Like CSBEND, but incorporates a simulation of Coherent Synchrotron radiation.
Parallel capable? : yes
GPU capable? : yes
Backtracking capable? : yes
Parameter Name  Units  Type  Default  Description 
L  M  double  0.0  arc length 
ANGLE  RAD  double  0.0  bend angle 
K1  1∕M^{2}  double  0.0  geometric quadrupole strength 
K2  1∕M^{3}  double  0.0  geometric sextupole strength 
K3  1∕M^{4}  double  0.0  geometric octupole strength 
K4  1∕M^{5}  double  0.0  geometric decapole strength 
K5  1∕M^{6}  double  0.0  geometric 12pole strength 
K6  1∕M^{7}  double  0.0  geometric 14pole strength 
K7  1∕M^{8}  double  0.0  geometric 16pole strength 
K8  1∕M^{9}  double  0.0  geometric 18pole strength 
E1  RAD  double  0.0  entrance edge angle 
E2  RAD  double  0.0  exit edge angle 
TILT  RAD  double  0.0  rotation about incoming longitudinal axis 
H1  1∕M  double  0.0  entrance poleface curvature 
H2  1∕M  double  0.0  exit poleface curvature 
HGAP  M  double  0.0  halfgap between poles 
FINT  double  0.5  edgefield integral 

DX  M  double  0.0  misalignment 
DY  M  double  0.0  misalignment 
DZ  M  double  0.0  misalignment 
FSE  double  0.0  fractional strength error 

ETILT  RAD  double  0.0  error rotation about incoming longitudinal axis 
N_SLICES  long  4  Number of slices (full integrator steps). 

N_KICKS  long  4  number of kicks. Deprecated. Use N_SLICES 

ETILT_SIGN  short  1  Sign of ETILT relative to TILT. 1 is the old convention prior to 2020.5 

NONLINEAR  short  1  include nonlinear field components? 

CSRCSBEND continued
Like CSBEND, but incorporates a simulation of Coherent Synchrotron radiation.
Parameter Name  Units  Type  Default  Description 
LINEARIZE  short  0  use linear matrix instead of symplectic integrator? 

SYNCH_RAD  short  0  include classical, singleparticle synchrotron radiation? 

EDGE1_EFFECTS  short  1  include entrance edge effects? 

EDGE2_EFFECTS  short  1  include exit edge effects? 

EDGE_ORDER  short  1  order to which to include edge effects 

INTEGRATION_ORDER  short  4  integration order (2, 4, or 6) 

BINS  long  0  number of bins for CSR wake 

BIN_ONCE  short  0  bin only at the start of the dipole? 

BIN_RANGE_FACTOR  double  1.2  Factor by which to increase the range of histogram compared to total bunch length. Large value eliminates binning problems in CSRDRIFTs. 

SG_HALFWIDTH  short  0  SavitzkyGolay filter halfwidth for smoothing current histogram. If less than 1, no SG smoothing is performed. 

SG_ORDER  short  1  SavitzkyGolay filter order for smoothing current histogram 

SGDERIV_HALFWIDTH  short  0  SavitzkyGolay filter halfwidth for taking derivative of current histogram. Defaults to SG_HALFWIDTH (if positive) or else 1. 

SGDERIV_ORDER  short  1  SavitzkyGolay filter order for taking derivative of current histogram 

CSRCSBEND continued
Like CSBEND, but incorporates a simulation of Coherent Synchrotron radiation.
Parameter Name  Units  Type  Default  Description 
TRAPAZOID_INTEGRATION  short  1  Select whether to use trapazoidrule integration (default) or a simple sum. 

OUTPUT_FILE  STRING  NULL  output file for CSR wakes 

OUTPUT_INTERVAL  long  1  interval (in kicks) of output to OUTPUT_FILE 

OUTPUT_LAST_WAKE_ONLY  short  0  output final wake only? 

STEADY_STATE  short  0  use steadystate wake equations? 

IGF  short  0  use integrated Greens function (requires STEADY_STATE=1)? 

USE_BN  short  0  use b<n> instead of K<n>? 

EXPANSION_ORDER  short  0  Order of field expansion. (0=auto) 

B1  1∕M  double  0.0  K1 = b1/rho, where rho is bend radius 
B2  1∕M^{2}  double  0.0  K2 = B2/rho 
B3  1∕M^{3}  double  0.0  K3 = B3/rho 
B4  1∕M^{4}  double  0.0  K4 = B4/rho 
B5  1∕M^{5}  double  0.0  K5 = B5/rho 
B6  1∕M^{6}  double  0.0  K6 = B6/rho 
B7  1∕M^{7}  double  0.0  K7 = B7/rho 
B8  1∕M^{8}  double  0.0  K8 = B8/rho 
ISR  short  0  include incoherent synchrotron radiation (quantum excitation)? 

