FRC plasma studies on the FRX-L plasma injector for MTF

International Nuclear Information System (INIS)

Wurden, G.A.; Intrator, T.P.; Zhang, S.Y.; Furno, I.G.; Hsu, S.C.; Park, J.Y.; Kirkpatrick, R.; Renneke, R.M.; Schoenberg, K.F.; Taccetti, M.J.; Tuszewski, M.G.; Waganaar, W.J.; Zhehui Wang; Siemon, R.E.; Degnan, J.H.; Gale, D.G.; Grabowski, C.; Ruden, E.L.; Sommars, W.; Frese, M.H.; Coffey, S.; Craddock, G.; Frese, S.D.; Roderick, N.F.

2005-01-01

To demonstrate the physics basis for Magnetized Target Fusion (MTF), we have designed a field reversed configuration (FRC) target plasma to ultimately be compressed within an imploding metal flux conserver (liner). This new, high energy density FRC device, named FRX-L, is operating at Los Alamos as a compact 'theta-pinch' formation FRC. The system capability includes a 0.5 T bias field, 70 kV 250 kHz ringing pre-ionization, and a 1.5 MA, 200 kJ main-theta-coil bank. We show FRC data with plasma parameters approaching the desired MTF requirements, examples of substantial Ohmic heating from magnetic flux annihilation, and measurements of plasma anomalous resistivity. Improvements are underway to reduce the main bank crowbar ringing, which will increase the trapped flux in the FRC. A prototype deformable flux-conserving liner with large entrance holes to accept an FRC has also been designed with MACH2 (2-D MHD modelling code) and successfully imploded at Kirtland Air Force Base on the Shiva Star pulsed power facility. (author)

On Early Age Crack Formation in FRC Slabs

DEFF Research Database (Denmark)

Olesen, John Forbes; Stang, Henrik

1997-01-01

The problem of early age crack formation in FRC slabs due to restrained temperature and shrinkage deformations, is given an analytical treatment. A model taking into account the ageing properties of the tensile softening curve and the continued development in the temperature and shrinkage...... deformations after crack initiation, is presented. Based on this model a design strategy for FRC slabs is outlined....

Conceptual design of D-3He FRC reactor 'ARTEMIS'

International Nuclear Information System (INIS)

Momota, H.; Ishida, A.; Kohzaki, Y.

1991-07-01

A comprehensive design study of the D- 3 He fueled field-reversed configuration (FRC) reactor 'ARTEMIS' is carried out for the purpose of proving its attractive characteristics and clarifying the critical issues for a commercial fusion reactor. The FRC burning plasma is stabilized and sustained in a steady equilibrium by means of a preferential trapping of D- 3 He fusion-produced energetic protons. A novel direct energy converter for 15MeV protons is also presented. On the bases of a consistent scenario of the fusion plasma production and simple engineering, a compact and simple reactor concept is presented. The design of the D- 3 He FRC power plant definitely offers the most attractive prospect for energy development. It is environmentally acceptable in view of radio-activity and fuel resources; and the estimated cost of electricity is low compared to a light water reactor. Critical issues concerning physics or engineering for the development of the D- 3 He FRC reactor are clarified. (author)

Development of Fracture Energy of FRC Materials. Freeze-Thaw Resistance of FRC Materials

DEFF Research Database (Denmark)

Stoklund Larsen, E.

During the past four years research has been carried out at the Danish Building Research Institute on different aspects of the long term performance of fibre reinforced cementitious composites (FRC) exposed to climate stresses. Some of the most important results have been brought together in this...

Recent FRC translation experiments on FRX-C/T

International Nuclear Information System (INIS)

Rej, D.J.; Armstrong, W.T.; Chrien, R.E.; Hugrass, W.N.; Klingner, P.L.; McKenna, K.F.; Sherwood, E.G.; Siemon, R.E.; Tuszewski, M.

1985-01-01

Since the last CT Symposium, several accomplishments have been realized from the FRC translation studies on the FRX-C/T device: (1) FRCs have been launched into, and trapped in, a dc magnetic guide field region without the use of any pulsed ''gate'' coils; (2) detailed studies of translation dynamics have been performed which are consistent with energy conservation, adiabatic compression theory, and 2-D MHD simulations; (3) the confinement properties of translated FRC has been evaluated; (4) translation through either puff or static deuterium gas fill has been demonstrated; (5) higher density (n less than or equal to 4 x 10 15 cm -3 ) FRCs have been translated over 10-m lengths; (6) the n = 2 rotational instability has been stabilized by FRC translation into a weak helical quadrupole field

A functional analysis of the formyl-coenzyme A (frc) gene from Lactobacillus reuteri 100-23C.

Science.gov (United States)

Kullin, B; Tannock, G W; Loach, D M; Kimura, K; Abratt, V R; Reid, S J

2014-06-01

To examine the role of the Lactobacillus reuteri 100-23C frc gene product in oxalate metabolism, host colonization and the acid stress response. Genes encoding putative formyl-CoA transferase (frc) and oxalyl-CoA decarboxylase (oxc) enzymes are present in the genome sequences of Lact. reuteri strains. Two strains isolated from humans harboured an IS200 insertion sequence in the frc ORF and a group 2 intron-associated transposase downstream of the frc gene, both of which were lacking in two strains of animal origin, which contained intact frc and oxc genes. An frc(-) insertional mutant of Lact. reuteri 100-23C was compared with the parent strain with respect to oxalate degradation, colonization of an RLF-mouse host model and growth in the presence of acids. Neither parent nor mutant degraded oxalate in vitro or in vivo. However, the parent outcompeted the frc(-) mutant in the mouse intestine during co-colonization and the frc(-) mutant showed a reduced growth rate in the presence of hydrochloric acid. Intact oxc and frc genes do not ensure oxalate degradation under the conditions tested. The frc gene product is important during host colonization and survival of acid stress by Lact. reuteri 100-23C. Oxalate metabolism by oxalate-degrading intestinal bacterial strains may be important in preventing urolithiasis and might lead to the derivation of probiotic products. To produce safe and efficacious probiotics, however, an understanding of the genetic characteristics of potential oxalate degraders must be obtained, together with knowledge of their functional ramifications. © 2014 The Society for Applied Microbiology.

UEDGE Simulations for Power and Particle Flow Analysis of FRC Rocket

Science.gov (United States)

Zheng, Fred; Evans, Eugene S.; McGreivy, Nick; Kaptanoglu, Alan; Izacard, Olivier; Cohen, Samuel A.

2017-10-01

The field-reversed configuration (FRC) is under consideration for use in a direct fusion drive (DFD) rocket propulsion system for future space missions. To achieve a rocket configuration, the FRC is embedded within an asymmetric magnetic mirror, in which one end is closed and contains a gas box, and the other end is open and incorporates a magnetic nozzle. Neutral deuterium is injected into the gas box, and flows through the scrape-off layer (SOL) around the core plasma and out the magnetic nozzle, both cooling the core and serving as propellant. Previous studies have examined a range of operating conditions for the SOL of a DFD using UEDGE, a 2D fluid code; discrepancies on the order of 5% were found during the analysis of overall power balance. This work extends the analysis of the previously-studied SOL geometry by updating boundary conditions and conducting a detailed study of power and particle flows within the simulation with the goals of modeling electrical power generation instead of thrust and achieving higher specific impulse. This work was supported, in part, by DOE Contract Number DE-AC02-09CH11466 and Princeton Environmental Institute.

Overview of C-2U FRC Experimental Program and Plans for C-2W

Science.gov (United States)

Gota, H.; Binderbauer, M. W.; Tajima, T.; Putvinski, S.; Tuszewski, M.; Dettrick, S.; Korepanov, S.; Smirnov, A.; Thompson, M. C.; Yang, X.; Cappello, M.; Ivanov, A. A.; TAE Team

2016-10-01

Tri Alpha Energy's experimental program has been focused on a demonstration of reliable field-reversed configuration (FRC) formation and sustainment, driven by fast ions via high-power neutral-beam (NB) injection. The world's largest compact-toroid experimental devices, C-2 and C-2U, have successfully produced a well-stabilized, sustainable FRC plasma state with NB injection (input power, PNB 10 + MW; 15 keV hydrogen) and end-on coaxial plasma guns. Remarkable improvements in confinement and stability of FRC plasmas have led to further improved fast-ion build up; thereby, an advanced beam-driven FRC state has been produced and sustained for up to 5 + ms (longer than all characteristic system time scales), only limited by hardware and electric supply constraints such as NB and plasma-gun power supplies. To further improve the FRC performance the C-2U device is being replaced by C-2W featuring higher injected NB power, longer pulse duration as well as enhanced edge-biasing systems and substantially upgraded divertors. Main C-2U experimental results and key features of C-2W will be presented. Tri Alpha Energy, Inc.

Influence of bending test configuration on cracking behavior of FRC

DEFF Research Database (Denmark)

Finazzi, Silvia; Paegle, Ieva; Fischer, Gregor

2014-01-01

the flexural load-deformation response of FRC. This research focuses particularly on the influence of the appearance and depth of the notch on the cracking behavior of FRC. For this purpose, several specimens, both un-notched and notched with different depths of the notch (25 mm and 45 mm), were tested....... The results obtained in the various tests are compared to determine to what extent the notch can affect cracking behavior and the resulting evaluation of the material according to the method described in the standard. Formation of cracking and the crack development has been documented by means of a digital...

Ion accelerators for space

International Nuclear Information System (INIS)

Slobodrian, R.J.; Potvin, L.

1991-01-01

The main purpose of the accelerators is to allow ion implantation in space stations and their neighborhoods. There are several applications of interest immediately useful in such environment: as ion engines and thrusters, as implanters for material science and for hardening of surfaces (relevant to improve resistance to micrometeorite bombardment of exposed external components), production of man made alloys, etc. The microgravity environment of space stations allows the production of substances (crystalline and amorphous) under conditions unknown on earth, leading to special materials. Ion implantation in situ of those materials would thus lead uninterruptedly to new substances. Accelerators for space require special design. On the one hand it is possible to forego vacuum systems simplifying the design and operation but, on the other hand, it is necessary to pay special attention to heat dissipation. Hence it is necessary to construct a simulator in vacuum to properly test prototypes under conditions prevailing in space

Formation and sustainment of field reversed configuration (FRC) plasmas by spheromak merging and neutral beam injection

Energy Technology Data Exchange (ETDEWEB)

Yamada, Masaaki [Princeton Plasma Physics Laboratory, Princeton University Princeton, New Jersey USA (United States)

2016-03-25

This paper briefly reviews a compact toroid reactor concept that addresses critical issues for forming, stabilizing and sustaining a field reversed configuration (FRC) with the use of plasma merging, plasma shaping, conducting shells, neutral beam injection (NBI). In this concept, an FRC plasma is generated by the merging of counter-helicity spheromaks produced by inductive discharges and sustained by the use of neutral beam injection (NBI). Plasma shaping, conducting shells, and the NBI would provide stabilization to global MHD modes. Although a specific FRC reactor design is outside the scope of the present paper, an example of a promising FRC reactor program is summarized based on the previously developed SPIRIT (Self-organized Plasmas by Induction, Reconnection and Injection Techniques) concept in order to connect this concept to the recently achieved the High Performance FRC plasmas obtained by Tri Alpha Energy [Binderbauer et al, Phys. Plasmas 22,056110, (2015)]. This paper includes a brief summary of the previous concept paper by M. Yamada et al, Plasma Fusion Res. 2, 004 (2007) and the recent experimental results from MRX.

Formation of Field Reversed Configuration (FRC on the Yingguang-I device

Directory of Open Access Journals (Sweden)

Qizhi Sun

2017-09-01

Full Text Available As a hybrid approach to realizing fusion energy, Magnetized Target Fusion (MTF based on the Field Reversed Configuration (FRC, which has the plasma density and confinement time in the range between magnetic and inertial confinement fusion, has been recently widely pursued around the world. To investigate the formation and confinement of the FRC plasma injector for MTF, the Yingguang-I, which is an FRC test device and contains a multi-bank program-discharged pulsed power sub-system, was constructed at the Institute of Fluid Physics (IFP, China. This paper presents the pulsed power components and their parameters of the device in detail, then gives a brief description of progress in experiments of FRC formation. Experimental results of the pulsed power sub-system show that the peak current/magnetic field of 110 kA/0.3 T, 10 kA/1.2 T and 1.7 MA/3.4 T were achieved in the bias, mirror and θ-pinch circuits with quarter cycle of 80 μs, 700 μs and 3.8 μs respectively. The induced electric field in the neutral gas was greater than 0.25 kV/cm when the ionization bank was charged to 70 kV. With H2 gas of 8 Pa, the plasma target of density 1016 cm−3, separatrix radius 4 cm, half-length 17 cm, equilibrium temperature 200 eV and lifetime 3 μs (approximately the half pulse width of the reversed field have been obtained through the θ-pinch method when the bias, mirror, ionization and θ-pinch banks were charged to 5 kV, 5 kV, 55 kV and ±45 kV respectively. The images from the high-speed end-on framing camera demonstrate the formation processes of FRC and some features agree well with the results with the two-dimension magneto hydrodynamics code (2D-MHD.

Design Basis for Fibre Reinforced Concrete (FRC) Pavements

DEFF Research Database (Denmark)

Bendixen, Søren; Stang, Henrik

1996-01-01

-crack opening relationship can beused to descibe the properties of fibre reinforced concrete (FRC) intension and how the stress-crack opening relationship can beapplied in a simple design scheme for pavements. The projectincludes development of design tools, experiments to determine thestress-crack opening...

