CSR Effects in the ANKA Storage Ring
A.-S. Müller, J.Ch. Heip, N. Hiller, A. Hofmann, E. Huttel, V. Judin, B. Kehrer, M. Klein,
S. Marsching, Y.-L. Mathis, A. Plech, N. Smale, K.G. Sonnad, P.F. Tavares
Institute for Synchrotron Radiation
KIT - University of the State of Baden-Wuerttemberg and National
Laboratory of the Helmholtz Association
www.kit.edu
The ANKA Storage Ring
C = 110.4 m
Energy range: 0.5 - 2.5 GeV
RF frequency 500 MHz
DBA lattice
120 ns
368
2
Topics CSR Workshop, Saskatoon, 1.-2.11.2010
A.-S. Müller - CSR Observations t ANKA
ns
Institute for Synchrotron Radiation
Low-!c Optics at ANKA
Dedicated low-!c optics with negative dispersion in the long and short
straight sections for flexible bunch length tuning following the pioneering
!
1
D(s)
work of e.g. BESSY II
α =
ds
c
L
ρ(s)
At ANKA: Observed momentum compaction factor range as extrapolated
from Qs measurements:
40
horizontal !
Dispersion*10
vertical !
30
20
!s / mm
! and D*10 !m"
from 7.2 10-3 to 1.4 10-4
15
10
"c scan at 0.8 GeV
"c scan at 1.0 GeV
"c scan at 1.3 GeV
"c scan at 1.6 GeV
"c scan at 1.8 GeV
∝ E3/2
from fit with VRF=0.6 MV
from fit with VRF=1.2 MV
10
5
0
-10
0
0
5
10
15
20
25
s !m"
3
Topics CSR Workshop, Saskatoon, 1.-2.11.2010
A.-S. Müller - CSR Observations t ANKA
1000
working point
2000
Ebeam / MeV
Institute for Synchrotron Radiation
Bursting and Bunch Length
Time evolution of a THz detector signal frequency spectrum during
a low-!c squeeze
the two steps in synchrotron frequency are clearly visible
onset of bursting for shorter bunches
time
frequency
4
Topics CSR Workshop, Saskatoon, 1.-2.11.2010
A.-S. Müller - CSR Observations t ANKA
Institute for Synchrotron Radiation
CSR for Users
Currently THz CSR
can be observed at
two beamlines:
IR1 & IR2 (in
commissioning)
also for pump-probe
experiments
5
Topics CSR Workshop, Saskatoon, 1.-2.11.2010
A.-S. Müller - CSR Observations t ANKA
Institute for Synchrotron Radiation
IR1 - Diagnostic port
THz Port at ANKA
Synchrotron (Edge) Radiation
IR1 - Diagnostic port
source: entrance edge of a b
source: entrance edge of a bending magnet
flux > 1013 photons/s/0.1%bw
flux > 1013 photons/s/0.1%
CSR is observed as
‘regular’ synchrotron
radiation but also as
‘edge’ radiation
Can be an advantage
for a beamline
(src.: ANKA-Archiv)
5 / 33
Vitali Judin
Hot Electron Bolometer at ANKA
Courtesy E. Bründermann,
Ruhr Universität Bochum
lower frequencies
observable for the
same aperture
+4,
"#
+,#
"#
Aperture
#4,
Vitali Judin
Hot Electron Bolometer at ANKA
+##
#
+4#$
#4,
#4#
!#4,
-/2>0>/1'/1'D;E0>?A='0E;F=?0/E&'($)
%4#
#
!+4#
!%#
9
,#
#4#
9
!%#
%4,
%#
&'($$)
&'($$)
5 / 33
:;>1'6=1B>1<'G>=AB';2'2/HE?=
fringe field region
-./0/123234+5673$$8%'*+# '
-./0/123234+5673$$8%'*+# '
Aperture
%#
ANKA-Archiv)
+4#
:;<1=0>?'@>=AB'(C)
I/HE?=';0'JKLJ!MNO'GE>1<='G>=AB
(src.:
+4,
P;A?HA;0=B'G/E';'GE=QH=1?&'/G'R'CST
Courtesy Y.-L.Mathis
!"#$$
!"#$$
#
!"#$$
6
!%#
#
*'($$)
%#
!"#$$
"#
(spatial distribution of
the radiation 3m from
the source)
Topics CSR Workshop, Saskatoon, 1.-2.11.2010
A.-S. Müller - CSR Observations t ANKA
!%#
#
*'($$)
%#
"#
(spatial distribution of
Institute for Synchrotron Radiation
the radiation 3m from
the source)
be absorbed. The correspon-ding gas load of 2·10 mbarl/s hasto be pumped to maintain a pressure
he chambers in the dipoles and the adjacent multipoles downstream, which receive most of the
load, have ante chambers equipped with lumped absorbers. All other vacuum chambers have dis-
Dipole chamber
cuum absorbers along the outer side of the chamber. Pumping is performed by diode ion pumps (500
lumped absorbers, 150 l/s elsewhere). In total pumps with a nominal pumping speed of 20 000 l/s
Pictures of the dipole vacuum chamber and the lumped absorber are shown in Figure 2-7.
