| 1. |
- Chen, S., et al.
(author)
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Coffin-Mansson equation of Sn-4.0Ag-0.5Cu solder joint
- 2009
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In: Soldering and Surface Mount Technology. - : Emerald. - 1758-6836 .- 0954-0911. ; 21:2, s. 48-54
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Journal article (peer-reviewed)abstract
- Purpose: The purpose of this paper is to fit Coffin-Manson equation of Sn-4.0Ag-0.5Cu lead free solder joint by using results of solders joint reliability test and finite element analysis. Also to present a novel device for solder joint reliability test. Design/methodology/approach: Two-points bending test of Sn-4.0Ag-0.5Cu lead free solder joint was carried out at three deflection levels by using a special bending tester that can control displacement exactly by a cam system. The failure criterion was defined as resistance of solder joint getting 10 percent increase. The X-section was done for all failure samples to observe crack initiation and propagation in solder joint. Finite element analysis was presented with ANSYS for obtaining shear strain range, analyzing distribution of stress and strain and supporting experimental results. Findings: The experimental results indicate that the fatigue life decreased obviously with the displacement increased. By using optical microscope and SEM photographs, two kinds of failure mode were found in solder joint. The majority failure mode took place at the bottom corner of solder joint under the termination of resistor initially, and propagated into the solder matrix. Another failure mode was delamination. It appeared at the interface between the termination of resistor and its ceramic body. The distribution status of stress and strain in solder joint and the calculation results of shear strain range at different deflection levels were obtained from simulation result. The Coffin-Manson equation of Sn-4.0Ag-0.5Cu lead free solder joint was fitted by combining experimental data with result of finite element analysis. Originality/value: This paper presents Coffin-Manson equation of Sn-4.0Ag-0.5Cu solder joint with two-points bending test. An effective and economical device was designed and applied.
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| 2. |
- Eliasson, Bengt, et al.
(author)
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Laser acceleration of monoenergetic protons via a double layer emerging from an ultra-thin foil
- 2009
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In: New Journal of Physics. - : IOP Publishing Ltd and Deutsche Physikalische Gesellschaft. - 1367-2630. ; 11, s. 073006-073025
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Journal article (peer-reviewed)abstract
- We present theoretical and numerical studies of the acceleration of monoenergetic protons in a double layer formed by the laser irradiation of an ultra-thin film. The ponderomotive force of the laser light pushes the electrons forward, and the induced space charge electric field pulls the ions and makes the thin foil accelerate as a whole. The ions trapped by the combined electric field and inertial force in the accelerated frame, together with the electrons trapped in the well of the ponderomotive and ion electric field, form a stable double layer. The trapped ions are accelerated to monoenergetic energies up to 100 MeV and beyond, making them suitable for cancer treatment. We present an analytic theory for the laser-accelerated ion energy and for the amount of trapped ions as functions of the laser intensity, foil thickness and the plasma number density. We also discuss the underlying physics of the trapped and untrapped ions in a double layer. The analytical results are compared with those obtained from direct Vlasov simulations of the fully nonlinear electron and ion dynamics that is controlled by the laser light.
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| 3. |
- Eliasson, Bengt, et al.
(author)
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Laser radiation pressure acceleration of monoenergetic protons in an ultra-thin foil
- 2009
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In: New Developments in Nonlinear Plasma Physics. - : American Institute of Physics. - 9780735407541 ; , s. 35-49
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Conference paper (peer-reviewed)abstract
- Wepresent theoretical and numerical studies of the acceleration of monoenergeticprotons in a double layer formed by the laser irradiationof an ultra-thin film. The stability of the foil isinvestigated by direct Vlasov-Maxwell simulations for different sets of laser-plasmaparameters. It is found that the foil is stable, dueto the trapping of both electrons and ions in thethin laser-plasma interaction region, where the electrons are trapped ina potential well composed of the ponderomo-tive potential of thelaser light and the electrostatic potential due to the ions,and the ions are trapped in a potential well composedof the inertial potential in an accelerated frame and theelectrostatic potential due to the electrons. The result is astable double layer, where the trapped ions are accelerated tomonoenergetic energies up to 100 MeV and beyond, which makesthem suitable for medical applications cancer treatment. The underlying physicsof trapped and untapped ions in a double layer isalso investigated theoretically and numerically.
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| 4. |
- Tripathi, V. K., et al.
(author)
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Laser acceleration of monoenergetic protons in a self-organized double layer from thin foil
- 2009
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In: Plasma Physics and Controlled Fusion. - : IOP Publishing. - 0741-3335 .- 1361-6587. ; 51, s. 024014-024022
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Journal article (peer-reviewed)abstract
- We present a theory for the acceleration of monoenergetic protons, trapped in a self-organized double layer, by short pulse laser irradiation on a thin foil with the specific thickness suggested by the simulation study of Yan et al (2008 Phys. Rev. Lett. 100 135003). The laser ponderomotive force pushes the electrons forward, leaving the ions behind until the space charge electric field balances the ponderomotive force at a distance Δ. For the optimal target thickness D = Δ > c/ωp, the electron sheath is piled up at the rear surface and the sheath electric field accelerates the protons until they are reflected by the inertial force in the accelerated frame. These protons are therefore trapped by the combined forces of the electrostatic field of the electron sheath and the inertial force of the accelerating target. Together with the electron layer, they form a double layer and are collectively accelerated by the laser ponderomotive force, leading to monoenergetic ion production.
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