Ultimate pressure capacity assessment of R FRC PCCV based on the tension stiffening tests

International Nuclear Information System (INIS)

Hahm, Dae Gi; Choun, Young Sun

2012-01-01

The use of fibers in concrete or cement composites can enhance the performance of structural elements. Fibers have been used for a cement mixture to increase the toughness and tensile strength, and to improve the cracking and deformation characteristics. The addition of fibers into concrete can improve the ductility and increase the tensile resistance of concrete structures. Recently, the application of fibers to prestressed concrete containment vessels (PCCVs) has been a major research topic. However, the tensile stiffening behavior of reinforced - fiber reinforced concrete (RFRC) is not fully developed yet especially for specimens using large diameter re bars. In nuclear power plant (NPP) PCCVs, large diameter re bars are applied. Therefore, the tensile stiffening behavior model should be developed to assess ultimate pressure capacity (UPC) of R FRC PCCVs. In this study, we modeled the tensile stiffening behavior of R FRC PCCVs by using recently developed model, and assessed the UPC of R FRC PCCVs. To do this, we performed tension stiffening test of R FRC with large diameter re bar

Ultimate pressure capacity assessment of R FRC PCCV based on the tension stiffening tests

Energy Technology Data Exchange (ETDEWEB)

Hahm, Dae Gi; Choun, Young Sun [KAERI, Daejeon (Korea, Republic of)

2012-10-15

The use of fibers in concrete or cement composites can enhance the performance of structural elements. Fibers have been used for a cement mixture to increase the toughness and tensile strength, and to improve the cracking and deformation characteristics. The addition of fibers into concrete can improve the ductility and increase the tensile resistance of concrete structures. Recently, the application of fibers to prestressed concrete containment vessels (PCCVs) has been a major research topic. However, the tensile stiffening behavior of reinforced - fiber reinforced concrete (RFRC) is not fully developed yet especially for specimens using large diameter re bars. In nuclear power plant (NPP) PCCVs, large diameter re bars are applied. Therefore, the tensile stiffening behavior model should be developed to assess ultimate pressure capacity (UPC) of R FRC PCCVs. In this study, we modeled the tensile stiffening behavior of R FRC PCCVs by using recently developed model, and assessed the UPC of R FRC PCCVs. To do this, we performed tension stiffening test of R FRC with large diameter re bar.

Laboratory studies of magnetized collisionless flows and shocks using accelerated plasmoids

Science.gov (United States)

Weber, T. E.; Smith, R. J.; Hsu, S. C.

2015-11-01

Magnetized collisionless shocks are thought to play a dominant role in the overall partition of energy throughout the universe, but have historically proven difficult to create in the laboratory. The Magnetized Shock Experiment (MSX) at LANL creates conditions similar to those found in both space and astrophysical shocks by accelerating hot (100s of eV during translation) dense (1022 - 1023 m-3) Field Reversed Configuration (FRC) plasmoids to high velocities (100s of km/s); resulting in β ~ 1, collisionless plasma flows with sonic and Alfvén Mach numbers of ~10. The FRC subsequently impacts a static target such as a strong parallel or anti-parallel (reconnection-wise) magnetic mirror, a solid obstacle, or neutral gas cloud to create shocks with characteristic length and time scales that are both large enough to observe yet small enough to fit within the experiment. This enables study of the complex interplay of kinetic and fluid processes that mediate cosmic shocks and can generate non-thermal distributions, produce density and magnetic field enhancements much greater than predicted by fluid theory, and accelerate particles. An overview of the experimental capabilities of MSX will be presented, including diagnostics, selected recent results, and future directions. Supported by the DOE Office of Fusion Energy Sciences under contract DE-AC52-06NA25369.

Simulations of a Plasma Thruster Utilizing the FRC Configuration

Energy Technology Data Exchange (ETDEWEB)

Rognlien, T. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Cohen, B. I. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2016-10-10

This report describes work performed by LLNL to model the behavior and performance of a reverse-field configuration (FRC) type of plasma device as a plasma thruster as summarized by Razin et al. [1], which also describes the MNX device at PPPL used to study this concept.

Rayleigh-Taylor mixing with space-dependent acceleration

Science.gov (United States)

Abarzhi, Snezhana

2016-11-01

We extend the momentum model to describe Rayleigh-Taylor (RT) mixing driven by a space-dependent acceleration. The acceleration is a power-law function of space coordinate, similarly to astrophysical and plasma fusion applications. In RT flow the dynamics of a fluid parcel is driven by a balance per unit mass of the rates of momentum gain and loss. We find analytical solutions in the cases of balanced and imbalanced gains and losses, and identify their dependence on the acceleration exponent. The existence is shown of two typical sub-regimes of self-similar RT mixing - the acceleration-driven Rayleigh-Taylor-type mixing and dissipation-driven Richtymer-Meshkov-type mixing with the latter being in general non-universal. Possible scenarios are proposed for transitions from the balanced dynamics to the imbalanced self-similar dynamics. Scaling and correlations properties of RT mixing are studied on the basis of dimensional analysis. Departures are outlined of RT dynamics with space-dependent acceleration from canonical cases of homogeneous turbulence as well as blast waves with first and second kind self-similarity. The work is supported by the US National Science Foundation.

Kinetic theory in maximal-acceleration invariant phase space

International Nuclear Information System (INIS)

Brandt, H.E.

1989-01-01

A vanishing directional derivative of a scalar field along particle trajectories in maximal acceleration invariant phase space is identical in form to the ordinary covariant Vlasov equation in curved spacetime in the presence of both gravitational and nongravitational forces. A natural foundation is thereby provided for a covariant kinetic theory of particles in maximal-acceleration invariant phase space. (orig.)

Accelerated testing of space batteries

Science.gov (United States)

Mccallum, J.; Thomas, R. E.; Waite, J. H.

1973-01-01

An accelerated life test program for space batteries is presented that fully satisfies empirical, statistical, and physical criteria for validity. The program includes thermal and other nonmechanical stress analyses as well as mechanical stress, strain, and rate of strain measurements.

Preparasi Minimal pada Pembuatan Gigi Tiruan Cekat dengan Fiber Reinforced Composite (FRC

Directory of Open Access Journals (Sweden)

Aditya Ayat Santiko

2016-11-01

Full Text Available Dalam praktek sering kali dokter gigi dihadapkan pada pasien yang kehilangan gigi anterior dan ingin segera dibuatkan gigi tiruan karena alasan estetik. Gigi tiruan yang dibuat bisa berupa gigi tiruan sebagian lepasan (GTSL atau gigi tiruan cekat (GTC. Pada GTSL, adanya plat pada palatum menyebabkan rasa tidak nyaman, selain itu pasien setiap kali harus buka pasang gigi tiruan kembali sehingga cukup merepotkan. Oleh karena itu pada umumnya pasien ingin dibuatkan GTC dan hal ini memang sesuai dengan indikasi GTC. Hal yang menjadi pertimbangan pada pembuatan GTC adalah pengasahan permukaan gigi secara keseluruhan bila akan dibuat desain full crown. Pada perkembangan desain GTC ada desain yang disebut resin bonded bridge atau adhesive bridge yaitu GTC yang dibuat pada gigi abutment yang dipreparasi minimal pada bagian palatal saja dan dilekatkan secara mikromekanikal antara retainer sayap logam dan gigi yang telah dipreparasi. Pasien wan ita usia 22 tahun datang ke klinik Prostodonsia RSGM Prof Soedomo UGM karena kehilangan gigi insisif sentral kiri atas. Pada kasus ini dilakukan pembuatan GTC dengan bahan fiber reinforced composite (FRC. Pembuatan bridge dengan bahan FRC dapat dilakukan secara langsung dan tidak langsung. Pada makalah ini akan dibahas pembuatan bridge FRC secara tidak langsung yaitu dengan menggunakan gigi artlfisial komposit. Hasil menunjukkan estetis yang baik, kontrol setelah 2 bulan tidak ada perubahan warna dan pasien merasa puas dengan penampilannya, jaringan gingiva di sekitarnya normal.

Particle acceleration in the interplanetary space

International Nuclear Information System (INIS)

Tverskoj, B.A.

1983-01-01

A review on the problem of particle acceleration in the interplanetary space is given. The main lationship attention is paid to the problem of the re/ between the impact- and turbulent acceleration when an undisturbed magnetic field forms not too small angle THETA > 10 deg with the shock wave front. The following conclusions are drawn. Particle acceleration at the shock wave front is manifested in the explicit form, if the shock wave propagates along a homogeneous (in the 11 cm range) solar wind. The criterion of such an acceleration is the exponential distribution function F approximately vsup(-ν) (v is the particle velocity and ν is the accelerated particle spectrum index) in the low energy range and the conservation of this function at considerable distances behind the front. The presence of an additional turbulent acceleration behind the front is manifested in decreasing ν down to approximately 3.5 in the low energy range and in the spectrum evolution behind the front

Accelerated testing of space mechanisms

Science.gov (United States)

Murray, S. Frank; Heshmat, Hooshang

1995-01-01

This report contains a review of various existing life prediction techniques used for a wide range of space mechanisms. Life prediction techniques utilized in other non-space fields such as turbine engine design are also reviewed for applicability to many space mechanism issues. The development of new concepts on how various tribological processes are involved in the life of the complex mechanisms used for space applications are examined. A 'roadmap' for the complete implementation of a tribological prediction approach for complex mechanical systems including standard procedures for test planning, analytical models for life prediction and experimental verification of the life prediction and accelerated testing techniques are discussed. A plan is presented to demonstrate a method for predicting the life and/or performance of a selected space mechanism mechanical component.

Nonlinear transport of accelerator beam phase space

International Nuclear Information System (INIS)

Xie Xi; Xia Jiawen

1995-01-01

Based on the any order analytical solution of accelerator beam dynamics, the general theory for nonlinear transport of accelerator beam phase space is developed by inverse transformation method. The method is general by itself, and hence can also be applied to the nonlinear transport of various dynamic systems in physics, chemistry and biology

Steady state theta pinch concept for slow formation of FRC

International Nuclear Information System (INIS)

Hirano, K.

1987-05-01

A steady state high beta plasma flow through a channel along the magnetic field increasing downstream can be regarded as a ''steady state theta pinch'', because if we see the plasma riding on the flow we should observe very similar process taking place in a theta pinch. Anticipating to produce an FRC without using very high voltage technics such as the ones required in a conventional theta pinch, we have studied after the analogy a ''steady state reversed field theta pinch'' which is brought about by steady head-on collision of counter plasma streams along the channel as ejected from two identical co-axial plasma sources mounted at the both ends of the apparatus. The ideal Poisson and shock adiabatic flow models are employed for the analysis of the steady colliding process. It is demonstrated that an FRC involving large numbers of particles is produced only by the weak shock mode which is achieved in case energetic plasma flow is decelerated almost to be stagnated through Poisson adiabatic process before the streams are collided. (author)

PERFORMANCE OF RC AND FRC WALL PANELS REINFORCED WITH MILD STEEL AND GFRP COMPOSITES IN BLAST EVENTS

Energy Technology Data Exchange (ETDEWEB)

Timothy Garfield; William D. Richins; Thomas K. Larson; Chris P. Pantelides; James E. Blakeley

2011-06-01

The structural integrity of reinforced concrete structures in blast events is important for critical facilities. This paper presents experimental data generated for calibrating detailed finite element models that predict the performance of reinforced concrete wall panels with a wide range of construction details under blast loading. The test specimens were 1.2 m square wall panels constructed using Normal Weight Concrete (NWC) or Fiber Reinforced Concrete (FRC). FRC consists of macro-synthetic fibers dispersed in NWC. Five types of panels were tested: NWC panels with steel bar reinforcement (Type A); FRC panels without additional reinforcement (Type B); FRC panels with steel bar reinforcement (Type C); NWC panels with glass fiber reinforced polymer (GFRP) bar reinforcement (Type D); and NWC panels reinforced with steel bar reinforcement and external bidirectional GFRP overlays on both faces (Type E). An additional three Type C panels were used as control specimens (CON). Each panel type was constructed with three thicknesses: 152 mm, 254 mm, and 356 mm. The panels were instrumented with strain gauges, and accelerometers; in addition, pressure sensors and high speed videos were employed during the blast events. Panel types C and E had the best performance, whereas panel type B did not perform well. Preliminary dynamic simulations show crack patterns similar to the experimental results.

Space experiments with particle accelerators: SEPAC

International Nuclear Information System (INIS)

Obayashi, T.

1978-01-01

In this paper, the program of the space experiments with particle accelerators (SEPAC) is described. The SEPAC is to be prepared for the Space Shuttle/First Spacelab Mission. It is planned in the SEPAC to carry out the active and interactive experiments on and in the Earth's ionosphere and magnetosphere. It is also intended to make an initial performance test for the overall program of Spacelab/SEPAC experiments. The instruments to be used are electron beam accelerators, MPD arcjects, and associated diagnostic equipments. The main scientific objectives of the experiments are Vehicle Charge Neutralization, Beam Plasma Physics, and Beam Atmosphere Interactions. The SEPAC system consists of the following subsystems. Those are accelerators, monitoring and diagnostic equipments, and control and data management equipments. The SEPAC functional objectives for experiment operations are SEPAC system checkout, EBA firing test, MPD firing test, electron beam experiments, plasma beam propagation, artificial aurora excitation, equatorial aerochemistry, electron echo experiment, E parallel B experiment, passive experiments, SEPAC system deactivation, and battery charging. Most experiment procedures are carried out by the pre-set computer program. (Kato, T.)

