... reduce or eliminate the influence of the walls on the ... in this way, the selection of wall material and ... can be made independently of its effect that the ...
DTIC Science & Technology
The electron cloud effect (ECE) causes beam instabilities in accelerator structures with intense positively charged bunched beams. Reduction of the secondary electron yield (SEY) of the beam pipe inner wall is effective in controlling cloud formation. We ...
National Technical Information Service (NTIS)
As part of our ongoing development of the Dielectric Wall Accelerator, we are studying the performance of multilayer high-gradient insulators. These vacuum insulating structures are composed of thin, alternating layers of metal and dielectric, and have been shown to withstand higher gradients than conventional vacuum insulator ...
Energy Citations Database
The effect of finite resistance in the vacuum-tank walls on the longitudinal stability of an intense beam of particles in an accelerator is investigated theoretically. We show that even if the particle frequency is an increasing function of particle energy, the wall resistance can render the beam unstable against longitudinal bunching. ...
DOE Information Bridge
According to the work program and schedule there was developed the methodology of experiments on the discharge chamber material influence on the Hall thruster characteristics there was prepared Hall thruster model of the SPT- 100 type for these experiment...
The magnetic system of the compression chamber (adhesator) of the heavy-ion accelerator is contained in a thin-walled rotational shell of viscoelastic material. This container is stressed by the static pressure of the cooling media from within and by a pe...
Synchrotron light absorbers intercept synchrotron radiation to protect chamber walls from excessive heat. When subjected to the high temperature of the beam, these absorbers undergo thermal stress. If the stress is too great or fatigues the material, the ...
The dielectric wall accelerator (DWA) system being developed at the Lawrence Livermore National Laboratory (LLNL) uses fast switched high voltage transmission lines to generate pulsed electric fields on the inside of a high gradient insulating (HGI) acceleration tube. High electric field gradients are achieved by the use of alternating ...
A demonstration project leading to commercialization of a passive thermal wall using phase change storage materials (PCM) in masonry construction is reported. Techniques of vacuum forming have been identified and characterized making it possible to produce high-volume low-cost packages for insertion into the core of cement blocks. PCM filled packages with ...
NASA Astrophysics Data System (ADS)
Using the dielectric wall accelerator technology, they are developing a compact induction accelerator system primarily intended for pulsed radiography. Unlike the typical induction accelerator cell that is long compared with its accelerating gap width, th...
Usual treatments of resistive wall effects in accelerators are limited to the normal skin effect regime of electrical conductivity in metals. Therefore they do not generally apply to the situations when beam-exposed metallic surfaces of the vacuum chamber are held at cryogenic temperatures, where simple metals exhibit anomalous skin effect behavior. These ...
A 200kV light ion accelerator has been linked to the specimen chamber of a 500kV transmission electron microscope to simulate some of the radiation environment conditions expected for first wall material in a fusion reactor. Both the electrons of the HVEM...
The electron cloud effect (ECE) causes beam instabilities in accelerator structures with intense positively charged bunched beams. Reduction of the secondary electron yield (SEY) of the beam pipe inner wall is effective in controlling cloud formation. We summarize SEY results obtained from flat TiN, TiZrV and Al surfaces carried out in a laboratory ...
Compact dielectric wall (DWA) accelerator technology is being developed at the Lawrence Livermore National Laboratory. The DWA accelerator uses fast switched high voltage transmission lines to generate pulsed electric fields on the inside of a high gradient insulating (HGI) acceleration tube. Its high electric ...
A projectile is accelerated along a confined path by supplying a pulsed high pressure, high velocity plasma jet to the rear of the projectile as the projectile traverses the path. The jet enters the confined path at a non-zero angle relative to the projectile path. The pulse is derived from a dielectric capillary tube having an interior wall from which ...
DOEpatents
... residence time of the particles in the ... consequence of incurring considerable wall friction losses. ... a ready account of the particle acceleration process ...
These lectures treat some of the common collective beam instability effects encountered in accelerators. In choosing the material for these lectures, it is attempted to introduce this subject with a more practical approach, instead of a more theoretical approach starting with first principles. After introducing the terminologies, emphasis will be placed on ...
A number of questions which deal with the serviceability of structural materials for the beam stop first-wall and stripper targets of the Moscow Meson Facility (MMF) are considered. This report compares the effects on target lifetime of factors such as radiation damage, thermal heating, constant and dynamic thermostresses, and erosion of target ...
