def _measBetaQuad(elem, **kwargs):
dqk1 = abs(kwargs.get("dqk1", 0.01))
num_points = kwargs.get("num_points", 5)
minwait = kwargs.get("minwait", 3)
qk10 = elem.k1
qk1 = qk10 + np.linspace(-dqk1, dqk1, num_points)
nu = np.zeros((num_points, 2), "d")
for i, k1 in enumerate(qk1):
v0 = getOrbit()
elem.k1 = k1
waitStableOrbit(v0, minwait=minwait, maxwait=15)
nu[i, :] = getTunes()
elem.k1 = qk10
return qk1, nu
def measDispersion(
elem, dfmax=5e-7, alphac=3.6261976841792413e-04, gamma=5.870841487279844e3, num_points=5, full=False, verbose=0
):
"""measure dispersion at BPMs
Parameters
-----------
elem : BPM name, list or pattern
dfmax : float. frequency change (check the unit)
alphac : float. momentum compaction factor.
gamma : float. beam energy.
num_points : int. points to fit line
full : reserved.
Returns
--------
eta : numpy.array. (nelem, 3) with columns etax, etay and s
Examples
---------
>>> eta = measDispersion('p*c0[1-4]*')
"""
eta = alphac - 1.0 / gamma / gamma
bpmobj = [b for b in getElements(elem) if b.family == "BPM"]
bpmnames = [b.name for b in bpmobj]
nbpm = len(bpmnames)
_logger.info("measure dispersions at %d elements '%s'" % (len(bpmnames), str(elem)))
f0 = getRfFrequency(handle="setpoint")
dflst = np.linspace(-abs(dfmax), abs(dfmax), num_points)
# incase RF does not allow large step change, ramp down first
for df in np.linspace(0, abs(dfmax), num_points)[1:-1]:
putRfFrequency(f0 - df)
time.sleep(2.0 / num_points)
# avoid a bug in virtac
obt0 = getOrbit(bpmnames)
cod = np.zeros((len(dflst), 2 * nbpm), "d")
for i, df in enumerate(dflst):
v0 = getOrbit()
putRfFrequency(f0 + df)
if verbose > 0:
print(i, "df=", df, " f=", f0)
waitStableOrbit(v0)
# repeat the put/get in case simulator did not response latest results
obt = getOrbit(bpmnames)
# print i, obt[0,:2], obt0[0,:2], np.shape(obt), np.shape(obt0)
cod[i, :nbpm] = obt[:, 0] - obt0[:, 0]
cod[i, nbpm:] = obt[:, 1] - obt0[:, 1]
# restore
for df in np.linspace(0, abs(dfmax), num_points):
putRfFrequency(f0 + abs(dfmax) - df)
time.sleep(2.0 / num_points)
# fitting
p = np.polyfit(dflst, cod, deg=1)
disp = -p[0, :] * f0 * eta
s = np.array([e.sb for e in bpmobj], "d")
ret = np.zeros((len(bpmobj), 3), "d")
ret[:, 0] = disp[:nbpm]
ret[:, 1] = disp[nbpm:]
ret[:, 2] = s
if verbose > 0:
for i, bpm in enumerate(bpmobj):
print(i, bpm.name, bpm.sb, ret[i, 0], ret[i, 1])
return ret
def measDispersion(elem,
dfmax=5e-7,
alphac=3.6261976841792413e-04,
gamma=5.870841487279844e3,
num_points=5,
full=False,
verbose=0):
"""measure dispersion at BPMs
Parameters
-----------
elem : BPM name, list or pattern
dfmax : float. frequency change (check the unit)
alphac : float. momentum compaction factor.
gamma : float. beam energy.
num_points : int. points to fit line
full : reserved.
Returns
--------
eta : numpy.array. (nelem, 3) with columns etax, etay and s
Examples
---------
>>> eta = measDispersion('p*c0[1-4]*')
"""
eta = alphac - 1.0 / gamma / gamma
bpmobj = [b for b in getElements(elem) if b.family == 'BPM']
bpmnames = [b.name for b in bpmobj]
nbpm = len(bpmnames)
_logger.info("measure dispersions at %d elements '%s'" %
(len(bpmnames), str(elem)))
f0 = getRfFrequency(handle="setpoint")
dflst = np.linspace(-abs(dfmax), abs(dfmax), num_points)
# incase RF does not allow large step change, ramp down first
for df in np.linspace(0, abs(dfmax), num_points)[1:-1]:
putRfFrequency(f0 - df)
time.sleep(2.0 / num_points)
# avoid a bug in virtac
obt0 = getOrbit(bpmnames)
cod = np.zeros((len(dflst), 2 * nbpm), 'd')
for i, df in enumerate(dflst):
v0 = getOrbit()
putRfFrequency(f0 + df)
if verbose > 0:
print(i, "df=", df, " f=", f0)
waitStableOrbit(v0)
# repeat the put/get in case simulator did not response latest results
obt = getOrbit(bpmnames)
#print i, obt[0,:2], obt0[0,:2], np.shape(obt), np.shape(obt0)
cod[i, :nbpm] = obt[:, 0] - obt0[:, 0]
cod[i, nbpm:] = obt[:, 1] - obt0[:, 1]
# restore
for df in np.linspace(0, abs(dfmax), num_points):
putRfFrequency(f0 + abs(dfmax) - df)
time.sleep(2.0 / num_points)
# fitting
p = np.polyfit(dflst, cod, deg=1)
disp = -p[0, :] * f0 * eta
s = np.array([e.sb for e in bpmobj], 'd')
ret = np.zeros((len(bpmobj), 3), 'd')
ret[:, 0] = disp[:nbpm]
ret[:, 1] = disp[nbpm:]
ret[:, 2] = s
if verbose > 0:
for i, bpm in enumerate(bpmobj):
print(i, bpm.name, bpm.sb, ret[i, 0], ret[i, 1])
return ret