Calibration and application of medical particle accelerators to space radiation experiments

International Nuclear Information System (INIS)

Ryu, Kwangsun; Park, Miyoung; Chae, Jangsoo; Yoon, Sangpil; Shin, Dongho

2012-01-01

In this paper, we introduce radioisotope facilities and medical particle accelerators that can be applied to space radiation experiments and the experimental conditions required by the space radiation experiments. Space radiation experiments on the ground are critical in determining the lifetimes of satellites and in choosing or preparing the appropriate electrical parts to assure the designated mission lifetime. Before the completion of building the 100-MeV proton linear accelerator in Gyeongju, or even after the completion, the currently existing proton accelerators for medical purposes could suggest an alternative plan. We have performed experiments to calibrate medical proton beam accelerators to investigate whether the beam conditions are suitable for applications to space radiation experiments. Based on the calibration results, we propose reference beam operation conditions for space radiation experiments.

Space charge effect in an accelerated beam

Directory of Open Access Journals (Sweden)

G. Stupakov

2008-01-01

Full Text Available It is usually assumed that the space charge effects in relativistic beams scale with the energy of the beam as γ^{-2}, where γ is the relativistic factor. We show that for a beam accelerated in the longitudinal direction there is an additional space charge effect in free space that scales as E/γ, where E is the accelerating field. This field has the same origin as the “electromagnetic mass of the electron” discussed in textbooks on electrodynamics. It keeps the balance between the kinetic energy of the beam and the energy of the electromagnetic field of the beam. We then consider the effect of this field on a beam generated in an rf gun and calculate the energy spread produced by this field in the beam.

The use of particle accelerators for space projects

International Nuclear Information System (INIS)

Virtanen, Ari

2006-01-01

With the introduction of CMOS technology radiation effects in components became an important issue in satellite and space mission projects. At the end of the cold war, the market of radiation hard (RadHard) components crashed and during the 90's their fabrication practically stopped. The use of 'commercial-off-the-shelf' (COTS) components became more common but required increased evaluation activities at radiation test sites. Component manufacturers and space project engineers were directed towards these test sites, in particular, towards particle accelerators. Many accelerator laboratories developed special beam lines and constructed dedicated test areas for component evaluations. The space environment was simulated at these test sites and components were tested to levels often exceeding mission requirements. In general, space projects environments were predicted in respects to particle mass and energy distributions with the expected fluxes and fluences. In order to validate this information in tests, concepts like stopping power, linear energy transfer, ion penetration ranges etc. have to be understood. The knowledge from the component structure also defines the way of irradiation. For example, the higher ion energies resulting in much deeper ion penetration ranges allow successful reverse side irradiation of thinned Integrated Circuits (ICs). So overall increased demands for radiation testing attracted the European Space Agency (ESA) to the JYFL-accelerator laboratory of the University of Jyvaeskylae, Finland. A contract was signed between ESA and JYFL for the development of a 'High Penetrating Heavy Ion Test Site'. Following one year development, this test site was commissioned in May 2005. This paper addresses the various issues around the JYFL laboratory with its accelerator and radiation effects facility as the focal point in service of component evaluations for the space community

Achievable space elevators for space transportation and starship acceleration

Science.gov (United States)

Pearson, Jerome

1990-04-01

Space elevator concepts for low-cost space launches are reviewed. Previous concepts suffered from requirements for ultra-high-strength materials, dynamically unstable systems, or from danger of collision with space debris. The use of magnetic grain streams solves these problems. Magnetic grain streams can support short space elevators for lifting payloads cheaply into Earth orbit, overcoming the material strength problem in building space elevators. Alternatively, the stream could support an international spaceport circling the Earth daily tens of miles above the equator, accessible to advanced aircraft. Mars could be equipped with a similar grain stream, using material from its moons Phobos and Deimos. Grain-stream arcs about the sun could be used for fast launches to the outer planets and for accelerating starships to near lightspeed for interstellar reconnaisance. Grain streams are essentially impervious to collisions, and could reduce the cost of space transportation by an order of magnitude.

Late time solution for interacting scalar in accelerating spaces

Energy Technology Data Exchange (ETDEWEB)

Prokopec, Tomislav, E-mail: t.prokopec@uu.nl [Institute for Theoretical Physics, Spinoza Institute and EMME$\\Phi$, Utrecht University, Postbus 80.195, Utrecht, 3508 TD The Netherlands (Netherlands)

2015-11-01

We consider stochastic inflation in an interacting scalar field in spatially homogeneous accelerating space-times with a constant principal slow roll parameter ε. We show that, if the scalar potential is scale invariant (which is the case when scalar contains quartic self-interaction and couples non-minimally to gravity), the late-time solution on accelerating FLRW spaces can be described by a probability distribution function (PDF) ρ which is a function of φ/H only, where φ=φ( x-vector ) is the scalar field and H=H(t) denotes the Hubble parameter. We give explicit late-time solutions for ρarrow ρ{sub ∞}(φ/H), and thereby find the order ε corrections to the Starobinsky-Yokoyama result. This PDF can then be used to calculate e.g. various n-point functions of the (self-interacting) scalar field, which are valid at late times in arbitrary accelerating space-times with ε= constant.

High-Power Electron Accelerators for Space (and other) Applications

Energy Technology Data Exchange (ETDEWEB)

Nguyen, Dinh Cong [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lewellen, John W. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2016-05-23

This is a presentation on high-power electron accelerators for space and other applications. The main points covered are: electron beams for space applications, new designs of RF accelerators, high-power high-electron mobility transistors (HEMT) testing, and Li-ion battery design. In summary, the authors have considered a concept of 1-MeV electron accelerator that can operate up to several seconds. This concept can be extended to higher energy to produce higher beam power. Going to higher beam energy requires adding more cavities and solid-state HEMT RF power devices. The commercial HEMT have been tested for frequency response and RF output power (up to 420 W). Finally, the authors are testing these HEMT into a resonant load and planning for an electron beam test in FY17.

FRC [field-reversed configuration] translation studies on FRX-C/LSM

International Nuclear Information System (INIS)

Rej, D.; Barnes, G.; Baron, M.

1989-01-01

In preparation for upcoming compression-heating experiments, field-reversed configurations (FRCs) have been translated out of the FRX-C/LSM θ-pinch source, and into the 0.4-m-id, 6.7-m-long translation region formerly used on FRX-C/T. Unlike earlier experiments FRCs are generated without magnetic tearing in the larger FRX-C/LSM source (nominal coil id = 0.70 m, length = 2 m); larger, lower-energy-density FRCs are formed: r/sub s/ ≅ 0.17 m, B/sub ext/ ≅ 0.35 T, ≅ 7 /times/ 10 20 m/sup /minus/3/ and T/sub e/ + T/sub i/ ≅ 400 eV. An initial 3-mtorr D 2 pressure is introduced by either static or puff fill. Asymmetric fields from auxiliary end coils (used for non-tearing formation) provide the accelerating force on the FRC, thereby eliminating the need for a conical θ-pinch coil. An important feature is the abrupt 44% decrease in the flux-conserving wall radius at the transition between the θ-pinch and translation region, similar to that in the compressor. In this paper we review a variety of issues addressed by the recent translation experiments: translation dynamics; translation through a modulated magnetic field; stabilization of the n = 2 rotational instability by weak helical quadrupole fields; and confinement properties. Results from internal magnetic field measurements in translating FRCs may be found in a companion paper. 10 refs., 5 figs

High Fidelity Modeling of Field-Reversed Configuration (FRC) Thrusters (Briefing Charts)

Science.gov (United States)

2017-05-24

THRUSTERS (Briefing Charts) Robert Martin , Eder Sousa, Jonathan Tran Air Force Research Laboratory (AFMC) AFRL/RQRS 1 Ara Drive Edwards AFB, CA 93524... Martin N/A HIGH FIDELITY MODELING OF FIELD-REVERSED CONFIGURATION (FRC) THRUSTERS Robert Martin1, Eder Sousa2, Jonathan Tran2 1AIR FORCE RESEARCH...Distribution is unlimited. PA Clearance No. 17314 MARTIN , SOUSA, TRAN (AFRL/RQRS) DISTRIBUTION A - APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED. PA

Theoretical studies of field-reversed configurations (FRCs) and experimental study of the FRC during translation

Energy Technology Data Exchange (ETDEWEB)

Siemon, R.E.; Armstrong, W.T.; Chrien, R.E.; Klingner, P.L.; Linford, R.K.; McKenna, K.F.; Rej, D.J.; Schwarzmeier, J.L.; Sgro, A.; Sherwood, E.G.

1984-08-01

Theoretical studies of FRC stability and tranport are summarized. Finite Larmor radius theories are shown to be unreliable for explaining the experimentally observed stability to tilting. Control of the n=2 rotational instability has been demonstrated in 2-dimensional hybrid-code simulations, and the stability appears to be described within MHD if the nearly square equilibria that result from quadrupole fields are taken into account. Simulations of the lower-hybrid-drift instability in parameter regimes relevant to experiments show good agreement with a nonlocal theory of the instability. A 1.5-dimensional transport code shows agreement with the energy confinement time but disagreement with the flux loss time observed in FRX-C. The process of FRC translation in which the plasma is formed, translated into a dc solenoid, and trapped by magnetic mirrors has been studied in the FRX-C/T experiment.

Theoretical studies of field-reversed configurations (FRCs) and experimental study of the FRC during translation

International Nuclear Information System (INIS)

Siemon, R.E.; Armstrong, W.T.; Chrien, R.E.

1984-08-01

Theoretical studies of FRC stability and tranport are summarized. Finite Larmor radius theories are shown to be unreliable for explaining the experimentally observed stability to tilting. Control of the n=2 rotational instability has been demonstrated in 2-dimensional hybrid-code simulations, and the stability appears to be described within MHD if the nearly square equilibria that result from quadrupole fields are taken into account. Simulations of the lower-hybrid-drift instability in parameter regimes relevant to experiments show good agreement with a nonlocal theory of the instability. A 1.5-dimensional transport code shows agreement with the energy confinement time but disagreement with the flux loss time observed in FRX-C. The process of FRC translation in which the plasma is formed, translated into a dc solenoid, and trapped by magnetic mirrors has been studied in the FRX-C/T experiment

Biogeochemistry of Fe and Tc Reduction and Oxidation in FRC Sediment

International Nuclear Information System (INIS)

John M, Zachara; James K, Fredrickson; Ravi K, Kukkadapu; Steven C, Smith; David W, Kennedy

2004-01-01

The objectives are: (1) To rigorously characterize the distribution of Fe(II) and Fe(III) in FRC sediment. (2) To identify changes to Fe(II)/Fe(III) distribution and concentration resulting from DIRB activity. (3) To determine the dependence of Tc(VII) reduction rate on biogenic Fe(II) and it's forms. (4) To establish tendency of Tc(IV) and biogenic Fe(II) to oxidize and their effects on Tc immobilization. The mineralogic and chemical properties of the pristine, bioreduced, and chemically extracted FRC sediments were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), X-ray microscopy (XRM, at the PNC-CAT beamline at APS), Moessbauer spectroscopy, and scanning and transmission electron microscopy with lattice fringe imaging. Chemical extraction included dithionite-citrate-bicarbonate (DCB), acid ammonium oxalate (AAO), and hydroxylamine hydrochloride (HAH). The FRC sediment was incubated under anoxic conditions with the facultative dissimilatory metal-reducing bacterium Shewanella putrefaciens, strain CN32 in defined aqueous solutions/media with bicarbonate and PIPES buffers for time periods exceeding 75 d. Lactate was used as the electron donor. Aqueous and sorbed Fe(II) (ferrozine assay and 0.5 N HCl extraction) and Mn(II) (ICP-MS and 10 mM CuSO 4 extraction), and pH were monitored to define the reduction progress and extent. The bioreduced materials were characterized using the abovementioned techniques. Bioreduced (pasteurized) sediment or chemically extracted/reduced sediment spiked with Fe(II) was washed with a PIPES buffer/electrolyte solution, and spiked with NaTc(VII)O 4 to yield a concentration of 20 (micro)M. The Tc(VII)-spiked samples were agitated and equilibrated at 25 C and sampled over time to assess the Tc(VII) reduction rate. Selected sediment samples containing 20 (micro)M of reduced Tc [Tc(IV)] were subjected to oxidation by: (1) successive headspace replacements of air, and (2) open system equilibration with air. Removed aqueous

Design considerations for a large anti s FRC facility

International Nuclear Information System (INIS)

Hoffman, A.L.; Crawford, E.A.; Milroy, R.D.; Slough, J.T.; Steinhauer, L.C.

1986-01-01

The number of internal gyroradii between the field null and the separatrix of field-reversed-configurations (FRC), has been identified as a key parameter governing both stability and transport. Present experiments have anti s in the range of 2, while values of about 30 are thought to be necessary in a reactor. It is thus desirable to conduct experiments in some intermediate range. A value of 10 has been chosen as a reasonable goal for a next experiment. In this paper some of the design considerations and cost optimization procedures used to pick a point design for an anti s = 10 facility are discussed

Space charge tracking code for a synchrotron accelerator

Energy Technology Data Exchange (ETDEWEB)

Ottinger, M.B.; Tajima, T. [Univ. of Texas, Austin, TX (United States); Hiramoto, K. [Hitachi Ltd., Hitachi, Ibaraki (Japan). Hitachi Research Lab.

