Magnetic Focusing Lenses Research Articles

Development of Beam Optics Code LEADS-v5

To calculate nonlinear transport of space charge dominated beam in 6D phase spaces, a computer code package LEADS-v5 (Linear and Electrostatic Accelerator Dynamics Simulations) has been developed. The codes calculate particle motions in the beam transport systems consisting of electrostatic and magnetic focusing lenses, ion analyzers, multipoles and RF accelerating structures. The nonlinear forces of external electric/magnetic fields are analyzed by the Lie algebraic method, and the space charge forces are obtained by the particle in cell (PIC) scheme. In the codes, Uniform and Gaussian particle distributions can be chosen to generate randomly the particle initial coordinates. The optimization procedures are provided to make the beam optics designs reasonable and fast. Graphically displays of calculated results are provided.

Simulation of the static spatial resolution characteristics for a dilation imager with long magnetic focusing lens

A dilation imager with long magnetic focusing lens is simulated by using the Monte Carlo method. The theoretical static spatial resolution characteristics of the imager are studied. The relationship between the spatial resolution and the inner diameter of the magnetic coil is obtained. The variation of the spatial resolution with the coil ampere-turn is also provided. Moreover, the connection between the spatial resolution and the photo-cathode (PC) voltage is acquired. Furthermore, the spatial resolution versus the photoelectron emitting point on PC is achieved.

Double Magnetic Focusing Lens for a Pb-Coated Superconducting Inertial Fusion Energy Target

The focusing performance of a double magnetic lens and the delay in the arrival time at the shot point are presented for a Pb-coated superconducting inertial fusion energy target injection system. Magnets placed symmetrically in the injection path adjust the target trajectory and focus it toward the designated point. When the target passes through the magnetic lens, it receives deceleration and acceleration forces, producing a delay in the arrival time. c © 2009 The Japan Society of Plasma Science and Nuclear Fusion Research

The IH structure—a new approach to the fusion RF linac

Short zero degree synchronous particle structures and magnetic focusing lenses can be combined in such a way that the emittance of each section is well adapted to the acceptance of the following section. By that way drift tube linacs can do the particle acceleration more close to the crest of the RF wave, the transverse RF defocusing effect can be minimized and the emittance growth of the beam is kept low. Specific problems of the heavy-ion fusion linacs are the acceleration of 1+charged ions with mass numbers around 200 and beam currents around 100 mA. This paper investigates the suitability of theInterdigitalH-type structure for that application. Technical as well as beam-dynamical aspects and the beam-cavity interaction are discussed.

Development of an automatic ion beam focusing system for a nuclear microprobe

If a nuclear microprobe with a beam size in the submicron region is to be attained, an objective measure of beam profile is a prerequisite. We have developed an automatic beam-focusing system for the Lund achromatic lens system. Using a knife-edge method, projections of the beam profile are determined. The resolutions of the measured profiles are then used as feedback in an automatic focusing procedure which uses computer-controlled power supplies for the electrostatic and magnetic focusing lenses. The beam spot size is minimized using a modified SIMPLEX iterative method. The system can use signals from any detectors, which permits it to be used informing the highest resolution microbeams.

A Scanning Electron Microscope Study of the Pore Structure of Sandstone

The scanning electron microscope can be used to produce, in a way that is not possible with optical techniques or with casts of pore space, a quasi three-dimensional representation of the pore structure of sandstone, making it possible to determine the pore structure of sandstone, making it possible to determine the number of interconnected flow channels. Introduction Efforts have been made for many years to observe pore structure of sedimentary rocks on a microscopic pore structure of sedimentary rocks on a microscopic scale. A better description of the pore structure in reservoir rock would aid in the development of relations between flow through tube network models and flow in consolidated reservoir rock. The unique qualities of the scanning electron miscroscope (SEM) make it the ideal tool to use in a study of pore structure. Previous methods of studying pore structure included plastic casts of pore space and optical microscopy. There is now available a new method to observe three-dimensional flow channels in reservoir rock: a scanning electron microscope having variable magnification from 20 x to 20,000 x and approximately 1,000 times the depth of focus of the conventional light microscopes. This microscope also can obtain stereoscopic images, and can measure and diagram flow channels so that it is possible to construct a network of tubes that will model consolidated reservoir rock. Theory of the Scanning Electron Microscope The scanning electron microscope (SEM) functions by projecting a beam of electrons through magnetic focusing lenses at a specimen and recording secondary electrons excited by the primary beam. The amount of secondary electron emission portrays the topography of the specimen because more secondary electrons are emitted from high points than from low points. A schematic of the SEM is shown in Fig. 1. points. A schematic of the SEM is shown in Fig. 1. The property of the SEM that is of most importance in this study is its great depth of focus. The depth of focus results from using electrons rather than light. In the SEM, no electron trajectory is inclined more than 0.5 degrees from the optic axis, in contrast with the more than 60 degrees in optical microscopy (Fig. 2). The major problem encountered with the SEM is the build-up of a space charge on insulating specimens under bombardment by the 20 kev primary beam. To prevent charge build-up, insulating specimens must prevent charge build-up, insulating specimens must be coated with a conducting film to drain away the space charge. Sample Preparation The technique used to prepare rocks for examination with the SEM is the most critical part of obtaining micrographs. To obtain information about the pores of a rock, a surface must be prepared in such a way that the grains are cut through without being pulled from the rock matrix. This is difficult because the grains are stronger than the matrix. The problem was solved by application of techniques used to make thin-sections. Rock samples 5 cm in diameter x 5 cm thick were mounted in polyester resin, with care being taken not to allow the resin to enter the pores. JPT P. 543

A Three Stage Mass Spectrometer

A three stage mass spectrometer, utilizing two consecutive magnetic focusing lenses of 20″ radii followed by a 20” radius of curvature electrostatic analyzer, is described An abundance sensitivity of 1010 was measured for this instrument in the low mass region. Application of this instrument to analytical and research problems in the field of mass spectrometry and results obtained are discussed.

A Diffraction Specimen Holder for Electron Microscopes

The basic elements of an electron diffraction camera—a source of high velocity monochromatic electrons, a magnetic focusing lens, and a recording photographic system—are found in the magnetic electron microscope. This has naturally led to the development of a diffraction adapter1 for electron microscopes which has proved most useful for supplementing electron micrographs with data on specimen composition. A specimen holder for an adapter lens to the Model B RCA electron microscope is here described. It is designed to accommodate a wide range of specimen sizes and shapes for diffraction investigations by both electron reflection and transmission methods. Three completely independent motions of the specimen are provided, namely: (1) translation in a direction perpendicular to the electron beam, (2) rotation about the direction of translation, and (3) rotation about an axis perpendicular to both the electron beam and the direction of translation.