Development of a radiographic method for measuring the discrete spectrum of the electron beam from a plasma focus device

An indirect method is proposed for measuring the relative energy spectrum of the pulsed electron beam of a plasma focus device. The Bremsstrahlung x-ray, generated by the collision of electrons against the anode surface, was measured behind lead filters with various thicknesses using a radiographic film system. A matrix equation was considered in order to explain the relation between the x-ray dose and the spectral amplitudes of the electron beam. The electron spectrum of the device was measured at 0.6 mbar argon and 22 k V charging voltage, in four discrete energy intervals extending up to 500 ke V. The results of the experiments show that most of the electrons are emitted in the 125–375 ke V energy range and the spectral amplitude becomes negligible beyond 375 ke V.?     

光纤在RIBLL束流诊断中的应用

介绍了ＢＣＦ－１２光纤的特性,着重描述了ＢＣＦ－１２光纤为主体,用光电倍增管读出的束流诊断元件的结构,特性及其在兰州放射性离子次级束流装置ＲＩＢＬＬ上的应用。     

Development and Evaluation of a Fast Calculation Method for Gamma Ray Skyshine Dose Using Data Libraries

A fast calculation method for gamma ray skyshine dose was developed. Four data libraries including anisotropy factors and buildup factors in the gamma ray transport calculation in air and the buildup flux energy spectrum and edge correction factor in the calculation of the precise energy spectrum of gamma ray flux penetrating through the upper shields were used. The anisotropy factors were generated on the basis of line beam response functions obtained by Hirayama et al. using the EGS4 code. The other three data libraries were generated by the invariant embedding method. Multilayer shields and angular distributions of gamma rays from sources were assumed to have a rotational symmetry with respect to the center axis of the shields along which the sources were located. Accuracy of the method was evaluated through comparison with the measured dose in the skyshine benchmark experiment and doses calculated by other dependable methods. It was found that the present method could simulate the measured dose with a discrepancy of 50% or less, and that transport of gamma rays in air due to a conical beam could be solved within an error of about 10–20%, except for the cases in which the beam angle lies in the range < 10 deg. The present method has two advantageous features: the skyshine dose can be obtained very quickly and very easily by general users.     

Optimized analysis of sharpening characteristics of a compact RF pulse source based on a gyro-magnetic nonlinear transmission line for ultrawideband electromagnetic pulse application

We constructed a compact high-power RF pulse generator based on a gyro-magnetic nonlinear transmission line (GNLTL) to produce a high-voltage pulse with a sub-nanosecond rise time and a relatively high repetition rate, which shows great potential for application in the high-power ultrawideband electromagnetic effect, etc. The influence of incident pulse parameters (rise time and voltage amplitude) and line length on the sharpening characteristics of the GNLTL were investigated experimentally to optimize the rising rate of the modulated pulse front. Based on the GNLTL equivalent circuit model consisting of an LC ladder network, the rise time, the voltage conversion coefficient and the rising rate properties of a modulated pulse were also numerically analyzed in a wider range. The results show that a>90 kV RF pulse with a rise time of 350 ps and a repetition rate of 1 kHz in burst mode is produced by the GNLTL at an axial biasing magnetic field of 22 kA m⁻¹ and a line length of 30 cm under the condition of a 70 kV incident pulse. Applying a faster and higher incident pulse is conducive to improving the sharpening effect of the GNLTL. Furthermore, within a certain range, increasing the line length of the GNLTL not only reduces the rise time, but increases the voltage conversion coefficient and the rising rate of a modulated pulse. Furthermore, considering the energy loss of ferrite rings, there is an optimal line length to obtain the fastest rising rate of a modulated pulse front edge.     

Service oriented architecture for scientific analysis at W7-X. An example of a field line tracer

Service oriented architecture based on web-services is a universal method of combining software components. SOAP web-services chosen for W7-X are characterized by strong standards and readily available tools. In this paper the SOAP technology is explained and is illustrated with a new service for field line tracing.The field line tracing package consists of a C++ library and a web-service interface. It features a flexible structure and can handle a realistic machine geometry. The following problems can be solved: getting a field line; making Poincaré maps; calculating flux surface characteristics; calculating heat fluxes to the wall; constructing magnetic coordinates, etc. The service is applied to estimate W7-X divertor loads with an 1/1 error field.