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Energy loss tracking #393

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merged 4 commits into from
Apr 6, 2022
Merged

Energy loss tracking #393

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56be608
fix issue with particle lost in one turn
swhite2401 Mar 26, 2022
34c505d
add method input for tapering
swhite2401 Mar 26, 2022
0942608
add method input for tapering
swhite2401 Mar 26, 2022
c469a79
tracking as default for set cavity phase
swhite2401 Mar 26, 2022
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15 changes: 11 additions & 4 deletions pyat/at/physics/energy_loss.py
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Original file line number Diff line number Diff line change
Expand Up @@ -70,9 +70,16 @@ def tracking(ring):
sextupole_pass=None,
octupole_pass=None,
copy=True)
o0 = numpy.zeros(6)
o6 = numpy.squeeze(lattice_pass(ringtmp, o0, refpts=len(ringtmp)))
return -o6[4] * ring.energy

o6 = numpy.squeeze(lattice_pass(ringtmp, numpy.zeros(6), refpts=len(ringtmp)))
if numpy.isnan(o6[0]):
dp = 0
for e in ringtmp:
ot = numpy.squeeze(lattice_pass([e], numpy.zeros(6)))
dp += -ot[4] * ring.energy
return dp
else:
return -o6[4] * ring.energy

if isinstance(method, str):
method = ELossMethod[method.upper()]
Expand Down Expand Up @@ -150,7 +157,7 @@ def deq(x):
return timelag, ts


def set_cavity_phase(ring, method=ELossMethod.INTEGRAL,
def set_cavity_phase(ring, method=ELossMethod.TRACKING,
refpts=None, cavpts=None, copy=False):
"""
Adjust the TimeLag attribute of RF cavities based on frequency,
Expand Down
8 changes: 6 additions & 2 deletions pyat/at/physics/radiation.py
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,7 @@
from at.tracking import lattice_pass
from at.physics import find_orbit6, find_m66, find_elem_m66
from at.physics import find_mpole_raddiff_matrix, get_tunes_damp
from at.physics import ELossMethod

__all__ = ['ohmi_envelope', 'get_radiation_integrals', 'quantdiffmat',
'gen_quantdiff_elem', 'tapering']
Expand Down Expand Up @@ -397,21 +398,24 @@ def tapering(ring, multipoles=True, niter=1, **kwargs):

KEYWORDS
multipoles=True scale all multipoles
method Method for energy loss computation
(see get_energy_loss)
niter=1 number of iteration
XYStep=1.0e-8 transverse step for numerical computation
DPStep=1.0E-6 momentum deviation used for computation of orbit6
"""

xy_step = kwargs.pop('XYStep', DConstant.XYStep)
dp_step = kwargs.pop('DPStep', DConstant.DPStep)
method = kwargs.pop('method', ELossMethod.TRACKING)
dipoles = get_refpts(ring, Dipole)
b0 = get_value_refpts(ring, dipoles, 'BendingAngle')
k0 = get_value_refpts(ring, dipoles, 'PolynomB', index=0)
ld = get_value_refpts(ring, dipoles, 'Length')

for i in range(niter):
_, o6 = find_orbit6(ring, refpts=range(len(ring)+1),
XYStep=xy_step, DPStep=dp_step)
XYStep=xy_step, DPStep=dp_step, method=method)
dpps = (o6[dipoles, 4] + o6[dipoles+1, 4]) / 2
set_value_refpts(ring, dipoles, 'PolynomB', b0/ld*dpps+k0*(1+dpps),
index=0)
Expand All @@ -420,7 +424,7 @@ def tapering(ring, multipoles=True, niter=1, **kwargs):
mults = get_refpts(ring, Multipole)
k0 = get_value_refpts(ring, dipoles, 'PolynomB', index=0)
_, o6 = find_orbit6(ring, refpts=range(len(ring)+1),
XYStep=xy_step, DPStep=dp_step)
XYStep=xy_step, DPStep=dp_step, method=method)
dpps = (o6[mults, 4] + o6[mults+1, 4]) / 2
for dpp, el in zip(dpps, ring[mults]):
el.PolynomB *= 1+dpp
Expand Down