Charpy V-notch specimens (ASTM Type A) and 5.74-mm diameter tension test specimens of the Shippingport Reactor Neutron Shield Tank (NST) (outer wall material) were irradiated together with Charpy V-notch specimens of the Oak Ridge National Laboratory (ORN...
It was proposed that the ''pressure bump'' phenomenon observed in the CERN ISR proton machine is caused by ion induced desorption of gas molecules from the vacuum chamber wall.Residual gas molecules ionized by the proton beam are accelerated by the beam to wall potential (order of kV), and ...
It is well known that exposure to an accelerator environment can cause ``conditioning'' of the vacuum chamber surfaces. In order to understand the manner in which the surface structure might influence the production of gases and electrons in the accelerator, such surfaces should be studied both before and after exposure to accelerator ...
... rays is used to study acceleration and higher order discontinuities in nonlinear simple elastic materials. No special material symmetry is assumed ...
... Title : Accelerating Utilization of New Materials. Descriptive Note : Final rept. ... The advantages to be derived from new materials are documented. ...
A new accelerator technology, the dielectric wall accelerator (DWA), is potentially an ultra compact accelerator/pulsed power driver. This new accelerator relies on three new components: the ultra-high gradient insulator, the asymmetric Blumlein and low j...
... Chitin is the resistant cell wall material in the component cells of all of these fungi and results of efforts to identify cellulose in the same cell walls ...
... overall length of the duct or the length of the wall of the duct. In order to reduce the thickness of the boundary layer, ducts of ...
AD-A 247 769 k4 49c16(- 0 ACCELERATED DRYING OF WETTED MATERIALS ... evidence for accelerated drying of wetted materials emanating ...
Page 1. 0 Acceleration Waves in Elasti3-Plastic Materials tM. ... Abstract. -Acceleration waves in elastic-plastic materials are studied in ...
The phenomenon of high-amplitude inflation waves resulting from a sharp axial acceleration of the aorta, as may occur in road accidents, is investigated theoretically. The aorta is modeled as an axisymmetric tapered membranic shell (tube) made of an incompressible, nonlinear viscoelastic material with cylindrical orthotropy. It is filled with an inviscid, ...
PubMed
In a qualification life test of a Hall thruster it was found that the erosion of the acceleration channel practically stopped after ~5600 h. Numerical simulations using a two-dimensional axisymmetric plasma solver with a magnetic field-aligned mesh reveal that when the channel receded from its early-in-life to its steady-state configuration the following changes occurred near ...
... The pectic material in the wall of the alga is in the form of a pectic-protein comples and the chitin in the walls of the fungal cells is in the form of a ...
Normally, the walls of an artery are smooth, allowing blood to flow unimpeded. Atherosclerosis is when harmful material collects on the wall of an artery. ...
MedlinePLUS
A general model for wakefield-generated instabilities in linear accelerators, originally developed for cumulative beam breakup [1], is applied to the resistive wall instability. The general solution for various bunch charge distributions and application to various accelerator configurations are presented.
We report on compact accelerator technology development for potential use as a pulsed neutron source quantitative post verifier. The technology is derived from our on-going compact accelerator technology development program for radiography under the US Department of Energy and for a clinic sized compact proton therapy systems under an industry sponsored ...
A 200kV light ion accelerator has been linked to the specimen chamber of a 500kV transmission electron microscope to simulate some of the radiation environment conditions expected for first wall material in a fusion reactor. Both the electrons of the HVEM and the ions from the attached accelerator impinge ...
An acceleration responsive device is described. A housing has at one end normally open electrical contacts and contains a piston system with a first part of non-magnetic material having metering orifices in the side walls for forming an air bearing between it and the walls of the housing; this first piston ...
... ADD422981. Title : On the Use of Acceleration Waves to Characterize the Dynamic Response of Nonlinear Viscoelastic Materials,. ...
Wall turnover was studied in Bacillus subtilis. The loss of radioactively labeled wall polymers was followed during exponential growth in batch and chemostat cultures. Turnover kinetics were identical under all growth conditions; pulse-labeled wall material was lost with first-order kinetics, but only after ...
PubMed Central
A new high-density material is evaluated for use as shielding at medical radiation therapy facilities. The substance is supplied in the form of prefabricated interlocking blocks that contain steel scrap as the aggregate in a matrix of Portland cement. This material, called Ledite by its manufacturer, permits the dimensions of radiation therapy room ...
The strength of cylindrical pressure vessels subjected to dynamic loads was investigated to provide design data for small irradiation capsules for unstable or chemically reactive materials to be included in reactors or near accelerators. An empirical approach was taken to learn how a mass of detonating explosive can be contained completely in a ...
