Parallel capable? : yes

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 | |

K5 | double | 0.0 | geometric 12-pole strength | |

K6 | double | 0.0 | geometric 14-pole strength | |

K7 | double | 0.0 | geometric 16-pole strength | |

K8 | double | 0.0 | geometric 18-pole 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? | |

SYNCH_RAD | long | `0` |
include classical synchrotron radiation? | |

EDGE1_EFFECTS | long | 1 | include entrance edge effects? | |

EDGE2_EFFECTS | long | 1 | include exit edge effects? | |

EDGE_ORDER | long | 1 | order to which to include edge effects |

A canonical kick sector dipole magnet.

Parameter Name | Units | Type | Default | Description |

FRINGE | long | `0` |
Include fringe effects (1=linear, 2=higher order) | |

INTEGRATION_ORDER | long | 4 | integration order (2 or 4) | |

EDGE1_KICK_LIMIT | double | -1 | maximum kick entrance edge can deliver | |

EDGE2_KICK_LIMIT | double | -1 | maximum kick exit edge can deliver | |

KICK_LIMIT_SCALING | long | `0` |
scale maximum edge kick with FSE? | |

USE_BN | long | `0` |
use bn instead of Kn? | |

EXPANSION_ORDER | long | `0` |
Order of field expansion. (0=auto) | |

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 | |

B5 | double | 0.0 | K5 = b5/rho | |

B6 | double | 0.0 | K6 = b6/rho | |

B7 | double | 0.0 | K7 = b7/rho | |

B8 | double | 0.0 | K8 = b8/rho | |

XREFERENCE | double | 0.0 | reference x for interpretation of fn values | |

F1 | double | 0.0 | Fractional field error fn=bn*xrn/n!, adds to K1 or b1. | |

F2 | double | 0.0 | Fractional field error fn=bn*xrn/n!, adds to K2 or b2. | |

F3 | double | 0.0 | Fractional field error fn=bn*xrn/n!, additive. | |

F4 | double | 0.0 | Fractional field error fn=bn*xrn/n!, additive. | |

F5 | double | 0.0 | Fractional field error fn=bn*xrn/n!, additive. | |

F6 | double | 0.0 | Fractional field error fn=bn*xrn/n!, additive. | |

F7 | double | 0.0 | Fractional field error fn=bn*xrn/n!, additive. |

A canonical kick sector dipole magnet.

Parameter Name | Units | Type | Default | Description |

F8 | double | 0.0 | Fractional field error fn=bn*xrn/n!, additive. | |

ISR | long | `0` |
include incoherent synchrotron radiation (scattering)? | |

ISR1PART | long | 1 | Include ISR for single-particle beam only if ISR=1 and ISR1PART=1 | |

SQRT_ORDER | long | `0` |
Order of expansion of square-root in Hamiltonian. 0 means no expansion. | |

USE_RAD_DIST | long | `0` |
If nonzero, overrides SYNCH_RAD and ISR, causing simulation of radiation from distributions, optionally including opening angle. | |

ADD_OPENING_ANGLE | long | 1 | If nonzero, radiation opening angle effects are add if USE_RAD_DIST is nonzero. | |

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

This element provides a symplectic bending magnet with the exact
Hamiltonian. For example, it retains all orders in the momentum offset
and curvature. The field expansion is available to fourth order.

One pitfall of symplectic integration is the possibility of orbit and
path-length errors for the reference orbit if too few kicks are used.
This may be an issue for rings. Hence, one must verify that a
sufficient number of kicks are being used by looking at the trajectory
closure and length of an on-axis particle by tracking. Using
`INTEGRATION_ORDER=4` is recommended to reduce the number of
required kicks.

Normally, one specifies the higher-order components of the field with
the `K1`, `K2`, `K3`, and `K4` parameters. The field
expansion in the midplane is
. By setting the `USE_bN`
flag to a nonzero value, one may instead specify the `b1` through
`b4` parameters, which are defined by the expansion
. This is convenient if one is
varying the dipole radius but wants to work in terms of constant field
quality.

Setting `NONLINEAR=0` turns off all the terms above `K_1` (or `b_1`) and
also turns off effects due to curvature that would
normally result in a gradient producing terms of higher order.

Edge effects are included using a first- or second-order matrix. The
order is controlled using the `EDGE_ORDER` parameter, which has a
default value of 1. N.B.: if you choose the second-order matrix, it
is not symplectic.

Incoherent synchrotron radiation, when requested with `ISR=1`,
normally uses gaussian distributions for the excitation of the electrons.
Setting `USE_RAD_DIST=1` invokes a more sophisticated algorithm that
uses correct statistics for the photon energy and number distributions.
In addition, if `USE_RAD_DIST=1` one may also set `ADD_OPENING_ANGLE=1`,
which includes the photon angular distribution when computing the effect on
the emitting electron.

Some confusion may exist about the edge angles, particularly the signs.
For a sector magnet, we have of course `E1=E2=0`

. For a symmetric rectangular
magnet, `E1=E2=ANGLE/2`

. If `ANGLE`

is negative, then so are
`E1`

and `E2`

. To understand this, imagine a rectangular magnet with positive `ANGLE`

.
If the magnet is flipped over, then `ANGLE`

becomes negative, as does the bending
radius . Hence, to keep the focal length
of the edge
constant, we must also change the sign of
.

When adding errors, care should be taken to choose the right
parameters. The `FSE`

and `ETILT`

parameters are used for
assigning errors to the strength and alignment relative to the ideal
values given by `ANGLE`

and `TILT`

. One can also assign
errors to `ANGLE`

and `TILT`

, but this has a different meaning:
in this case, one is assigning errors to the survey itself. The reference
beam path changes, so there is no orbit/trajectory error. The most common
thing is to assign errors to `FSE`

and `ETILT`

. Note that when
adding errors to `FSE`

, the error is assumed to come from the power
supply, which means that multipole strengths also change.

*Special note about splitting dipoles*: when dipoles are long, it is
common to want to split them into several pieces, to get a better look
at the interior optics. When doing this, care must be exercised not
to change the optics. `elegant` has some special features that
are designed to reduce or manage potential problems. At issue is the
need to turn off edge effects between the portions of the same dipole.

First, one can simply use the `divide_elements`

command to set up
the splitting. Using this command, `elegant` takes care of everything.

Second, one can use a series of dipoles *with the same name*. In this case,
elegant automatically turns off interior edge effects. This is true when the
dipole elements directly follow one another or are separated by a MARK element.

Third, one can use a series of dipoles with different names. In this case, you
must also use the `EDGE1_EFFECTS`

and `EDGE2_EFFECTS`

parameters to
turn off interior edge effects.