Measurements of field decay and snapback effect on tevatron dipole magnets

Velev, G.; Annala, G.; Bauer, P.; Carcagno, R.; DiMarco, J.; Glass, H.; Hanft, R.; Kephart, R.; Lamm, M.J.; Martens, M.; Schlabach, P.; Tartaglia, M.; Tompkins, J.

doi:10.1109/pac.2003.1288743

Cited by 6 publications

(17 citation statements)

References 5 publications

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“…Examples of the decay and snapback of the dodecapole component for a duration of injection of ~900 s in three MQXB magnets. The dashed line is a fit of the decay and snapback according to [11], [12].…”

Section: Discussionmentioning

confidence: 99%

“…The uncertainties, returned by the fit procedure, are approximately 0.05 units and 2 s for the decay amplitude and snapback time respectively. In this analysis, the decay and the snapback are parametrized with the logarithmic and gaussian functional forms typically used for correction of these effects in the Tevatron [11], [12]. The average decay amplitude is relatively small, approximately 0.4 units after 900 s, followed by a snapback of ~11 s.…”

Section: F Dynamic Effectsmentioning

confidence: 99%

See 1 more Smart Citation

Magnetic Field Measurements of LHC Inner Triplet Quadrupoles Fabricated at Fermilab

Velev

Bossert

Carcagno

et al. 2007

IEEE Trans. Appl. Supercond.

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Abstract-Fermilab, as part of the US-LHC AcceleratorProject, is producing superconducting low-beta quadrupole magnets for the Large Hadron Collider (LHC). These 5.5 m long magnets are designed to operate in superfluid helium at 1.9 K with a nominal gradient of 205 T/m in the 70 mm bore. Two quadrupoles separated by a dipole orbit corrector in a single cryogenic assembly comprise the Q2 optical elements of the final focus triplets in the LHC interaction regions. The field quality of the quadrupoles is measured at room temperature during construction of the cold masses as well as during cold testing of the cryogenic assembly. We summarize data from the series measurements of the magnets and discuss various topics of interest.

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Section: Discussionmentioning

confidence: 99%

Section: F Dynamic Effectsmentioning

confidence: 99%

Magnetic Field Measurements of LHC Inner Triplet Quadrupoles Fabricated at Fermilab

Velev

Bossert

Carcagno

et al. 2007

IEEE Trans. Appl. Supercond.

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“…[1]- [4] and the references found in [8].) 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%

“…To optimize these corrections for the ongoing Tevatron Run II, a detailed measurement program on the sextupole decay and snapback in the main dipoles was executed and results were reported elsewhere [3]- [4]. A new algorithm for Tevatron operation was proposed [5] and has been adopted recently [6].…”

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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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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“…Fig. 2 shows the drift and snapback during and after a 30 min injection porch in a dozen Tevatron magnets measured with a rotating coil system in MTF [14,18]. All magnets had been prepared with the same pre-cycle (20 min flat-top at 980 GeV, 1 min back-porch at 150 GeV, followed by a brief reset at 90 GeV and a ramp to the 150 GeV injection porch).…”

Section: Magnet Datamentioning

confidence: 99%

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 magnets

Cited by 6 publications

References 5 publications

Magnetic Field Measurements of LHC Inner Triplet Quadrupoles Fabricated at Fermilab

Magnetic Field Measurements of LHC Inner Triplet Quadrupoles Fabricated at Fermilab

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

Advances in the Understanding and Operations of Superconducting Colliders

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