Parameter Name | Units | Type | Default | Description |
L | double | 0.0 | arc length | |
ANGLE | double | 0.0 | bend angle | |
K1 | double | 0.0 | geometric quadrupole strength | |
K2 | double | 0.0 | geometric sextupole strength | |
K3 | double | 0.0 | geometric octupole strength | |
K4 | double | 0.0 | geometric decapole strength | |
E1 | double | 0.0 | entrance edge angle | |
E2 | double | 0.0 | exit edge angle | |
TILT | double | 0.0 | rotation about incoming longitudinal axis | |
H1 | double | 0.0 | entrance pole-face curvature | |
H2 | double | 0.0 | exit pole-face curvature | |
HGAP | double | 0.0 | half-gap between poles | |
FINT | double | 0.5 | edge-field integral | |
DX | double | 0.0 | misalignment | |
DY | double | 0.0 | misalignment | |
DZ | double | 0.0 | misalignment | |
FSE | double | 0.0 | fractional strength error | |
ETILT | double | 0.0 | error rotation about incoming longitudinal axis | |
N_KICKS | long | 4 | number of kicks | |
NONLINEAR | long | 1 | include nonlinear field components? | |
LINEARIZE | long | 0 |
use linear matrix instead of symplectic integrator? | |
SYNCH_RAD | long | 0 |
include classical synchrotron radiation? | |
EDGE1_EFFECTS | long | 1 | include entrace edge effects? | |
EDGE2_EFFECTS | long | 1 | include exit edge effects? | |
EDGE_ORDER | long | 1 | order to which to include edge effects | |
INTEGRATION_ORDER | long | 2 | integration order (2 or 4) |
Like CSBEND, but incorporates a simulation of Coherent Synchrotron radiation.
Parameter Name | Units | Type | Default | Description |
BINS | long | 0 |
number of bins for CSR wake | |
BIN_ONCE | long | 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 | long | 0 |
Savitzky-Golay filter half-width for smoothing current histogram | |
SG_ORDER | long | 1 | Savitzky-Golay filter order for smoothing current histogram | |
SGDERIV_HALFWIDTH | long | 0 |
Savitzky-Golay filter half-width for taking derivative of current histogram | |
SGDERIV_ORDER | long | 1 | Savitzky-Golay filter order for taking derivative of current histogram | |
TRAPAZOID_INTEGRATION | long | 1 | Select whether to use trapazoid-rule 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 | long | 0 |
output final wake only? | |
STEADY_STATE | long | 0 |
use steady-state wake equations? | |
USE_BN | long | 0 |
use Bn instead of Kn? | |
B1 | double | 0.0 | K1 = B1*rho, where rho is bend radius | |
B2 | double | 0.0 | K2 = B2*rho | |
B3 | double | 0.0 | K3 = B3*rho | |
B4 | double | 0.0 | K4 = B4*rho | |
ISR | long | 0 |
include incoherent synchrotron radiation (scattering)? |
Like CSBEND, but incorporates a simulation of Coherent Synchrotron radiation.
Parameter Name | Units | Type | Default | Description |
CSR | long | 1 | enable CSR computations? | |
BLOCK_CSR | long | 0 |
block CSR from entering CSRDRIFT? | |
DERBENEV_CRITERION_MODE | STRING | disable | disable, evaluate, or enforce | |
PARTICLE_OUTPUT_FILE | STRING | NULL | name of file for phase-space output | |
PARTICLE_OUTPUT_INTERVAL | long | 0 |
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) | |
HIGH_FREQUENCY_CUTOFF0 | double | -1 | Spatial frequency at which smoothing 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 filter is 0. If not given, defaults to HIGH_FREQUENCY_CUTOFF0. |
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).
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.