beam section (mandatory)

Here we define the main properties of the beam at the entrance of the linac. Note that with TraceWin, most of these properties are defined within its own .ini file. The units must be consistent with LightWin’s system of units, see also Units and conventions.

Entry

Type

Description

Allowed values

Mandatory?

e_mev

float

Energy of particle at entrance in \(\mathrm{MeV}\)

✅

e_rest_mev

float

Rest energy of particle in \(\mathrm{MeV}\)

✅

f_bunch_mhz

float

Beam bunch frequency in \(\mathrm{MHz}\)

✅

i_milli_a

float

Beam current in \(\mathrm{mA}\). Warning: this key is not used. EnvelopeiD solvers do not model space-charge, and the current in TraceWin solver is controlled by the current1 key.

❌

q_adim

float

Adimensioned charge of particle

✅

sigma

list or ndarray

Input \(\sigma\) beam matrix in \(\mathrm{m}\); \(\mathrm{rad}\). Must be a list of lists of floats that can be transformed to a 6*6 matrix.

✅

Format for the sigma entry:

sigma = [
   [ 1e-6, -2e-7,  0e+0, 0e+0,  0e+0, 0e+0],
   [-2e-7,  8e-7,  0e+0, 0e+0,  0e+0, 0e+0],
   [ 0e+0,  0e+0, -2e-7, 8e-7,  0e+0, 0e+0],
   [ 0e+0,  0e+0, -2e-7, 8e-7,  0e+0, 0e+0],
   [ 0e+0,  0e+0,  0e+0, 0e+0, -2e-7, 8e-7],
   [ 0e+0,  0e+0,  0e+0, 0e+0, -2e-7, 8e-7]
 ]