Coherent Synchrotron Radiation in the ANKA Storage Ring · Marcel Schuh - Coherent Synchrotron...

KIT – University of the State Baden-Wuerttemberg and National Laboratory of the Helmholtz Association

Laboratory for Applications of Synchrotron Radiation (LAS) / Institute of Synchrotron Radiation (ISS)

[email protected]

Coherent Synchrotron Radiation in the ANKA Storage Ring

Marcel Schuh On behalf of the ANKA THz-Group

http://www.kit.edu

http://www.kit.edu

Marcel Schuh - Coherent Synchrotron Radiation in the ANKA Storage Ring - FLS2012

OutlineANKA storage ring

Operating with a low-alpha optics

Studies of / with CSR

Bursting patterns & micro bunching instability

Influence of geometric impedance

Influence of long range wake fields

Next steps

Summary

2


ANKA Storage RingKey parameters:

Circumference: 110.4 MeterRF-frequency: 500 MHzRevolution time: ≈ 368 nsHarmonic number: 184Lattice: double DBA

Normal operation mode:Beam energy: 2.5 GeVMulti bunch mode: up to 200 mABunch length: > 30 ps

3

! a

nd

D*10 [

m]

s [m]

horizontal ! Dispersion*10 vertical !

0

5

10

15

20

25

30

0 5 10 15 20 25


Ports Used for Accelerator Studies

4

IR1 beamline

IR2 beamlinein commissioning

THz port planned

courtesy E. Bründermann

Optical light diagnostics port


Low-αc Optics at ANKA a

nd D

*10 [m]

s [m]

horizontal Dispersion*10 vertical

-10

0

10

20

30

40

0 5 10 15 20 25

5

Dedicated low-αc optics with negative dispersion in the long and short straight sections for flexible bunch length tuning following the pioneering work of e.g. BESSY II

At ANKA: Observed momentum compaction factor range as extrapolated from Qs measurements:

from 7.2 10-3 to 1.4 10-4

αc =1

L

�ds

D(s)

ρ(s)

s / m

m

Ebeam / MeV

c scan at 0.8 GeVc scan at 1.0 GeVc scan at 1.3 GeVc scan at 1.6 GeVc scan at 1.8 GeV

from fit with VRF=0.6 MVfrom fit with VRF=1.2 MV

0

5

10

15

1000 2000

∝ E3/2

working point


Operation in the Low-αc ModeEnergy ramp (reguar optics)

fill various pattern at 0.5 GeVLow-αc “squeeze”

change quadrupoles & sextupolesorbit correction between steps

f RF /

kH

z

c

-1

-0.5

0

0.5

1

0 0.002 0.004 0.006 0.008

RF frequency adjustmentBeam energy: contribution from correctorsdepends on αc

solution: correct simultaneously orbit and fRF

∆pp = − 1

αc

(fRF−fcRF)

fRF

E ∝�

BdL

6


THz Detector SystemHot Electron Bolometer (HEB) detectorBased on: SC niobium nitrideResponse time < 160 psSpectral range 150 GHz - 3 THz

7

High temporal resolution of HEB allows to study signals from

individual bunches in multi- and single bunch environment.

Joint development of IMS (KIT) & DLR (Berlin) courtesy V. Judin


THz Bunch Signals in Time DomainObserve one bunch in its natural environment over many turnsSaturation of the generating instability and subsequent radiation damping leads to a sawtooth-like pattern as a function of time

8

Observation of bursting

Bursts of radiation in multi turn measurements

6 Vitali Judin Longitudinal Diagnostics at ANKA

V. Judin


Current and Bursting Spectrum

Spectrogram for a decaying current (fs = 9 kHz )

9

Single bunch observations

Multi-turn single bunch evolution - 20 GS/s

0 1000 2000 3000 4000 5000 6000 7000 8000 90000

0.2

0.4

0.6

0.8

1

Graph

Turn

HE

B S

ignal [a

.u.]

0 200 400 600 800 1000 1200 1400

-1010

-910

-810

-710

-610

-510

-410

-310

-210

Graph

Span: 1357.86 kHzResolution: 331.51 Hz1. Peak at: 0.663 kHz2. Peak at: 0.995 kHz

Frequency [kHz]

0 50 100 150 200 250 300 350 400

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

Graph

HE

B S

ignal [a

.u.]

Time [ns]

25 / 33 Vitali Judin Hot Electron Bolometer at ANKA

Measurement

104

105

140 145 150 155 160 165

coh.

pow

er [a

.u.]

synchrotron periods

N = 5·108

N = 6·108

N = 8·108

N = 13·108

Simulation

Spectrogram

V. Judin

M. Klein


Bunch Lengthening for Different αc-Settings

10

-210 -110 11

2

10

20

beam current / mA

RM

S bu

nch

leng

th /

ps

= 30.8 kHzsf = 18.6 kHzsf = 15.1 kHzsf = 9.3 kHzsf = 8.4 kHzsf = 6.6 kHzsf = 5.6 kHzsf

Previous bursting data (multi-bunch)

for “high” currents

σz ∼ I37

bunch

σz = σz,0for “low” currents

N. Hiller et al.: DPG Spring Meeting 2012


Electro Optical Bunch Length Measurement

11

Spectral decoding (single shot)Int.