1997-06-01

An algorithm has been developed to compute particle tracking, including self-consistent space charge effects for synchrotron accelerators. In low-energy synchrotrons space charge plays a central role in enhancing emittance of the beam. The space charge effects are modeled by mutually interacting (through the Coulombic force) N cylindrical particles (2-{1/2}-dimensional dynamics) whose axis is in the direction of the equilibrium particle flow. On the other hand, their interaction with synchrotron lattice magnets is treated with the thin-lens approximation and in a fully 3-dimensional way. Since the existing method to treat space charge fully self-consistently involved 3-D space charge effect computation, the present method allows far more realistic physical parameters and runs in far shorter time (about 1/20). Some examples on space charge induced instabilities are presented.

Computational study of the influence of mirror parameters on FRC (field-reversed configuration) equilibria:

International Nuclear Information System (INIS)

Fuentes, N.O.; Sakanaka, P.H.

1990-01-01

Field-reversed configuration equilibria are studied by solving the Grad-Shafranov equation. A multiple coil system (main coil and end mirrors) is considered to simulate the coil geometry of CNEA device. First results are presented for computed two-dimensional FRC equilibria produced varying the mirror coil current with two different mirror lenghts. (Author)

Effect of surface treatment of FRC-Post on bonding strength to resin cements

Directory of Open Access Journals (Sweden)

Chan-Hyun Park,

2011-03-01

Full Text Available Objectives The purpose of this study was to evaluate the effect of surface treatment of FRC-Post on bonding strength to resin cements. Materials and Methods Pre-surface treated LuxaPost (DMG, Rely-X Fiber Post (3M ESPE and self adhesive resin cement Rely-X Unicem (3M ESPE, conventional resin cement Rely-X ARC (3M ESPE, and Rely-X Ceramic Primer (3M ESPE were used. After completing the surface treatments of the posts, posts and resin cement were placed in clear molds and photo-activation was performed. The specimens were sectioned perpendicular to the FRC-Post into 2 mm-thick segments, and push-out strength were measured. The results of bond strength value were statistically analyzed using independent samples t-test and one-way ANOVA with multiple comparisons using Scheffe's test. Results Silanization of posts affect to the bond strength in LuxaPost, and did not affect in Rely-X Fiber Post. Rely-X ARC showed higher value than Rely-X Unicem. Conclusions Silanization is needed to enhance the bond strength between LuxaPost and resin cements.

Direct longitudinal laser acceleration of electrons in free space

Directory of Open Access Journals (Sweden)

Sergio Carbajo

2016-02-01

Full Text Available Compact laser-driven accelerators are pursued heavily worldwide because they make novel methods and tools invented at national laboratories widely accessible in science, health, security, and technology [V. Malka et al., Principles and applications of compact laser-plasma accelerators, Nat. Phys. 4, 447 (2008]. Current leading laser-based accelerator technologies [S. P. D. Mangles et al., Monoenergetic beams of relativistic electrons from intense laser-plasma interactions, Nature (London 431, 535 (2004; T. Toncian et al., Ultrafast laser-driven microlens to focus and energy-select mega-electron volt protons, Science 312, 410 (2006; S. Tokita et al. Single-shot ultrafast electron diffraction with a laser-accelerated sub-MeV electron pulse, Appl. Phys. Lett. 95, 111911 (2009] rely on a medium to assist the light to particle energy transfer. The medium imposes material limitations or may introduce inhomogeneous fields [J. R. Dwyer et al., Femtosecond electron diffraction: “Making the molecular movie,”, Phil. Trans. R. Soc. A 364, 741 (2006]. The advent of few cycle ultraintense radially polarized lasers [S. Carbajo et al., Efficient generation of ultraintense few-cycle radially polarized laser pulses, Opt. Lett. 39, 2487 (2014] has ushered in a novel accelerator concept [L. J. Wong and F. X. Kärtner, Direct acceleration of an electron in infinite vacuum by a pulsed radially polarized laser beam, Opt. Express 18, 25035 (2010; F. Pierre-Louis et al. Direct-field electron acceleration with ultrafast radially polarized laser beams: Scaling laws and optimization, J. Phys. B 43, 025401 (2010; Y. I. Salamin, Electron acceleration from rest in vacuum by an axicon Gaussian laser beam, Phys. Rev. A 73, 043402 (2006; C. Varin and M. Piché, Relativistic attosecond electron pulses from a free-space laser-acceleration scheme, Phys. Rev. E 74, 045602 (2006; A. Sell and F. X. Kärtner, Attosecond electron bunches accelerated and

Discrete Calderon’s projections on parallelepipeds and their application to computing exterior magnetic fields for FRC plasmas

International Nuclear Information System (INIS)

Kansa, E.; Shumlak, U.; Tsynkov, S.

2013-01-01

Confining dense plasma in a field reversed configuration (FRC) is considered a promising approach to fusion. Numerical simulation of this process requires setting artificial boundary conditions (ABCs) for the magnetic field because whereas the plasma itself occupies a bounded region (within the FRC coils), the field extends from this region all the way to infinity. If the plasma is modeled using single fluid magnetohydrodynamics (MHD), then the exterior magnetic field can be considered quasi-static. This field has a scalar potential governed by the Laplace equation. The quasi-static ABC for the magnetic field is obtained using the method of difference potentials, in the form of a discrete Calderon boundary equation with projection on the artificial boundary shaped as a parallelepiped. The Calderon projection itself is computed by convolution with the discrete fundamental solution on the three-dimensional Cartesian grid.

The longitudinal space charge problem in the high current linear proton accelerators

International Nuclear Information System (INIS)

Lustfeld, H.

1984-01-01

In a linear proton accelerator peak currents of 200 mA lead to high space charge densities and the resultant space charge forces reduce the effective focussing considerably. In particular the longitudinal focussing is affected. A new concept based on linear theory is proposed that restricts the influence of the space charge forces on the longitudinal focussing by increasing a, the mean transverse bunch radius, as a proportional(βγ)sup(3/8). This concept is compared with other concepts for the Alvarez (1 MeV - 100 MeV) and for the high energy part (100 MeV - 1100 MeV) of the SNQ linear accelerator. (orig.)

High Energy Research and Applications (HERA) Pulsed Power and Pulsed Power Systems R&D for Magnetized Target Fusion Using Field Reversed Configurations (MTF-FRC)

Science.gov (United States)

2013-03-12

that we also advocate for potentially increasing the plasma lifetime. The first is the use of a coaxial plasma gun on axis to effectively bias the FRC...of their FRC plasmas by a factor of three over what had been achieved before using the gun . Admittedly, their plasmas are larger and lower density...were able to show, by the use of the plasma gun , that distortion and centering improved dramatically, and this stabilization is believed to be a major

Space charge beam dynamics studies for a pulsed spallation source accelerator

Energy Technology Data Exchange (ETDEWEB)

Cho, Y.; Lessner, E.

1995-12-31

Feasibility studies for 2-GeV, 1-MW and 10-GeV, 5-MW rapid cycling synchrotrons (RCS) for spallation neutron sources have been completed. Both synchrotrons operate at a repetition rate of 30 Hz, and accelerate 1.04 {times} 10{sup 14} protons per pulse. The injection energy of the 2-GeV ring is 400 MeV, and the 10-GeV RCS accepts the beam from the 2-GeV machine. Work performed to-date includes calculation of the longitudinal space charge effects in the 400-MeV beam transfer line, and of both longitudinal and transverse space charge effects during the injection, capture and acceleration processes in the two rings. Results of space charge calculations in the rings led to proper choices of the working points and of rf voltage programs that prevents beam loss. Space charge effects in the 2-GeV synchrotron, in both transverse and longitudinal phase space, have major impact on the design due to the fact that the injection energy is 400 MeV. The design achieves the required performance while alleviating harmful effects due to space charge.

D-3He fueled FRC reactor 'ARTEMIS-L'

International Nuclear Information System (INIS)

Momota, Hiromu; Tomita, Yukihiro; Ishida, Akio; Kohzaki, Yasuji; Nakao, Yasuyuki; Nishikawa, Masabumi; Ohi, Shoichi; Ohnishi, Masami.

1992-09-01

A neutron-lean D- 3 He fueled field reversed configuration (FRC) fusion reactor is studied on the bases of former high-efficiency ARTEMIS design. Certain improvements such as effective axial contracting plasma heating and cusp-type direct energy converters as well as an empirical scale of the energy confinement are introduced. The resultant total neutron load onto the first wall of the plasma chamber is as low as 0.1 MW/m 2 , which enable the life of the first wall or the structural materials to be longer than the whole life of the reactor. The attractive characteristics of the neutron-lean reactor follow in the ARTEMIS design: it is socially acceptable in views of radioactivity and fuel resources, and the cost of electricity appears to be cheap compared with that from a light water reactor. Critical physics and engineering issues for performing the ARTEMIS-L reactor are clarified. (author)

Effect of length and diameter of fiber reinforced composite post (FRC on fracture resistance of remaining tooth structure

Directory of Open Access Journals (Sweden)

Mahdiyeh seifi

2013-03-01

Full Text Available Introduction: Post and core has been considered for endodontically treated tooth, especially in cases with severe damage crowns. Recently fiber reinforced composite posts (FRC post have been used in the treatment of endodontically treated teeth. Because the length and diameter of posts are effective in stress distribution, the purpose of this study is to evaluate the effect of length and diameter of FRC post on fracture resistance. Methods: In this experimental study, 36 glass fiber posts with combination of 7mm, 9mm, and 12mm length and 1.1mm, 1.3mm and 1.5mm diameter were divided into 9 groups of 4. These posts were cemented in root canals by Panavia. Samples were tested with 45° compressive forces for the evaluation of fracture resistance. Datas were analyzed using SPSS soft ware and One- way and Two-way ANOVA analyses. Results: Fracture resistance did not increase significantly with the effect of length and diameter simultaneously (P=0.85. Samples with 12mm length and 1.5mm diameter had the greatest fracture resistance (1023/33N±239/22. The minimum fracture resistance had occurred in post with 7mm length and 1.5mm diameter (503/13N ±69/18. Fracture resistance increased significantly by increasing the length and the same diameter. Conclusion: It can be concluded that fracture resistance is affected by the length and not the diameter of FRC post.

Some questions of the technique of high-voltage testing of accele-- rating tube space in electrostatic accelerators

International Nuclear Information System (INIS)

Romanov, V.A.; Ivanov, V.V.; Mukhametshin, V.I.; Dmitriev, E.P.; Kidalov, A.I.

1983-01-01

In the course of high-voltage testing of accelerating spaces a wide spread of experimental values of electric strength is observed. This circumstance is determined by a number of factors one of which is the technique used for high-voltage testing. For the purpose of obtaining more reliable experimental data on electric strength of accelerating spaces it is suggested to take for a criterion of electric strength of an accelerating space in long accelerating tubes a long-time withstood voltage which is equal approximately to a doubled working space voltage obtained as a result of a smooth voltage rise at dark current density not exceeding (1...5)x10 -2 A/cm 2 . In the course of testing of accelerating spaces of 25 mm height with total working area of electrodes approximately 360 cm 2 and insulator area onto vacuum approximately 150 cm 2 a long-time 70 kV voltage with dark current less than 1.10 -8 A is obtained

Space charge physics for particle accelerators

CERN Document Server

Hofmann, Ingo

2017-01-01

Understanding and controlling the physics of space charge effects in linear and circular proton and ion accelerators are essential to their operation, and to future high-intensity facilities. This book presents the status quo of this field from a theoretical perspective, compares analytical approaches with multi-particle computer simulations and – where available – with experiments. It discusses fundamental concepts of phase space motion, matched beams and modes of perturbation, along with mathematical models of analysis – from envelope to Vlasov-Poisson equations. The main emphasis is on providing a systematic description of incoherent and coherent resonance phenomena; parametric instabilities and sum modes; mismatch and halo; error driven resonances; and emittance exchange due to anisotropy, as well as the role of Landau damping. Their distinctive features are elaborated in the context of numerous sample simulations, and their potential impacts on beam quality degradation and beam loss are discussed....

Hybrid FRC under repeated loading

International Nuclear Information System (INIS)

Komlos, K.; Babal, B.; Nuernbergerova, T.

1993-01-01

Fibre reinforced concretes (FRC) containing several volume fractions in different ratios of two types of fibres - polypropylene and steel, were tested under repeated loading. Mechanical properties of specimens - cubes 150/150/150 mm (for compressive strength), prisms 100/100/400 (for flexural strength), short cylinders 150/60 mm (for impact strength) have been experimentally investigated before and after cyclic loading at the age of 28 days curing time. Mix proportions were designed after DIN 1045 with max. aggregate size 8 mm and grading curve B 8. Portland Cement PC 400 in the amount of 450 kg. m -3 was applied and W/C ratio 0.55. Workability of mixes was measured by Vebe method and regulated by plasticizing admixture Ligoplast Na. Maximum hybrid fibre volume fraction (polypropylene + steel) was 1.0%. Dynamic forces generated in Schenck testing machine with frequency 16 Hz had sinusoidal wave form varying between 0.7 and 0.1 of static mechanical characteristics. The number of cycles in all tests was 10 5 . The residual MOR at static four point bending test and working diagram force-deflection was carried out as well. The impact properties after repeated loading in compression were tested by means of falling weight test. Relationships between composition of fibre composites with different combination of polypropylene (0.2, 0.3, 0.5% by volume) and steel (0.5, 0.7, and 0.8% by volume) fibre content were obtained and technological properties of mixes as well. (author)

1.4D quasistatic profile model of transport in a field-reversed configuration (FRC)

International Nuclear Information System (INIS)

Steinhauer, L.C.

