Recent lead ion storage tests on LEAR

Bosser, J.; Broere, J; Carli, C.; Chanel, M.; Hill, C.; Ley, R.; Lombardi, A.; Maccaferri, R.; Maury, S.; Möhl, D.; Molinari, G.; Mulder, H.; Tanke, E.; Tranquille, G.; Vretenar, M.

doi:10.1109/pac.1997.749889

Cited by 4 publications

(5 citation statements)

References 2 publications

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“…With the calculated pumping speed of S 26:8 '=s (for H 2 ) this results in an effective desorption yield eff of 2 10 4 molecules per incident Pb 53 ion. The reported pressure increase in LEAR was a factor of 5 for a loss rate of about 5 10 7 ions lost per second [2], from which a desorption yield of about 7 10 4 molecules per incident Pb 54 can be estimated.…”

Section: B Equilibrium Measurementsmentioning

confidence: 96%

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Molecular desorption of stainless steel vacuum chambers irradiated with4.2 MeV/ulead ions

Mahner

Hansen

Laurent

et al. 2003

Phys. Rev. ST Accel. Beams

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In preparation for the heavy ion program of the Large Hadron Collider at CERN, accumulation and cooling tests with lead ion beams have been performed in the Low Energy Antiproton Ring. These tests have revealed that due to the unexpected large outgassing of the vacuum system, the dynamic pressure of the ring could not be maintained low enough to reach the required beam intensities. To determine the actions necessary to lower the dynamic pressure rise, an experimental program has been initiated for measuring the molecular desorption yields of stainless steel vacuum chambers by the impact of 4:2 MeV=u lead ions with the charge states 27 and 53. The test chambers were exposed either at grazing or at perpendicular incidence. Different surface treatments (glow discharges, nonevaporable getter coating) are reported in terms of the molecular desorption yields for H 2 , CH 4 , CO, Ar, and CO 2 . Unexpected large values of molecular yields per incident ion up to 2 10 4 molecules=ion have been observed. The reduction of the ion-induced desorption yield due to continuous bombardment with lead ions (beam cleaning) has been investigated for five different stainless steel vacuum chambers. The implications of these results for the vacuum system of the future Low Energy Ion Ring and possible remedies to reduce the vacuum degradation are discussed.

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Section: B Equilibrium Measurementsmentioning

confidence: 96%

“…During LEAR studies in 1997 it was measured that the intensity obtained and the stacking time were both a factor of 2 below the LHC requirements [2]. The static LEAR vacuum pressure was about 5 10 ÿ12 Torr, but local pressure bumps up to 10 ÿ9 Torr occurred during continuous injection of about 10 8 ions=s.…”

Section: Introductionmentioning

confidence: 99%

Molecular desorption of stainless steel vacuum chambers irradiated with4.2 MeV/ulead ions

Mahner

Hansen

Laurent

et al. 2003

Phys. Rev. ST Accel. Beams

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“…Resonant electron capture at small relative energy, e.g. by dielectronic recombination, could be an explanation for the enhanced recombination rates and the strong variations with the charge state which have been reported previously [6].…”

Section: Recombination Of Highly Charged Ionssupporting

confidence: 64%

Electron cooling assisted beam accumulation in the heavy ion synchrotron SIS by repeated multiturn injection

Steck

Groening²,

Blasche³

et al.

Proceedings of the 1999 Particle Accelerator Conference (Cat. No.99CH36366)

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The heavy ion synchrotron SIS has been equipped with an electron cooling system for fast beam accumulation at the injection energy. Optimization of injection and cooling resulted in synchrotron pulses with more than an order of magnitude higher intensity. For highly charged ions the intensity is limited by recombination with free electrons. The rate coefficients have been measured thus allowing a selection of the most favorable charge state in order to maximize the beam intensity for highly charged ions.

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“…In this application, for a total L of 50 µH, the value of C would need to be varied between 180 µF and 1000 µF to produce the 120 µs and 300 µs slope lengths respectively. Previous proof-of-principle tests of the multi-turn injection scheme [1,2] employed bumper power supplies using this principle of slope variation, albeit over a different range of slope lengths. Change of slope length required manual intervention to connect different capacitor values; an alternative would have been a programmable high-current switching array.…”

Section: Injection Slope Length Adjustment 1) Variation Of the Valmentioning

confidence: 99%

The injection bumper system for Leir

Fowler

Conference Record of the Twenty-Sixth International Power Modulator Symposium, 2004 and 2004 High-Voltage Workshop.

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To satisfy the ion beam luminosity requirements for CERN's future Large Hadron Collider (LHC), a small accumulator, the Low Energy Ion Ring (LEIR), is being built in the injector chain of accelerators. LEIR will use a combined longitudinal and transverse multi-turn injection scheme which requires a bumper system comprising four individually pulsed dipole magnets. The paper discusses the bumper system, in particular the power supplies which will produce a pulsed current linearly decreasing from 1.2kA to zero in a time variable between 120µs and 300µs. Each power supply employs a primary discharge circuit, comprising a storage capacitor, an IGBT switch and the magnet load inductance, to establish the peak current, and a free-wheel circuit in parallel with the magnet, comprising a diode and capacitor, to produce the linear current slope. A novel feature of the circuit is the use of a variable bias voltage on the free-wheel capacitor, allowing continuous variation of the slope duration. THE INJECTION BUMPER SYSTEM FOR LEIR A. Fowler AB Department, CERN CH-1211 Geneva 23, Switzerland AbstractTo satisfy the ion beam luminosity requirements for CERN's future Large Hadron Collider (LHC), a small accumulator, the Low Energy Ion Ring (LEIR), is being built in the injector chain of accelerators. LEIR will use a combined longitudinal and transverse multiturn injection scheme that requires a bumper system comprising four individually pulsed dipole magnets.The paper discusses the bumper system, in particular the power supplies that will produce a pulsed current linearly decreasing from 1.2 kA to zero in a time variable between 120 µs and 300 µs. Each power supply employs a primary discharge circuit, comprising a storage capacitor, an IGBT switch and the magnet load inductance, to establish the peak current, and a free-wheel circuit in parallel with the magnet, comprising a diode and capacitor, to produce the linear current slope. A novel feature of the circuit is the use of a variable bias voltage on the free-wheel capacitor, allowing continuous variation of the slope duration.

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Recent lead ion storage tests on LEAR

Cited by 4 publications

References 2 publications

Molecular desorption of stainless steel vacuum chambers irradiated with4.2 MeV/ulead ions

Molecular desorption of stainless steel vacuum chambers irradiated with4.2 MeV/ulead ions

Electron cooling assisted beam accumulation in the heavy ion synchrotron SIS by repeated multiturn injection

The injection bumper system for Leir

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