E

t

laser(long chirped pulse)

electron bunch

t

Spectrometer

EO-crystal

Crossed pol.

Pol.

λ/2

λ/4

Installation at ANKA ➡ Spring 2012

N. Hiller et al.: IPAC11, TUPC086

Phase sensitive detection of THz radiation with electro-optical femto-second sampling

A. Plech et al.: PAC 2009, TU5RFP026


Impedance & CSR PowerThe total power radiated by a bunch of N particles is described by

change in form factor fλ is seen on the emitted THz power

121. November 2009 Marit Klein Institut für Synchrotronstrahlung

Influence of additional wake fields:The scraper wake

The strength of the scraper wake field can be measured from the effect (kick) on the closed orbit

Scraper wake increases THz radiation

!y /

mm

s / m

-0.02

-0.01

0

0.01

0.02

0 20 40 60 80 100

3.70

3.80

3.90

4.00

4.10

4.20

6.406.506.606.706.80

Sig

nal [V

]

Current [mA]

scraper in

scraper out

Ptotal = N Pincoh(1 + N fλ)

V. Judin

N. Hiller

Controlled change of the impendance by an asymmetric vertical scraper

clear influence on emitted CSR


Scraper Effects

13

➡ Geometrical impedance plays an important role for CSR!

courtesyA.-S. Mueller


Microwave Wake at ANKALow cost Low Noise Block (LNB) device used as detector (∼11 GHz)Signal shows spikes corresponding to ring structure

14

Time (ns)0 50 100 150 200 250 300 350

Envelope (a.u.)

0

0.5

1

1.5

2

2.5

3

stripline

IR2

IR1inj. line

rf cavity

V. Judin (KIT), F. Caspars (CERN)

Institute for Synchrotron RadiationLab. for the Appl. of Synchrotron Radiation

Karlsruhe, 9.11.2011 A.-S. Müller - Coherent THz Radiation in Electron Storage Rings

Single & Multi-Bunch EffectsFast THz detector (HEB) allows to study signals from individual bunches in a multi-bunch environment

151. November 2009 Marit Klein Institut für Synchrotronstrahlung

Influence of additional wake fieldsLeading bunch analysis

-0.1 -0.08 -0.06 -0.04 -0.02 0 0.02 0.04 0.06 0.08 0.10

20

40

60

80

100

120

140

160

180

200

220

difference to global fit [V]

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.40

0.05

0.1

0.15

0.2

0.25

bunch current / mA

HE

B S

ignal / V

THz signal dependent on current of leading bunch

A leading bunch with 10% higher current increases the radiation

>10%

>10%

THz emission depends on filling pattern

∝ I2bunch

V. Judin

Neighbor interactions

HEB allows to study CSR

signals from individual bunches

in multibunch environment

THz emission depends on

filling pattern

! !"!# !"$ !"$# !"% !"%# !"& !"&#!

!"!#

!"$

!"$#

!"%

!"%#

!"#$%&$"''(#)&*&+,

-./&012#34&*&5

!"#$%&'()%&*+',-&*,.)&#,(/%!+-

!"#$%&'()%&%(/%,-&*,.)&#,(/%!+-

67

11 Vitali Judin Longitudinal Diagnostics at ANKA


Next stepsNew HEB + fast readout electronics, developed by KIT, allows continuous bunch by bunch and turn by turn measurements in order to study bursting dynamics.

16


FLUTE: A Test Experiment

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Allow small scale tests of THz generation, compression, radiation transport and instrumentation, ...Outline:

Photo injector (CTF Type)S band normal conducting linac Chicane compressor THz beamline

Use existing bunker

Output Energy < 50 MeVBunch charge ≤ 3 nCRep. Rate 10-100 HzUsed bandwith 0.05 - 5 THz

Institute for Synchrotron RadiationTU Darmstadt, 13.12.2010A.-S. Müller - Coherent Synchrotron Radiation in

Storage Rings2

FLUTE

Parameters


SummaryLow Alpha operation for different energies and machine settings (fill pattern, RF) on a regular basis

CSR emission is influenced by the beam current, fill pattern and geometrical impedance

Ongoing projects to study bursting dynamics, bunch deformations, and micro bunching with novel high resolution detector systems

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Thank you for your attention!

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KIT ISS / LAS, Karlsruhe, Germany:V. Judin, N. Hiller, A. Hofmann, B. Kehrer, M. Klein, S. Marsching, S. Naknaimueang, M. Nasse, N.J. Smale, E. Huttel, A.-S. Müller, M. Schwarz, C. Meuter, M. Steichert

DLR, Berlin, Germany:A. Semenov, H.-W. Hübers

SLS, Villingen, Switzerland:P. Peier, V. Schlott

CERN, Geneva, Switzerland:F. Caspers

KIT IMS, Karlsruhe, Germany:P. Probst, S. Wuensch, M. Siegel

Acknowledgments:

KIT IPE, Karlsruhe, Germany:M. Caselle, I. Bauer, A. Menshikov, M. Schleicher, B. Osswald, S. Chilingaryan, M. Weber

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