cavity7: lcavity, tracking_method = time_runge_kutta,  mat6_calc_method = tracking,  
field_calc = fieldmap, rf_frequency = 1.3e9,
L = 	1.0	,
grid_field = call::cavity7_grid.bmad
CALL, FILE = cavity7_wall.bmad

cavity7_reverse: lcavity, tracking_method = time_runge_kutta, mat6_calc_method = tracking,  
field_calc = fieldmap, rf_frequency = 1.3e9,
L = 	1.0	,
grid_field = call::cavity7_reverse_grid.bmad
CALL, FILE = cavity7_reverse_wall.bmad