ISR1PART  short  1  Include ISR for singleparticle beam only if ISR=1 and ISR1PART=1 

CSR  short  1  enable CSR computations? 

BLOCK_CSR  short  0  block CSR from entering CSRDRIFT? 

DERBENEV_CRITERION_MODE  STRING  disable  disable, evaluate, or enforce 

PARTICLE_OUTPUT_FILE  STRING  NULL  name of file for phasespace output 

CSRCSBEND continued
Like CSBEND, but incorporates a simulation of Coherent Synchrotron radiation.
Parameter Name  Units  Type  Default  Description 
PARTICLE_OUTPUT_INTERVAL  long  1  interval (in kicks) of output to PARTICLE_OUTPUT_FILE 

SLICE_ANALYSIS_INTERVAL  long  0  interval (in kicks) of output to slice analysis file (from slice_analysis command) 

LOW_FREQUENCY_CUTOFF0  double  1  Highest spatial frequency at which lowfrequency cutoff filter is zero. If not positive, no lowfrequency cutoff filter is applied. Frequency is in units of Nyquist (0.5/binsize). 

LOW_FREQUENCY_CUTOFF1  double  1  Lowest spatial frequency at which lowfrequency cutoff filter is 1. If not given, defaults to LOW_FREQUENCY_CUTOFF1. 

HIGH_FREQUENCY_CUTOFF0  double  1  Spatial frequency at which smoothing (highfrequency cutoff) filter begins. If not positive, no frequency filter smoothing is done. Frequency is in units of Nyquist (0.5/binsize). 

HIGH_FREQUENCY_CUTOFF1  double  1  Spatial frequency at which smoothing (highfrequency cutoff) filter is 0. If not given, defaults to HIGH_FREQUENCY_CUTOFF0. 

CLIP_NEGATIVE_BINS  short  1  If nonzero, then any bins with negative counts after the filters are applied have the counts set to zero. 

WAKE_FILTER_FILE  STRING  NULL  Name of file supplying wakefield filtering data. 

WFF_FREQ_COLUMN  STRING  NULL  Name of column supplying frequency values for wakefield filtering data. 

CSRCSBEND continued
Like CSBEND, but incorporates a simulation of Coherent Synchrotron radiation.
Parameter Name  Units  Type  Default  Description 
WFF_REAL_COLUMN  STRING  NULL  Name of column supplying real values for wakefield filtering data. 

WFF_IMAG_COLUMN  STRING  NULL  Name of column supplying imaginary values for wakefield filtering data. 

GROUP  string  NULL  Optionally used to assign an element to a group, with a userdefined name. Group names will appear in the parameter output file in the column ElementGroup 

For a discussion of the method behind this element, see M. Borland, “Simple method for particle tracking with coherent synchrotron radiation,” Phys. Rev. ST Accel. Beams 4, 070701 (2001) and G. Stupakov and P. Emma, SLAC LCLSTN0112 (2001).
Recommendations for using this element. The default values for this element are not the best ones to use. They are retained only for consistency through upgrades. In using this element, it is recommended to have 50 to 100 k particle in the simulation. Setting BINS=600 and SG_HALFWIDTH=1 is also recommended to allow resolution of fine structure in the beam and to avoid excessive smoothing. It is strongly suggested that the user vary these parameters and view the histogram output to verify that the longitudinal distribution is well represented by the histograms (use OUTPUT_FILE to obtain the histograms). For LCLS simulations, we find that the above parameters give essentially the same results as obtained with 500 k particles and up to 3000 bins.
In order to verify that the 1D approximation is valid, the user should also set DERBENEV_CRITERION_MODE = ‘‘evaluate’’ and view the data in OUTPUT_FILE. Generally, the criterion should be much less than 1. See equation 11 of [20].
In order respects, this element is just like the CSBEND element, which provides a symplectic bending magnet that is accurate to all orders in momentum offset. Please see the manual page for CSBEND for more details about features not related to CSR.
Splitting dipoles: Splitting dipoles with continuation of CSR effects is possible provided the dipole sections (all of which must have the same name) are either consecutive or separated only by MARK, WATCH, or LSCDRIFT elements. The LSCDRIFT elements must have L=0 and should have LEFFECTIVE set to the length of the upstream dipole segment. This allows simulating LSC and CSR within a single dipole.
CSRDRIFT