Gas Core Reactor Numerical Simulation Using a Coupled MHD-MCNP Model

Analysis is provided in this report of using two head-on magnetohydrodynamic (MHD) shocks to achieve supercritical nuclear fission in an axially elongated cylinder filled with UF4 gas as an energy source for deep space missions. The motivation for each aspect of the design is explained and supported by theory and numerical simulations. A subsequent report will provide detail on relevant experimental work to validate the concept. Here the focus is on the theory of and simulations for the proposed gas core reactor conceptual design from the onset of shock generations to the supercritical state achieved when the shocks collide. The MHD model is coupled to a standard nuclear code (MCNP) to observe the neutron flux and fission power attributed to the supercritical state brought about by the shock collisions. Throughout the modeling, realistic parameters are used for the initial ambient gaseous state and currents to ensure a resulting supercritical state upon shock collisions

Experimental Plans for Subsystems of a Shock Wave Driven Gas Core Reactor

This Contractor Report proposes a number of plans for experiments on subsystems of a shock wave driven pulsed magnetic induction gas core reactor (PMI-GCR, or PMD-GCR pulsed magnet driven gas core reactor). Computer models of shock generation and collision in a large-scale PMI-GCR shock tube have been performed. Based upon the simulation results a number of issues arose that can only be addressed adequately by capturing experimental data on high pressure (approx.1 atmosphere or greater) partial plasma shock wave effects in large bore shock tubes ( 10 cm radius). There are three main subsystems that are of immediate interest (for appraisal of the concept viability). These are (1) the shock generation in a high pressure gas using either a plasma thruster or pulsed high magnetic field, (2) collision of MHD or gas dynamic shocks, their interaction time, and collision pile-up region thickness, and (3) magnetic flux compression power generation (not included here)

Pulsed Plasma Accelerator Modeling

This report presents the main results of the modeling task of the PPA project. The objective of this task is to make major progress towards developing a new computational tool with new capabilities for simulating cylindrically symmetric 2.5 dimensional (2.5 D) PPA's. This tool may be used for designing, optimizing, and understanding the operation of PPA s and other pulsed power devices. The foundation for this task is the 2-D, cylindrically symmetric, magnetohydrodynamic (MHD) code PCAPPS (Princeton Code for Advanced Plasma Propulsion Simulation). PCAPPS was originally developed by Sankaran (2001, 2005) to model Lithium Lorentz Force Accelerators (LLFA's), which are electrode based devices, and are typically operated in continuous magnetic field to the model, and implementing a first principles, self-consistent algorithm to couple the plasma and power circuit that drives the plasma dynamics

Kinetic formulation and global existence for the Hall-Magneto-hydrodynamics system

This paper deals with the derivation and analysis of the the Hall Magneto-Hydrodynamic equations. We first provide a derivation of this system from a two-fluids Euler-Maxwell system for electrons and ions, through a set of scaling limits. We also propose a kinetic formulation for the Hall-MHD equations which contains as fluid closure different variants of the Hall-MHD model. Then, we prove the existence of global weak solutions for the incompressible viscous resistive Hall-MHD model. We use the particular structure of the Hall term which has zero contribution to the energy identity. Finally, we discuss particular solutions in the form of axisymmetric purely swirling magnetic fields and propose some regularization of the Hall equation

Effects of Iron Oxide Nanoparticles and Iron Ions on Reproductive Indices of Pregnant Syrian Rats and Neuro-Behavioral Development of Newborns