ANKA vacuum chamber:
nonmagnetic 316LN stainless steel
internal width of 70 mm and height of 32 mm
Figure 2-7: Photo of the dipole vacuum chamber (left) and two different absorbers
7
Topics CSR Workshop, Saskatoon, 1.-2.11.2010
A.-S. Müller - CSR Observations t ANKA
Institute for Synchrotron Radiation
THz Pulse in the Time Domain
Superposition of
! plane
! waves emitted over the bunch:
∞
A(t) =
dω
0
∞
dx s(ω) ρ(x) e−iω(t−x/c)
−∞
Resulting electrical field: E(t) ∼ cos φ · ReA(t) + sin φ · ImA(t)
(The phase determines the relative weight of the two independent solutions. It is
not fixed a priori and given by the ring structure.)
E-field/a.u.
Phase sensitive detection of THz radiation with
electro-optical femto-second sampling
1
! = 325 deg
0.8
0.6
0.4
0.2
0
-0.2
-20
-15
-10
-5
0
5
10
15
20
time/a.u.
ASM et al.: Modeling the Shape of Coh.THz Pulses
Emitted by Short Bunches in an El. SR, EPAC 2008
8
Topics CSR Workshop, Saskatoon, 1.-2.11.2010
A. Plech et al.: Electro-Optical sampling of Terahertz radiation
emitted by short bunches in the ANKA synchrotron, PAC 2009
A.-S. Müller - CSR Observations t ANKA
Institute for Synchrotron Radiation
Asynchronous Sampling
3
A. Plech et al. PAC 2009
Electrical field [arb.u.]
Laser synchronized to RF of the
synchrotron
Small shift in frequency ("f = 10
kHz) leads to a beat
Mapping picoseconds on nanoseconds with fs time resolution
2
1
0
-1
-2
-15
-10
-5
0
5
10
15
20
25
30
Spectral Amplitude [arb. u.]
delay [ps]
Bartels et al., APL 2006, Opt. Express 2006
0
10
time domain sampling
FTIR comparison
-1
10
-2
10
-3
10
0
preliminary
1
2
3
Frequency (THz)
9
Topics CSR Workshop, Saskatoon, 1.-2.11.2010
A.-S. Müller - CSR Observations t ANKA
Institute for Synchrotron Radiation
FTIR Spectrum
Detector used for CSER studies: liquid He cooled Si bolometer
(1.8 K and 4.2 K)
Filter used for studies shown here: < 35 cm-1
The spectral dependence is recorded using a Bruker IFS66v/S
spectrometer equipped with Mylar beam splitters with thicknesses
between 6 and 125 #m depending on the application.
Source: edge radiation
Courtesy Y.-L. Mathis
in the visible
10
Topics CSR Workshop, Saskatoon, 1.-2.11.2010
in the mid-IR (700-1400 cm-1)
A.-S. Müller - CSR Observations t ANKA
Institute for Synchrotron Radiation
ANKA
joint development
of Physics
HEBs
in Accelerator
IMS
(Karlsruhe) & DLR (Berlin)
An ultra-fast detector can resolve individual bunches of a multi-bunch filling,
thusniobium
making it possible
to study
not only single bunch effects with varying
SC
nitride
detector
currents in a single shot but also possible influences on the THz emission from
the filling pattern.
response
time < 160 ps
A detector system based on a superconducting NbN ultra-fast bolometer with an
spectral
rangetime
150
GHzps-can
3 be
THz
intrinsic response
of $100
used for this purpose
Joint development of
U. Karlsruhe (Institute of Microand Nanoelectronic Systems)
and DLR (Berlin).
