共查询到20条相似文献,搜索用时 15 毫秒
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A concept of the magnetic implosion of quasi-spherical liners, concentration of their kinetic energies, conversion of energy into thermal radiation, confinement of its energy in the cavity of an emitting plasma shell in the “double liner”/“dynamic hohlraum” system, and the irradiation of a spherical target is proposed for the physics of high energy densities and inertial confinement fusion. The radiation intensity on the target was shown to increase considerably due to capture of radiation in the process of converting the kinetic energy of the liner into radiation. The dynamics of the liners and the generation of radiation are simulated by the ZETA code using a physical model developed for a nonequilibrium plasma in a cylindrical geometry. The effect of the instability and inhomogeneity of the liners on confinement of radiation energy is estimated. 相似文献
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利用PIC(particle-in-cell)方法模拟研究了超短强激光与锥型三明治结构靶相互作用快电子束的产生和传输,并与锥通道靶、锥丝靶和锥靶在相同激光参数下的作用结果进行了比较.研究发现强激光与锥三明治靶作用产生的快电子能被不同密度材料产生的准静态界面强磁场有效地准直传输.相对其他三种锥型结构靶,锥三明治靶能产生更多数目及更高能量的快电子,提高了激光到快电子的能量转换效率和快电子束的品质,这对快点火能量沉积是有利的. 相似文献
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K. G. Kostov M. A. Algatti E. J.D.M. Pillaca M. E. Kayama R. P. Mota R. Y. Honda 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,54(2):205-209
In this work we describe a two-dimensional computer simulation of magnetic field enhanced plasma immersion implantation system.
Negative bias voltage of 10.0 kV is applied to a cylindrical target located on the axis of a grounded vacuum chamber filled
with uniform nitrogen plasma. A pair of external coils creates a static magnetic field with main vector component along the
axial direction. Thus, a system of crossed E×B field is generated inside the vessel forcing plasma electrons to rotate in azimuthal direction. In addition, the axial variation
of the magnetic field intensity produces magnetic mirror effect that enables axial particle confinement. It is found that
high-density plasma regions are formed around the target due to intense background gas ionization by the trapped electrons.
Effect of the magnetic field on the sheath dynamics and the implantation current density of the PIII system is investigated.
By changing the magnetic field axial profile (varying coils separation) an enhancement of about 30% of the retained dose can
be achieved. The results of the simulation show that the magnetic mirror configuration brings additional benefits to the PIII
process, permitting more precise control of the implanted dose. 相似文献
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An investigation of hot plasma interaction with solid target is carried out at the CASTOR tokamak (IPP Prague) and the GOL-3 multi-mirror magnetic trap faccility (Budker Institute, Novosibirsk) [1], [5]. In both experiments, the Imaging Seya-Namioka Spectrometer based on a spherical dispersion grating has been upraded to monitor the radial profiles of the chord-integrated low-Z impurity line intensities in VUV spectral range. Such spatial resolved intensity monitoring in radial direction together with application of the radiation code simulation allows obtaining a radial distribution of ions of different ionization stages near the target immersed in edge plasma. The energy release from plasma to the target is order of 100 J/m2 in the CASTOR tokamak and 30 MJ/m2 int he GOL-3 magnetic open confinement system. 相似文献
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超短超强激光因其极端的物理参数范围以及可用于研究相对论等离子体等特征,成为当前激光驱动磁重联物理的研究热点.通常采用两路激光与平面靶相互作用实现激光驱动磁重联,然而在实验诊断中,由于激光等离子体自身的复杂性导致很难辨别磁重联的物理特征.本文对两路短脉冲激光驱动平面靶磁重联进行了数值模拟,重点分析了靶后电势分布特征和磁重联之间的关系.模拟结果显示,靶后电势分布可以直接影响被加速离子在探测面上的空间分布,因此可用来直接诊断短脉冲激光驱动磁重联实验. 相似文献
