Secondary-electron yields and their dependence on the angle of incidence on stainless-steel surfaces for three energetic ion beams

Thieberger, P.; Hanson, A.L.; Steski, D.; Zajic, V.; Zhang, S. Y.; Ludewig, H.

doi:10.1103/physreva.61.042901

Cited by 39 publications

(39 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The electron emission coefficient is observed to vary with the ion angle of incidence θ as γ e ∝ 1/cos(θ), where d/cos(θ) is the ion path length through a thin d ≈ 2 nm thick surface layer (where the beam-induced emitted electrons originate). Similar scaling of emission with θ is observed at higher ion energies by Thieberger [13].…”

Section: B Additional Experimental Tools and Applicationssupporting

confidence: 83%

“…We found that emission scaled with the electronic component of ion stopping in stainless steel, dE/dx [14], as has been found previously at higher energies [15]. However, the emission varied more slowly with the ion angle of incidence than 1/cos(θ), unlike measurements with 1 MeV K+ [12] and higher energy ions [13]. Based on a modified Sternglass model [16], we have modeled the dependence on ion energy and the ion angle of incidence [14], evaluating a dE/dx model with the SRIM code [20].…”

Section: B Additional Experimental Tools and Applicationssupporting

confidence: 80%

“…However, this technique is restricted to ions of low enough energy that their range is less than the thickness of the micro-crater rims. Much higherenergy grazing-incidence ions can penetrate multiple crater rims, generating electrons and gas at each entrance and exit [13]. An axially-thick, antigrazing ring can be used to stop high energy ions at normal incidence, before they strike a wall at grazing incidence [18].…”

Section: B Additional Experimental Tools and Applicationsmentioning

confidence: 99%

See 2 more Smart Citations

Quantitative experiments with electrons in a positively charged beam

et al. 2007

View full text Add to dashboard Cite

Intense ion beams are an extreme example of, and difficult to maintain as, a non-neutral plasma. Experiments and simulations are used to study the complex interactions between beam ions and (unwanted) electrons. Such "electron clouds" limit the performance of many accelerators. To characterize electron clouds, a number of parameters are measured including: total and local electron production and loss for each of three major sources, beam potential versus time, electron line-charge density, and gas pressure within the beam. Electron control methods include surface treatments to reduce electron and gas emission, and techniques to remove, or block, electrons from the beam. Detailed, selfconsistent simulations include beam-transport fields, and electron and gas generation and transport, to compute unexpectedly rich behavior, much of which is confirmed experimentally. For example, in a quadrupole magnetic field, ion and dense electron plasmas interact to produce multi-kV oscillations in the electron plasma and distortions of the beam velocity space distribution, without becoming homogenous or locally neutral.[159 words, ~150 allowed] 2

show abstract

Section: B Additional Experimental Tools and Applicationssupporting

confidence: 83%

Section: B Additional Experimental Tools and Applicationssupporting

confidence: 80%

Section: B Additional Experimental Tools and Applicationsmentioning

confidence: 99%

See 1 more Smart Citation

Quantitative experiments with electrons in a positively charged beam

et al. 2007

View full text Add to dashboard Cite

show abstract

“…For the PSR, for example, it is estimated that the proton loss rate is ~4x10 -6 per stored proton per turn, and that the electron yield per proton striking the wall is ~100-200 [19]. For heavy ions striking a chamber wall, such as Au 79+ used at RHIC, the electron yield is significantly higher than for protons [20]. For K + ions used in present HIF test drivers, the yield appears to be comparable to that for protons at the PSR, at least a low ion energies [21].…”