1990-01-01

Global confinement models are useful for determining how a given transport mechanism (dependent on local parameters) translates into global confinement times. Such models are also useful for inferring the overall magnitudes of transport rates, and limited information about their spatial profiles. They are especially important in a field reversed configuration (FRC) where the equilibrium and transport rates are so intimately coupled, and where the flux loss time is such an important factor. An earlier global FRC confinement model, sometimes called QUASI, was based on the assumption of a quasi-steady equilibrium. The equilibrium was assumed to have square-ends with some features of 2D equilibria: (1) equal pressure on inner and outer branches of the flux lines; and (2) average-beta relation. Models of this type have been called 1-1/4D transport models. The same general approach has now been applied in a straightforward way to an equilibrium with realistic axial structure. This might be called a 1.4D quasisteady transport model. The assumed axial structure can be that of an analytic equilibrium, or a more complicated computed equilibrium as desired. The example used here is an elongated Hill's vortex equilibrium. As will be shown later, the equilibrium is reflected by two integral quantities that appear in the quasistatic diffusion equation

Measuring test mass acceleration noise in space-based gravitational wave astronomy

Science.gov (United States)

Congedo, Giuseppe

2015-03-01

The basic constituent of interferometric gravitational wave detectors—the test-mass-to-test-mass interferometric link—behaves as a differential dynamometer measuring effective differential forces, comprising an integrated measure of gravity curvature, inertial effects, as well as nongravitational spurious forces. This last contribution is going to be characterized by the LISA Pathfinder mission, a technology precursor of future space-borne detectors like eLISA. Changing the perspective from displacement to acceleration can benefit the data analysis of LISA Pathfinder and future detectors. The response in differential acceleration to gravitational waves is derived for a space-based detector's interferometric link. The acceleration formalism can also be integrated into time delay interferometry by building up the unequal-arm Michelson differential acceleration combination. The differential acceleration is nominally insensitive to the system's free evolution dominating the slow displacement dynamics of low-frequency detectors. Working with acceleration also provides an effective way to subtract measured signals acting as systematics, including the actuation forces. Because of the strong similarity with the equations of motion, the optimal subtraction of systematic signals, known within some amplitude and time shift, with the focus on measuring the noise provides an effective way to solve the problem and marginalize over nuisance parameters. The F statistic, in widespread use throughout the gravitation waves community, is included in the method and suitably generalized to marginalize over linear parameters and noise at the same time. The method is applied to LPF simulator data and, thanks to its generality, can also be applied to the data reduction and analysis of future gravitational wave detectors.

Development of high-power inverter supply for current drive of FRC plasma

International Nuclear Information System (INIS)

Kitano, Katsuhisa; Higashikozono, Takamitsu; Okada, Shigefumi; Goto, Seiichi

2003-01-01

High-Power RF supply is developed for the current drive of FRC (Field Reversed Configuration) plasma. The rotating magnetic field is produced by the four antennas set in the parallel direction to the geometrical axis of the FRC and faced each other. The sinusoidal currents with shifted phases by 90 degree each other should be supplied to the antennas. The two power supplies are necessary if a pair of the antennas faced oppositely are connected. Considering the plasma parameters, the rotating field of 50-100kHz and 50G at the center axis is expected to be required. We develop the adequate RF power supply for the purpose. The power supply consists of the inverter circuit, the step-up transformer and the LC tank ciruit. For the switching device of the inverter circuit, the IGBT (Insulated Gate Bipolar Transistor) is adopted. The inverter circuit is full bridge type. To operate it at high voltages, its arm consists of the 3 IGBTs arranged series. The output of the inverter is connected to the tank circuit by way of the step-up transformer with air core. The tank circuit is the parallel circuit of the antenna and the capacitor. By the adjustment of the frequency of the inverter output to the resonance frequency of the tank circuit, the large sinusoidal waveform current is obtained. The developed power supply can produce the current of 5kA at 10kV to the dummy antenna with almost the same inductance of the antenna. (author)

A Plasmoid Thruster for Space Propulsion

Science.gov (United States)

Koelfgen, Syri J.; Hawk, Clark W.; Eskridge, Richard; Smith, James W.; Martin, Adam K.

2003-01-01

There are a number of possible advantages to using accelerated plasmoids for in-space propulsion. A plasmoid is a compact plasma structure with an integral magnetic field. They have been studied extensively in controlled fusion research and are classified according to the relative strength of the poloidal and toroidal magnetic field (B(sub p), and B(sub t), respectively). An object with B(sub p), / B(sub t) much greater than 1 is classified as a Field Reversed Configuration (FRC); if B(sub p) approximately equal to B(sub t), it is called a Spheromak. The plasmoid thruster operates by producing FRC-like plasmoids and subsequently ejecting them from the device at a high velocity. The plasmoid is formed inside of a single-turn conical theta-pinch coil. As this process is inductive, there are no electrodes. Similar experiments have yielded plasmoid velocities of at least 50 km/s, and calculations indicate that velocities in excess of 100 km/s should be possible. This concept should be capable of producing Isp's in the range of 5,000 - 15,000 s with thrust densities on the order of 10(exp 5) N per square meters. The current experiment is designed to produce jet powers in the range of 5 - 10 kW, although the concept should be scalable to several MW's. The plasmoid mass and velocity will be measured with a variety of diagnostics, including internal and external B-dot probes, flux loops, Langmuir probes, high-speed cameras and a laser interferometer. Also of key importance will be measurements of the efficiency and mass utilization. Simulations of the plasmoid thruster using MOQUI, a time-dependent MHD code, will be carried out concurrently with experimental testing.

Novel imaging techniques, integrated with mineralogical, geochemical and microbiological characterizations to determine the biogeochemical controls on technetium mobility in FRC sediments

Energy Technology Data Exchange (ETDEWEB)

Jonathan R. Lloyd

2009-02-03

The objective of this research program was to take a highly multidisciplinary approach to define the biogeochemical factors that control technetium (Tc) mobility in FRC sediments. The aim was to use batch and column studies to probe the biogeochemical conditions that control the mobility of Tc at the FRC. Background sediment samples from Area 2 (pH 6.5, low nitrate, low {sup 99}Tc) and Area 3 (pH 3.5, high nitrate, relatively high {sup 99}Tc) of the FRC were selected (http://www.esd.ornl.gov/nabirfrc). For the batch experiments, sediments were mixed with simulated groundwater, modeled on chemical constituents of FRC waters and supplemented with {sup 99}Tc(VII), both with and without added electron donor (acetate). The solubility of the Tc was monitored, alongside other biogeochemical markers (nitrate, nitrite, Fe(II), sulfate, acetate, pH, Eh) as the 'microcosms' aged. At key points, the microbial communities were also profiled using both cultivation-dependent and molecular techniques, and results correlated with the geochemical conditions in the sediments. The mineral phases present in the sediments were also characterized, and the solid phase associations of the Tc determined using sequential extraction and synchrotron techniques. In addition to the batch sediment experiments, where discrete microbial communities with the potential to reduce and precipitate {sup 99}Tc will be separated in time, we also developed column experiments where biogeochemical processes were spatially separated. Experiments were conducted both with and without amendments proposed to stimulate radionuclide immobilization (e.g. the addition of acetate as an electron donor for metal reduction), and were also planned with and without competing anions at high concentration (e.g. nitrate, with columns containing Area 3 sediments). When the columns had stabilized, as determined by chemical analysis of the effluents, we used a spike of the short-lived gamma emitter {sup 99m}Tc (50

3rd International Conference on Particle Physics Beyond the Standard Model : Accelerator, Non-Accelerator and Space Approaches

CERN Document Server

Beyond The Desert 2002

2003-01-01

The third conference on particle physics beyond the Standard Model (BEYOND THE DESERT'02 - Accelerator, Non-accelerator and Space Approaches) was held during 2--7 June, 2002 at the Finish town of Oulu, almost at the northern Arctic Circle. It was the first of the BEYOND conference series held outside Germany (CERN Courier March 2003, pp. 29-30). Traditionally the Scientific Programme of BEYOND conferences, brought into life in 1997 (see CERN Courier, November 1997, pp.16-18), covers almost all topics of modern particle physics (see contents).

Course Notes: United States Particle Accelerator School Beam Physics with Intense Space-Charge

International Nuclear Information System (INIS)

Barnard, J.J.; Lund, S.M.

2008-01-01

The purpose of this course is to provide a comprehensive introduction to the physics of beams with intense space charge. This course is suitable for graduate students and researchers interested in accelerator systems that require sufficient high intensity where mutual particle interactions in the beam can no longer be neglected. This course is intended to give the student a broad overview of the dynamics of beams with strong space charge. The emphasis is on theoretical and analytical methods of describing the acceleration and transport of beams. Some aspects of numerical and experimental methods will also be covered. Students will become familiar with standard methods employed to understand the transverse and longitudinal evolution of beams with strong space charge. The material covered will provide a foundation to design practical architectures. In this course, we will introduce you to the physics of intense charged particle beams, focusing on the role of space charge. The topics include: particle equations of motion, the paraxial ray equation, and the Vlasov equation; 4-D and 2-D equilibrium distribution functions (such as the Kapchinskij-Vladimirskij, thermal equilibrium, and Neuffer distributions), reduced moment and envelope equation formulations of beam evolution; transport limits and focusing methods; the concept of emittance and the calculation of its growth from mismatches in beam envelope and from space-charge non-uniformities using system conservation constraints; the role of space-charge in producing beam halos; longitudinal space-charge effects including small amplitude and rarefaction waves; stable and unstable oscillation modes of beams (including envelope and kinetic modes); the role of space charge in the injector; and algorithms to calculate space-charge effects in particle codes. Examples of intense beams will be given primarily from the ion and proton accelerator communities with applications from, for example, heavy-ion fusion, spallation

Design considerations for the use of laser-plasma accelerators for advanced space radiation studies

Science.gov (United States)

Königstein, T.; Karger, O.; Pretzler, G.; Rosenzweig, J. B.; Hidding, B.; Hidding

2012-08-01

We present design considerations for the use of laser-plasma accelerators for mimicking space radiation and testing space-grade electronics. This novel application takes advantage of the inherent ability of laser-plasma accelerators to produce particle beams with exponential energy distribution, which is a characteristic shared with the hazardous relativistic electron flux present in the radiation belts of planets such as Earth, Saturn and Jupiter. Fundamental issues regarding laser-plasma interaction parameters, beam propagation, flux development, and experimental setup are discussed.

Particle-in-cell/accelerator code for space-charge dominated beam simulation

Energy Technology Data Exchange (ETDEWEB)

2012-05-08

Warp is a multidimensional discrete-particle beam simulation program designed to be applicable where the beam space-charge is non-negligible or dominant. It is being developed in a collaboration among LLNL, LBNL and the University of Maryland. It was originally designed and optimized for heave ion fusion accelerator physics studies, but has received use in a broader range of applications, including for example laser wakefield accelerators, e-cloud studies in high enery accelerators, particle traps and other areas. At present it incorporates 3-D, axisymmetric (r,z) planar (x-z) and transverse slice (x,y) descriptions, with both electrostatic and electro-magnetic fields, and a beam envelope model. The code is guilt atop the Python interpreter language.

Novel imaging techniques, integrated with mineralogical, geochemical and microbiological characterizations to determine the biogeochemical controls on technetium mobility in FRC sediments. Final report

International Nuclear Information System (INIS)

Lloyd, Jonathan R.

2009-01-01

The objective of this research program was to take a highly multidisciplinary approach to define the biogeochemical factors that control technetium (Tc) mobility in FRC sediments. The aim was to use batch and column studies to probe the biogeochemical conditions that control the mobility of Tc at the FRC. Background sediment samples from Area 2 (pH 6.5, low nitrate, low 99 Tc) and Area 3 (pH 3.5, high nitrate, relatively high 99 Tc) of the FRC were selected (http://www.esd.ornl.gov/nabirfrc). For the batch experiments, sediments were mixed with simulated groundwater, modeled on chemical constituents of FRC waters and supplemented with 99 Tc(VII), both with and without added electron donor (acetate). The solubility of the Tc was monitored, alongside other biogeochemical markers (nitrate, nitrite, Fe(II), sulfate, acetate, pH, Eh) as the 'microcosms' aged. At key points, the microbial communities were also profiled using both cultivation-dependent and molecular techniques, and results correlated with the geochemical conditions in the sediments. The mineral phases present in the sediments were also characterized, and the solid phase associations of the Tc determined using sequential extraction and synchrotron techniques. In addition to the batch sediment experiments, where discrete microbial communities with the potential to reduce and precipitate 99 Tc will be separated in time, we also developed column experiments where biogeochemical processes were spatially separated. Experiments were conducted both with and without amendments proposed to stimulate radionuclide immobilization (e.g. the addition of acetate as an electron donor for metal reduction), and were also planned with and without competing anions at high concentration (e.g. nitrate, with columns containing Area 3 sediments). When the columns had stabilized, as determined by chemical analysis of the effluents, we used a spike of the short-lived gamma emitter 99m Tc (50-200 MBq; half life 6 hours) and its

Space-charge limits in linear accelerators

International Nuclear Information System (INIS)

Wangler, T.P.