Abstract: Procedure for halogenation of confining walls of both gelatin ... Halogenation decreases permeability of wall material to encapsulated materials. ...
NASA Website
... Descriptors : *CERAMIC MATERIALS, *FERROELECTRIC MATERIALS, *FERROELECTRIC CRYSTALS, *ELASTIC WAVES, *DOMAIN WALLS ...
... (Author). Descriptors : *SINGLE CRYSTALS, *CERAMIC MATERIALS, *FERROELECTRIC MATERIALS, *ELASTIC WAVES, *DOMAIN WALLS ...
... Accession Number : ADA372324. Title : A Domain Wall Model for Hysteresis in Piezoelectric Materials. Corporate Author ...
... Title : A TECHNIQUE FOR THE CALCULATION OF ACCELERATION WAVES IN NONLINEAR VISCOELASTIC MATERIALS. ...
Using the dielectric wall accelerator technology, they are developing a compact induction accelerator system primarily intended for pulsed radiography. Unlike the typical induction accelerator cell that is long compared with its accelerating gap width, the proposed dielectric ...
The decelerating mechanisms and existence conditions for the pinch structures obtained in plasma rail guns are considered. The plasma is confined by the magnetic field of the self-current. It is shown that under experimental conditions the predominant effect is induction deceleration of the pinches by plasma formed behind the pinches as a result of ionization of vaporized electrode and ...
A new irradiation facility, PIREX II, became operational in March 1987. It is located on a dedicated beam line split from the main beam of the 590 MeV proton accelerator at the Paul Scherrer Institute (PSI). Irradiation with protons of this energy introdu...
HAT STIFFENED PANEL PROCESSING AND PAST CHALLENGES: * Hat side wall/cap ballooning where the sidewalls are not flat * Upper and lower radius thin-out (fiber movement and resin starvation) * Hat miss-location (hat to hat spacing) * Curved or snaking stiffe...
Long time mechanical and thermal stability of polymeric materials predicted from accelerated testing
NASA Technical Reports Server (NTRS)
... Accession Number : ADP023824. Title : Accelerated Modeling and New Ferroelectric Materials for Naval SONAR. Descriptive ...
... Center for Materials Design (CCMD), an entity coupled with Ohio State University's (OSU) Center for the Accelerated Maturation of Materials (CAMM ...
Page 1. Accelerated Insertion of Materials � Manufacturing and Producibility of Hat Stiffened Structure ... AIM-C Producibility Heuristics ...
Rim of secondary wall material (top) has been deposited around the margin of the end wall delimiting the future perforation. Part of the end wall not covered by the rim (bottom) has been removed.
NSDL National Science Digital Library
During the acceleration cycle of the AGS synchrotron, eddy currents are generated within the walls of the vacuum chambers of the AGS main magnets. The vacuum chambers have elliptical cross section, are made of inconel material with a wall thickness of 2 mm and are placed within the gap of the combined-function main ...
Interaction of plasma with plasma facing components in fusion devices leads to dust production, which can enhance impurity inflow toward the core plasma. It is known that the dust particles are accelerated by plasma flows in tokamaks to high speeds (�1km/s) that under effect of centrifugal acceleration leads to intensive dust-wall ...
An ultra-thin-walled superconducting warm bore solenoid has been developed for the WASA detector set-up at the CELSIUS accelerator of the The Svedberg Laboratory (TSL), Sweden. It gives a central magnetic field up to 1.3T, and can be operated in persistent mode. The total thickness of the superconducting coil is 9mm with an inner diameter of 554mm and an ...
Theoretical models and experimental results are presented for the retarded fall of a strong magnet inside a vertical conductive non-magnetic tube. Predictions and experimental results are in good agreement modelling the magnet as a simple magnetic dipole. The effect of varying the pipe wall thickness on the retarding magnetic drag is studied for pipes of different ...
ERIC Educational Resources Information Center
The nonlinear, transient dynamic finite element code, MSC.Dytran, was used to simulate an impact test of an energy absorbing cellular structure. This pre-test simulation was performed to aid in the design of an energy absorbing concept for a highly reliable passive Earth Entry Vehicle (EEV) that will directly impact the Earth without a parachute. In addition, a goal of the simulation was to bound ...
E-print Network
... It is believed that, since removal of the existing inlet panel is unnecessary, all makes of forced-convection ovens using wall-to-wall air flow can ...
Removal of vessel end wall with middle part consisting of primary wall material. Around the end wall margin, secondary wall material protects unthickened primary wall, which becomes hydrolyzed and disappear. This stage is shown below: the rim now ...
