An alpha magnet implemented as a matrix, up to 3rd order.
Parallel capable? : yes
GPU capable? : yes
Back-tracking capable? : no
size of alpha
inner scraper position relative to XMAX
outer scraper position relative to XMAX
inner scraper fractional momentum deviation
outer scraper fractional momentum deviation
position of scraper puck
size of scraper puck
rotation about incoming longitudinal axis
0=full, 1=first half, 2=second half
matrix order [1,3]
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 matrix-based implementation of an alpha magnet . Matrices up to third order are available .
The parameter XMAX determines the size of the alpha, which is related to the gradient g in the magnet and the central momentum βγ by
The path length of the central particle is 2.554xmax.
Because an alpha magnet has large dispersion at the midplane, it is often used for momentum filtration in addition to bunch compression. The dispersion at the center is given by the simple relation
To use an alpha magnet for momentum filtration in elegant, one must split the alpha magnet into two pieces. One may then either use the scraper features of the ALPH element or other elements such as SCRAPER or RCOL.
To split an alpha magnet, one uses the PART parameter. E.g.,
As just illustrated, the parameters DP1 and DP2 may be used to filter the momentum by providing fractional momentum deviation limits. These are implemented in a physical fashion by computing the corresopnding horizontal position deviations and imposing these as limits on the particle coordinates. One may also do this directly using the XS1 and XS2 parameters, which specify maximum acceptable deviations from the nominal horizontal position. XS1 is the allowed deviation on the low-energy side while XS2 is the allowed deviation on the high-energy side.