1980-12-01

This report presents equations that allow an approximate evaluation of the limiting beam current for a large class of radio-frequency linear accelerators, which use quadrupole strong focusing. Included are the Alvarez, the Wideroe, and the radio-frequency quadrupole linacs. The limiting-current formulas are presented for both the longitudinal and the transverse degrees of freedom by assuming that the average space-charge force in the beam bunch arises from a uniformly distributed charge within an azimuthally symmetric three-dimensional ellipsoid. The Mathieu equation is obtained as an approximate, but general, form for the transverse equation of motion. The smooth-approximation method is used to obtain a solution and an expression for the transverse current limit. The form of the current-limit formulas for different linac constraints is discussed

Thermal Modeling for Pulsed Inductive FRC Plasmoid Thrusters

Science.gov (United States)

Pfaff, Michael

Due to the rising importance of space based infrastructure, long-range robotic space missions, and the need for active attitude control for spacecraft, research into Electric Propulsion is becoming increasingly important. Electric Propulsion (EP) systems utilize electric power to accelerate ions in order to produce thrust. Unlike traditional chemical propulsion, this means that thrust levels are relatively low. The trade-off is that EP thrusters have very high specific impulses (Isp), and can therefore make do with far less onboard propellant than cold gas, monopropellant, or bipropellant engines. As a consequence of the high power levels used to accelerate the ionized propellant, there is a mass and cost penalty in terms of solar panels and a power processing unit. Due to the large power consumption (and waste heat) from electric propulsion thrusters, accurate measurements and predictions of thermal losses are needed. Excessive heating in sensitive locations within a thruster may lead to premature failure of vital components. Between the fixed cost required to purchase these components, as well as the man-hours needed to assemble (or replace) them, attempting to build a high-power thruster without reliable thermal modeling can be expensive. This paper will explain the usage of FEM modeling and experimental tests in characterizing the ElectroMagnetic Plasmoid Thruster (EMPT) and the Electrodeless Lorentz Force (ELF) thruster at the MSNW LLC facility in Redmond, Washington. The EMPT thruster model is validated using an experimental setup, and steady state temperatures are predicted for vacuum conditions. Preliminary analysis of the ELF thruster indicates possible material failure in absence of an active cooling system for driving electronics and for certain power levels.

Exploring phase space using smartphone acceleration and rotation sensors simultaneously

International Nuclear Information System (INIS)

Monteiro, Martín; Cabeza, Cecilia; Martí, Arturo C

2014-01-01

A paradigmatic physical system as the physical pendulum is experimentally studied using the acceleration and rotation (gyroscope) sensors available on smartphones and other devices such as iPads and tablets. A smartphone is fixed to the outside of a bicycle wheel whose axis is kept horizontal and fixed. The compound system, wheel plus smartphone, defines a physical pendulum which can rotate, giving full turns in one direction, or oscillate about the equilibrium position (performing either small or large oscillations). Measurements of the radial and tangential acceleration and the angular velocity obtained with smartphone sensors allow a deep insight into the dynamics of the system to be gained. In addition, thanks to the simultaneous use of the acceleration and rotation sensors, trajectories in the phase space are directly obtained. The coherence of the measures obtained with the different sensors and by traditional methods is remarkable. Indeed, due to their low cost and increasing availability, smartphone sensors are valuable tools that can be used in most undergraduate laboratories. (paper)

Exploring phase space using smartphone acceleration and rotation sensors simultaneously

Science.gov (United States)

Monteiro, Martín; Cabeza, Cecilia; Martí, Arturo C.

2014-07-01

A paradigmatic physical system as the physical pendulum is experimentally studied using the acceleration and rotation (gyroscope) sensors available on smartphones and other devices such as iPads and tablets. A smartphone is fixed to the outside of a bicycle wheel whose axis is kept horizontal and fixed. The compound system, wheel plus smartphone, defines a physical pendulum which can rotate, giving full turns in one direction, or oscillate about the equilibrium position (performing either small or large oscillations). Measurements of the radial and tangential acceleration and the angular velocity obtained with smartphone sensors allow a deep insight into the dynamics of the system to be gained. In addition, thanks to the simultaneous use of the acceleration and rotation sensors, trajectories in the phase space are directly obtained. The coherence of the measures obtained with the different sensors and by traditional methods is remarkable. Indeed, due to their low cost and increasing availability, smartphone sensors are valuable tools that can be used in most undergraduate laboratories.

Investigation of Technetium Redox Cycling in FRC Background Sediments using EXAFS and Gamma Camera Imaging

Energy Technology Data Exchange (ETDEWEB)

Lloyd, J.R.; McBeth, J.M.; Lear, G.; Morris, K.; Burke, I.T.; Livens, F.R.; Ellis, B.; Lawson, R.

2006-04-05

Technetium-99 is a priority pollutant at numerous DOE sites, due to its long half-life (2.1 x 105 years), high mobility as Tc(VII) in oxic waters, and bioavailability as a sulfate analogue. {sup 99}Tc is far less mobile under anaerobic conditions, forming insoluble Tc(IV) precipitates. As anaerobic microorganisms can reduce soluble Tc(VII) to insoluble Tc(IV), microbial metabolism may have the potential to treat sediments and waters contaminated with Tc. Baseline studies of fundamental mechanisms of Tc(VII) bioreduction and precipitation (reviewed by Lloyd et al., 2005, in press) have generally used pure cultures of metal-reducing bacteria, in order to develop conceptual models for the biogeochemical cycling of {sup 99}Tc. There is, however, comparatively little known about interactions of metal-reducing bacteria with environmentally relevant trace concentrations of {sup 99}Tc, against a more complex biogeochemical background provided by mixed microbial communities in aquifer sediments. The objective of this project is to probe the site specific biogeochemical conditions that control the mobility of {sup 99}Tc at the US DOE Field Research Center Site (FRC; Oak Ridge, Tennessee). This information is required for the rational design of in situ bioremediation strategies for technetium-contaminated subsurface environments. We are using a combination of geochemical, mineralogical, microbiological and spectroscopic techniques to determine the solubility and phase associations of {sup 99}Tc in FRC sediments, and characterize the underpinning biogeochemical controls.

Some Aspects of Formation of Cracks in FRC with Main Reinforcement

DEFF Research Database (Denmark)

Brincker, Rune; Simonsen, J.; Hansen, W.

1997-01-01

In this paper the response of fibre reinforced concrete (FRC) with main reinforcement in pure tension is considered. Test results are presented showing three distinct regimes: a regime og linear elasticity, a regime of yielding at approximately constant stress, and finally, a regime of strain...... hardening. a simple model is presented which takes into account the debonding between the reinforcement and the fiber reinforced matrix as well as the crack opening relation of the fiber reinforced matrix. The fracture process is described from the un-cracked state and formation of the first crack till......, and a more ductile contribution from the fiber bridging, a plastic regime will be present in the tensile response. The case of a parabolic crack opening relation defines a brittleness number that describes the transition from formation of unstable discrete cracks to smaller cracks controlled by the softening...

Correlated histogram representation of Monte Carlo derived medical accelerator photon-output phase space

Science.gov (United States)

Schach Von Wittenau, Alexis E.

2003-01-01

A method is provided to represent the calculated phase space of photons emanating from medical accelerators used in photon teletherapy. The method reproduces the energy distributions and trajectories of the photons originating in the bremsstrahlung target and of photons scattered by components within the accelerator head. The method reproduces the energy and directional information from sources up to several centimeters in radial extent, so it is expected to generalize well to accelerators made by different manufacturers. The method is computationally both fast and efficient overall sampling efficiency of 80% or higher for most field sizes. The computational cost is independent of the number of beams used in the treatment plan.

Average accelerator simulation Truebeam using phase space in IAEA format

International Nuclear Information System (INIS)

Santana, Emico Ferreira; Milian, Felix Mas; Paixao, Paulo Oliveira; Costa, Raranna Alves da; Velasco, Fermin Garcia

2015-01-01

In this paper is used a computational code of radiation transport simulation based on Monte Carlo technique, in order to model a linear accelerator of treatment by Radiotherapy. This work is the initial step of future proposals which aim to study several treatment of patient by Radiotherapy, employing computational modeling in cooperation with the institutions UESC, IPEN, UFRJ e COI. The Chosen simulation code is GATE/Geant4. The average accelerator is TrueBeam of Varian Company. The geometric modeling was based in technical manuals, and radiation sources on the phase space for photons, provided by manufacturer in the IAEA (International Atomic Energy Agency) format. The simulations were carried out in equal conditions to experimental measurements. Were studied photons beams of 6MV, with 10 per 10 cm of field, focusing on a water phantom. For validation were compared dose curves in depth, lateral profiles in different depths of the simulated results and experimental data. The final modeling of this accelerator will be used in future works involving treatments and real patients. (author)

Acceleration-enlarged symmetries in nonrelativistic space-time with a cosmological constant TH1"-->

Science.gov (United States)

Lukierski, J.; Stichel, P. C.; Zakrzewski, W. J.

2008-05-01

By considering the nonrelativistic limit of de Sitter geometry one obtains the nonrelativistic space-time with a cosmological constant and Newton Hooke (NH) symmetries. We show that the NH symmetry algebra can be enlarged by the addition of the constant acceleration generators and endowed with central extensions (one in any dimension (D) and three in D=(2+1)). We present a classical Lagrangian and Hamiltonian framework for constructing models quasi-invariant under enlarged NH symmetries that depend on three parameters described by three nonvanishing central charges. The Hamiltonian dynamics then splits into external and internal sectors with new noncommutative structures of external and internal phase spaces. We show that in the limit of vanishing cosmological constant the system reduces to the one, which possesses acceleration-enlarged Galilean symmetries.

Biogeochemical Controls on Technetium Mobility in Biogeochemical Controls on Technetium Mobility in FRC Sediments

International Nuclear Information System (INIS)

Lloyd, J.R.; McBeth, J.M.; Livens, F.R.; Bryan, N.D.; Ellis, B.; Sharma, H.; Burke, I.T.; Morris, K.

2004-01-01

Technetium-99 is a priority pollutant at numerous DOE sites, due to its long half-life (2.1 x 10 5 years), high mobility as Tc(VII) in oxic waters, and bioavailability as a sulfate analog. 99 Tc is far less mobile under anaerobic conditions, forming insoluble Tc(IV) precipitates. As anaerobic microorganisms can reduce soluble Tc(VII) to insoluble Tc(IV), microbial metabolism may have the potential to treat sediments and waters contaminated with Tc. Baseline studies of fundamental mechanisms of Tc(VII) bioreduction and precipitation (reviewed by Lloyd et al, 2002) have generally used pure cultures of metal-reducing bacteria, in order to develop conceptual models for the biogeochemical cycling of Tc. There is, however, comparatively little known about interactions of metal-reducing bacteria with environmentally relevant trace concentrations of Tc, against a more complex biogeochemical background provided by mixed microbial communities in the subsurface. The objective of this new NABIR project is to probe the site specific biogeochemical conditions that control the mobility of Tc at the FRC (Oak Ridge, TN). This information is required for the rational design of in situ bioremediation strategies for technetium-contaminated subsurface environments. We will use a combination of geochemical, mineralogical, microbiological and spectroscopic techniques to determine the solubility and phase associations of Tc in FRC sediments, and characterize the underpinning biogeochemical controls. A key strength of this project is that many of the techniques we are using have already been optimized by our research team, who are also studying the biogeochemical controls on Tc mobility in marine and freshwater sediments in the UK in a NERC funded companion study.

Anisotropic SD2 brane: accelerating cosmology and Kasner-like space-time from compactification

International Nuclear Information System (INIS)

Nayek, Kuntal; Roy, Shibaji

2017-01-01

Starting from an anisotropic (in all directions including the time direction of the brane) non-SUSY D2 brane solution of type IIA string theory we construct an anisotropic space-like D2 brane (or SD2 brane, for short) solution by the standard trick of a double Wick rotation. This solution is characterized by five independent parameters. We show that compactification on six-dimensional hyperbolic space (H_6) of a time-dependent volume of this SD2 brane solution leads to accelerating cosmologies (for some time t ∝ t_0, with t_0 some characteristic time) where both the expansions and the accelerations are different in three spatial directions of the resultant four-dimensional universe. On the other hand at early times (t << t_0) this four-dimensional space, in certain situations, leads to four-dimensional Kasner-like cosmology, with two additional scalars, namely, the dilaton and a volume scalar of H_6. Unlike in the standard four-dimensional Kasner cosmology here all three Kasner exponents could be positive definite, leading to expansions in all three directions. (orig.)

PREFACE: Acceleration and radiation generation in space and laboratory plasmas

Science.gov (United States)

Bingham, R.; Katsouleas, T.; Dawson, J. M.; Stenflo, L.

1994-01-01

Sixty-six leading researchers from ten nations gathered in the Homeric village of Kardamyli, on the southern coast of mainland Greece, from August 29-September 4, 1993 for the International Workshop on Acceleration and Radiation Generation in Space and Laboratory Plasmas. This Special Issue represents a cross-section of the presentations made at and the research stimulated by that meeting. According to the Iliad, King Agamemnon used Kardamyli as a dowry offering in order to draw a sulking Achilles into the Trojan War. 3000 years later, Kardamyli is no less seductive. Its remoteness and tranquility made it an ideal venue for promoting the free exchange of ideas between various disciplines that do not normally interact. Through invited presen tations, informal poster discussions and working group sessions, the Workshop brought together leaders from the laboratory and space/astrophysics communities working on common problems of acceleration and radiation generation in plasmas. It was clear from the presentation and discussion sessions that there is a great deal of common ground between these disciplines which is not at first obvious due to the differing terminologies and types of observations available to each community. All of the papers in this Special Issue highlight the role collective plasma processes play in accelerating particles or generating radiation. Some are state-of-the-art presentations of the latest research in a single discipline, while others investi gate the applicability of known laboratory mechanisms to explain observations in natural plasmas. Notable among the latter are the papers by Marshall et al. on kHz radiation in the magnetosphere ; Barletta et al. on collective acceleration in solar flares; and by Dendy et al. on ion cyclotron emission. The papers in this Issue are organized as follows: In Section 1 are four general papers by Dawson, Galeev, Bingham et al. and Mon which serves as an introduction to the physical mechanisms of acceleration

Benchmark of Space Charge Simulations and Comparison with Experimental Results for High Intensity, Low Energy Accelerators

CERN Document Server

Cousineau, Sarah M

2005-01-01

Space charge effects are a major contributor to beam halo and emittance growth leading to beam loss in high intensity, low energy accelerators. As future accelerators strive towards unprecedented levels of beam intensity and beam loss control, a more comprehensive understanding of space charge effects is required. A wealth of simulation tools have been developed for modeling beams in linacs and rings, and with the growing availability of high-speed computing systems, computationally expensive problems that were inconceivable a decade ago are now being handled with relative ease. This has opened the field for realistic simulations of space charge effects, including detailed benchmarks with experimental data. A great deal of effort is being focused in this direction, and several recent benchmark studies have produced remarkably successful results. This paper reviews the achievements in space charge benchmarking in the last few years, and discusses the challenges that remain.