V. Judin, KIT
11
Topics CSR Workshop, Saskatoon, 1.-2.11.2010
A.-S. Müller - CSR Observations t ANKA
Institute for Synchrotron Radiation
THz Signal and Beam Current
HEB Signal / V
relative bunch currents
from pickup
The total power radiated by a bunch
is proportional to N2
VRF = 150 kV
0.2
0.1
bunches with currents above a
threshold show stronger
dependence on the current
0
-0.2
---- HEB signal
---- bunch current in a.u.
0
50
100
150
200
250
300
350
Time / ns
HEB Signal / V
-0.1
V RF = 150 kV
0.25
theor. bursting/stable
threshold
0.2
∝ I2bunch
0.15
The observations show the
expected quadratic dependence
on bunch current below threshold
0.1
0.05
0
12
Topics CSR Workshop, Saskatoon, 1.-2.11.2010
0
A.-S. Müller - CSR Observations t ANKA
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
bunch current / mA
Institute for Synchrotron Radiation
of bursting
THzObservation
Bunch Signals
in Time Domain
Bursts of radiation in multi turn measurements
Observe one bunch in its natural environment over many turns:
V. Judin
13
Diagnostics
at -ANKA
6Topics CSR
Vitali
JudinSaskatoon,Longitudinal
Workshop,
1.-2.11.2010
A.-S. Müller
CSR Observations t ANKA
Institute for Synchrotron Radiation
Current and Bursting Spectrum
Spectrogram for a decaying current
the synchrotron frequency signal (5.5 kHz) slowly disappears
Sample Number
current dependent structure in the low frequency region
10
1
0
2000
4000
6000 0
Frequency / Hz
14
Topics CSR Workshop, Saskatoon, 1.-2.11.2010
A.-S. Müller - CSR Observations t ANKA
10
Ibeam / mA
Institute for Synchrotron Radiation
Observation of bursting
Current and Bursting Spectrum
Spectrogram
for a decaying current (fs = 9 kHz )
Bursting
modes
V. Judin
15
7
Topics CSR Workshop, Saskatoon, 1.-2.11.2010
Vitali Judin
A.-S. Müller - CSR Observations t ANKA
Longitudinal Diagnostics at ANKA
Institute for Synchrotron Radiation
Bunch Profile & Current
Bunch shapes (normalized)
1.5 mA
0.02
0.015
0.03
%z = 4.5 - 12 ps
0.02
0.015
0.01
0.005
0.005
0
-100
-50
Ibunch = 1.71 mA
Ibunch = 1.37 mA
Ibunch = 1.22 mA
Ibunch = 0.95 mA
Ibunch = 0.83 mA
Ibunch = 0.73 mA
Ibunch = 0.65 mA
Ibunch = 0.59 mA
Ibunch = 0.54 mA
Ibunch = 0.48 mA
Ibunch = 0.43 mA
Ibunch = 0.35 mA
Ibunch = 0.30 mA
0.025
0.01
0
1.7 mA
f s = 5.6 kHz
Ibunch = 1.47 mA
Ibunch = 1.29 mA
Ibunch = 1.17 mA
Ibunch = 0.97 mA
Ibunch = 0.87 mA
Ibunch = 0.76 mA
Ibunch = 0.68 mA
Ibunch = 0.52 mA
Ibunch = 0.45 mA
Ibunch = 0.40 mA
Ibunch = 0.35 mA
Ibunch = 0.30 mA
Ibunch = 0.26 mA
0.22
mA
Ibunch
= 0.22
mA
probability density
probability density
0.03
0.025
Bunch shapes (normalized)
0
50
100
f s = 15.1 kHz
%z = 9.5 - 13 ps
0.3 mA
Tail
Head
-100
position in bunch / pixel
-50
0
50
100
position in bunch / pixel
N. Hiller
16
Topics CSR Workshop, Saskatoon, 1.-2.11.2010
A.-S. Müller - CSR Observations t ANKA
Institute for Synchrotron Radiation
RMS bunch length / ps
Current Dependent Bunch Lengthening
20
f s = 30.8 kHz
theoretical zero current
bunch lengths σz,0
f s = 18.6 kHz
10
9
8
7
6
5
4
for “high” currents
f s = 15.1 kHz
theoretical
prediction
(Stupakov)
3
7
σz ∼ I
bunch
f s = 9.3 kHz
5!10-2
σz ∝ I
for “low” currents
σz = σz,0
f s = 6.6 kHz
3
10-1
2!10-1
1
Topics CSR Workshop, Saskatoon, 1.-2.11.2010
3
7
thresh
“high” and “low”
depends on
threshold current
f s = 5.6 kHz
N. Hiller
17
empirical fits with
theoretical
constraints
2
3 4 56
10
beam current / mA
A.-S. Müller - CSR Observations t ANKA
Institute for Synchrotron Radiation
Systematic Effects FD
Amplitude / A.U.
