Linac4 source extraction and low energy beam transport study

Noll, Daniel; Bencini, Vittorio; Lallement, Jean-Baptiste; Lettry, J.; Lombardi, A. M.; Lorenzo, F. Di; Mattei, S.; O’Neil, M.

doi:10.1063/1.5053381

Cited by 2 publications

(2 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As an illustration, the potential well simulated with ONIX covering the IS03 beam intensity range is presented in figure 3c, for a 35 mA beam, the potential well is of the order of −0.5 V. The H − current originating from the surface (noted H − surf) is driven by surface emission and the volume contribution (H − volume = H − total − H − surf) by plasma parameters. The slit-grid beam profile measurement is located after the first solenoid [18,19] in the Low Energy Beam Transport (LEBT) section that matches the 45 keV beam to the Radio Frequency Quadrupole (RFQ) accelerator. The limited detection size imposes focusing the beam.…”

Section: Jinst 18 C06023mentioning

confidence: 99%

Correlation of H^- beam properties to Cs-coverage

et al. 2023

Self Cite

View full text Add to dashboard Cite

A caesiated RF driven source delivers H- ions that, after stripping at the end of the 160 MeV H- linear injector, provides protons to CERN's accelerator complex including LHC, where the protons reached a record energy of 6.8 TeV. In Caesiated RF sources, H- ions are produced via dissociative attachment of electrons onto roto-vibrationally excited H2-molecules (volume) and re-emission as negative ions of protons or hydrogen atoms colliding on a low work function caesiated molybdenum plasma electrode (surface). During initial caesiation, the production mechanism evolves from the initial Cs-free volume production to a predominant surface production mode; the observed stunning reduction of co-extracted electrons is concomitant to an increase of the H- ion current to RF-power yield. This paper describes the evolution of the beam-profile at today's operational beam intensities of 35 mA for various ratios of volume and surface ion-origin. The presence of surface produced ions occurring on a conical plane is characterized by the electron to ion ratio and by measurement of the Cs-coverage of the molybdenum plasma electrode down to a fraction of a monolayer. Angular distributions are extracted from beam profile and Beam Emission Spectroscopy (BES) measurements. These experimental results provide an initial comparison to beam formation simulation that, at a later stage, could be coupled to beam transport software packages. The paper focuses on the caaesiation transient to present experimental evidence for 3D beam formation studies, it provides insight into the mixing of volume and surface production modes, reduction of co-extracted electrons and Cs-coverage. The paper also establishes magnetic field induced asymmetries in the beam's current density.

show abstract

Section: Jinst 18 C06023mentioning

confidence: 99%

Correlation of H^- beam properties to Cs-coverage

et al. 2023

Self Cite

View full text Add to dashboard Cite

show abstract

“…The phase space scan is a critically important diagnostic tool not only because it provides the distribution of the beam to be used for designing the beam transport downstream of the scan location but also for studying the beam formation of the ion source either by backtracking the beam toward the ion source 57 or by comparing beam phase space distributions from simulations to measurements, for example. In the field of ECR ion sources, thorough characterizations of the beams produced have been made with emittance measurements of magnetically separated charge states by Leitner et al 22,58 The measurements and their comparison to the conventionally used model, predicting that emittance increases for each element when charge state increases, indicate that the model does not take into account all the relevant physics.…”

Section: Reviewmentioning

confidence: 99%

Ion beam intensity and phase space measurement techniques for ion sources

Kalvas

2022

Review of Scientific Instruments

View full text Add to dashboard Cite

Ion sources produce beams used in accelerators and other applications. Both development and use of ion sources need beam diagnostics to probe the plasma processes and beam formation for optimization purposes and to produce beam parameters needed for transport tuning. These diagnostics include beam intensity measurements usually carried out with Faraday cups or inductive pickups, magnetic separation, profile measurements with scintillation screens and wires, and phase space measurements with different types of emittance scanners.

show abstract

Linac4 source extraction and low energy beam transport study

Cited by 2 publications

References 1 publication

Correlation of H^- beam properties to Cs-coverage

Correlation of H^- beam properties to Cs-coverage

Ion beam intensity and phase space measurement techniques for ion sources

Contact Info

Product

Resources

About

Linac4 source extraction and low energy beam transport study

Cited by 2 publications

References 1 publication

Correlation of H- beam properties to Cs-coverage

Correlation of H- beam properties to Cs-coverage

Ion beam intensity and phase space measurement techniques for ion sources

Contact Info

Product

Resources

About

Correlation of H^- beam properties to Cs-coverage

Correlation of H^- beam properties to Cs-coverage