Charge Exchange Effect on Space-Charge-Limited Current Densities in Ion Diode

The article theoretically studied the charge-exchange effects on space charge limited electron and ion current densities of non-relativistic one-dimensional slab ion diode,and compared with those of without charge exchange.     

Charge Exchange Cross Sections

A review is presented on charge exchange cross sections of heavy ions at energies primarily in the range below 100 keV. Particular emphasis is given to the cross sections for capture of one or more electrons in single encounters of multiply charged ions with atoms. The system of the noble gases as projectile ions and target atoms is studied in detail. Systematic trends are examined. Attention is given to the influence of metastable ions on the cross sections.     

Determination of Average Ion Temperature of the TVD Tokamak by a Simple Charge Exchange Analyzer Detector

In this paper the average ion temperature of the TVD tokamak plasma is determined by a low cost charge exchange analyzer. When the neutral beam energy was equal to 3 keV, the stripping efficiency was 0.065. Estimated average ion temperatures for cold and hot regions of the plasma were 100 and 650 eV, respectively. Unlike the cold region of the plasma in which ion temperature was not related to the time, ion temperature in the hot region was maximum when the plasma current reached its maximum value.     

高电荷态ECR离子源

综述了中国科学院院近代物理研究所近几年来高电荷态ＥＣＲ离子源的最新进展。     

Negative Ion Confinement in the Multicusp Ion Source

To optimize the negative ion source and generate intense beams of negative ions, understanding of transport properties of both electrons and negative ions is indispensable. Transport process of negative hydrogen ions (H^?) in a multicusp H^? source, has been simulated by three-dimensional Femlab simulation software. Multipolar plasma confinement is known to result in enhanced plasma density, homogeneous plasma of a large volume, and quiescent plasmas. The effect of plasma confinement by applying multi-polar magnetic field was investigated. Results are obtained for ten different configurations of permanent magnet and discussed. Full line cusps are found to give optimum plasma density. Negative ions created on the sidewall hardly can reach the center of the source due to trapping by the multicusp magnetic field. As a result, H^? ions created on the sidewall do not have a significant effect on the H^? current.     

Source for intense collimated beams of fast Cs+ and Cs0

The characteristics of a surface-ionization source for Cs⁺ of 20–55 keV are described. For applications requiring fast Cs⁰ atoms, the Cs⁺ beam is neutralized to 90% by passage through Cs vapor. The observed Cs⁰ beam intensity through a 1.1 cm diameter aperture 78 cm from the ionizer is 10 particle-mA.     

Proposed Multiply Charged Ion Source

A proposal is presented in this work for a new type of ion source that employs a hyperbolic potential field for the dual purpose of trapping the plasma ions, and permitting the electrons to impact the trapped ions successively, which by turn render the ions highly stripped. The pvwposed souroe consists of an axially symmetric hyperbolic Penning assembly energized with fixed and cosinusoidal voltage and is immersed in a homogeneous axial magnetic field. The anode and both of the two cathodes follow hyperboloid surfaces of one and two sheets respectively. Extraction of the stripped ions can be accomplished either radially or axially through an extracting system, which is optimized to satisfy Pierce conditions of rectilinear flow. Filtering the extracted ions is done by a quadrupole mass analyzer. Under the influence of the imposed hyperbolic potential field, electrons are allowed to ascillate with bound or unbound trajectories depending on the operating conditions. From the solutions of the equations of motion governing such oscillating electrons, it is possible to optimize the overall performance of the proposed ion source.     

紧凑型强流ECR源

建立了１台紧凑型强流ＥＣＲ源。共振磁场由１个小电磁线圈及软铁回路产生,磁场可调,能保证放电处于最佳条件。研究了气压,微波功率及共振场对放电的影响。在５５０Ｗ的放电功率下,从直径４ｍｍ引出孔引出了３５ｍＡ的Ｈ＾＋离子束,引出Ｈ＾＋离子的质子比超过９０％,从源中还引出了７ｍＡＯ＾＋、８ｍＡＮ＾＋、１２ｍＡ Ａｒ＾＋的束流。     

Solidification of Spent Ion Exchange Resin Using New Cementitious Material, (II)

When using cement solidification for spent ion exchange resin, resin content in the waste form is typically controlled below 20vol%. This is because the waste forms crack and deteriorate in water at higher resin contents. The deterioration mechanism and its preventive measures were investigated in this study.

Swelling pressure of the resin was experimentally measured for various waste forms. The resin in the waste form tended to swell under a water immersion condition and tensile stress was exerted on the cement matrix. The stress value changed in the region of 1.5~5.5 MP a depending on such factors as resin content and its type. The waste form was deteriorated in water when the tensile stress was higher than the tensile strength of the cement. These results suggested that the deterioration could be prevented by increasing the tensile strength of cement. A fiber reinforced cement was developed for which tensile strength was almost doubled (~7MP a) by adding 10 wt% steel fiber to the cement. This prevented deterioration and allowed the resin content to be increased from 20 to 42 Vol%     

The TFTR Charge Exchange Diagnostic Software Systems

This paper describes the applications software systems for computer control and monitoring of diagnostic hardware, and for data acquisition and analysis of the TFTR (Tokamak Fusion Test Reactor) Charge Exchange diagnostics. The TFTR Charge Exchange diagnostics are comprised of two autonomous systems, each consisting of up to six independent analyzer modules viewing the plasma at different angles and toroidal locations. Each system will have the capability of acquiring up to 2.5 megabytes of raw data for each shot. Users will have the capability of controlling all analyzers, and analyzing hydrogen mass species for up to ten analysis pulse time regions for multiple plasma shots. These features make the Charge Exchange systems among the largest diagnostic applications software systems on TFTR.     

