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Pseudo-orbit averages injection TBT data per-BPM across turns, bridging the gap between raw TBT (beam threading) and closed-orbit (stable operation) reading modes. Needed for ALSU commissioning after stitching achieves multi-turn survival. - BPMSystem.capture_pseudo_orbit(): delegates to capture_injection + nanmean - pySCPseudoOrbitInterface: plugs into orbit_correction with orbit RM - Tuning.correct_orbit(pseudo=True, n_turns=N): one-flag switch - Fix pre-existing np.concat bug in fit_dispersive_orbit - Remove commented-out correct_pseudo_orbit_at_injection prototype
kparasch
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Mar 30, 2026
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kparasch
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kparasch
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I agree with the API, I have requested some small changes.
| return fake_trajectory_x_tbt, fake_trajectory_y_tbt | ||
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| def capture_pseudo_orbit(self, n_turns=1, bba=True, subtract_reference=True, | ||
| use_design=False, return_transmission=False): |
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Would be nice to have a "starting_turn=1" option in case one wants to define the pseudo-orbit from later turns for reasons like fast-kicker orbit bumps, decoherence, e.t.c
| ) | ||
| if return_transmission: | ||
| x, y, transmission = result | ||
| return np.nanmean(x, axis=1), np.nanmean(y, axis=1), transmission |
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I would prefer to catch np.nanmean warnings. They can get quite annoying.
with warnings.catch_warnings():
warnings.simplefilter("ignore", category=RuntimeWarning)
mean_data = np.nanmean(data, axis=1)
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| class pySCPseudoOrbitInterface(pySCOrbitInterface): | ||
| SC: "SimulatedCommissioning" = Field(repr=False) | ||
| n_turns: int = 1 |
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starting_turn=1 from above should be an attribute of the class here
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| def correct_orbit(self, n_reps=1, method='tikhonov', parameter=100, gain=1, virtual=False): | ||
| def correct_orbit(self, n_reps=1, method='tikhonov', parameter=100, gain=1, virtual=False, | ||
| pseudo=False, n_turns=1): |
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Should raise an error/warning if n_turns and starting_turn is redefined but pseudo is False
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Summary
BPMSystem.capture_pseudo_orbit()— injects, tracks N turns, averages per-BPM across turns viananmean. Returns(n_bpms,)arrays matching orbit interface shape.pySCPseudoOrbitInterfacethat plugs directly intoorbit_correction()using the orbit response matrix.Tuning.correct_orbit()withpseudo=True, n_turns=N— one-flag switch from closed-orbit to pseudo-orbit correction.np.concat→np.concatenatebug infit_dispersive_orbit().correct_pseudo_orbit_at_injectionprototype.Motivation
Pseudo-orbit is the natural reading mode between TBT (beam threading) and closed-orbit (stable operation). After stitching achieves multi-turn survival, pseudo-orbit averages out turn-by-turn jitter to give a smoother correction target. This is needed for ALSU accumulator ring commissioning.
@kparasch — I'm open to alternative implementations of this feature, but pseudo-orbit as a first-class reading mode is something we definitely need for ALSU commissioning. It would be nice to have a convenient high-level function for this in pySC. Happy to iterate on the API if you have preferences.
Usage
Test plan
correct_orbit(pseudo=True))