Formation and mitigation of halo particles in the Spallation Neutron Source linac

Jeon, D.; Stovall, J.; Aleksandrov, A.; Wei, J.; Staples, J.; Keller, R.; Young, L.M.; Takeda, H.; Nath, S.

doi:10.1103/physrevstab.5.094201

Cited by 16 publications

(9 citation statements)

References 7 publications

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“…Compared with the nominal MEBT optics, the halo is visibly reduced and the rms emittance is significantly reduced from 0.454 to 0.289 mm mrad when the proposed round beam optics is employed. This confirms experimentally the halo generation mechanism identified in the previous paper [7]. It should be noted that substantial halo is generated mainly in the horizontal plane for the nominal beam optics even though MEBT is matched to DTL in the sense of minimizing rms emittances.…”

Section: Experimental Verification Of the Halo Formation Mechanismsupporting

confidence: 89%

“…This particle loss at higher energies results in radio activation of the CCL. A new halo generation mechanism was reported in the nonperiodic lattices such as the SNS linac MEBT (between RFQ and DTL) [7]. The nonlinear space charge force resulting from large transverse beam eccentricity $2:1 in the 1.6-m-long MEBT chopper section shown in the upper plot of Fig.…”

Section: Introductionmentioning

confidence: 75%

“…It is vital to remove potential mismatch between the MEBT and DTL tank 1. It should be pointed out that this particular round beam optics is slightly different in the middle of MEBT from that presented in the previous paper [7]. There are many sets of possible round beam optics and the one used in this study is one of them.…”

Section: Experimental Verification Of the Halo Formation Mechanismmentioning

confidence: 91%

“…Modifying the MEBT optics and introducing adjustable collimators in the MEBT chopper target significantly reduce beam losses in the CCL, which is a preferred halo mitigation scheme. For the details, please refer to the previous study [7].…”

Section: Dong-o Jeonmentioning

confidence: 99%

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Evidence of a halo formation mechanism in the Spallation Neutron Source linac

Jeon

2013

Phys. Rev. ST Accel. Beams

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Phys. Rev. ST Accel. Beams 5, 094201 (2002)] are verified experimentally through a series of emittance measurements performed during the drift tube linac tank 1 commissioning of the Spallation Neutron Source. This is a rare experiment evidence of a halo formation mechanism. As the simulation predicts, the emittance measurements clearly show a visible halo reduction as well as a significant rms emittance reduction when the proposed round beam optics is employed. The emittance measurement results are consistent with multiparticle simulations and also consistent with wire scanner results. These measurements serve as a valuable code benchmarking for a beam under an intense space charge effect.

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Section: Experimental Verification Of the Halo Formation Mechanismsupporting

confidence: 89%

Section: Introductionmentioning

confidence: 75%

Section: Experimental Verification Of the Halo Formation Mechanismmentioning

confidence: 91%

Section: Dong-o Jeonmentioning

confidence: 99%

See 2 more Smart Citations

Evidence of a halo formation mechanism in the Spallation Neutron Source linac

Jeon

2013

Phys. Rev. ST Accel. Beams

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“…Beam halos are typically observed in particle beams [1,2]. There is no well-accepted or rigorous definition of halo, but it is usually described as a low intensity distribution of particles that are observed at large radii from a more intense centralized portion of the beam, i.e., the ''core''.…”

Section: Introductionmentioning

confidence: 99%

Beam halo imaging with a digital optical mask

Zhang

Fiorito

Shkvarunets

et al. 2012

Phys. Rev. ST Accel. Beams

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Beam halo is an important factor in any high intensity accelerator. It can cause difficulties in the control of the beam, emittance growth, particle loss, and even damage to the accelerator. It is therefore essential to understand the mechanisms of halo formation and its dynamics. Experimental measurement of the halo distribution is a fundamental tool for such studies. In this paper, we present a new high dynamic range, adaptive masking method to image beam halo, which uses a digital micromirror-array device. This method has been thoroughly tested in the laboratory using standard optical techniques, and with an actual beam produced by the University of Maryland Electron Ring (UMER). A high dynamic range (DR $ 10 5 ) has been demonstrated with this new method at UMER and recent studies, with more intense beams, indicate that this DR can be exceeded by more than an order of magnitude. The method is flexible, easy to implement, low cost, and can be used at any accelerator or light source. We present the results of our measurements of the performance of the method and illustrative images of beam halos produced under various experimental conditions.

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Tailoring light with a digital micromirror device

2015

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A digital micromirror device (DMD) is a product of micromechanics. The DMD employs numerous micromirrors as the actuating components to switch small portions of light on and off. During the past few decades, such devices have been widely applied in digital light processing technology. The expanding range of applications makes the DMD increasingly important in various research aspects. Recent advances demonstrate that the DMD is potentially better than the traditional liquid crystal spatial light modulator in speed, spectrum sensitivity, and polarization modulation. These characteristics have been verified in a series of recently reported experiments. This review summarizes the related theory, experimental techniques, and applications for wavefront shaping with DMDs in both statically shaping various spatial modes and dynamically compensating for wavefront distortion caused by the scattering medium.

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Formation and mitigation of halo particles in the Spallation Neutron Source linac

Cited by 16 publications

References 7 publications

Evidence of a halo formation mechanism in the Spallation Neutron Source linac

Evidence of a halo formation mechanism in the Spallation Neutron Source linac

Beam halo imaging with a digital optical mask

Tailoring light with a digital micromirror device

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