Production of Coherent Synchrotron Radiation at …July 2011 Marit Klein Laboratory for Applications...

KIT – University of the State of Baden-Wuerttemberg andNational Research Center of the Helmholtz Association

LABORATORY FOR APPLICATIONS OF COHERENT SYNCHROTRON RADIATION

www.kit.edu

Marit Klein July 2011

Production of Coherent Synchrotron Radiation at ANKA Using Low-momentum-compaction Lattices

July 2011 Marit Klein Laboratory for Applications of Synchrotron Radiationmarit.klein@kit.edu

Karlsruhe Institute of Technology

ANKA @ Karlsruhe

Karlsruhe Institute of Technology

N. Hiller, A. Hofmann, J.C. Heip, E. Huttel, V. Judin, B. Kehrer,

S. Marsching, S. Naknaimueang, Y.-L. Mathis, A.-S. Müller,

N. Smale, M. Süpfle

Ruhr Universität Bochum E. Bründermann

Cornell UniversityK. Sonnad

Overview

IntroductionThe ANKA storage ringLow-alpha mode and CSR productionStable vs. bursting emission

Measurements with a hot electron bolometer (HEB)

Measurements with a streak camera

Spectral measurements

Modeling the low-alpha mode with the Accelerator Toolbox

The ANKA storage ring

120 ns

368 ns

C = 110.4 mEnergy range: 0.5 - 2.5 GeVRF frequency 500 MHzDBA lattice

Beamlines:13 in operation

4 in construction / commissioning

Normal operation:Energy 2.5 GeV

Current 120-200 mA Multi-bunch (3 trains with 30ish bunches each)

Natural bunch length σz,0 ≈ 13 mm

Low-alpha mode:Coherent THz radiation

Energy 1.3 GeV Current ≈ 0.1 - 70 mA

Single- or multi-bunchNatural bunch length σz,0 ≈ 0.3 - 4.5 mm

ANKA - Parameters

Coherent synchrotron radiation (CSR)Short bunches emit usable coherent synchrotron radiationEnormous increase in power in comparison to incoherent emissionDedicated optics with negative dispersion in the long and short straight sections for flexible bunch length tuning

Low-αc optics

Coherent radiation is produced in two regimes:

low power stable emissionhigh power radiation bursts

The low-alpha mode

Low-alpha user operation: 12 days/year

Operation procedure:Fill at 0.5 GeVRamp energy (regular optics) to 1.3 GeVLow-αc “squeeze”

change quadrupoles & sextupolesorbit correction between steps

Observed αc range as derived from Qs measurements: from 8.5 10-3 to 2.4 10-4

horizontal Dispersion*10 vertical

0 5 10 15 20 25

CSR for Userstime resolved experiments

streak camera port

Synchrotron (Edge) Radiation at IR1

CSR is observed as ‘regular’ synchrotron radiation but also as ‘edge’ radiationCan be an advantage for a beamline

lower frequencies observable for the same aperture

THz Port at ANKA

(src.: ANKA-Archiv)

IR1 - Diagnostic port

source: entrance edge of a bending magnet

flux > 1013photons/s/0.1%bw

5 / 33 Vitali Judin Hot Electron Bolometer at ANKA

-40mm -20 0 20 40x [mm]

Photons/s/.1%bw

^2 x109

(spatial distribution of the radiation 3m from

the source)

(spatial distribution of the radiation 3m fromthe source)

1.0m 0.5 0.0 -0.5 -1.0Position on particle trajectory [m]

fringe field region

-40mm -20 0 20 40x [mm]

Photons/s/.1%bw

^2 x109

Main bending field as sourceSource at ANKA IR: fringe field

Calculated for a frequency of 3 THz

Aperture Aperture

Courtesy Y.-L.Mathis

The THz Beam Profile

incoherent, Amax ≈ 0.1 mV coherent, Amax ≈ 2.9 mV

Courtesy E. Bründermann, Ruhr Universität Bochum

Setup of beam line and detector : measurement behind a Si or CaF2 vacuum windowroom temperature pneumatic (Golay) detectordetector and aperture are mounted on a x-y imaging stage and scanned vs distance and lateral position relative to the vacuum window

The bursting stable thresholdHight electron densities lead to microbunching instability

Measured bursting stable threshold with Si bolometer

Good agreement with theoretical prediction+:

Ithresh ∝ σ7/3s

+G. Stupakov and S. Heifets,Phys. Rev. ST Accel. Beams 5, 054402 (2002)

-6 -4 -2 0 2 4 6

Microbunching cycle

THz Signal and Beam Current

0 50 100 150 200 250 300 350

Time / ns

---- HEB signal---- bunch current in a.u.