FTIR interferometer used
Onset of spectrum sensitive to
buch length changes
Amplitude / A.U.
Choice of beamsplitter important
for the interpretation of the
results...
70
black body
Bolo 4.2K, 2, 50 µm Myl
Bolo 4.2K, 2, 125 µm Myl
10
8
6
4
accelerator
E0 = 1.3 GeV
Bolo 4.2K, 2, 6 µm Si/Myl
2
Bolo 4.2K, 2, 50 µm Myl
60
Bolo 4.2K, 2, 125 µm Myl
0
50
0
10
40
20
30
40
50
60
Detector: Si bolometer
20
Same 3 beamsplitters for Hg arc
lamp and coherent synchrotron
radiation
0
0
10
20
30
Topics CSR Workshop, Saskatoon, 1.-2.11.2010
40
50
60
-1
Wave Number / cm
30
10
18
Bolo 4.2K, 2, 6 µm Si/Myl
Hg lamp
12
-1
Wave Number / cm
A.-S. Müller - CSR Observations t ANKA
Institute for Synchrotron Radiation
Coherent Radiation
Ibunch = 1295 µA
Ibunch = 1204 µA
Ibunch = 1135 µA
Ibunch = 1074 µA
Ibunch = 1006 µA
Ibunch = 953 µA
Ibunch = 905 µA
Ibunch = 853 µA
Ibunch = 814 µA
Ibunch = 778 µA
Ibunch = 737 µA
Ibunch = 704 µA
Ibunch = 675 µA
Ibunch = 646 µA
Ibunch = 615 µA
Ibunch = 592 µA
Ibunch = 569 µA
Ibunch = 542 µA
Ibunch = 523 µA
Ibunch = 506 µA
Ibunch = 485 µA
Ibunch = 470 µA
Ibunch = 451 µA
Ibunch = 439 µA
Ibunch = 425 µA
10
1
10
1
10-1
Wavenumber / cm
10
1
multi bunch
10-1
10
-1
Wavenumber / cm
Topics CSR Workshop, Saskatoon, 1.-2.11.2010
single bunch
Wavenumber / cm-1
Ibunch = 492 µA
Ibunch = 467 µA
Ibunch = 443 µA
Ibunch = 422 µA
Ibunch = 403 µA
Ibunch = 384 µA
Ibunch = 367 µA
Ibunch = 351 µA
Ibunch = 336 µA
Ibunch = 321 µA
Ibunch = 308 µA
Ibunch = 295 µA
Ibunch = 283 µA
Ibunch = 272 µA
Ibunch = 262 µA
Ibunch = 252 µA
Ibunch = 243 µA
Ibunch = 234 µA
Ibunch = 226 µA
Ibunch = 218 µA
Ibunch = 211µA
Ibunch = 204 µA
Ibunch = 197 µA
Ibunch = 191 µA
Ibunch = 185 µA
Ibunch = 179 µA
Ibunch = 174 µA
Ibunch = 169 µA
Ibunch = 164 µA
Ibunch = 159 µA
Ibunch = 155 µA
Ibunch = 151 µA
Ibunch = 147 µA
Ibunch = 145 µA
10-2
fs = 9.6 kHz / 5.3 ps
19
a.u.
a.u.
