A PIC (particle-in-cell)-MC (Monte Carlo) code to model electron beam transport into dense matter is developed. The background target is treated as a cold, stationary fluid and the fast electrons as particles with...A PIC (particle-in-cell)-MC (Monte Carlo) code to model electron beam transport into dense matter is developed. The background target is treated as a cold, stationary fluid and the fast electrons as particles with the relativistic motions. The process is described by a particle-in-cell method with consideration of the influence of both the self-generated electric and magnetic fields as well as collisions between the fast electrons and the target. The collisional part of the code is solved by the Monte Carlo-type method. Furthermore by assuming that the background current balances with the fast electron current, the electric field is given by the Ohm's law and the magnetic field is calculated from the Faraday's law. Both are solved in a two-dimensional cylindrical geometry. The algorithms implemented in the code are demonstrated and the numerical experiments are performed for monoenergy homogeneous fast electron beam transport in an aluminum target when the fields, collision and angular scattering are switched on and off independently.展开更多
We have developed a three dimensional (3D) PIC (particle-in-cell)-MC (Monte Carlo) code in order to simulate an electron beam transported into the dense matter based on our previous two dimensional code. The rel...We have developed a three dimensional (3D) PIC (particle-in-cell)-MC (Monte Carlo) code in order to simulate an electron beam transported into the dense matter based on our previous two dimensional code. The relativistic motion of fast electrons is treated by the particle-in-cell method under the influence of both a self-generated transverse magnetic field and an axial electric field, as well as collisions. The electric field generated by return current is expressed by Ohm's law and the magnetic field is calculated from Faraday's law. The slowing down of monoenergy electrons in DT plasma is calculated and discussed.展开更多
A two-dimensional hybrid code is developed to model the transport of a high-current electron beam in a dense plasma target. The beam electrons are treated as particles and described by particle-in-cell simulation incl...A two-dimensional hybrid code is developed to model the transport of a high-current electron beam in a dense plasma target. The beam electrons are treated as particles and described by particle-in-cell simulation including collisions with the target plasma particles. The background target plasma is assumed to be a stationary fluid with temperature variations. The return current and the self-generated electric and magnetic fields are obtained by combining Amp^re's law without the displacement current, the resistive Ohm's law and Faraday's law. The equations are solved in two-dimensional cylindrical geometry with rotational symmetry on a regular grid, with centered spatial differencing and first-order implicit time differencing. The algorithms implemented in the code are described, and a numerical experiment is performed for an electron beam with Maxwellian distribution ejected into a uniform deuterium-tritium plasma target.展开更多
The accelerator beam transport operator presents the evolution of beam phasespace point with given transport elements and given initial point,while the inverse beamtransport operator presents the evolution of beam pha...The accelerator beam transport operator presents the evolution of beam phasespace point with given transport elements and given initial point,while the inverse beamtransport operator presents the evolution of beam phase space configuration with giveninitial phase space geometry.Therefore,it is necessary to develop a general theory be-tween these two operators.Several concrete examples are worked out in detail to showthe practical applications of such a theory.This paper deals with the linear acceleratorbeam transport operator,and a theorem of finding the inverse linear beam transportoperator for both autonomous and nonautonomous accelerator dynamics is developed.展开更多
This paper deals with the theory of nonlinear accelerator beam transport op-erator.For nonautonomous accelerator dynamics,a theorem of finding the inversenonlinear beam transport operator is developed.Several concrete...This paper deals with the theory of nonlinear accelerator beam transport op-erator.For nonautonomous accelerator dynamics,a theorem of finding the inversenonlinear beam transport operator is developed.Several concrete examples are workedout in detail to show the practical applications of this theory.展开更多
