A. G. Shishkin

Automating Computations in the Virtual Tokamak Software System

We describe the concept, functional capabilities, graphic user interface (GUI), and operating technique of a specialized system for distributing the computational burden encountered in solving typical problems of controlled thermonuclear fusion. The system is employed in the Virtual Tokamak simulation modeling complex to automate the distribution of computing on a network of computers, making it possible to dramatically improve the productivity of a researcher’s work. The system is useful in various applications that require massive multivariate calculations using one or more application codes, and for supporting websites that provide computing services using locally stored science-intensive application software.

The ScopeShell graphic interface: Support for computational experiments and data visualization

We consider problems of the visualization and automation of routine tasks that arise in the process of a computational experiment. We describe ScopeShell, a state-of-the-art universal platform independent graphic interface for computational codes that includes data visualization and the monitoring of calculations on distributed computing systems. We describe the concept behind ScopeShell, along with the interface’s functionality and methods of application. The ScopeShell system is used to support computational experiments in the field of controlled thermonuclear fusion. The system considerably increases the efficiency of research requiring the application of voluminous computer codes.

Integrated Modeling Environment “Virtual Computational Network”

Wireless modeling is an extremely important part of wireless networks research and design. Nowadays many advanced of numerical (simulation) codes are being developed and widely used in different areas of wireless networks research. The key problem is that such codes are often proprietary and poorly documented. Another problem is that most codes cannot be used together due to different input/output formats. A set of data adapters and converters should be developed and adopted to couple such codes. At the same time, a number of problems with data processing, monitoring and results visualization must be solved. “virtual computational network” (VCN) modeling environment is designed as a universal easy-to-use toolbox to create complicated modeling cases and scenarios for numerical experiments built atop of different codes and pre-calculated data. VCN is a powerful tool supporting distributed parallel computing, input/output data transformation, and results visualization “out-of-the-box”, allowing end-users to greatly improve numerical modeling studies efficiency.

Toroidal current control in the problem of plasma equilibrium evolution

The results of application of automatic control methods to the problem of the given total current sustainment in toroidal plasma are presented. Plasma current control is performed mainly by solenoid with the use of electromagnetic inductance effect. The mathematical problem is formulated, the methods and developed software are described, and the solutions of test and real problems are given. The comparison of experimental and numerical data allows drawing a conclusion on the nature of plasma conductivity in spherical tokamaks.

The NNTMM code: Mathematical modeling, optimization, and data analysis through neural networks

The concept, functional capabilities, graphic interface, and application technology for the NNTMM code (Neural Network Tool for Mathematical Modeling), designed for analyzing large amounts of experimental and computational data in an interactive mode, are described. The software can be used to solve a wide range of applied problems where automated extraction of meaningful information from randomly presented data is required, along with data classification, clear representation of established relationships and dependences, analysis of parameter importance, and prediction. Examples of using the NNTMM code to analyze data in controlled nuclear fusion problems are presented.

Toroidal Current Control in the Problem of Plasma Equilibrium Evolution

Abstract The results of application of automatic control methods to the problem of total current sustainment in a toroidal plasma are presented. Plasma current control is performed mainly by means of the solenoid using electromagnetic inductance effect. The mathematical problem is formulated, the methods and developed software are described, the solutions of test and real problems are given. Comparison of experimental and numerical data allows to draw a conclusion on the nature of plasma conductivity in spherical tokamaks.

Virtual Tokamak library software

We describe the concept of the Virtual Tokamak library, its functionality, major components, and method of use. The library is designed to predict, support, and interpret experiments as well as handle measurements on tokamak instruments implementing the idea of energy production on the basis of controlled thermonuclear fusion. The library software consists of an interactive graphic shell and a number of interrelated computer codes simulating various processes in the tokamak plasma, its structural elements, diagnostics and control system. This is a specific implementation of advanced information technologies including Internet technologies and approaches of distributed computations in the field of the mathematical modeling of plasma. The Virtual Tokamak is unique in terms of combined application and system software.

Mathematical and numerical modeling of moving inhomogeneous weakly ionized gas-plasma flows for determination of target scattered fields

The electrodynamic models of scattered fields of moving inhomogeneous weakly ionized plasma media are based on the study of its gas dynamic and plasma physical properties. The solution of different radio physical (radar) problems requires the determination of the electron density distribution over jet volume. Such distributions have been obtained by the help of presented in this paper full and simplified analytical and numerical models of gas dynamical jet in air wake. It has been detected that these distributions are not connected with the gas density distribution and are determined by the temperature distribution. The developed model allows simulating the jet behaviour with high enough accuracy. The calculations of spatial electron density distribution in the wide range of flight velocities and power plant parameters and for different regimes of jet effluxes in ambient space were performed.