1
Filter #2 < 35
cm-1
102
Ibunch = 743 µA
Ibunch = 695 µA
Ibunch = 680 µA
Ibunch = 666 µA
Ibunch = 652 µA
Ibunch = 639 µA
Ibunch = 626 µA
Ibunch = 614 µA
Ibunch = 602 µA
Ibunch = 590 µA
Ibunch = 579 µA
Ibunch = 568 µA
Ibunch = 558 µA
Ibunch = 547 µA
Ibunch = 537 µA
Ibunch = 528 µA
Ibunch = 518 µA
Ibunch = 509 µA
Ibunch = 500 µA
Ibunch = 492 µA
Ibunch = 484 µA
Ibunch = 476 µA
Ibunch = 468 µA
Ibunch = 460 µA
Ibunch = 453 µA
Ibunch = 446 µA
Ibunch = 439 µA
Ibunch = 432 µA
Ibunch = 425 µA
Ibunch = 419 µA
Ibunch = 413 µA
Ibunch = 407 µA
Ibunch = 401 µA
Ibunch = 395 µA
Ibunch = 389 µA
Ibunch = 384 µA
Ibunch = 379 µA
Ibunch = 374 µA
Ibunch = 369 µA
Ibunch = 364 µA
Ibunch = 359 µA
Ibunch = 354 µA
Ibunch = 350 µA
Ibunch = 346 µA
Ibunch = 343 µA
10
10
-1
10
10-1
Ibunch = 1352 µA
Ibunch = 863 µA
Ibunch = 803 µA
Ibunch = 746 µA
Ibunch = 700 µA
Ibunch = 656 µA
Ibunch = 615 µA
Ibunch = 576 µA
Ibunch = 541 µA
Ibunch = 510 µA
Ibunch = 480 µA
Ibunch = 454 µA
Ibunch = 431 µA
Ibunch = 409 µA
Ibunch = 386 µA
Ibunch = 370 µA
Ibunch = 353 µA
Ibunch = 336 µA
Ibunch = 322 µA
Ibunch = 308 µA
Ibunch = 296 µA
Ibunch = 284 µA
Ibunch = 275 µA
Ibunch = 264 µA
Ibunch = 255 µA
Ibunch = 248 µA
10
10-1
10-2
M. Klein, J.Chr. Heip
a.u.
Pcoh/Pincoh
Comparison of single and multi-bunch fillings
Wavenumber / cm-1
fs = 6.6 kHz / 3.8 ps
A.-S. Müller - CSR Observations t ANKA
Institute for Synchrotron Radiation
Gain Curves
Pcoh/Pincoh
Comparison of single and multi-bunch fillings
104
3
10
2
10
Pcoh/Pincoh
Ibunch = 1295 µA
Ibunch = 1204 µA
Ibunch = 1135 µA
Ibunch = 1074 µA
Ibunch = 1006 µA
Ibunch = 953 µA
Ibunch = 905 µA
Ibunch = 853 µA
Ibunch = 814 µA
Ibunch = 778 µA
Ibunch = 737 µA
Ibunch = 704 µA
Ibunch = 675 µA
Ibunch = 646 µA
Ibunch = 615 µA
Ibunch = 592 µA
Ibunch = 569 µA
Ibunch = 542 µA
Ibunch = 523 µA
Ibunch = 506 µA
Ibunch = 485 µA
Ibunch = 470 µA
Ibunch = 451 µA
Ibunch = 439 µA
Ibunch = 425 µA
104
103
2
10
1
Wavenumber / cm
Ibunch = 743 µA
Ibunch = 695 µA
Ibunch = 680 µA
Ibunch = 666 µA
Ibunch = 652 µA
Ibunch = 639 µA
Ibunch = 626 µA
Ibunch = 614 µA
Ibunch = 602 µA
Ibunch = 590 µA
Ibunch = 579 µA
Ibunch = 568 µA
Ibunch = 558 µA
Ibunch = 547 µA
Ibunch = 537 µA
Ibunch = 528 µA
Ibunch = 518 µA
Ibunch = 509 µA
Ibunch = 500 µA
Ibunch = 492 µA
Ibunch = 484 µA
Ibunch = 476 µA
Ibunch = 468 µA
Ibunch = 460 µA
Ibunch = 453 µA
Ibunch = 446 µA
Ibunch = 439 µA
Ibunch = 432 µA
Ibunch = 425 µA
Ibunch = 419 µA
Ibunch = 413 µA
Ibunch = 407 µA
Ibunch = 401 µA