The focusing and the stable transport of an intense elliptic sheet electron beam in a uniform magnetic field are investigated thoroughly by using the macroscopic cold-fluid model and the single-particle orbit theory.T...The focusing and the stable transport of an intense elliptic sheet electron beam in a uniform magnetic field are investigated thoroughly by using the macroscopic cold-fluid model and the single-particle orbit theory.The results indicate that the envelopes and the tilted angles of the sheet electron beam obtained by the two theories are consistent.The single-particle orbit theory is more accurate due to its treatment of the space-charge fields in a rectangular drift tube.The macroscopic cold-fluid model describes the collective transport process in order to provide detailed information about the beam dynamics,such as beam shape,density,and velocity profile.The tilt of the elliptic sheet beam in a uniform magnetic field is carefully studied and demonstrated.The results presented in this paper provide two complete theories for systemically discussing the transport of the sheet beam and are useful for understanding and guiding the practical engineering design of electron optics systems in high power vacuum electronic devices.展开更多
The beam transport design of a novel proton dielectric wall accelerator is introduced in this paper. The protons will be accelerated from 40 keV to nearly 1 MeV under an accelerating gradient that is as high as 20 MV/...The beam transport design of a novel proton dielectric wall accelerator is introduced in this paper. The protons will be accelerated from 40 keV to nearly 1 MeV under an accelerating gradient that is as high as 20 MV/m. A consideration of the beam line as well as the transport simulation is presented. The influences of the injection timing jitter and the accelerating pulse timing jitter are also discussed.展开更多
In this article, we present the design of the beam transport line and injection system of the compact storage ring for the Tsinghua Thomson scattering X-ray (TTX) source. The layout of the beam transport line fits in ...In this article, we present the design of the beam transport line and injection system of the compact storage ring for the Tsinghua Thomson scattering X-ray (TTX) source. The layout of the beam transport line fits in with the limited available space. The injection system is simplified, consisting of only one single kicker; the stray field on the reference orbit is also reduced without the septum magnet. We choose a travelling wave kicker and present both 2D and 3D simulations for the structure design.展开更多
The design and the early commissioning of the ELI-Beamlines laser facility’s 30 J,30 fs,10 Hz HAPLS(High-repetitionrate Advanced Petawatt Laser System)beam transport(BT)system to the P3 target chamber are described i...The design and the early commissioning of the ELI-Beamlines laser facility’s 30 J,30 fs,10 Hz HAPLS(High-repetitionrate Advanced Petawatt Laser System)beam transport(BT)system to the P3 target chamber are described in detail.It is the world’s first and with 54 m length,the longest distance high average power petawatt(PW)BT system ever built.It connects the HAPLS pulse compressor via the injector periscope with the 4.5 m diameter P3 target chamber of the plasma physics group in hall E3.It is the largest target chamber of the facility and was connected first to the BT system.The major engineering challenges are the required high vibration stability mirror support structures,the high pointing stability optomechanics as well as the required levels for chemical and particle cleanliness of the vacuum vessels to preserve the high laser damage threshold of the dielectrically coated high-power mirrors.A first commissioning experiment at low pulse energy shows the full functionality of the BT system to P3 and the novel experimental infrastructure.展开更多
Evolution of an electrostatic plasma wave driven by a low-density ultra-relativistic electron beam in dense inhomogeneous plasma is considered. In particular, the wavelength variation as observed at fixed locations in...Evolution of an electrostatic plasma wave driven by a low-density ultra-relativistic electron beam in dense inhomogeneous plasma is considered. In particular, the wavelength variation as observed at fixed locations in the plasma is analyzed in terms of the wave characteristics. It is shown that for a negative density gradient, the observed local wavelength decreases monotonically with time, but for a positive density gradient, it first increases and then decreases with time, accompanied by reversal of the wave phase. However, in both cases the local wavelength eventually decreases with time since Landau damping becomes significant as the wavelength becomes of the order of the plasma Debye length. Results from particle-in-cell simulations agree well with theoretical analyses of the wavelength variation.展开更多