The Hot Electron Bolometer (HEB) detects the THz signal of individual bunches

Relative bunch currents from pickup

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.40

bunch current / mA

V = 150 kVRFV

∝ I2bunch

theor. bursting/stable threshold

V. Judin

THz Signal and Beam Current

0 0.05 0.1 0.15 0.2 0.25 0.3 0.350

HEB-backgroundlevel: 0.01427V

bunch current / mA

=150kVRFV

bunch with lower left neighbor

bunch with higher left neighbor

V. Judin

A comparison shows a dependency of CSR on the current of the leading bunch

Investigations with tailor made filling pattern

CSR of Adjacent BunchesCorrelated bursting?

CSR of adjacent bunches

0 500 1000 1500 2000 2500 3000 3500 4000 4500

leading bunch

following bunch

Simultanous increase of the THz-signal intensity

the signals of the bunches are correlated

this effect is being investigated

9 Vitali Judin Longitudinal Diagnostics at ANKA

V. Judin

Effect is under systematic investigation

Radiation Bursts

Bursting behavior dependent on electron density

V. Judin

Streak Camera

s)µSlow time axis (640 pixels = 500 0 100 200 300 400 500 600Fa

500Entries 327680Mean x 319.8Mean y 253.8RMS x 184.8RMS y 145.7

Entries 327680Mean x 319.8Mean y 253.8RMS x 184.8RMS y 145.7

Single image (#45) out of sequence

one bunch over many revolutions

averaged bunch profile

-40 -30 -20 -10 0 10 20 30 400

0.03 = 1.47 mAbunchI = 1.17 mAbunchI = 0.97 mAbunchI = 0.76 mAbunchI = 0.52 mAbunchI = 0.45 mAbunchI = 0.40 mAbunchI = 0.35 mAbunchI = 0.30 mAbunchI = 0.26 mAbunchI = 0.22 mAbunchI

position in bunch / ps

abilit

Double-sweep synchroscan streak camera from HamamatsuOptical port at IR beamline, now new dedicated beam portRecording of sequences of 500 consecutive imagesCorrect for oscillations

N. Hiller

Bunch length

-210×2 -110 -110×2 1 2 3 4 5 6 7 8 910

beam current / mA

ps = 30.8 kHzsf

= 18.6 kHzsf

= 15.1 kHzsf

= 9.3 kHzsf

= 6.6 kHzsf = 5.6 kHzsf

Low currents: Converging to the zero current bunch lengthAbove bursting stable threshold: Turbulent bunch lengthening

empirical fits

N. Hiller

σz ∝ I7/3thresh

frequency (THz)-210 -110 1

FTIRstreak cam.calculationcutoff

CSR spectra are proportional to Fourier transform of the electron distributionSpectral measurements with a Michelson InterferometerExpectation from streak cam. measurement below cutoffExplanation: substructure or stronger deformation

Single shot measurement needed

Measured and Expected Spectra

FFT-40 -30 -20 -10 0 10 20 30 400

0.03 = 1.47 mAbunchI = 1.17 mAbunchI = 0.97 mAbunchI = 0.76 mAbunchI = 0.52 mAbunchI = 0.45 mAbunchI = 0.40 mAbunchI = 0.35 mAbunchI = 0.30 mAbunchI = 0.26 mAbunchI = 0.22 mAbunchI

position in bunch / ps

abilit

Coherent Radiation Comparison of single and multi-bunch fillings

10-210

10AµIbunch = 1295 AµIbunch = 1204 AµIbunch = 1135 AµIbunch = 1074 AµIbunch = 1006 AµIbunch = 953 AµIbunch = 905 AµIbunch = 853 AµIbunch = 814 AµIbunch = 778 AµIbunch = 737 AµIbunch = 704 AµIbunch = 675 AµIbunch = 646 AµIbunch = 615 AµIbunch = 592 AµIbunch = 569 AµIbunch = 542 AµIbunch = 523 AµIbunch = 506 AµIbunch = 485 AµIbunch = 470 AµIbunch = 451 AµIbunch = 439 AµIbunch = 425