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The conditions under which the magnetic adiabatic compression of a plasma in a direct magnetic trap is accompanied by the accumulation of high energy in the hot anisotropic electron component are found. The basic instabilities resulting in the emission of the accumulated energy in the form of a pulse of stimulated electromagnetic radiation are analyzed. The possibility of creating terahertz radiation sources with the use of the magnetic compression of the plasma is discussed. 相似文献
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Acceleration of ions in a solitary wave produced by shock-wave decay in a plasma slab irradiated by an intense picosecond laser pulse is studied via particle-in-cell simulation. Instead of exponential distribution as in known mechanisms of ion acceleration from the target surface, these ions accelerated forwardly form a bunch with relatively low energy spread. The bunch is shown to be a solitary wave moving over expanding plasma; its velocity can exceed the maximal velocity of ions accelerated forward from the rear side of the target. 相似文献
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研究了激光辐射压驱动的两级质子加速的相关问题。当超短超强激光脉冲与处在背景等离子体前方的薄固体平靶相互作用时,在固体靶后部形成一个电子层-离子层组成的双层结构。在激光的不断推进下,双层结构在背景等离子体里以一定速度传播,可以看成运动在背景等离子体中的电场。这样,在背景等离子体中的质子被这个运动电场捕获并能加速到很高的能量。通过二维PIC模拟方法和理论分析研究了质子加速的相关问题。研究结果表明,被加速质子的最大能量达到20GeV。 相似文献
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The dynamical processes of an energetic electron beam propagating through a high-density plasma have been analyzed using an electromagnetic two-dimensional hybrid simulation code. After an initially solid cylindrical electron beam breaks up into a number of small beamlets, they start to merge with each other by means of their mutual current attractive force. The results show that detailed processes which take place when a pair of beamlets merge into a single one are different for different sizes of beamlets. When the size of the beamlet is small, the merging process is accompanied by magnetic field generation and the energy of the beam electrons then decreases in time. On the other hand, when the beamlet becomes sufficiently large, the merging no longer generates an excess magnetic field, and the energy of beam electrons is kept constant. The difference comes from the magnitude of the return current induced in the surrounding background plasma. 相似文献
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M. P. Brizhinev S. V. Golubev D. S. Dorozhkina B. G. Eremin V. G. Zorin A. G. Litvak I. V. Plotnikov S. V. Razin V. E. Semenov A. V. Strikovskii O. N. Tolkacheva 《Journal of Experimental and Theoretical Physics》2001,92(6):986-990
The paper describes the results of investigation of a discharge arising in vacuum on the surface of solid dielectric materials when irradiated by intense (up to 25 MW/cm2) electromagnetic centimeter wave radiation. When the density of the microwave energy flux exceeds some threshold value depending on the target material, a discharge emerges in the vicinity of the surface. Its emergence is associated with the evaporation of the target material and the breakdown of evaporated matter. The thus forming plasma initially has the form of a thin (on the wavelength scale) layer with the electron density of the order of 1016 cm?3. It is demonstrated experimentally that effective generation of multiply charged ions occurs in the plasma. The measured energy distribution of ions in expanding plasma agrees with the predicted distribution obtained in solving the problem on quasineutral expansion into vacuum of a localized bunch of collisionless plasma with cold ions. 相似文献
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Hiroshi Tsukuda Masaru Masuzaki Norio Toyosugi Cha Yeol Lee Ritoku Ando Keiichi Kamada Tsuguhiro Watanabe 《International Journal of Infrared and Millimeter Waves》2001,22(8):1147-1162