This paper investigates the transverse 3:1 internal resonance of an axially transporting nonlinear viscoelastic Euler-Bernoulli beam with a two-frequency parametric excitation caused by a speed perturbation.The Kelvin...This paper investigates the transverse 3:1 internal resonance of an axially transporting nonlinear viscoelastic Euler-Bernoulli beam with a two-frequency parametric excitation caused by a speed perturbation.The Kelvin-Voigt model is introduced to describe the viscoelastic characteristics of the axially transporting beam.The governing equation and the associated boundary conditions are obtained by Newton’s second law.The method of multiple scales is utilized to obtain the steady-state responses.The RouthHurwitz criterion is used to determine the stabilities and bifurcations of the steady-state responses.The effects of the material viscoelastic coefficient on the dynamics of the transporting beam are studied in detail by a series of numerical demonstrations.Interesting phenomena of the steady-state responses are revealed in the 3:1 internal resonance and two-frequency parametric excitation.The approximate analytical method is validated via a differential quadrature method.展开更多
The n-ZnO/p-Si heterojunction was fabricated by depositing high quality single crystalline aluminium-doped n-type ZnO film on p-type Si using the laser molecular beam epitaxy technique. The heterojunction exhibited a ...The n-ZnO/p-Si heterojunction was fabricated by depositing high quality single crystalline aluminium-doped n-type ZnO film on p-type Si using the laser molecular beam epitaxy technique. The heterojunction exhibited a good rectifying behavior. The electrical properties of the heterojunction were investigated by means of temperature dependence current density-voltage measurements. The mechanism of the current transport was proposed based on the band structure of the heterojunction. When the applied bias V is lower than 0.15 V, the current follows the Ohmic behavior. When 0.15 V ~ V 〈 0.6 V, the transport property is dominated by diffusion or recombination in the junction space charge region, while at higher voltages (V 〉 0.6 V), the space charge limited effect becomes the main transport mechanism. The current-voltage characteristic under illumination was also investigated. The photovoltage and the short circuit current density of the heterojunction aproached 270 mV and 2.10 mA/cm^2, respectively.展开更多
基金supported by the National High Technology ICF Committee of Chinathe National Natural Science Fund of China(Nos. 10335020, 10375011, 10576007)the Laboratory of Computational Physics (No. 51479050205ZW0905)
文摘A PIC (particle-in-cell)-MC (Monte Carlo) code to model electron beam transport into dense matter is developed. The background target is treated as a cold, stationary fluid and the fast electrons as particles with the relativistic motions. The process is described by a particle-in-cell method with consideration of the influence of both the self-generated electric and magnetic fields as well as collisions between the fast electrons and the target. The collisional part of the code is solved by the Monte Carlo-type method. Furthermore by assuming that the background current balances with the fast electron current, the electric field is given by the Ohm's law and the magnetic field is calculated from the Faraday's law. Both are solved in a two-dimensional cylindrical geometry. The algorithms implemented in the code are demonstrated and the numerical experiments are performed for monoenergy homogeneous fast electron beam transport in an aluminum target when the fields, collision and angular scattering are switched on and off independently.
基金National High Technology ICF Committee in ChinaNational Natural Science Fund of China(Nos.10675024,10335020,10375011,and 10576007)+1 种基金National Basic Research Program of China(973 Program)(No.2007CB815101)the Laboratory of Computational Physics(No.51479050205ZW0905)
文摘We have developed a three dimensional (3D) PIC (particle-in-cell)-MC (Monte Carlo) code in order to simulate an electron beam transported into the dense matter based on our previous two dimensional code. The relativistic motion of fast electrons is treated by the particle-in-cell method under the influence of both a self-generated transverse magnetic field and an axial electric field, as well as collisions. The electric field generated by return current is expressed by Ohm's law and the magnetic field is calculated from Faraday's law. The slowing down of monoenergy electrons in DT plasma is calculated and discussed.