-1Wavenumber / cm

10-110

AµIbunch = 743 AµIbunch = 695 AµIbunch = 680 AµIbunch = 666 AµIbunch = 652 AµIbunch = 639 AµIbunch = 626 AµIbunch = 614 AµIbunch = 602 AµIbunch = 590 AµIbunch = 579 AµIbunch = 568 AµIbunch = 558 AµIbunch = 547 AµIbunch = 537 AµIbunch = 528 AµIbunch = 518 AµIbunch = 509 AµIbunch = 500 AµIbunch = 492 AµIbunch = 484 AµIbunch = 476 AµIbunch = 468 AµIbunch = 460 AµIbunch = 453 AµIbunch = 446 AµIbunch = 439 AµIbunch = 432 AµIbunch = 425 AµIbunch = 419 AµIbunch = 413 AµIbunch = 407 AµIbunch = 401 AµIbunch = 395 AµIbunch = 389 AµIbunch = 384 AµIbunch = 379 AµIbunch = 374 AµIbunch = 369 AµIbunch = 364 AµIbunch = 359 AµIbunch = 354 AµIbunch = 350 AµIbunch = 346 AµIbunch = 343

-1Wavenumber / cm

10-110

AµIbunch = 1352 AµIbunch = 863 AµIbunch = 803 AµIbunch = 746 AµIbunch = 700 AµIbunch = 656 AµIbunch = 615 AµIbunch = 576 AµIbunch = 541 AµIbunch = 510 AµIbunch = 480 AµIbunch = 454 AµIbunch = 431 AµIbunch = 409 AµIbunch = 386 AµIbunch = 370 AµIbunch = 353 AµIbunch = 336 AµIbunch = 322 AµIbunch = 308 AµIbunch = 296 AµIbunch = 284 AµIbunch = 275 AµIbunch = 264 AµIbunch = 255 AµIbunch = 248

-1Wavenumber / cm

10-210

210 AµIbunch = 492 AµIbunch = 467 AµIbunch = 443 AµIbunch = 422 AµIbunch = 403 AµIbunch = 384 AµIbunch = 367 AµIbunch = 351 AµIbunch = 336 AµIbunch = 321 AµIbunch = 308 AµIbunch = 295 AµIbunch = 283 AµIbunch = 272 AµIbunch = 262 AµIbunch = 252 AµIbunch = 243 AµIbunch = 234 AµIbunch = 226 AµIbunch = 218 AµIbunch = 211 AµIbunch = 204 AµIbunch = 197 AµIbunch = 191 AµIbunch = 185 AµIbunch = 179 AµIbunch = 174 AµIbunch = 169 AµIbunch = 164 AµIbunch = 159 AµIbunch = 155 AµIbunch = 151 AµIbunch = 147 AµIbunch = 145

-1Wavenumber / cm

single bunch

multi bunch

fs = 9.6 kHz / 5.3 ps fs = 6.6 kHz / 3.8 ps

Filter #2 < 35 cm-1

Gain CurvesComparison of single and multi-bunch fillings

AµIbunch = 1295 AµIbunch = 1204 AµIbunch = 1135 AµIbunch = 1074 AµIbunch = 1006 AµIbunch = 953 AµIbunch = 905 AµIbunch = 853 AµIbunch = 814 AµIbunch = 778 AµIbunch = 737 AµIbunch = 704 AµIbunch = 675 AµIbunch = 646 AµIbunch = 615 AµIbunch = 592 AµIbunch = 569 AµIbunch = 542 AµIbunch = 523 AµIbunch = 506 AµIbunch = 485 AµIbunch = 470 AµIbunch = 451 AµIbunch = 439 AµIbunch = 425