On the Radio Frequency Ion Source

A radio frequency positive ion source employing a non-magnetic analyzer is proposed with the eventual purpose to overcome the difficulties involved in confining, extracting and filtering ion beams.     

The Orsay Electron Beam Ion Source

Basic parameters of the electron beam ion source (EBIS) are defined. The experimental results of the Orsay EBIS are described. We give also the design of a synchrotron source for production of fully-stripped heavy ion beams and polarized protons.     

Isolation of 137Cs with Copper Ferrocyanide-Anion Exchange Resin

The adsorption and desorption of ¹³⁷Cs on copper ferrocyanide-anion exchange resin, prepared in the manner previously reported in this Journal in a Short Note, are presented in detail.

This resin can also be used for the concentration of the ¹³⁷Cs found in sea water. The nuclide is adsorbed effectively on the resin from water, hydrochloric acid below 4 M, and on nitric acid below 1M. After adsorpsion on the resin, ¹³⁷Cs is eluted easily with either nitric acid (>6M), ammonium water, or silver nitrate solution.

Adsorption on the resin is specific for ¹³⁷Cs, and the action is due entirely to the ferrocyanide moiety of the resin.

This method is more efficient than the co-precipitation method with copper ferrocyanide for the concentration of radiocesium from a large volume of sea water.     

Simulation of Electron Trajectories in the Multicusp Ion Source Using Geantn4 Monte Carlo Code

To optimize the negative ion source and generate intense beams of negative ions, understanding of transport properties of both electrons and negative ions is indispensable. Transport process of negative hydrogen ions (H⁻) in a multicusp H⁻ source, has been simulated by three-dimensional Femlab simulation software. Multipolar plasma confinement is known to result in enhanced plasma density, homogeneous plasma of a large volume, and quiescent plasmas. The effect of plasma confinement by applying multi-polar magnetic field was investigated. Results are obtained for ten different configurations of permanent magnet and discussed. Full line cusps are found to give optimum plasma density. Negative ions created on the sidewall hardly can reach the center of the source due to trapping by the multicusp magnetic field. As a result, H⁻ ions created on the sidewall do not have a significant effect on the H⁻ current.     

Enrichment of 6Li by Ion Exchange

Elementary solutions to the energy-dependent Boltzmann equation with a one-term degenerate scattering kernel are derived in plane geometry, and the weight function W (z) is obtained which makes these solutions mutually orthogonal over the half-range interval of the continuum. The weight function greatly facilitates determination of the expansion coefficients in general solutions and is applied to the problems in infinite half space.

The diffusion length (discrete space eigenvalue) υ₀ is exactly expressed by using the halfrange characteristic function X(z). In a 1/υ-absorbing medium, as the absorption concentration q increases from zero to a critical value g^*, the diffusion length decreases from infinity to the end of the continuum 1/σ_min. For q≥q^*, v₀ vanishes and the neutron density can be represented by the transient term alone, whose exact expression is obtained.     

Ion Exchange Technology in Spent Fuel Reprocessing

Solvent extraction is the major unit operation employed in spent nuclear fuel reprocessing. The operation yields three streams; fission product waste, uranium product and plutonium product. Ion exchange is primarily used in reprocessing as a tail-end method to concentrate and isolate the plutonium product stream. This review will describe the details of plutonium recovery and purification by both cation- and anion-exchange processing. A brief overview of miscellaneous uses of ion-exchange employed in reprocessing will also be given.     

Profile Measurement of Ion Temperature and Toroidal Rotation Velocity with Charge Exchange Recombination Spectroscopy Diagnostics in the HL-2A Tokamak

This paper deals with the profile measurement of impurity ion temperature and toroidal rotation velocity that can be achieved by using the charge exchange recombination spectrum (CXRS) diagnostics tool built on the HL-2A toknmak. By using CXRS, an accurate impurity ion temperature and toroidal plasma rotation velocity profile can be achieved under the condition of neutrM beam injection (NBI) heating. Considering the edge effect of the line of CVI 529.06 nm (n= 8-7), which contains three lines (active exciting spectral line (ACX), passivity exciting spectral line (PCX) and electron exciting spectral line (ICE)), and using three Gaussian fitted curves, we obtain the following experimental results: the core ion temperature of HL-2A device is nearly thousands of eV, and the plasma rotation velocity reaches about 104 m· s^-1. At the end of paper, some explanations are presented for the relationship between the curves and the inner physical mechanism.