基金supported by National Natural Science Foundation of China(Nos.11175030,11475030,91230205,11175029 and 11375032)the National High-Tech ICF Committee of Chinathe Science and Technology Foundation of China Academy of Engineering Physics(No.2011A0102008)
文摘A two-dimensional hybrid code is developed to model the transport of a high-current electron beam in a dense plasma target. The beam electrons are treated as particles and described by particle-in-cell simulation including collisions with the target plasma particles. The background target plasma is assumed to be a stationary fluid with temperature variations. The return current and the self-generated electric and magnetic fields are obtained by combining Amp^re's law without the displacement current, the resistive Ohm's law and Faraday's law. The equations are solved in two-dimensional cylindrical geometry with rotational symmetry on a regular grid, with centered spatial differencing and first-order implicit time differencing. The algorithms implemented in the code are described, and a numerical experiment is performed for an electron beam with Maxwellian distribution ejected into a uniform deuterium-tritium plasma target.
基金The project supported by the Key Projects of National Natural Science Foundation of China under Grant No. 70431002 and National Natural Science Foundation of China under Grant Nos. 70371068 and 10247005
基金The project supported by the Key Projects of National Natural Science Foundation of China under Grant No. 70431002 and National Natural Science Foundation of China under Grants Nos. 70371068 and 10247005
文摘The accelerator beam transport operator presents the evolution of beam phasespace point with given transport elements and given initial point,while the inverse beamtransport operator presents the evolution of beam phase space configuration with giveninitial phase space geometry.Therefore,it is necessary to develop a general theory be-tween these two operators.Several concrete examples are worked out in detail to showthe practical applications of such a theory.This paper deals with the linear acceleratorbeam transport operator,and a theorem of finding the inverse linear beam transportoperator for both autonomous and nonautonomous accelerator dynamics is developed.
文摘This paper deals with the theory of nonlinear accelerator beam transport op-erator.For nonautonomous accelerator dynamics,a theorem of finding the inversenonlinear beam transport operator is developed.Several concrete examples are workedout in detail to show the practical applications of this theory.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 60501019,10775139 and 60971073)
文摘The focusing and the stable transport of an intense elliptic sheet electron beam in a uniform magnetic field are investigated thoroughly by using the macroscopic cold-fluid model and the single-particle orbit theory.The results indicate that the envelopes and the tilted angles of the sheet electron beam obtained by the two theories are consistent.The single-particle orbit theory is more accurate due to its treatment of the space-charge fields in a rectangular drift tube.The macroscopic cold-fluid model describes the collective transport process in order to provide detailed information about the beam dynamics,such as beam shape,density,and velocity profile.The tilt of the elliptic sheet beam in a uniform magnetic field is carefully studied and demonstrated.The results presented in this paper provide two complete theories for systemically discussing the transport of the sheet beam and are useful for understanding and guiding the practical engineering design of electron optics systems in high power vacuum electronic devices.
基金Supported by National Natural Science Foundation of China(11035004)Nuclear Energy Development Project of State Administration of Science,Technology and Industry for National Defence and Science and Technology Development Foundation of CAEP(2013A0402018)
文摘The beam transport design of a novel proton dielectric wall accelerator is introduced in this paper. The protons will be accelerated from 40 keV to nearly 1 MeV under an accelerating gradient that is as high as 20 MV/m. A consideration of the beam line as well as the transport simulation is presented. The influences of the injection timing jitter and the accelerating pulse timing jitter are also discussed.
基金supported by the National Natural Science Foundation of China (Grant No. 10735050)the National Basic Research Program of China (Grant No. 2007CB815102)
文摘In this article, we present the design of the beam transport line and injection system of the compact storage ring for the Tsinghua Thomson scattering X-ray (TTX) source. The layout of the beam transport line fits in with the limited available space. The injection system is simplified, consisting of only one single kicker; the stray field on the reference orbit is also reduced without the septum magnet. We choose a travelling wave kicker and present both 2D and 3D simulations for the structure design.
基金The authors acknowledge support from the project Advanced Research Using High-Intensity Laser-Produced Photons and Particles(ADONIS)(CZ.02.1.01/0.0/0.0/16—019/0000789)by the project High Field Initiative(HiFI)(CZ.02.1.01/0.0/0.0/15_003/0000449),both from European Regional Development Fund.