Phase-space holes due to electron and ion beams accelerated by a current-driven potential ramp

Directory of Open Access Journals (Sweden)

M. V. Goldman

2003-01-01

Full Text Available One-dimensional open-boundary simulations have been carried out in a current-carrying plasma seeded with a neutral density depression and with no initial electric field. These simulations show the development of a variety of nonlinear localized electric field structures: double layers (unipolar localized fields, fast electron phase-space holes (bipolar fields moving in the direction of electrons accelerated by the double layer and trains of slow alternating electron and ion phase-space holes (wave-like fields moving in the direction of ions accelerated by the double layer. The principal new result in this paper is to show by means of a linear stability analysis that the slow-moving trains of electron and ion holes are likely to be the result of saturation via trapping of a kinetic-Buneman instability driven by the interaction of accelerated ions with unaccelerated electrons.

Anisotropic SD2 brane: accelerating cosmology and Kasner-like space-time from compactification

Energy Technology Data Exchange (ETDEWEB)

Nayek, Kuntal; Roy, Shibaji [Saha Institute of Nuclear Physics, Calcutta (India); Homi Bhabha National Institute, Mumbai (India)

2017-07-15

Starting from an anisotropic (in all directions including the time direction of the brane) non-SUSY D2 brane solution of type IIA string theory we construct an anisotropic space-like D2 brane (or SD2 brane, for short) solution by the standard trick of a double Wick rotation. This solution is characterized by five independent parameters. We show that compactification on six-dimensional hyperbolic space (H{sub 6}) of a time-dependent volume of this SD2 brane solution leads to accelerating cosmologies (for some time t ∝ t{sub 0}, with t{sub 0} some characteristic time) where both the expansions and the accelerations are different in three spatial directions of the resultant four-dimensional universe. On the other hand at early times (t << t{sub 0}) this four-dimensional space, in certain situations, leads to four-dimensional Kasner-like cosmology, with two additional scalars, namely, the dilaton and a volume scalar of H{sub 6}. Unlike in the standard four-dimensional Kasner cosmology here all three Kasner exponents could be positive definite, leading to expansions in all three directions. (orig.)

Multigrid Algorithms for the Fast Calculation of Space-Charge Effects in Accelerator Design

NARCIS (Netherlands)

Pöplau, G.; Rienen, van U.; Geer, van der S.B.; Loos, de M.J.

2004-01-01

Numerical prediction of charged particle dynamics in accelerators is essential for the design and understanding of these machines. Methods to calculate the self-fields of the bunch, the so-called space-charge forces, become increasingly important as the demand for high-quality bunches increases. We

Preliminary analysis of accelerated space flight ionizing radiation testing

Science.gov (United States)

Wilson, J. W.; Stock, L. V.; Carter, D. J.; Chang, C. K.

1982-01-01

A preliminary analysis shows that radiation dose equivalent to 30 years in the geosynchronous environment can be accumulated in a typical composite material exposed to space for 2 years or less onboard a spacecraft orbiting from perigee of 300 km out to the peak of the inner electron belt (approximately 2750 km). Future work to determine spacecraft orbits better tailored to materials accelerated testing is indicated. It is predicted that a range of 10 to the 9th power to 10 to the 10th power rads would be accumulated in 3-6 mil thick epoxy/graphite exposed by a test spacecraft orbiting in the inner electron belt. This dose is equivalent to the accumulated dose that this material would be expected to have after 30 years in a geosynchronous orbit. It is anticipated that material specimens would be brought back to Earth after 2 years in the radiation environment so that space radiation effects on materials could be analyzed by laboratory methods.

An acceleration of the characteristics by a space-angle two-level method using surface discontinuity factors

Energy Technology Data Exchange (ETDEWEB)

Grassi, G. [Commissariat a l' Energie Atomique, CEA de Saclay, DM2S/SERMA/LENR, 91191, Gif-sur-Yvette (France)

2006-07-01

We present a non-linear space-angle two-level acceleration scheme for the method of the characteristics (MOC). To the fine level on which the MOC transport calculation is performed, we associate a more coarsely discretized phase space in which a low-order problem is solved as an acceleration step. Cross sections on the coarse level are obtained by a flux-volume homogenisation technique, which entails the non-linearity of the acceleration. Discontinuity factors per surface are introduced as additional degrees of freedom on the coarse level in order to ensure the equivalence of the heterogeneous and the homogenised problem. After each fine transport iteration, a low-order transport problem is iteratively solved on the homogenised grid. The solution of this problem is then used to correct the angular moments of the flux resulting from the previous free transport sweep. Numerical tests for a given benchmark have been performed. Results are discussed. (authors)

An acceleration of the characteristics by a space-angle two-level method using surface discontinuity factors

International Nuclear Information System (INIS)

Grassi, G.

2006-01-01

We present a non-linear space-angle two-level acceleration scheme for the method of the characteristics (MOC). To the fine level on which the MOC transport calculation is performed, we associate a more coarsely discretized phase space in which a low-order problem is solved as an acceleration step. Cross sections on the coarse level are obtained by a flux-volume homogenisation technique, which entails the non-linearity of the acceleration. Discontinuity factors per surface are introduced as additional degrees of freedom on the coarse level in order to ensure the equivalence of the heterogeneous and the homogenised problem. After each fine transport iteration, a low-order transport problem is iteratively solved on the homogenised grid. The solution of this problem is then used to correct the angular moments of the flux resulting from the previous free transport sweep. Numerical tests for a given benchmark have been performed. Results are discussed. (authors)

Direction for the Future - Successive Acceleration of Positive and Negative Ions Applied to Space Propulsion

CERN Document Server

Aanesland, A.; Popelier, L.; Chabert, P.

2013-12-16

Electrical space thrusters show important advantages for applications in outer space compared to chemical thrusters, as they allow a longer mission lifetime with lower weight and propellant consumption. Mature technologies on the market today accelerate positive ions to generate thrust. The ion beam is neutralized by electrons downstream, and this need for an additional neutralization system has some drawbacks related to stability, lifetime and total weight and power consumption. Many new concepts, to get rid of the neutralizer, have been proposed, and the PEGASES ion-ion thruster is one of them. This new thruster concept aims at accelerating both positive and negative ions to generate thrust, such that additional neutralization is redundant. This chapter gives an overview of the concept of electric propulsion and the state of the development of this new ion-ion thruster.

Multiple solutions of a free-boundary FRC equilibrium problem in a metal cylinder

International Nuclear Information System (INIS)

Spencer, R.L.; Hewett, D.W.

1981-01-01

A new approach to the computation of FRC equilibria that avoids previously encountered difficulties is presented. For arbitrary pressure profiles it is computationally expensive, but for one special pressure profile the problem is simple enough to require only minutes of Cray time; it is this problem that we have solved. We solve the Grad-Shafranov equation, Δ/sup */psi = r 2 p'(psi), in an infinitely long flux conserving cylinder of radius a with the boundary conditions that psi(a,z) = -psi/sub w/ and that delta psi/delta z = 0 as [z] approaches infinity. The pressure profile is p'(psi) = cH(psi) where c is a constant and where H(x) is the Heaviside function. We have found four solutions to this problem: There is a purely vacuum state, two z-independent plasma solutions, and an r-z-dependent plasma state

CAS CERN Accelerator School: Advanced accelerator physics. Proceedings. Vol. 2

International Nuclear Information System (INIS)

Turner, S.

1987-01-01

This advanced course on general accelerator physics is the second of the biennial series given by the CERN Accelerator School and follows on from the first basic course given at Gif-sur-Yvette, Paris, in 1984. Stress is placed on the mathematical tools of Hamiltonian mechanics and the Vlasov and Fokker-Planck equations, which are widely used in accelerator theory. The main topics treated in this present work include: nonlinear resonances, chromaticity, motion in longitudinal phase space, growth and control of longitudinal and transverse beam emittance, space-charge effects and polarization. The seminar programme treats some specific accelerator techniques, devices, projects and future possibilities. (orig.)

Beam transport through electrostatic accelerators and matching into post accelerators

International Nuclear Information System (INIS)

Larson, J.D.

1986-01-01

Ion beam transport through electrostatic acceleration is briefly reviewed. Topics discussed include injection, matching into the low-energy acceleration stage, matching from the terminal stripper into the high-energy stage, transport to a post accelerator, space charge, bunching isochronism, dispersion and charge selection. Beam transport plans for the proposed Vivitron accelerator are described. (orig.)

Effect of Rayleigh accelerations applied to an initially moving fluid. [in circular cylinders under low gravity associated with space flight

Science.gov (United States)

Dressler, R. F.; Robertson, S. J.; Spradley, L. W.

1982-01-01

The General Interpolant Method computer code was used to analyze two-dimensional unsteady thermal convection in circular cylinders under variable low-g conditions associated with space flight. When an acceleration vector was applied parallel to the thermal gradient, in the case of a fluid at rest, no convection resulted for the stable direction, and an instability led to Rayleigh convection for the opposite direction. However, when the acceleration had a component orthogonal to the gradient, convection resulted at any Rayleigh number. The effect on convection of both types of acceleration, applied concurrently or sequentially, was investigated, including the case when the resultant vector varied in direction with time. An analysis of experimental results shows that for space flight conditions, the Rayleigh accelerations induce significant, but not dominating, changes in the established convection even when the Rayleigh number is less than critical.

Final report on the Magnetized Target Fusion Collaboration

Energy Technology Data Exchange (ETDEWEB)

John Slough

2009-09-08

Nuclear fusion has the potential to satisfy the prodigious power that the world will demand in the future, but it has yet to be harnessed as a practical energy source. The entry of fusion as a viable, competitive source of power has been stymied by the challenge of finding an economical way to provide for the confinement and heating of the plasma fuel. It is the contention here that a simpler path to fusion can be achieved by creating fusion conditions in a different regime at small scale (~ a few cm). One such program now under study, referred to as Magnetized Target Fusion (MTF), is directed at obtaining fusion in this high energy density regime by rapidly compressing a compact toroidal plasmoid commonly referred to as a Field Reversed Configuration (FRC). To make fusion practical at this smaller scale, an efficient method for compressing the FRC to fusion gain conditions is required. In one variant of MTF a conducting metal shell is imploded electrically. This radially compresses and heats the FRC plasmoid to fusion conditions. The closed magnetic field in the target plasmoid suppresses the thermal transport to the confining shell, thus lowering the imploding power needed to compress the target. The undertaking to be described in this proposal is to provide a suitable target FRC, as well as a simple and robust method for inserting and stopping the FRC within the imploding liner. The timescale for testing and development can be rapidly accelerated by taking advantage of a new facility funded by the Department of Energy. At this facility, two inductive plasma accelerators (IPA) were constructed and tested. Recent experiments with these IPAs have demonstrated the ability to rapidly form, accelerate and merge two hypervelocity FRCs into a compression chamber. The resultant FRC that was formed was hot (T&ion ~ 400 eV), stationary, and stable with a configuration lifetime several times that necessary for the MTF liner experiments. The accelerator length was less than

Evaluation of High Energy Nuclear Data of Importance for Use in Accelerator and Space Technology

International Nuclear Information System (INIS)

Lee, Young Ouk

2005-10-01

New evaluation were performed for neutron- and proton-induced reactions for energies up to 250 400 MeV on C-12, N-14, O-16, Al-27, Si-28, Ca-40, Ar-40, Fe-54,58, Ni-64, Cu-63,65, Zr-90, Pb-208, Th-232, U-233,234,236, and Cm-243246. The evaluated results are then applied to the accelerator and space technology. A set of optical model parameters were optimized by searching a number of adjustable coefficients with the Simulated Annealing(SA) method for the spherical nuclei. A parameterization of the empirical formula was proposed to describe the proton-nucleus non-elastic cross sections of high-priority elements for space shielding purpose for proton energies from reaction threshold up to 400 MeV, which was then implemented into the fast scoping space shielding code CHARGE, based on the results of the optical model analysis utilizing up-to-date measurements. For proton energies up to 400 MeV covering most of the incident spectrum for trapped protons and solar energetic particle events, energy-angle spectra of secondary neutrons produced from the proton-induced neutron production reaction were prepared. The evaluated cross section set was applied to the thick target yield (TTY) and promp radiation benchmarks for the accelerator shielding. As for the assessment of the radiological impact of the accelerator to the environment, relevant nuclear reaction cross sections for the activation of the air were recommended among the author's evaluations and existing library based on the available measurements

Evaluation of High Energy Nuclear Data of Importance for Use in Accelerator and Space Technology

Energy Technology Data Exchange (ETDEWEB)

Lee, Young Ouk

2005-10-15

New evaluation were performed for neutron- and proton-induced reactions for energies up to 250 400 MeV on C-12, N-14, O-16, Al-27, Si-28, Ca-40, Ar-40, Fe-54,58, Ni-64, Cu-63,65, Zr-90, Pb-208, Th-232, U-233,234,236, and Cm-243246. The evaluated results are then applied to the accelerator and space technology. A set of optical model parameters were optimized by searching a number of adjustable coefficients with the Simulated Annealing(SA) method for the spherical nuclei. A parameterization of the empirical formula was proposed to describe the proton-nucleus non-elastic cross sections of high-priority elements for space shielding purpose for proton energies from reaction threshold up to 400 MeV, which was then implemented into the fast scoping space shielding code CHARGE, based on the results of the optical model analysis utilizing up-to-date measurements. For proton energies up to 400 MeV covering most of the incident spectrum for trapped protons and solar energetic particle events, energy-angle spectra of secondary neutrons produced from the proton-induced neutron production reaction were prepared. The evaluated cross section set was applied to the thick target yield (TTY) and promp radiation benchmarks for the accelerator shielding. As for the assessment of the radiological impact of the accelerator to the environment, relevant nuclear reaction cross sections for the activation of the air were recommended among the author's evaluations and existing library based on the available measurements.

