HOMDYN

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HOMDYN (Higher Order Modes DYNamics) Massimo.Ferra
rio_at_LNF.INFN.IT Acknowledgements J. B.
Rosensweig, L. Serafini, J.P. Carneiro, J.
Clendenin, H. Edwards, V. Fusco, L. Giannessi, M.
Migliorati, A. Mosnier, D.T. Palmer, L. Palumbo,
Ph. Piot, M. Quattromini ,T. Ronsivalle, J.
Sekutowicz, F. Tazzioli.
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Historical motivation Superconducting
Photo-injectors Requirements Relativistic
and Non-Relativistic Beams gt Space Charge
Effects Long term multi-bunch beam cavity
interaction (msec-1000 bunches) gt
Transients, Beam Loading, HOM excitation
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Self Consistent Code and Reasonable CPU Time
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The HOMDYN model Normal Modes Expansion of
Cavity fields We describe the field evolution
under the slowly varying envelope approximation
for each resonant mode Analytical propagation of
field from bunch to bunch, including an external
generator Longitudinal and Transverse Beam
Laminarity We describe the bunch dynamics of a
uniform charged cylinder under the Multi-Slice
approximation Analytically computation of slice
Space Charge Fields
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Artistic view of the Envelope Equations
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Multi-Slice approximation and Envelope Equations
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Space Charge Field
Aspect Ratio
Longitudinal Component (on axis)
Radial Component (on envelope)
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g 10
g 1
g 5
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Beam Generation and Cathode Image Charges
e
e-
No Image Charges
With Images Charges
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Elliptical cross section bunch
R
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Beam Line
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Cylindrical Symmetry
Elliptical Symmetry
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Undulator (Compressor?)
Lc
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TW structures
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Wake Fields
Convolution with a Uniform charge distribution
Delta Wake Function
V/pc/m
MV/m
m
m
Wake field along a 40 mm bunch
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Comparison with PARMELA/UCLA gt good agreement
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Comparison HOMDYN with ASTRA (Ph. Piot)
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Experimental validation at the A0
photoinjector (J. P. Carneiro et al.)
1.6 cells gun, 1.3 GHz, 40 MV/m peak field, 1.3
KG solenoid 9 cells Tesla structure, 1.3 GHz, 15
MV/m accelerating field
Solenoid Scan _at_ 8nC
Emittance (mm-mrad) computed by HOMDYN and
PARMELA/Orsay
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Homdyn
Parmela
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HREAD.COR
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INPUTDECK - 4 (the output)
saving outputs every DZZSCREEN in files
HSCREEN.OUT and HFEL.OUT
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Range of the parameter scan MAXBSTEP
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INPUTDECK - 6 (elements)
SOLMAP ZSOLEN BMAX 'sanel' 1.3223500d0 0.06d0 '
sanel' 4.900d0 0.0d0 'gtfbz' 0.000d0 0.27d0 ZQUAD
QGRAD QLENGTH 8.636d0 4.7828d0 0.132d0 8.918d0
-4.7828d0 0.132d0 12.60d0 -0.2281d0 0.132d0 1
2.882d0 0.2281d0 0.132d0 14.875d0 4.8562d0 0.1
32d0 Z0CAV FI0 EPEAK IRISWF 0.d0 27.5d0 120.d
6 -11.6d-3 ZK taug rfoff 0.00045d0 -10.d-6 0
.801d0 nmod ik itrans 1 0 0 MODO WN QEX USTOR VS
FH 'new45' 2856.d6 23616.74 0.39478e-05 0.999892d0
MODO Z0FR DNCEL ZINC WN PSI FI0
EP bl IRISWF 'twnew' 1.5d0 86 0.05248467 2856.d6
120. -8. 33.33d6 1
11.6d-3 Z0TWA FI0TW EPTWA 5.d0 -13.d0 33.33d6
Z0WIG ZPER NW BRMS KX NMODULES DRIFT 18.1d0 3.d-2
71 0.504d0 0.d0 6 0.36d0
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HomDyn HomeWork for the SPARC project