Ibunch = 395 µA
Ibunch = 389 µA
Ibunch = 384 µA
Ibunch = 379 µA
Ibunch = 374 µA
Ibunch = 369 µA
Ibunch = 364 µA
Ibunch = 359 µA
Ibunch = 354 µA
Ibunch = 350 µA
Ibunch = 346 µA
Ibunch = 343 µA
103
102
10
10
10
-1
Filter #2 < 35
cm-1
Pcoh/Pincoh
Pcoh/Pincoh
10
10
104
103
102
multi bunch
10
10
-1
Wavenumber / cm
Topics CSR Workshop, Saskatoon, 1.-2.11.2010
Wavenumber / cm-1
Ibunch = 492 µA
Ibunch = 467 µA
Ibunch = 443 µA
Ibunch = 422 µA
Ibunch = 403 µA
Ibunch = 384 µA
Ibunch = 367 µA
Ibunch = 351 µA
Ibunch = 336 µA
Ibunch = 321 µA
Ibunch = 308 µA
Ibunch = 295 µA
Ibunch = 283 µA
Ibunch = 272 µA
Ibunch = 262 µA
Ibunch = 252 µA
Ibunch = 243 µA
Ibunch = 234 µA
Ibunch = 226 µA
Ibunch = 218 µA
Ibunch = 211µA
Ibunch = 204 µA
Ibunch = 197 µA
Ibunch = 191 µA
Ibunch = 185 µA
Ibunch = 179 µA
Ibunch = 174 µA
Ibunch = 169 µA
Ibunch = 164 µA
Ibunch = 159 µA
Ibunch = 155 µA
Ibunch = 151 µA
Ibunch = 147 µA
Ibunch = 145 µA
1
fs = 9.6 kHz / 5.3 ps
20
single bunch
10
4
1
Ibunch = 1352 µA
Ibunch = 863 µA
Ibunch = 803 µA
Ibunch = 746 µA
Ibunch = 700 µA
Ibunch = 656 µA
Ibunch = 615 µA
Ibunch = 576 µA
Ibunch = 541 µA
Ibunch = 510 µA
Ibunch = 480 µA
Ibunch = 454 µA
Ibunch = 431 µA
Ibunch = 409 µA
Ibunch = 386 µA
Ibunch = 370 µA
Ibunch = 353 µA
Ibunch = 336 µA
Ibunch = 322 µA
Ibunch = 308 µA
Ibunch = 296 µA
Ibunch = 284 µA
Ibunch = 275 µA
Ibunch = 264 µA
Ibunch = 255 µA
Ibunch = 248 µA
105
10
1
M. Klein, J.Chr. Heip
Wavenumber / cm-1
fs = 6.6 kHz / 3.8 ps
A.-S. Müller - CSR Observations t ANKA
Institute for Synchrotron Radiation
Pcoh/Pincoh
Observations
multi bunch gain curve seems to lie
significantly higher than single
bunch curve for similar single
bunch current for longer bunches
for shorter bunches, the curves are
closer
- f s = 9.6kHz, 500µA, single bunch
104
- f s = 9.6kHz, 490µA, multi bunch
103
102
preliminary
fs = 9.6 kHz / 5.3 ps
1
10
Pcoh/Pincoh
10
105
Wavenumber / cm-1
hypothesis:
effects from the ring impedance are
more significant if the CSR effect is
less pronounced
- f s = 6.6kHz, 420µA, single bunch
- f s = 6.6kHz, 420µA, multi bunch
104
103
preliminary
102
10
fs = 6.6 kHz / 3.8 ps
1
M. Klein
21
Topics CSR Workshop, Saskatoon, 1.-2.11.2010
A.-S. Müller - CSR Observations t ANKA
10
Wavenumber / cm-1
Institute for Synchrotron Radiation
CSR of Adjacent
Bunches
CSR of adjacent
bunches
HEB Signal (a.u.)
CorrelatedSimultanous
bursting?increase of the THz-signal intensity
0.5
leading bunch
0.4
0.3
0.2
0.1
Turn
0
HEB Signal (a.u.)