-1Wavenumber / cm

AµIbunch = 743 AµIbunch = 695 AµIbunch = 680 AµIbunch = 666 AµIbunch = 652 AµIbunch = 639 AµIbunch = 626 AµIbunch = 614 AµIbunch = 602 AµIbunch = 590 AµIbunch = 579 AµIbunch = 568 AµIbunch = 558 AµIbunch = 547 AµIbunch = 537 AµIbunch = 528 AµIbunch = 518 AµIbunch = 509 AµIbunch = 500 AµIbunch = 492 AµIbunch = 484 AµIbunch = 476 AµIbunch = 468 AµIbunch = 460 AµIbunch = 453 AµIbunch = 446 AµIbunch = 439 AµIbunch = 432 AµIbunch = 425 AµIbunch = 419 AµIbunch = 413 AµIbunch = 407 AµIbunch = 401 AµIbunch = 395 AµIbunch = 389 AµIbunch = 384 AµIbunch = 379 AµIbunch = 374 AµIbunch = 369 AµIbunch = 364 AµIbunch = 359 AµIbunch = 354 AµIbunch = 350 AµIbunch = 346 AµIbunch = 343

-1Wavenumber / cm

AµIbunch = 1352 AµIbunch = 863 AµIbunch = 803 AµIbunch = 746 AµIbunch = 700 AµIbunch = 656 AµIbunch = 615 AµIbunch = 576 AµIbunch = 541 AµIbunch = 510 AµIbunch = 480 AµIbunch = 454 AµIbunch = 431 AµIbunch = 409 AµIbunch = 386 AµIbunch = 370 AµIbunch = 353 AµIbunch = 336 AµIbunch = 322 AµIbunch = 308 AµIbunch = 296 AµIbunch = 284 AµIbunch = 275 AµIbunch = 264 AµIbunch = 255 AµIbunch = 248

-1Wavenumber / cm

AµIbunch = 492 AµIbunch = 467 AµIbunch = 443 AµIbunch = 422 AµIbunch = 403 AµIbunch = 384 AµIbunch = 367 AµIbunch = 351 AµIbunch = 336 AµIbunch = 321 AµIbunch = 308 AµIbunch = 295 AµIbunch = 283 AµIbunch = 272 AµIbunch = 262 AµIbunch = 252 AµIbunch = 243 AµIbunch = 234 AµIbunch = 226 AµIbunch = 218 AµIbunch = 211 AµIbunch = 204 AµIbunch = 197 AµIbunch = 191 AµIbunch = 185 AµIbunch = 179 AµIbunch = 174 AµIbunch = 169 AµIbunch = 164 AµIbunch = 159 AµIbunch = 155 AµIbunch = 151 AµIbunch = 147 AµIbunch = 145

-1Wavenumber / cm

fs = 9.6 kHz / 5.3 ps fs = 6.6 kHz / 3.8 ps

single bunch

multi bunch

Filter #2 < 35 cm-1

ObservationsMulti bunch gain curve seems to lie significantly higher than single bunch curve for similar single bunch current for longer bunchesFor shorter bunches, the curves are closer

410 A, single bunchµ = 9.6kHz, 500s- fA, multi bunchµ = 9.6kHz, 490s- f

-1Wavenumber / cm

510 A, single bunchµ = 6.6kHz, 420s- fA, multi bunchµ = 6.6kHz, 420s- f

-1Wavenumber / cm

fs = 9.6 kHz / 5.3 ps

fs = 6.6 kHz / 3.8 ps

preliminary

preliminaryHypothesis: effects from the ring impedance are more significant if the CSR effect is less pronounced

Modeling the low-alpha mode with AT

measured fs model α0

A 30.7 kHz 8.5 ·10−3

B 29.2 kHz 7.8 ·10−3

C 24.2 kHz 5.7 ·10−3

D 8.5 kHz 0.74 ·10−3

E 6.7 kHz 0.46 ·10−3

Measurements for each model:Tunes: Qx, Qy, Qs

Orbit response matrixDispersionChromaticity

5 different low-alpha optics modeled

LOCO fits and Chroma fitsMagnet strength calculated from currents settingsCorrection of quadrupole strength:

LOCO fit of response matrices and dispersionsAdditional quadrupole components

fit of tunes and chromaticity curve shapesCorrection of sextupole strength

fit of chromaticity values 0 5 10 15 20 25 301.5

model Amodel E

1 0.5 0 0.5 1x 104

1000 500 0 500 1000

1 0.5 0 0.5 1x 104

1000 500 0 500 10000.01

horizontal vertical

Optics functions

0 5 10 15 20 25

s position / m

model A x

0 5 10 15 20 25

s position / m

model C x

0 5 10 15 20 25

s position / m

model D x

0 5 10 15 20 25

s position / m

model E x

0.75 0.8 0.85 0.9 0.950.65

ABCDE2nd3rd4th

0 0.002 0.004 0.006 0.008 0.010

1.5 x 10 4

alpha(model)

meas.model

Q2s ∝ α

Synchrotron tune:approximate the measurementsno impact seen in AT of higher order terms on synchrotron tune

Betatron tunes:approximate the measurementsbest agreement for lowest αlargest difference in the horizontal betatron tune

emphasis in modeling on sychrotron tune

Higher order alpha

-1 0 1-310×

6.6-310×

-5 0-310×

0.6-310×

model C

model E

α0 = +(6.28 ± 0.0014) · 10−3

α1 = −(99 ± 6) · 10−3

α0 = +(0.447 ± 0.004) · 10−3

α1 = −(20 ± 1) · 10−3

α2 = −(2, 710 ± 300) · 10−3

α3 = −(190, 000 ± 90, 000) · 10−3

⇒ αc = α0 + α1δ + α2δ2 + α3δ

3 + ...

αp =dL/L

dp/pαc =

∆L/L0

∆p/p0=⇒ αp =

1 + δ

1 + αcδ

d(αcδ)

fs(fRF ) → αp(dp/p) = αp(δ)

Longitudinal phase space

0.4 0.2 0 0.2 0.4 0.60.03

s / m0 0.1 0.2 0.3

model A model E

fixpointsLow α0 ➞ higher order terms have to be consideredAdditional fixpoints at:

Measurement: α0

α1= −0.023± 0.001

p fix≈ α0

α1= −0.036

Dynamic aperture

0.05 0 0.050

2 E1 E

01 E2 E

ph. ap.

0.05 0 0.050

2 E1 E

01 E2 E

ph. ap.

0.05 0 0.050

2 E1 E

01 E2 E

ph. ap.

0.05 0 0.050

2 E1 E

01 E2 E

ph. ap.

model A model C

model D model E

DA for different chromticities

0.05 0 0.050

model A

ΔQx‘ ΔQy‘-2-2-2-2-2-1-1-1-1-100000+1+1+1+1+1+2+2+2+2+2

-2-10+1+2-2-10+1+2-2-10+1+2-2-10+1+2-2-10+1+2 0.05 0 0.05

model E

-2-2-2-2-2-1-1-1-1-100000+1+1+1+1+1+2+2+2+2+2

-2-10+1+2-2-10+1+2-2-10+1+2-2-10+1+2-2-10+1+2

ΔQx‘ ΔQy‘

Small chromaticities enlarge dynamic apertureLow α0 optics are more sensitive to chromaticity changes

Summary

Regular low-alpha user operation

Characterized the properties of the CSRcalculated and observed bursting/stable thresholdinvestigated radiation behavior with HEB

Bunch shape and length measurements with streak camera

Spectral measurements, comparison multi and single bunch

Beam based modeling of the low-alpha modehigher order momentum compactionsecond stable fixpoints in long. phase spacedynamic aperture investigation

Outlook

Simulations of microbunching instability and bursting behavior with a Vlasov-Solver

Bunch to bunch interaction?

HEB leading bunch analysis, bursting triggering with additional wake fields

Single shot measurements of electron distribution with electrooptical sampling

0 0.05

0.1 0.15

0.2 0.25

0.3 0.35

followingleading

itylong. pos.

Production of Coherent Synchrotron Radiation at …July 2011 Marit Klein Laboratory for Applications...

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