COULOMB’05 , Senigallia, Italy, Sept. 14th 2005 Space Charge Issues in High Brightness Electron (Plasma)Beams for X-ray FEL’s Luca Serafini, INFN-Milan and University of Milan • Electron beams for X-ray FEL’s are cold relativistic plasmas propagating through the Linac in laminar flow (up to GeV’s) • To reach high brightness ( I > kA, n < 1 m) one needs Many Thanks to: SPARC&PLASMONX Project team 1) Transport the beam through a gentle funnel made by RF and acceleration focusing counteracting space charge # betatron oscillations << 1 # plasma oscillations ~ 1 transverse laminarity nchrotron oscillations ~ 1/4 (with velocity bunc longitudinal laminarity
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COULOMB’05, Senigallia, Italy, Sept. 14th 2005 Space Charge Issues in High Brightness Electron (Plasma)Beams for X-ray FEL’s Luca Serafini, INFN-Milan.
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COULOMB’05 , Senigallia, Italy, Sept. 14th 2005
Space Charge Issues in High Brightness Electron (Plasma)Beams for X-ray FEL’s
Luca Serafini, INFN-Milan and University of Milan
• Electron beams for X-ray FEL’s are cold relativistic plasmas
propagating through the Linac in laminar flow (up to GeV’s)
• To reach high brightness ( I > kA, n< 1 m) one needs
Many Thanks to: SPARC&PLASMONX Project team
1) Transport the beam through a gentle funnel made byRF and acceleration focusing counteracting space charge# betatron oscillations << 1 # plasma oscillations ~ 1
Example of an optimized matchingExample of an optimized matching
M. Ferrario et al., “HOMDYN Study For The LCLS RF Photo-Injector”, Proc. of the 2nd ICFA Adv. Acc. Workshop on “The Physics of High Brightness Beams”, UCLA, Nov., 1999, also in SLAC-PUB-8400
a SPARC-BNL/DUV-SLAC/LCLS a SPARC-BNL/DUV-SLAC/LCLS CollaborationCollaboration
The Beer-CanThe Beer-Can
DistributionDistribution
COULOMB’05 , Senigallia, Italy, Sept. 14th 2005
e-beam measurement Q=70 pCGaussian Flat top
COULOMB’05 , Senigallia, Italy, Sept. 14th 2005
e-beam temporal distributionQ=70 pC, after Dazzler optimization
COULOMB’05 , Senigallia, Italy, Sept. 14th 2005
e-beam temporal distribution Q=300 pC
COULOMB’05 , Senigallia, Italy, Sept. 14th 2005
• Inter-slice dynamics brings to projected emittance oscillations which are reversible emittance correction this can be described by a multi-envelope code like HOMDYN the prescription to reach full emittance correction is to match the beam onto the invariant envelope (beam equilibr. mode)
LS and JR, PRE 55 (1997) 2575
S.C.R.C.P. or Laminar Plasma-Beam
σ INV =1′ γ
2I ζ( )IA 1+4Ω2( )γ
• Intra-slice dynamics is affected by space charge field non-linearities (partially reversible, unless wave-breaking is reached) to model intra-slice dynamics we need a multi-particle code (Parmela) the prescription to avoid wave-breaking and irreversible slice emittance growth is to use uniform cylindrical charge density distribution (flat top laser pulses, spatially uniform)
COULOMB’05 , Senigallia, Italy, Sept. 14th 2005
The Blow-Out regime: The Blow-Out regime:
from Pancakes to Waterbagfrom Pancakes to Waterbag
Transition EnergyTransition Energybetween plasmabetween plasmaand gas regimeand gas regime
Beam matching con-Beam matching con-ditions on I. E.ditions on I. E.
COULOMB’05 , Senigallia, Italy, Sept. 14th 2005
QuickTime™ and aGraphics decompressor
are needed to see this picture.
See paper THPP019, C. Vaccarezza et al.
Further Magnetic Compression with or w/o additional X-band cavity at compressor entrance
without with
COULOMB’05 , Senigallia, Italy, Sept. 14th 2005
Effects of RF cavity misalignment
See paper MOPP015, V. Fusco et al.
Beam centroid walk-off
Observed negligibleeffect on emittance
No quad used! Only the funnel with
invariant envelope
COULOMB’05 , Senigallia, Italy, Sept. 14th 2005
Conclusions
• The SPARC Project is aiming at producing by 2006 @ LNF
electron beams of unique properties in 6D phase space density
• Investigation on Advanced Velocity Bunching is one of its main
goals, with applications ranging from high brightness beam
production for FEL Drivers to (see PLASMONX Proj.) advanced
plasma acceleration experiments combining fs electron beams with
high intensity (>1020 W/cm2) fs laser beams (plus Thomson X-rays
in spontaneous/coerent regime, i.e. a compact X-ray laser)
• The Sparxino Linac is conceived as a X-FEL Driver based on
Adv. Vel. Bunching: it will be a test bench for the theory of
relativistic cold plasma-beams
COULOMB’05 , Senigallia, Italy, Sept. 14th 2005
QuickTime™ and aTIFF (Uncompressed) decompressor
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Physics and Applications Physics and Applications of High Brightness Electron of High Brightness Electron
BeamsBeams
Organizers: L. Palumbo (Univ. Roma), J. Rosenzweig (UCLA), L. Serafini (INFN-Milano).
COULOMB’05 , Senigallia, Italy, Sept. 14th 2005
COULOMB’05 , Senigallia, Italy, Sept. 14th 2005
COULOMB’05 , Senigallia, Italy, Sept. 14th 2005
• This solution represents a beam equilibrium mode that turns out to be the transport mode for achieving minimum emittance at the end of the emittance correction process (L.S and J.B.R., PRE 55
(1997) 7565)
• The associated plasma frequency is
• This solution includes (at ) the so-called Brillouin flow (rigid rotation at constant spot-size in a solenoid field)
σBRI =σ INV ′ γ =0( ) =mc
eBsol
I2IAγ
kpINV = 3
Ω ′ γ γ
′ γ =0
Transverse Dynamics of a quasi-laminar plasma beam (constant current)