0
500
1000
1500
2000
2500
3000
3500
4000
4500
following bunch
0.5
0.4
0.3
0.2
0.1
0
Turn
-0.1
0
500
1000
1500
2000
2500
3000
the signals of the bunches are correlated
3500
4000
4500
V. Judin
Effect is under systematic investigation
this effect is being investigated
22
Topics CSR Workshop, Saskatoon, 1.-2.11.2010
9
Vitali Judin
A.-S. Müller - CSR Observations t ANKA
Longitudinal Diagnostics at ANKA
Institute for Synchrotron Radiation
Fast THz detectorof
(HEB)
allows to study wake fields
Influence
additional
signals from individual bunches in a
Leading
bunch analysis
multi-bunch environment
0.25
>10%
>10%
0.2
HEB Signal / V
HEB Signal / V
Influence of additional wake fields
CSR
of Adjacent
Leading
bunchBunches
analysis
0.15
>10%
0.25
0.1
>10%
0.2
0.05
0.15
0
0
0.05
0.1
∝ I2bunch
0.15
0.2
0.1
23
220
0.25
0.3
0.35
0.4
bunch current / mA
200
180
160
THz
signal
dependent
on
current
140
0.05
120
of leading bunch
100
0
80
0
0.05
0.1
0.15
0.2
0.25
0.3 higher
0.35
0.4
A leading
bunch
with
10%
bunch current / mA
60
current increases the radiation
THz signal dependent on current 4020
THz emission depends on filling pattern
0
of
leading bunch
-0.1
X-check with ‘impedance knob’?
A leading bunch with 10% higher
current increases the radiation
Topics CSR Workshop, Saskatoon, 1.-2.11.2010
1. November 2009
Marit Klein
A.-S. Müller - CSR Observations t ANKA
Institut für Synchrotronstrahlung
220
200
180
160
140
120
-0.08 -0.06 -0.04 -0.02
100V. Judin
0
0.02 0.04 0.06
0.08
0.1
difference to global fit [V]
80
60
40
20
Institute for Synchrotron Radiation
The Diagnostics Scraper
24
Figure: Drawing of scraper.
Topics CSR Workshop, Saskatoon, 1.-2.11.2010
A.-S. Müller - CSR Observations t ANKA
Institute for Synchrotron Radiation
Scraper Effect (Transverse)
0.02
1
0.01
0
-0.01
top jaw
-0.02
!y / mm
0
20
40
60
80
100
s /m
0.02
0.01
0
-0.01
bottom jaw
-0.02
0
20
40
60
80
100
scraper kick !"rad / mA#
!y / mm
Vertical asymmetric scraper as ‘impedance knob’
Wakefield strength from closed orbit kicks compared to MAD model
Fit with free scaling factor
Bane-Morton for !s = 12mm
0.5
0
-0.5
-1
0
s /m
1
2
3
4
5
6
7
distance of jaw from centre !mm#
Chamber half height b=16mm; distance of jaw from center a
Good description by equation
for asymmetric
gaps:
#
$
! π "3/2 r N
K.L.F. Bane, P. Morton, Proceedings of the
b−a
e b
!
1986 Linac Conference, Stanford, 1986.
!y " = 0.71
K.L.F. Bane et al., PAC95
2
σz γ b + a
A.-S. Müller et al., EPAC04
25
Topics CSR Workshop, Saskatoon, 1.-2.11.2010
A.-S. Müller - CSR Observations t ANKA
Institute for Synchrotron Radiation
Scraper Effect (longitudinal)
Longitudinal effect (energy loss) derived from change in horizontal beam
position in a dispersive region close to the scraper
∆xco
∆E
1
≈
=
κ|| eT0 ∆Ibunch
Dx
E0
E0
Z||
πZ0
b
≈
ln
8
a
and therefore
√
! " ∞
!
2
b
Z0 π
−( ω cσz )
κ|| ≈
ln
dω e
16
a
!E / E in permille
For high frequencies above cutoff, the real part of the impedance is
c/h
Exp. observations could be explained
by the presence of trapped modes....
