Electron proton two-stream instability at the PSR

Macek, R.; Browman, A.; Fitzgerald, D.; McCrady, R.; Merrill, F. E.; Plum, Michael; Spickermann, T.; Wang, T.S.; Griffin, James E.; Ng, K.Y.; Wildman, D.; Harkay, K.; Kustom, R.L.; Rosenberg, R. A.

doi:10.1109/pac.2001.987606

Cited by 13 publications

(13 citation statements)

References 7 publications

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“…Since about 1988, an electron-cloud instability has been observed at the Los Alamos PSR [23,24]. The characteristics of the instability are similar to those at the earlier proton storage rings.…”

Section: Fig 1 Observation Of An Electron-driven Instability At Thementioning

confidence: 59%

Review of single bunch instabilities driven by an electron cloud

Zimmermann

2004

Phys. Rev. ST Accel. Beams

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Electrons generated and accumulated inside the beam-pipe form an ''electron cloud'' that interacts with a charged particle beam. If the number of electrons is sizable, this beam-cloud interaction can give rise to a two-stream instability, resulting in beam loss or emittance growth. The instability can occur within a single bunch, e.g., passing through the cloud on successive turns in a storage ring, or it can be a multibunch instability, where the motion of successive bunches is coupled via the electron cloud. In this paper, I review the experimental evidence for, simulation approaches to, and analytical treatments of single-bunch two-stream instabilities caused by an electron cloud. Depending on the parameter regime, this type of instability may resemble a coasting-beam instability, classical beam breakup, or transverse mode coupling. It can also cause long-term emittance growth. Despite the apparent similarities, a few fundamental differences distinguish the two-stream instability from a conventional impedance-driven instability, and limit the applicability of established accelerator-physics concepts, like ''wakefield.'' On the other hand, if, in addition to the electron cloud, space-charge forces, conventional impedance, or beam-beam interaction are also present, these can conspire so as to enhance the growth rate.

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Section: Fig 1 Observation Of An Electron-driven Instability At Thementioning

confidence: 59%

Review of single bunch instabilities driven by an electron cloud

Zimmermann

2004

Phys. Rev. ST Accel. Beams

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“…Electron Cloud Effects (ECE) were observed in the proton storage rings at BINP [2], the intersecting storage rings at CERN [3], the proton storage ring at LANL [4], the relativistic heavy ion collider at BNL [5], the photon factory at KEK [6,7], the low energy ring at KEKB [8], and other storage rings. They can potentially limit the performance of the large hadron collider (LHC) at CERN, and have been subject of and featured in various meetings.…”

Section: Introductionmentioning

confidence: 99%

“…Simple biased electrodes change the collection length and increase the energy of electron striking the electrodes. Previous measurements were made only between bunches by sweeping them towards a detector with a pulsed electrode [4,9] or by selecting high energy electrons when the bunch pattern emerges [10]. section, an electrostatic and magnetic transport section.…”

Section: Introductionmentioning

confidence: 99%

Absolute measurement of electron cloud density

Covo¹,

Molvik

Cohen

et al. 2007

2007 IEEE Particle Accelerator Conference (PAC)

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Beam interaction with background gas and walls produces ubiquitous clouds of stray electrons that frequently limit the performance of particle accelerator and storage rings. Counterintuitively we obtained the electron cloud accumulation by measuring the expelled ions that are originated from the beam-background gas interaction, rather than by measuring electrons that reach the walls. The kinetic ion energy measured with a retarding field analyzer (RFA) maps the depressed beam space-charge potential and provides the dynamic electron cloud density. Clearing electrode current measurements give the static electron cloud background that complements and corroborates with the RFA measurements, providing an absolute measurement of electron cloud density during a 5 µs duration beam pulse in a drift region of the magnetic transport section of the High-Current Experiment (HCX) at LBNL.

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“…Further information on the effects of beam current with the buncher can be found in [7]. Most recently, PSR has accumulated beam intensity up to 9.7 uC (6 x 10 1 3 protons) per macropulse [8].…”

Section: Resultsmentioning

confidence: 99%

Low level RF control for the LANSCE Proton Storage Ring buncher

Lyles

Davis²

PACS2001. Proceedings of the 2001 Particle Accelerator Conference (Cat. No.01CH37268)

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The Los Alamos Neutron Science Center (LANSCE) has upgraded the Proton Storage Ring (PSR) for the Short Pulse Spallation Source (SPSS) [1]. 100 microamperes of average beam current is now delivered to the new target assembly. One major task of the improvement project was the design and construction of a power amplifier to increase the drive voltage to the cathode follower final power amplifier used to overcome longitudinal space charge forces in the accumulated beam. With this amplifier and power supply improvements, the buncher voltage from the 2.8 MHz radio frequency system was raised 50% to the present 18 kilovolts (kV) peak [2]. Improvements to the low level RF controls were incorporated, in both the amplitude feedback control and a new phase controller. These systems and the resulting RF performance improvements will be discussed. The upgraded RF buncher has delivered the required performance at LANSCE to ensure that the 100 microampere beam on target was achieved.

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Electron proton two-stream instability at the PSR

Cited by 13 publications

References 7 publications

Review of single bunch instabilities driven by an electron cloud

Review of single bunch instabilities driven by an electron cloud

Absolute measurement of electron cloud density

Low level RF control for the LANSCE Proton Storage Ring buncher

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