A linear analysis is described on stabilities driven by an intense relativistic electron beam in an infinitely long, plasma-filled, and dielectric-lined circular waveguide immersed in a finite strength axial magnetic field. A dispersion equation is derived from the cold fluid theory and solved numerically. Beam-plasma instabilities due to interaction between beam modes and the Trivelpiece-Gould modes appear as well as the Cherenkov and the cyclotron Cherenkov instabilities. Parametric researches are carried out varying magnetic field strength, plasma density, and dielectric constant. Effects of a finite magnetic field and plasma filling are discussed in connection with the possibilities of using this system as a microwave radiation source. 相似文献
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The University of Hong Kong positron beam employs conventional magnetic field transport to the target, but has a special hybrid lens design around the positron moderator that allows the beam to be focused to millimeter spot sizes at the target. The good focusing capabilities of the beam are made possible by extracting work-function positrons from the moderator in a magnetic field free region using a conventional Soa lens thus minimizing beam canonical angular momentum. An Einzel lens is used to focus the positrons into the magnetic funnel at the end of transportation magnetic field while at the same time bringing up the beam energy to the intermediate value of 7.5 keV. The beam is E × B filtered at this intermediate energy. The final beam energy is obtained by floating the Soa-Einzel system, E × B filter and flight tube, and accelerating the positrons just before the target. External beam steering saddle coils fine tune the position, and the magnetic field around the target chamber is adjusted so as to keep one of the beam foci always on the target. The system is fully computer controlled. Variable energy-Doppler broadened annihilation radiation (VEDBAR) data for a GaN sample are shown which demonstrate the performance of the positron beam system. 相似文献
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利用一维三温辐射磁流体力学程序对氖气和铝丝阵Z箍缩内爆过程中的能量转换过程进行了详细的数值研究,发现在内爆过程中离子和电子之间的碰撞能量交换是最主要的能量交换过程,其次是电子和光子之间的光电过程和轫致过程,而康普顿散射过程中的能量交换可以忽略不计;辐射出的x射线主要是在光电激发和光电复合过程中产生的,其次是在轫致辐射过程和康普顿散射过程中产生的.理论分析表明,辐射出的x射线能量可以超过,也可能小于其等离子体最大动能.数值模拟结果表明,在氖气Z箍缩中,辐射出的x射线能量没有超过其等离子体最大动能,而在铝丝阵列内爆中,辐射出的x射线能量超过了其等离子体最大动能,但小于磁压所做的功;在整个Z箍缩过程中欧姆加热能量是较小的.
关键词:
Z箍缩
能量转换
x射线辐射 相似文献
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提出了一种新型的双锥靶结构用于准单能质子束加速。利用二维PIC粒子模拟程序研究了强激光与双锥靶作用加速产生质子束的物理过程以及质子束品质。双锥靶产生的质子束在峰值能量和发散角度等方面都明显优于相同激光条件下单锥靶和平面靶的结果。尤其与平面靶相比,双锥靶质子束的峰值能量提高了5倍以上,而且很好地保持准单能性。一方面双锥靶的内锥部分是临界密度材料,提高了激光的吸收效率;另一方面双锥靶内形成了更强的准静态磁场,可以约束引导更多的超热电子传输过锥尖,进而增强加速质子束的鞘层电场。 相似文献
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《Physics letters. A》1998,249(4):324-329
Theoretical studies on intense laser radiation interacting with plasma reveal an induced nonlinear birefringence which turns out to be spontaneous Faraday rotation. Here, this rotation is called nonlinear Faraday rotation (NFR). The expressions for the nonlinear refractive indices of the laser fields are calculated both in relativistic and non-relativistic limits for a two-component plasma. The NFR angles due to nonlinear induced birefringence are derived in the absence of externally imposed magnetic fields. It is shown that, in the relativistic limit, the electron motion plays an important role in producing NFR and so in the generation of induced magnetic fields. 相似文献
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GU Peijun PEI Wenbing FENG Tinggui & WU Changshu Institute of Applied Physics Computational Mathematics P. O. Box Beijing China 《中国科学G辑(英文版)》2005,48(3):345-360
1 Introduction The laser-target coupling physics is a key topic in indirect-driven inertial confinement fusion (ICF) and X-ray application research[1―3]. When intense laser light irradiates the solid target, the plasmas are produced rapidly on the surface of the target. The laser en-ergy is mainly absorbed by inverse bremsstrahlung absorption, and a coronal region with high-temperature and low-density plasma is formed. Electron thermal conduction proc-ess transfers energy into over-dense re… 相似文献