BACKGROUND AND OBJECTIVE: Considering the high sensitivity of embryo and fetus to toxic agents and increasing use of nanomaterials such as iron oxide nanoparticles in medicine, this study aimed to determine the effects of iron oxide nanoparticles and iron ions on reproductive indices of pregnant Syrian rats and neuro-behavioral development of their newborns. METHODS: This experimental study was conducted on 49 pregnant Syrian rats, which were divided into one control and three study groups. The study groups were subcutaneously injected 100 and 1000 µg/kg of iron oxide nanoparticles and 1000 µg/kg of ferric iron ions (equivalent to the amount of iron ions in 1000 µg/kg of iron oxide nanoparticles), respectively. Injections were performed four days before mating until delivery on alternate days. Reproductive indices of pregnant rats, as well as neuro-behavioral and physical development of newborns, were evaluated with respect to sex; newborns’ development was recorded in days. FINDINGS: Multiple neuro-behavioral reflexes and developmental indices were delayed in the study groups, especially in the group receiving 1000 µg/kg of iron oxide nanoparticles, compared to the control group. Based on the findings, cliff-drop aversion reflex (1.35±0.13 and 2.70±0.13, respectively; p<0.001),  level or vertical stick reflex(2.55±0.20 and 3.45±0.20, respectively; p<0.01), negative geotaxis (2.60±0.22 and 3.50±0.22, respectively; p<0.01), bar holding reflex (5.85±0.44 and 7.30±0.44, respectively; p<0.05), running (7.75±0.23, 8.70±0.23; p<0.01), fur development (5.90±0.18 and 6.85±0.18, respectively; p<0.001), eye opening (14.25±0.22 and 15.25±0.22, respectively; p<0.01), and testes descent (21.20±0.18 and 22.40±0.18, respectively; p<0.001) were delayed in rats receiving 1000 µg/kg of iron oxide nanoparticles, compared to the control group. However, in most cases, shorter delays were observed in groups receiving 100 µg/kg of iron oxide nanoparticles and 1000 µg/kg of iron ions, respectively. CONCLUSION: The present study revealed that exposure to iron oxide nanoparticles in the embryonic period could lead to severe complications; also, iron oxide nanoparticles were shown to be more toxic than iron ion

The Effect of Annealing Temperature on the Structural, Magnetic and Dielectric Properties of PbFe11.8Ni0.2O19 Nanoparticles

In this paper, Ni-doped lead hexaferrites (PbFe12-xNixO19) nanoparticles with x = 0.2 were prepared by sol- gel method. Then, the effect of annealing temperature on its structural, magnetic and dielectric properties was studied. First, the dryed gel was evaluated by Thermogravimetry-Differential Thermal Analysis (TG/DTA) and then, the structural morphology, magnetic and dielectric properties of samples have been characterized by Fourier Transform Infrared (FT-IR) spectroscopy, X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Vibrating Sample Magnetometer (VSM) and LCR meter. The results of x-ray diffraction patterns show that by increasing annealing temperature up to 800 &deg;C, PbFe11.8Ni0.2O19 phase percentage in the samples increases. Also, by increasing annealing temperature, the magnetization increases because the unwanted phases disappear and pure and single-phase lead hexaferrite are formed. By increasing frequency, first the AC electrical conductivity of the samples decreases and then increases. These variations have been explained by Maxwell- Wanger model. The result measurements show that the best sample is PbFe11.8Ni0.2O19 with annealing temperature of 800 &deg;C for 3 h. &nbsp

Prognostic value of lymph node ratio in comparison to lymph node metastases in stage III colon cancer

Background & Objectives: Colon cancer is currently of high incidence and mortality rate. Identifying the factors influencing its prognosis can be very beneficial to its clinical treatment. Recent studies have shown that lymph nodes ratio can be considered as an important prognostic factor. The aim of the present study is to investigate the effect of this factor on the prognosis of the patients presenting with stage III colon cancer and to compare the result with the effect of lymph node stage on their prognosis. Methods: This cross-sectional study was carried out on 66 patients of stage III colon cancer, who met the study inclusion criteria. Patients were categorized into four groups based on Kaplan-Meier plots: LNR1 0-12, LNR2 13-40, LNR3 41-84 and LNR4 85-100. Survival was estimated by Kaplan-Meier method, and differences analyzed by Log-rank test. A Cox proportional hazards model was used for multivariate analysis. Results: Lymph nodes ratio was a significantly variable both in overall survival (P<0.0001) and in disease-free survival (P=0.009). Lymph node stage was significant in overall survival (P=0.008) but not in disease-free survival (P=0.05). Multivariable analysis of overall survival showed lymph nodes ratio as the only independent prognostic factor. Conclusion: Lymph node ratio is a more accurate prognostic factor than lymph node stage in overall survival and, in particular, in disease-free survival in patients with stage III colon cancer. © 2015, Iranian Society of Pathology. All rights reserved

2-D Unstructured Mesh Particle-MHD Solar Wind Flow Over the Earth: Magnetic Potential

This series of animations shows a two-dimensional unstructured mesh particle-magnetohydrodynamic solar wind flow simulation of the interaction of the solar wind with the Earths magnetosphere. Educational levels: Undergraduate lower division, Undergraduate upper division, Graduate or professional