mrad

r=1.4mm3

335mrad

r=1.4mm2

=335mrad

r=1.9mm1


h=38 mm

38

mm

h=38 mmh=38 mm

38

mm

38

mm

L=1000 mmL=1000 mmL=1000 mm

7mm

r=1/2 gate

=298mrad

=168mrad

r1 =3.8mm

r2 =1.4mm

4

1=/2 rad

2=168mrad

r1=3.8mm

r2=1.4mm

3

168mrad

r=1.4mm2

=/2rad

r=1.4mm1


=298mrad

=168mrad

r1 =3.8mm

r2 =1.4mm

4

1=/2 rad

2=168mrad

r1=3.8mm

r2=1.4mm

3

168mrad

r=1.4mm2

=/2rad

r=1.4mm1


h=38 mmh=38 mm

38 m

m38

mm

7 mm

208mm

28mm

159mm


T-480 Experiment

Vertical mover

BPMBPM

2 doublets

~40m

BPM BPM

Two triplets

~16m

Wakefields measured in running machines: move beam towards fixed collimators

Problem Beam movement oscillations Hard to separate wakefield effect

Solution Beam fixed, move collimators around beam Measure deflection from wakefields vs. beam-collimator separation Many ideas for collimator design to test…


Wakefield Box

ESA z ~ 300m – ILC nominaly ~ 100m (Frank/Deepa design)

Magnet mover, y range = mm, precision = 1m

1500mm

Ebeam=28.5GeV


Initial Comparison of Results

Just selecting one ref run (slot 0 ref) Just selecting one ref run (same slot ref)run q1 dq1 chisq/n run q1 dq1 chisq/n

599 -1.0117E-11 3.70281E-12 0.556841 599 -7.13552E-12 3.69547E-12 0.811254624 -1.16155E-13 3.39041E-12 0.861219 624 -6.36929E-13 3.4007E-12 1.153441

1491 1.26302E-11 1.10968E-12 73.30665 1491 1.26302E-11 1.10968E-12 73.30665w. mean 9.78258E-12 1.01429E-12 w. mean 9.96031E-12 1.01441E-12w. mean chisq -4.92422E-12 2.0283E-12 w. mean chisq-3.13033E-12 2.38158E-12

% %kf 1.74034675 0.180444912 10.36833 kf 1.771965811 0.180466779 10.18455

-0.876031954 0.360840007 -41.19028 kf (using chisq)-0.556893046 0.423690061 -76.08105

Analytical: 0.562 V/pC/mm

MAFIA: 0.408 V/pC/mm

Beam Test 0.556 V/pC/mm


Future Work

Continue study into beam damage/materials In the process of designing a 4th beam test

Collimators designed and built in EU, to be installed at SLAC ESA. 3rd Physics run Mar/April 2007

Application of the Moving Mesh Technique TDR Measurements with Optically generated 1 ps Pulse. Combine information on geometry, material, construction,

to find acceptable baseline design regarding all of Wakefield optimisation Collimation efficiency Damage mitigation

Collimation in the ILC BDS Carl Beard ASTeC Daresbury Laboratory People Requirement Recent Successes...

Documents

Transcript of Collimation in the ILC BDS Carl Beard ASTeC Daresbury Laboratory People Requirement Recent Successes...