Journals >Matter and Radiation at Extremes
Contents
2018
Volume: 3 Issue 5
5 Article(s)
Export citation format
Fundamental Physics at Extremes
Dipole and generalized oscillator strength derived electronic properties of an endohedral hydrogen atom embedded in a Debye-H ckel plasma
C. Martinez-Flores, and R. Cabrera-Trujillo
We report electronic properties of a hydrogen atom encaged by an endohedral cavity under the influence of a weak plasma interaction. We implement a finite-difference approach to solve the Schr€odinger equation for a hydrogen atom embedded in an endohedral cavity modeled by the Woods-Saxon potential with well depth V0, We report electronic properties of a hydrogen atom encaged by an endohedral cavity under the influence of a weak plasma interaction. We implement a finite-difference approach to solve the Schr€odinger equation for a hydrogen atom embedded in an endohedral cavity modeled by the Woods-Saxon potential with well depth V0, inner radius R0, thickness D, and smooth parameter g. The plasma interaction is described by a Debye-Huckel screening potential that characterizes the plasma in terms of a Debye screening length lD. The electronic properties of the endohedral hydrogen atom are reported for selected endohedral cavity well depths, V0, and screening lengths, lD, that emulate different confinement and plasma conditions. We find that for low screening lengths, the endohedral cavity potential dominates over the plasma interaction by confining the electron within the cavity. For large screening lengths, a competition between both interactions is observed. We assess and report the photo-ionization cross section, dipole polarizability, mean excitation energy, and electronic stopping cross section as function of lD and V0. We find a decrease of the Generalized Oscillator Strength (GOS) when the final excitation is to an s state as the plasma screening length decreases. For a final excitation into a p state, we find an increase in the GOS as the endohedral cavity well-depth increases. For the case of the electronic stopping cross section, we find that the plasma screening and endohedral cavity effects are larger in the low-to-intermediate projectile energies for all potential well depths considered. Our results agree well to available theoretical and experimental data and are a first step towards the understanding of dipole and generalized oscillator strength dependent properties of an atom in extreme conditions encaged by an endohedral cavity immersed in a plasma medium..
Matter and Radiation at Extremes
- Publication Date: Mar. 14, 2019
- Vol. 3, Issue 5, 227 (2018)
Inertial Confinement Fusion Physics
The theory of early nonlinear stage of m=1 instability with locally flattened q-profile
, and
In this paper, we analyze the modification of fast particles on the nonlinear radial displacement of m = 1 internal kink mode with a shoulderlike equilibrium current theoretically. Using the matching method on the solutions of the outer and inner regions, we derive the analytical form of nonlinear radial displacement iIn this paper, we analyze the modification of fast particles on the nonlinear radial displacement of m = 1 internal kink mode with a shoulderlike equilibrium current theoretically. Using the matching method on the solutions of the outer and inner regions, we derive the analytical form of nonlinear radial displacement in the limit of q' = q" = 0, which is valid to the cases of weak shear due to a slight flattening of the q(r) profile around q = 1. We have taken into consideration the effects of the circulating and trapped fast particles on the nonlinear state of the mode. It is found that a fast particle can modify the nonlinear saturation level by the change of potential energy, depending on the fast particle properties. By the matching of linear dispersion relation to early nonlinear result, we also obtain the relations of radial displacement to the mode frequency and linear growth rate, and discuss the scaling for different stabilities of the MHD modes..
Matter and Radiation at Extremes
- Publication Date: Mar. 14, 2019
- Vol. 3, Issue 5, 243 (2018)
Numerical studies on the radiation uniformity of Z-pinch dynamic hohlraum
, , , ... and |Show fewer author(s)
Radiation uniformity is important for Z-pinch dynamic hohlraum driven fusion. In order to understand the radiation uniformity of Z-pinch dynamic hohlraum, the code MULTI-2D with a new developed magnetic field package is employed to investigate the related physical processes on Julong-I facility with drive current aboutRadiation uniformity is important for Z-pinch dynamic hohlraum driven fusion. In order to understand the radiation uniformity of Z-pinch dynamic hohlraum, the code MULTI-2D with a new developed magnetic field package is employed to investigate the related physical processes on Julong-I facility with drive current about 7e8 MA. Numerical simulations suggest that Z-pinch dynamic hohlraum with radiation temperature more than 100 eV can be created on Julong-I facility. Although some X-rays can escape out of the hohlraum from Z-pinch plasma and electrodes, the radiation field near the foam center is quite uniform after a transition time. For the load parameters used in this paper, the transition time for the thermal wave transports from r = 1 mm to r = 0 mm is about 2.0 ns. Implosion of a testing pellet driven by cylindrical dynamic hohlraum shows that symmetrical implosion is hard to achieve due to the relatively slow propagation speed of thermal wave and the compression of cylindrical shock in the foam. With the help of quasi-spherical implosion, the hohlraum radiation uniformity and corresponding pellet implosion symmetry can be significantly improved thanks to the shape modulation of thermal wave front and shock wave front..
Matter and Radiation at Extremes
- Publication Date: Mar. 14, 2019
- Vol. 3, Issue 5, 248 (2018)
Photoconductive semiconductor switch-based triggering with 1 ns jitter for trigatron
, , and
Synchronization for multiple-pulse at nanosecond range shows a great value on the power multiplication and synchronous electric fields applications. Nanosecond or sub-ns jitter synchronization is essential for the improved working efficiency of the large amounts of pulse modules and accurate requirements for the power Synchronization for multiple-pulse at nanosecond range shows a great value on the power multiplication and synchronous electric fields applications. Nanosecond or sub-ns jitter synchronization is essential for the improved working efficiency of the large amounts of pulse modules and accurate requirements for the power coherent combining applications. This paper presents a trigger generator based on a laser diodetriggered GaAs photoconductive semiconductor switch (PCSS) with low jitter and compact size characteristics. It avoids the high currents that are harmful to high-gain mode PCSSs. In the trigger circuit, a 200 pF capacitor is charged by a microsecond-scale 18 kV pulse and then discharged via the high-gain mode GaAs PCSS to trigger the high-power trigatron switch. When triggered by the ~10 ns pulse generated by the PCSS, the DC-charged trigatron can operate in the 20e35 kV range with 10 ns rise time and 1 ns delay-time jitter..
Matter and Radiation at Extremes
- Publication Date: Mar. 14, 2019
- Vol. 3, Issue 5, 256 (2018)
High current pulse forming network switched by static induction thyristor
, , , ... and |Show fewer author(s)
A high-current pulse forming network (PFN) has been developed for applications to artificial solar-wind generation. It is switched by staticinduction thyristor (SIThy) and is capable of generating pulsed current of ~9.7 kA for a time duration of ~1 ms. The SIThy switch module is made that it can be controlled by an optA high-current pulse forming network (PFN) has been developed for applications to artificial solar-wind generation. It is switched by staticinduction thyristor (SIThy) and is capable of generating pulsed current of ~9.7 kA for a time duration of ~1 ms. The SIThy switch module is made that it can be controlled by an optical signal and it can be operated at elevated electrical potential. The experiments reported in this paper used two switch modules connected in series for maximum operating voltage of 3.5 kV. The experimental results have demonstrated a pulsed high-current generator switched by semiconductor devices, as well as the control and operation of SIThy for pulsed power application..
Matter and Radiation at Extremes
- Publication Date: Mar. 14, 2019
- Vol. 3, Issue 5, 261 (2018)
© Copyright 2018-2021 | Chinese Laser Press. All Rights Reserved 沪ICP备15018463号-20