Modeling of beam-target interaction during pulsed electron beam ablation of graphite: Case of melting

Ali, Muddassir; Henda, Redhouane

doi:10.1016/j.apsusc.2016.10.204

Cited by 10 publications

(3 citation statements)

References 42 publications

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“…Results from our recent investigations have indicated that the optimum values of beam efficiency and accelerating voltage are about 0.6 and 15 kV, respectively, for the target to reach optimal ablation performance [7,14]. The results correspond to a beam efficiency of 0.6 and accelerating voltage of 15 kV.…”

Section: Resultsmentioning

confidence: 86%

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Modeling of Plasma Expansion during Pulsed Electron Beam Ablation of Graphite

Ali

2017

MRS Advances

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Pulsed electron beam ablation (PEBA) has proven to be a promising and powerful technique for the growth of high quality thin films. Pulsed electron beam film deposition consists of many physical processes including target material heating, target ablation, plasma plume expansion, and film growth on a substrate. Plasma plume expansion into a vacuum or an ambient gas is a fundamental issue in PEBA as the quality of thin films deposited onto the substrate depends on the composition, energy and density of particles ejected from the target. In the present study, gas-dynamics equations are solved to investigate plasma expansion induced by interaction of a nanosecond electron beam pulse (~100 ns) with a graphite target in an argon atmosphere at reduced pressure. The spatio-temporal profiles of the temperature, pressure, velocity, and density of the plasma plume are numerically simulated for a beam efficiency of 0.6 and accelerating voltage of 15 kV. The preliminary results show a rich variety of behaviors. The model is validated by comparing some of the obtained simulation results with experimental data available in the literature.

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Section: Resultsmentioning

confidence: 86%

“…Towards the end of the pulse, the shock waves seem to blend together resulting in a broader shock wave, as depicted in Figure 1 at t = 80 ns, 100 ns. The plasma temperature slightly increases due to the polyenergetic nature of the electron beam [14,15]. Plasma velocity profile calculated for various time intervals is shown in Figure 2.…”

Section: Resultsmentioning

confidence: 99%

Modeling of Plasma Expansion during Pulsed Electron Beam Ablation of Graphite

Ali

2017

MRS Advances

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“…We have developed a flexible tool to study the target thermal field and the thermomechanical stress, which can be applied more in general to any material, target geometry, sequences and intensities of the positron bunches. In principle, our model can be also easily extended to other particle sources, as protons or electrons, for which the heat deposition can be again calculated with FLUKA and Geant4 [69][70][71].…”

Section: Discussionmentioning

confidence: 99%

Theoretical Modeling for the Thermal Stability of Solid Targets in a Positron-Driven Muon Collider

Cesarini

Antonelli

Anulli³

et al. 2021

Int J Thermophys

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A future multi-TeV muon collider requires new ideas to tackle the problems of muon production, accumulation and acceleration. In the Low EMittance Muon Accelerator concept a 45 GeV positron beam, stored in an accumulation ring with high energy acceptance and low angular divergence, is extracted and driven to a target system in order to produce muon pairs near the kinematic threshold. However, this scheme requires an intensity of the impinging positron beam so high that the energy dissipation and the target maintenance are crucial aspects to be investigated. Both peak temperature rises and thermomechanical shocks are related to the beam spot size at the target for a given material: these aspects are setting a lower bound on the beam spot size itself. The purpose of this paper is to provide a fully theoretical approach to predict the temperature increase, the thermal gradients, and the induced thermomechanical stress on targets, generated by a sequence of 45 GeV positron bunches. A case study is here presented for Beryllium and Graphite targets. We first discuss the Monte Carlo simulations to evaluate the heat deposited on the targets after a single bunch of 3 × 1011 positrons for different beam sizes. Then a theoretical model is developed to simulate the temperature increase of the targets subjected to very fast sequences of positron pulses, over different timescales, from ps regime to hundreds of seconds. Finally a simple approach is provided to estimate the induced thermomechanical stresses in the target, together with simple criteria to be fulfilled (i.e., Christensen safety factor) to prevent the crack formation mechanism.

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