mentioning

confidence: 99%

Electron-cloud build-up in hadron machines

Furman¹

2004

View full text Add to dashboard Cite

The first observations of electron-proton coupling effect for coasting beams and for long-bunch beams were made at the earliest proton storage rings at the Budker Institute of Nuclear Physics (BINP) in the mid-60's [1]. The effect was mainly a form of the two-stream instability. This phenomenon reappeared at the CERN ISR in the early 70's, where it was accompanied by an intense vacuum pressure rise. When the ISR was operated in bunched-beam mode while testing aluminum vacuum chambers, a resonant effect was observed in which the electron traversal time across the chamber was comparable to the bunch spacing [2]. This effect ("beam-induced multipacting"), being resonant in nature, is a dramatic manifestation of an electron cloud sharing the vacuum chamber with a positively-charged beam. An electron-cloud-induced instability has been observed since the mid-80's at the PSR (LANL) [3]; in this case, there is a strong transverse instability accompanied by fast beam losses when the beam current exceeds a certain threshold. The effect was observed for the first time for a positron beam in the early 90's at the Photon Factory (PF) at KEK, where the most prominent manifestation was a coupled-bunch instability that was absent when the machine was operated with an electron beam under otherwise identical conditions [4]. Since then, with the advent of ever more intense positron and hadron beams, and the development and deployment of specialized electron detectors [5][6][7][8][9], the effect has been observed directly or indirectly, and sometimes studied systematically, at most lepton and hadron machines when operated with sufficiently intense beams. The effect is expected in various forms and to various degrees in accelerators under design or construction.The electron-cloud effect (ECE) has been the subject of various meetings [10][11][12][13][14][15]. Two excellent reviews, covering the phenomenology, measurements, simulations and historical development, have been recently given by Frank Zimmermann [16,17]. In this article we focus on the mechanisms of electron-cloud buildup and dissipation for hadronic beams, particularly those with very long, intense, bunches. Primary sources of electrons and secondary electron emissionDepending upon the type of machine, the EC is seeded by primary electrons from three main sources: photoelectrons, ionization of residual gas, and electrons generated when stray beam particles hit the chamber walls. In addition, for HIF drivers, an important expected source of electrons is a combination of two of the above, namely: gas will be desorbed by stray ions striking the chamber walls which will subsequently be ionized by the beam. These electrons get kicked by successive bunches mostly in the * Published as Sec. 2.9 of the ICFA Beam Dynamics Newsletter No. 33, July 2004, p. 70. 2 direction perpendicular to the beam; as they strike the walls of the chamber, they generate secondary electrons which add to the existing electron population.Of all hadron machines presently existing or under construction...

show abstract

“…The measured yields will enable us to interpret electron emission currents from electrodes in beam tubes due to beamhalo loss, and the resulting gas desorption. η e (θ), which reaches 130 at 88 o , is observed to scale as η e ∝ 1/cos(θ), (θ = 0 is normal incidence), similar to the angular dependence at higher ion energies [6]. η o (θ), measured from the pressure rise after a pulse, is less steep than 1/cos(θ), varying from 6x10 3 to 9x10 3 for 80 ≤ θ ≤ 88 o .…”

Section: Experiments and Diagnosticsmentioning

confidence: 92%

Intense Ion Beam Transport in Magnetic Quadrupoles: Experiments on Electron and Gas Effects

Seidl

Molvik

Bieniosek

et al. 2005

AIP Conference Proceedings

View full text Add to dashboard Cite

Abstract. Heavy-ion induction linacs for inertial fusion energy and high-energy density physics have an economic incentive to minimize the clearance between the beam edge and the aperture wall. This increases the risk from electron clouds and gas desorbed from walls. We have measured electron and gas emission from 1 MeV K + incident on surfaces near grazing incidence on the High-Current Experiment (HCX) at LBNL. Electron emission coefficients reach values >100, whereas gas desorption coefficients are near 10 4 . Mitigation techniques are being studied: A bead-blasted rough surface reduces electron emission by a factor of 10 and gas desorption by a factor of 2. We also discuss the results of beam transport (of 0.03-0.18 A K + ) through four pulsed room-temperature magnetic quadrupoles in the HCX at LBNL. Diagnostics are installed on HCX, between and within quadrupole magnets, to measure the beam halo loss, net charge and expelled ions, from which we infer gas density, electron trapping, and the effects of mitigation techniques. A coordinated theory and computational effort has made significant progress towards a self-consistent model of positiveion beam and electron dynamics. We are beginning to compare experimental and theoretical results.

show abstract

Secondary-electron yields and their dependence on the angle of incidence on stainless-steel surfaces for three energetic ion beams

Cited by 39 publications

References 19 publications

Quantitative experiments with electrons in a positively charged beam

Quantitative experiments with electrons in a positively charged beam

Electron-cloud build-up in hadron machines

Intense Ion Beam Transport in Magnetic Quadrupoles: Experiments on Electron and Gas Effects

Contact Info

Product

Resources

About