文摘The design and the early commissioning of the ELI-Beamlines laser facility’s 30 J,30 fs,10 Hz HAPLS(High-repetitionrate Advanced Petawatt Laser System)beam transport(BT)system to the P3 target chamber are described in detail.It is the world’s first and with 54 m length,the longest distance high average power petawatt(PW)BT system ever built.It connects the HAPLS pulse compressor via the injector periscope with the 4.5 m diameter P3 target chamber of the plasma physics group in hall E3.It is the largest target chamber of the facility and was connected first to the BT system.The major engineering challenges are the required high vibration stability mirror support structures,the high pointing stability optomechanics as well as the required levels for chemical and particle cleanliness of the vacuum vessels to preserve the high laser damage threshold of the dielectrically coated high-power mirrors.A first commissioning experiment at low pulse energy shows the full functionality of the BT system to P3 and the novel experimental infrastructure.
基金supported by the National Key R&D Program of China (No. 2016YFA0401100)National Natural Science Foundation of China (Nos. 12175154, 11875092, and 12005149)the Natural Science Foundation of Top Talent of Shenzhen Technology University (Nos. 2019010801001 and 2019020801001)。
文摘Evolution of an electrostatic plasma wave driven by a low-density ultra-relativistic electron beam in dense inhomogeneous plasma is considered. In particular, the wavelength variation as observed at fixed locations in the plasma is analyzed in terms of the wave characteristics. It is shown that for a negative density gradient, the observed local wavelength decreases monotonically with time, but for a positive density gradient, it first increases and then decreases with time, accompanied by reversal of the wave phase. However, in both cases the local wavelength eventually decreases with time since Landau damping becomes significant as the wavelength becomes of the order of the plasma Debye length. Results from particle-in-cell simulations agree well with theoretical analyses of the wavelength variation.
基金Project supported by the National Natural Science Foundation of China (Nos.12002142,1187215951976087)+1 种基金the National Natural Science Foundation of Shanghai of China (No.21ZR1462500)the Natural Science Foundation of Shandong Province of China (No.ZR2021QB137)。
文摘This paper investigates the transverse 3:1 internal resonance of an axially transporting nonlinear viscoelastic Euler-Bernoulli beam with a two-frequency parametric excitation caused by a speed perturbation.The Kelvin-Voigt model is introduced to describe the viscoelastic characteristics of the axially transporting beam.The governing equation and the associated boundary conditions are obtained by Newton’s second law.The method of multiple scales is utilized to obtain the steady-state responses.The RouthHurwitz criterion is used to determine the stabilities and bifurcations of the steady-state responses.The effects of the material viscoelastic coefficient on the dynamics of the transporting beam are studied in detail by a series of numerical demonstrations.Interesting phenomena of the steady-state responses are revealed in the 3:1 internal resonance and two-frequency parametric excitation.The approximate analytical method is validated via a differential quadrature method.
基金Project supported by the Postdoctor Foundation of Hebei Province, Chinathe Natural Science Foundation of Hebei Province,China (Grant No. F2012201093)the Natural Science Foundation of Hebei University, China (Grant No. 2008127)
文摘The n-ZnO/p-Si heterojunction was fabricated by depositing high quality single crystalline aluminium-doped n-type ZnO film on p-type Si using the laser molecular beam epitaxy technique. The heterojunction exhibited a good rectifying behavior. The electrical properties of the heterojunction were investigated by means of temperature dependence current density-voltage measurements. The mechanism of the current transport was proposed based on the band structure of the heterojunction. When the applied bias V is lower than 0.15 V, the current follows the Ohmic behavior. When 0.15 V ~ V 〈 0.6 V, the transport property is dominated by diffusion or recombination in the junction space charge region, while at higher voltages (V 〉 0.6 V), the space charge limited effect becomes the main transport mechanism. The current-voltage characteristic under illumination was also investigated. The photovoltage and the short circuit current density of the heterojunction aproached 270 mV and 2.10 mA/cm^2, respectively.