free paramter yields 55 ±7 for
60 bunches
26
Topics CSR Workshop, Saskatoon, 1.-2.11.2010
multi-bunch with offset
multi-bunch, no offset
0.01
single bunch, no offset
0.005
0
A.-S. Müller - CSR Observations t ANKA
5
6
7
8
distance of jaw from centre ! mm "
Institute for Synchrotron Radiation
Impedance & CSR Power
0.03
probability density
The total power radiated by a
bunch of N particles is
Influence
of additional wake
described by
Bunch shapes (normalized)
Ibunch
Ibunch
Ibunch
Ibunch
Ibunch
Ibunch
Ibunch
Ibunch
Ibunch
Ibunch
Ibunch
Ibunch
Ibunch
Ibunch
fields:
The scraper wake
0.025
0.02
=
=
=
=
=
=
=
=
=
=
=
=
=
=
1.47
1.29
1.17
0.97
0.87
0.76
0.68
0.52
0.45
0.40
0.35
0.30
0.26
0.22
f s = 5.6 kHz
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
P
= N Pincoh
(1 + N fλ ) can be measured from the
total
The
strength of the
scraper wake field
effect
(kick)in
onform
the closed
change
factor forbit
& is
seenwake
on the
emitted THz
THz radiation
Scraper
increases
power
!y / mm
0.015
0.02
0.01
0.01
0
0.005
-0.01
0
Signal [V]
27
scraper in
3.90
60
0
80
50
100
100
position
in bunch / pixel
s /m
clear influence on emitted CSR
scraper out
6.70
6.60
Current [mA]
Topics CSR Workshop, Saskatoon, 1.-2.11.2010
1. November 2009
-50
40
Controlled change of the
impendance by an asymmetric
vertical scraper
4.00
3.70
6.80
-100
20
N. Hiller
4.10
3.80
0
-0.02
4.20
Marit Klein
6.50
6.40
V. Judin
A.-S. Müller - CSR Observations t ANKA
Institut für Synchrotronstrahlung
Institute for Synchrotron Radiation
CSR & Scraper Impedance
Effect of vertical scraper on CSR emission observed with the HEB
detector at IR1
A. Hofmann
28
Topics CSR Workshop, Saskatoon, 1.-2.11.2010
A.-S. Müller - CSR Observations t ANKA
Institute for Synchrotron Radiation
Pcoh/Pincoh
Observations
multi bunch gain curve seems to lie
significantly higher than single
bunch curve for similar single
bunch current for longer bunches
for shorter bunches, the curves are
closer
- f s = 9.6kHz, 500µA, single bunch
104
- f s = 9.6kHz, 490µA, multi bunch
103
102
preliminary
fs = 9.6 kHz / 5.3 ps
1
10
Pcoh/Pincoh
10
105
Wavenumber / cm-1
hypothesis:
effects from the ring impedance are
more significant if the CSR effect is
less pronounced
- f s = 6.6kHz, 420µA, single bunch
- f s = 6.6kHz, 420µA, multi bunch
104
103
preliminary
102
10
fs = 6.6 kHz / 3.8 ps
1
M. Klein
29
Topics CSR Workshop, Saskatoon, 1.-2.11.2010
A.-S. Müller - CSR Observations t ANKA
10
Wavenumber / cm-1
Institute for Synchrotron Radiation
Summary
THz radiation at ANKA is observed as coherent edge radiation
Observation in the time domain gives hints on fine structure
and complements FTIR studies
next step: EOS in the ring chamber
Ultrafast THz detectors allow to study one bunch within its
‘natural environment’
CSR emission changes
with bunch current (stable ! bursting)
with shape of charge distribution
(CSR & other impedances)
30
Topics CSR Workshop, Saskatoon, 1.-2.11.2010
A.-S. Müller - CSR Observations t ANKA
Institute for Synchrotron Radiation
Acknowledgements
The
Team
Karlsruhe Institute of Technology (KIT)
I. Birkel, S. Casalbuoni, M. Fitterer, B. Gasharova, S. Hillenbrand, J.Ch. Heip,
N. Hiller, A. Hofmann, E. Huttel, V. Judin, B. Kehrer, M. Klein, S. Marsching,
Y.-L. Mathis, D.A. Moss, A. Plech, N. Smale, K. Sonnad*, M. Süpfle,
P.F. Tavares**, P. Wesolowski
*now at Cornell
**now at Maxlab
31
Ruhr Universität Bochum
E. Bründermann
DLR Berlin
H.-W. Hübers, A. Semenov
HZB
G. Wüstefeld
PTB Berlin
R. Müller
Low Emittance Rings Workshop 2010,
CERN, 12.-15.1.2010
2
A.-S. Müller - CSR in Light Sources
Institute for Synchrotron Radiation