Finite-element analyses were performed to simulate the response of a hypothetical masonry shear wall with and without continuous filament ties to various lateral loads. The loads represented three different scenarios: (1) 100 mph wind, (2) explosive attack, and (3) an earthquake. In addition, a static loading analysis and cost comparison were performed to evaluate optimal ...
Interactions of plasma jets with solid surfaces are extensively studied in context with development of future fusion devices. In experiments carried out on the iodine laser system PALS, the energetic ions were produced at double-foil Al/Mg targets irradiated by one or two counter-propagating laser beams. The plasma jets from the rear surface of the laser-exploded Al foil streamed towards the Mg ...
In arterial dissection, blood may enter the arterial wall through an intimal tear, splitting the arterial wall and activating the coagulation cascade at the site of endothelial damage. Dissection of extracranial and intracranial vessels may lead to ischemic stroke through thromboembolic or hemodynamic mechanisms. Major blunt trauma or rapid ...
... Descriptors : *CERAMIC MATERIALS, *FERROELECTRIC MATERIALS, *DOMAIN WALLS, PARTICLE SIZE, VOLUME, POLARIZATION ...
The small diameters of CNTs or other nanoporous materials allow for ... with the wall material, we also wish to produce walls with carbonaceous material and ...
The theoretical performance of diagonal conducting wall crossed-field accelerators is examined on the basis of an infinite segmentation assumption using a cross-plane averaged generalized Ohm s law for a partially ionized gas, including ion slip. The desi...
The theoretical performance of diagonal conducting wall crossed field accelerators is examined on the basis of an infinite segmentation assumption using a cross-plane averaged generalized Ohm's law for a partially ionized gas, including ion slip. The desi...
Fast, low jitter command triggered switching is key to the successful implementation of the dielectric wall accelerator (DWA). We are studying a UV induced vacuum surface flashover switch for this purpose. We present our initial data using a Nd:YAG laser ...
Bearing in mind the well-known advantages of precast construction, we have the opportunity of fabricating concrete blocks of various weightvolume ratios for the shielding walls of nuclear reactors and particle accelerators. A mold of the casette type make...
A general model for wakefield-generated instabilities in linear accelerators, originally developed for cumulative beam breakup (1), is applied to the resistive wall instability. The general solution for various bunch charge distributions and application t...
... Descriptors : *PLASMAS(PHYSICS), *BETATRONS, HIGH POWER, INJECTION, STABILITY, WALLS, TRANSITIONS, PARTICLE ACCELERATORS ...
The temperature rise produced by synchrotron radiation incident on the vacuum chamber wall of a betatron is evaluated for a general acceleration cycle.
... sought. The solution was accelerate iron nanoparticles to a target, where they built up like snowballs thrown against a wall. ...
... positions near the tank walls shows ... ARC JET ENGINES, ENVIRONMENTAL TESTS ... PROPULSION SYSTEMS, TANKS(CONTAINERS), VACUUM ...
... Descriptors : *Electron beams, *Particle accelerators, *Betatrons, *Equations, Dynamics, Toroids, Corrections, Magnetic fields, Walls, Diffusion ...
At Lawrence Livermore National Laboratory, we are developing a new type of accelerator, known as a Dielectric Wall Accelerator, in which compact pulse forming lines directly apply an accelerating field to the beam through an insulating vacuum boundary. The electrical strength of this insulator may define the ...
Activation of various structural and shielding materials is an important issue for many applications. A model developed recently to calculate residual activity of arbitrary composite materials for arbitrary irradiation and cooling times is presented in the paper. Measurements have been performed at the Fermi National Accelerator ...
The Dielectric Wall Accelerator (DWA) offers the potential to produce a high gradient linear accelerator for proton therapy and other applications. The current status of the DWA for proton therapy will be reviewed. Recent progress in SiC photoconductive switch development will be presented. There are serious beam transport challenges ...
The Institute for Reference Materials and Measurements operates a 7.0 MV Van de Graaff accelerator to generate monoenergetic neutron radiation for experimental applications. Owing to increased intensities of generated neutron fields and the more stringent regulation related to the maximum dose for the public, a concrete shielding wall ...
The longitudinal electromagnetic interaction of an intense coasting beam with itself, including the effect of a resistive vacuum tank, is investigated theoretically. It is shown that even in the range where the particle frequency is an increasing function of particle energy, the beam can be longitudinally unstable due to the resistivity of the vacuum tank walls. In the absence ...
