| Paper |
Title |
Other Keywords |
Page |
| IT06 |
Short Bunch Beam Profiling
|
diagnostics, instrumentation, linac, free electron laser, optics, SPPS, LCLS |
25 |
| |
- P. Krejcik
SLAC, Stanford Linear Accelerator, Stanford, CA, USA
| |
The complete longitunal profiling of short electron bunches is discussed
in the context of 4th generation light sources. The high peak current
required for the SASE lasing process is achieved by longitudinal
compression of the electron bunch. The lasing process also depends on of
the preservation of the transverse emittance along the bunch during
this manipulation in longitudinal phase space. Beam diagnostic
instrumentation needs to meet several challenges: The bunch length and
longitudinal profile should be measured on a single bunch to characterize
the instantaneous, peak current along the bunch. Secondly, the transverse
emittance and longitudinal energy spread should be measured for slices of
charge along the bunch. Several techniques for invasive and noninvasive
bunch profiling will be reviewed, using as examples recent measurements
from the SLAC Sub Picosecond Photon Source (SPPS) and the planned
diagnostics for the Linac Coherent Light Source (LCLS). These include
transverse RF deflecting cavities for temporal streaking of the electron
bunch, RF zero-phasing techniques for energy correlation measurements,
and electro-optic measurements of the wake-field profile of the bunch.
|
|
|
|
| PM18 |
Residual Gas Fluorescence for Profile Measurements at the GSI UNILAC
|
diagnostics, instrumentation, linac, optics |
137 |
| |
- A. Bank, P. Forck
GSI, Gesellschaft für Schwerionenforschung, Darmstadt, Germany
| |
The high beam currents, delivered at the LINAC at GSI (UNILAC) can
destroy intercepting diagnostics within one macro-pulse. As an
alternative for a non-destructive profile measurement the methode for
residual-gas-fluorescence is investigated. The fluorescence light is
emitted by the N2 molecules of the residual gas at the blue wavelength
range and can be monitored with a modern CCD-camera. The images are
transferred via digital bus (IEEE 1394 'FireWire') and the profiles are
generated by analysis of the images with a modern software tool (National
Instruments 'LabView'). Due to the short beam pulses (about 0.2 ms) the
light intensities emitted by the residual gas are low and require a high
amplification (gain >106) which is realized with an image intensifier
with double MCP (multi channel plate), connected with a fiber taper to
the CCD-chip. The design parameters of the optics and electronics are
discussed as well as the advantages of the digital data transmission.
Measurements with heavy ion beams of several 100 μA and a comparison to
other profile measurement methods show a good signal-to-noise ratio and
prove a good applicability.
|
|
|
|
| PM24 |
Parasitic Bunch Measurement in e+/e- Storage Rings
|
diagnostics, instrumentation, bunching, synchrotron-radiation, lepton, undulator |
149 |
| |
- M. Seebach, M. Werner
DESY, Deutsches Elektronen-Synchrotron, Hamburg, Germany
- H. Franz, A. Ehnes
DESY-HASYLAB, Deutsches Elektronen-Synchrotron, Hamburg, Germany
| |
The lepton storage rings DORIS and PETRA at DESY are used as sources for
synchrotron radiation experiments. In normal operation the distance
between the bunches should be 96 ns in PETRA and 192 ns in DORIS. The
adjacent buckets must not have any stored particles or, in reality, as
few as possible. This is particularly important for time triggered photon
measuring experiments. The principle of the 'parasitic bunch' measurement
down to a fraction of 10-6 of the main bunch within 20 seconds are
described. Additionally, the sources of the 'parasitic bunches' and the
actions to minimize them are discussed.
|
|
|
|