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tefeld (HZB, Berlin) et al., MLS Low-, Future Light Sources, March 5-9, 2012, Jefferson Lab, USA 1 A. Hoehl, R. Klein, R. Müller, G. Ulm PTB Berlin (Germany) Low- Operation of the M etrology L ight S ource* J. Feikes, M. Ries, P.O. Schmid, G. Wüstefeld HZB Berlin (Germany) ICFA Workshop on Future Light Sources, March 5-9, 2012 Thomas Jefferson National Accelerator Facility, Newport News, VA (USA) * J. Feikes et al., PRSTAB-14, 030705 (2011)

A. Hoehl, R. Klein, R. Müller, G. Ulm PTB Berlin (Germany)

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Low- a Operation of the M etrology L ight S ource*. J. Feikes, M. Ries, P.O. Schmid, G. Wüstefeld HZB Berlin (Germany). A. Hoehl, R. Klein, R. Müller, G. Ulm PTB Berlin (Germany). * J. Feikes et al., PRSTAB-14, 030705 (2011). - PowerPoint PPT Presentation

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PowerPoint Presentation*
PTB Berlin (Germany)
HZB Berlin (Germany)
* J. Feikes et al., PRSTAB-14, 030705 (2011)
1.unknown
*
and operated by:
*
energy / MeV
100
octupole
*
optical functions
control of 3 leading
L=L0(1+ a Dp/p0)
a=momentum compaction factor
*
a = a0 + a1d + a2d2
2 4 6 8 10 12 14 16 18 20
mom. comp. factor / 10-4
a = a(Dp/p0)
MAD-8 simulation
rf-frequency change Dfrf / kHz
2 4 6 8 10 12 14 16 18 20
fs = 9.5 kHz
2
1
octupole off
octupole on
*
octupole current
figure parameters:
calibration:
for comparison:
- octupoles required !!
a
d
a
d
*
phase space at
H0=eVrffrev/E0
- double beam:
rf-buckets: ( , )
*
B2 C B1
fs02 = frevH0a0/2p
s0 = 2plrffs0d/H0
(0, )
fs0
s0
< 0
C
(p,0)
fs0
s0
< 0
*
ratio of synchrotron
C
B1
B2
C
B
triple beam a1 = 0
*
topping up with a-buckets
the electron flow rate from bucket B2 to bucket B1 is controlled by feedback of the rf-frequency, to keep the bucket B1 current constant within 2 % over 10 h.
-> M. Ries et al., ICFA Beam Dynamics Mini Workshop on Low Emittance Rings, 2011
B1
B2
A
C
C
by master clock manipulation
of time, the sum current B1+B2 is
indicated by the black line.
IB1 / mA
time / h
Isum / mA
*
- strong correlation between
Q1-current & THz power, THz power shows strong maximum
- small dip in beam life time at max. THz power, followed by large dip in lifetime
- cross section increase indicates
quad Q1 current scan, crossing a0 = 0
(Q1 acts on dispersion)
DI/I = 0.5%
*
(bursting CSR)
at 120 mA an average power of max. 60 mW achieved, measured with a calibrated power meter.
THz CSR measurements
current.
PTHz~0.86+0.031*I
*
CSR power spectrum
Spectral range 1.4 1/cm (not shown in fig.) to 50 1/cm.
incoherent signal mixed with coherent signals, corrected gain = 100,000
THz CSR measurements
Example of hardware setup at the THz beam port.
Different types of detectors are available.
Experiments: detector characterization and
and KIT (Karlsruhe)) and spectroscopy.
beam line
THz detector
FTIR spectrometer
IR microscope
*
BESSY II
data points
~
sb-current:
to coasting beam theory
*
- the MLS is the first storage ring optimized for CSR
- successful control of 3 orders of a
- no beam loss at the a0 = 0 crossing
- beam can be stored in 3 types of a-buckets
- stable and bursting THz-CSR can be produced
- bursting thresholds agree fairly well with theory
*
*
P. Kuske et al., PAC 2003
*
IR
THz
IR
THz
Undulator-IR
276.unknown
*
bunch current / mA
*
rf-scan:
time / seconds
arb. unit
*
beam current
time / hours
*
non-isochronous ring
L = orbit length
p = electron momentum
crossing of
chromatic orbits
starting point,
short bunch
long bunch,
½ revolution
2 Dp/p
starting point,
short bunch
short bunch,
½ revolution
*
comparison with theory
Nov. 2011
Jan. 2012
before 2003
10
8
6
4
2
1
coasting
beam
theory
*
bursting
stable
chopped
unchopped
InSb time domain signals recorded on an oscilloscope, stable and bursting CSR is detected.
CSR power
THz CSR measurements
*
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