Studies of the Chromaticity, Tune, and Coupling Drift in the Tevatron

Martens, M.; Annala, J.; Bauer, P.; Shiltsev, Vladimir; Velev, G.

doi:10.1109/pac.2005.1590541

Cited by 4 publications

(12 citation statements)

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“…However, recent Tevatron beam tests [6] and stand-alone magnet measurements [9] uncovered a new fast sextupole decay at the beginning of injection.…”

Section: A Sextupole Decaymentioning

confidence: 99%

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Measurements of the Persistent Current Decay and Snapback Effect in Tevatron Dipole Magnets

Velev

Bauer

DiMarco

et al. 2007

IEEE Trans. Appl. Supercond.

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Abstract-A systematic study of the persistent current decay and snapback effect in the fields of Tevatron accelerator dipoles was performed at the Fermilab Magnet Test Facility (MTF). The decay and snapback were measured under a range of conditions including variations of the current ramp parameters and magnet operational history. The study has mostly focused on the dynamic behavior of the normal sextupole component. In addition, the paper presents the persistent current effects observed in the other allowed field harmonics as well. The results provide new information about the previously observed "excess" decay during the first several seconds of the sextupole decay during injection and the correlation between the snapback amplitude and its duration.

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“…However, recent Tevatron beam tests [6] and stand-alone magnet measurements [9] uncovered a new fast sextupole decay at the beginning of injection.…”

Section: A Sextupole Decaymentioning

confidence: 99%

“…The modified Tevatron operational ramp profile, adopted after our recent proposal for the optimization of the sextupole corrections during injection [6], is shown in Fig. 1.…”

Section: Introductionmentioning

confidence: 99%

Measurements of the Persistent Current Decay and Snapback Effect in Tevatron Dipole Magnets

Velev

Bauer

DiMarco

et al. 2007

IEEE Trans. Appl. Supercond.

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“…This will be discussed in further detail below and in other, related contributions to these proceedings [21,22].…”

Section: ( )mentioning

confidence: 90%

“…At the same time the minimum tune split drifts by ~0.02 units [15,22]. The source of this effect remains uncertain to this day.…”

Section: Remarks On Tuneandcoupling Driftmentioning

confidence: 99%

“…2, however, shows that in some magnets the b 2 drift amplitude departs strongly from zero at t=0 sec, as if it underwent a very fast drift (and slowed down afterwards). Further exploration of this unexpected, fast drift contribution is under way [21,22]. First measurements were also conducted at CERN to investigate the possibility of fast drifts in the LHC dipoles.…”

Section: Magnet Datamentioning

confidence: 99%

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Advances in the Understanding and Operations of Superconducting Colliders

Annala

Bauer

Bottura

et al.

Proceedings of the 2005 Particle Accelerator Conference

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Chromaticity drift during injection is a well-known phenomenon in superconducting colliders, such as the Tevatron, HERA and RHIC. Imperfect compensation of the drift effects can contribute to beam loss and emittance growth. It is caused by the drift of the sextupole component in the dipole magnets due to current redistribution in its superconducting coils. Recently extensive studies of chromaticity drift were conducted at the Tevatron, aiming at the improvement of the luminosity performance in the ongoing run II. These studies included not only beam experiments, but also extensive off-line magnetic measurements on spare Tevatron dipoles.Less known, until recently, is that chromaticity drift is often accompanied by tune and coupling drift. This was recently discovered in the Tevatron. We believe that these effects are the product of systematic beam offset in conjunction with the sextupole drifts (and their compensation in the chromaticity correctors).These discoveries are most relevant to the upcoming LHC, where the drift effects will have even more dramatic consequences given the high beam current. It is therefore not a surprise that CERN has been the source of major advances in the understanding of dynamic effects during the LHC superconducting magnet development.The following will briefly review the CERN results as well as those of the recent Fermilab studies. A new result, which will be presented here also, is related to fast drifts occurring in the first few seconds of the injection plateau. Again, these fast drifts were observed first in the Tevatron and efforts are underway to explain them. Finally this paper will attempt to derive the implications of these drift effects on LHC commissioning and operation.

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Measurements of Field Decay and Snapback Effect on Tevatron Dipole and Quadrupole Magnets

Velev

Ambrosio

Annala

et al.

Proceedings of the 2005 Particle Accelerator Conference

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Since the beginning of 2002 an intensive measurement program has been performed at the Fermilab Magnet Test Facility (MTF) to understand dynamic effects in Tevatron magnets. Based on the results of this program a new correction algorithm was proposed to compensate for the decay of the sextupole field during the dwell at injection and for the subsequent field "snapback" during the first few seconds of the energy ramp. Beam studies showed that the new correction algorithm works better than the original one, and improves the Tevatron efficiency by at least 3%. The beam studies also indicated insufficient correction during the first 6s of the injection plateau where an unexpected discrepancy of 0.15 sextupole units of extra drift was observed. This paper reports on the most recent measurements of the Tevatron dipoles field at the beginning of the injection plateau. Results on the field decay and snapback in the Tevatron quadrupoles are also presented.

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Studies of the Chromaticity, Tune, and Coupling Drift in the Tevatron

Cited by 4 publications

References 0 publications

Measurements of the Persistent Current Decay and Snapback Effect in Tevatron Dipole Magnets

Measurements of the Persistent Current Decay and Snapback Effect in Tevatron Dipole Magnets

Advances in the Understanding and Operations of Superconducting Colliders

Measurements of Field Decay and Snapback Effect on Tevatron Dipole and Quadrupole Magnets

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