FRC formation studies in a field reversed theta pinch with a variable length coil

International Nuclear Information System (INIS)

Maqueda, R.; Sobehart, J.; Rodrigo, A.B.

1987-01-01

The formation phase of field reversed configurations (FRC) produced using a theta pinch has received considerable attention lately in connection with the possibility of developing formation methods in time scales longer than the Alven radial time, which would permit the use of low-voltage technology and represent an important engineering simplification in the trend towards larger scale machines sup (1)). The mechanisms leading to the loss of trapped reversed flux during the preheating 2 ) and formation sup (3,4)) stages, looking for maximization of this quantity in order to improve on the stability and transport properties of the configuration in its final equilibrium state are investigated. As a result, semi-emperical scaling laws have been obtained relating the reversed flux loss with experimental operating parameters during the early stages of the formation process 1 ). (author) [pt

Esthetic rehabilitation of single anterior edentulous space using fiber-reinforced composite

Directory of Open Access Journals (Sweden)

Hyeon Kim

2014-08-01

Full Text Available A fiber-reinforced composite (FRC fixed prosthesis is an innovative alternative to a traditional metal restoration, as it is a conservative treatment method. This case report demonstrates a detailed procedure for restoring a missing anterior tooth with an FRC. A 44-year-old woman visited our department with an avulsed tooth that had fallen out on the previous day and was completely dry. This tooth was replanted, but it failed after one year. A semi-direct technique was used to fabricate a FRC fixed partial prosthesis for its replacement. The FRC framework and the pontic were fabricated using a duplicated cast model and nanofilled composite resin. Later on, interproximal contact, tooth shape, and shade were adjusted at chairside. This technique not only enables the clinician to replace a missing tooth immediately after extraction for minimizing esthetic problems, but it also decreases both tooth reduction and cost.

The Berkeley Accelerator Space Effects (BASE) Facility - A new mission for the 88-Inch Cyclotron at LBNL

International Nuclear Information System (INIS)

McMahan, M.A.

2005-01-01

In FY04, the 88-Inch Cyclotron began a new operating mode that supports a local research program in nuclear science, R and D in accelerator technology and a test facility for the National Security Space (NSS) community (the US Air Force and NRO). The NSS community (and others on a cost recovery basis) can take advantage of both the light- and heavy-ion capabilities of the cyclotron to simulate the space radiation environment. A significant portion of this work involves the testing of microcircuits for single event effects. The experimental areas within the building that are used for the radiation effects testing are now called the Berkeley Accelerator Space Effects (BASE) Facility. Improvements to the facility to provide increased reliability, quality assurance and new capabilities are underway and will be discussed. These include a 16 A MeV 'cocktail' of beams for heavy ion testing, a neutron beam, more robust dosimetry, and other upgrades

Accelerated whole brain intracranial vessel wall imaging using black blood fast spin echo with compressed sensing (CS-SPACE).

Science.gov (United States)

Zhu, Chengcheng; Tian, Bing; Chen, Luguang; Eisenmenger, Laura; Raithel, Esther; Forman, Christoph; Ahn, Sinyeob; Laub, Gerhard; Liu, Qi; Lu, Jianping; Liu, Jing; Hess, Christopher; Saloner, David

2018-06-01

Develop and optimize an accelerated, high-resolution (0.5 mm isotropic) 3D black blood MRI technique to reduce scan time for whole-brain intracranial vessel wall imaging. A 3D accelerated T 1 -weighted fast-spin-echo prototype sequence using compressed sensing (CS-SPACE) was developed at 3T. Both the acquisition [echo train length (ETL), under-sampling factor] and reconstruction parameters (regularization parameter, number of iterations) were first optimized in 5 healthy volunteers. Ten patients with a variety of intracranial vascular disease presentations (aneurysm, atherosclerosis, dissection, vasculitis) were imaged with SPACE and optimized CS-SPACE, pre and post Gd contrast. Lumen/wall area, wall-to-lumen contrast ratio (CR), enhancement ratio (ER), sharpness, and qualitative scores (1-4) by two radiologists were recorded. The optimized CS-SPACE protocol has ETL 60, 20% k-space under-sampling, 0.002 regularization factor with 20 iterations. In patient studies, CS-SPACE and conventional SPACE had comparable image scores both pre- (3.35 ± 0.85 vs. 3.54 ± 0.65, p = 0.13) and post-contrast (3.72 ± 0.58 vs. 3.53 ± 0.57, p = 0.15), but the CS-SPACE acquisition was 37% faster (6:48 vs. 10:50). CS-SPACE agreed with SPACE for lumen/wall area, ER measurements and sharpness, but marginally reduced the CR. In the evaluation of intracranial vascular disease, CS-SPACE provides a substantial reduction in scan time compared to conventional T 1 -weighted SPACE while maintaining good image quality.

Simulation of Cascaded Longitudinal-Space-Charge Amplifier at the Fermilab Accelerator Science & Technology (Fast) Facility

Energy Technology Data Exchange (ETDEWEB)

Halavanau, A. [Northern Illinois U.; Piot, P. [Northern Illinois U.

2015-12-01

Cascaded Longitudinal Space Charge Amplifiers (LSCA) have been proposed as a mechanism to generate density modulation over a board spectral range. The scheme has been recently demonstrated in the optical regime and has confirmed the production of broadband optical radiation. In this paper we investigate, via numerical simulations, the performance of a cascaded LSCA beamline at the Fermilab Accelerator Science & Technology (FAST) facility to produce broadband ultraviolet radiation. Our studies are carried out using elegant with included tree-based grid-less space charge algorithm.

NASA FDL: Accelerating Artificial Intelligence Applications in the Space Sciences.

Science.gov (United States)

Parr, J.; Navas-Moreno, M.; Dahlstrom, E. L.; Jennings, S. B.

2017-12-01

NASA has a long history of using Artificial Intelligence (AI) for exploration purposes, however due to the recent explosion of the Machine Learning (ML) field within AI, there are great opportunities for NASA to find expanded benefit. For over two years now, the NASA Frontier Development Lab (FDL) has been at the nexus of bright academic researchers, private sector expertise in AI/ML and NASA scientific problem solving. The FDL hypothesis of improving science results was predicated on three main ideas, faster results could be achieved through sprint methodologies, better results could be achieved through interdisciplinarity, and public-private partnerships could lower costs We present select results obtained during two summer sessions in 2016 and 2017 where the research was focused on topics in planetary defense, space resources and space weather, and utilized variational auto encoders, bayesian optimization, and deep learning techniques like deep, recurrent and residual neural networks. The FDL results demonstrate the power of bridging research disciplines and the potential that AI/ML has for supporting research goals, improving on current methodologies, enabling new discovery and doing so in accelerated timeframes.

Absolute calibration of neutron detectors on the C-2U advanced beam-driven FRC

Energy Technology Data Exchange (ETDEWEB)

Magee, R. M., E-mail: rmagee@trialphaenergy.com; Clary, R.; Korepanov, S.; Jauregui, F.; Allfrey, I.; Garate, E.; Valentine, T.; Smirnov, A. [Tri Alpha Energy, Inc., Rancho Santa Margarita, California 92688 (United States)

2016-11-15

In the C-2U fusion energy experiment, high power neutral beam injection creates a large fast ion population that sustains a field-reversed configuration (FRC) plasma. The diagnosis of the fast ion pressure in these high-performance plasmas is therefore critical, and the measurement of the flux of neutrons from the deuterium-deuterium (D-D) fusion reaction is well suited to the task. Here we describe the absolute, in situ calibration of scintillation neutron detectors via two independent methods: firing deuterium beams into a high density gas target and calibration with a 2 × 10{sup 7} n/s AmBe source. The practical issues of each method are discussed and the resulting calibration factors are shown to be in good agreement. Finally, the calibration factor is applied to C-2U experimental data where the measured neutron rate is found to exceed the classical expectation.

High Flux FRC Facility for the Stability, Confinement and ITER Divertor Studies

Energy Technology Data Exchange (ETDEWEB)

Hoffman, Alan L. [Univ. of Washington, Seattle, WA (United States). Aerospace and Energetics Research Program. Redmond Plasma Physics Lab.; Milroy, Richard D. [Univ. of Washington, Seattle, WA (United States). Aerospace and Energetics Research Program. Redmond Plasma Physics Lab.

2014-01-31

The TCS (Translation, Confinement, & Sustainment) program was begun on 7 August, 1996 to renew basic studies of the Field Reversed Configuration (FRC). The program made use of the old LSX (Large s Experiment) device, which was constructed at STI during the period from 1986 to 1990, but only operated for one year due to a DOE decision at the time to focus exclusively on the tokamak configuration. LSX was transferred to the University of Washington in 1992 and modified (LSX/mod) to perform Tokamak Refueling by Accelerated Plasmoids (TRAP) experiments. The TRAP program was funded from 7 August, 1992 until 6 August, 1996, but was utilized for an additional year while TCS was being constructed. During the first TCS funding period TCS was completed and initial experiments were begun. A large multi-megawatt RF power supply was built by Los Alamos National Laboratory (LANL) for use with a Rotating Magnetic Field (RMF) system, and LANL has been a continuing participant in our experimental program. A smaller prototype facility, called the Star Thrust Experiment (STX) was also built and operated in this period, partly with NASA funding, before TCS came on-line. A final report for this construction period was submitted in September 2000. A first renewal period (2.5 years) provided operating funds for the period between July 7, 2000 and January 6, 2003. A great deal of progress was made in understanding the use of RMF to both form and sustain FRCs during this period. The principal result of the experimental program was the formation of quasi steady-state (as long as RMF power was available) FRCs with densities in the 1-3x10¹⁹ m^-3 range. However, the plasma temperature (T_e or T_i) was limited to sub-25 eV, except transiently during start-up, by the rapid accumulation of impurities. This is not surprising since TCS was only designed to demonstrate RMF flux build-up and was not provided with either fueling capabilities or modern vacuum

Acceleration factor for propagation of a stationary wave in its wave medium: movement of energy in the 3-D space

International Nuclear Information System (INIS)

Nagao, Shigeto

2013-01-01

According to the formerly reported 4-D spherical model of the time and universe, any energy in the 3-dimensional space is a vibration of the intrinsic space energy. There is a special frame stationary to the space energy and the principle of relativity is no longer valid. Accordingly, abandonment of the Special Relativity and then introduction of a factor of acceleration for energy in the 3-D space are proposed.

Long pulse FRC sustainment with enhanced edge driven rotating magnetic field current drive

International Nuclear Information System (INIS)

Hoffman, A.L.; Guo, H.Y.; Miller, K.E.; Milroy, R.D.

2005-01-01

FRCs have been formed and sustained for up to 50 normal flux decay times by Rotating Magnetic Fields (RMF) in the TCS experiment. For these longer pulse times a new phenomenon has been observed: switching to a higher performance mode delineated by shallower RMF penetration, higher ratios of generated poloidal to RMF drive field, and lower overall plasma resistivity. This global data is not explainable by previous RMF theory based on uniform electron rotational velocities or by numerical calculations based on uniform plasma resistivity, but agrees in many respects with new calculations made using strongly varying resistivity profiles. In order to more realistically model RMF driven FRCs with such non-uniform resistivity profiles, a double rigid rotor model has been developed with separate inner and outer electron rotational velocities and resistivities. The results of this modeling suggest that the RMF drive results in very high resistivity in a narrow edge layer, and that the higher performance mode is characterized by a sharp reduction in resistivity over the bulk of the FRC. (author)

Dynamics of the relativistic acceleration of charged particles in space plasma while surfing the package electromagnetic waves

International Nuclear Information System (INIS)

Erokhin, N.S.; Zol'nikova, N.N.; Kuznetsov, E.A.; Mikhajlovskaya, L.A.

2010-01-01

Based on numerical calculations considered the relativistic acceleration of charged particles in space plasma when surfing on the spatially localized package of electromagnetic waves. The problem is reduced to the study of unsteady, nonlinear equation for the wave phase at the carrier frequency at the location of the accelerated charge, which is solved numerically. We study the temporal dynamics of the relativistic factor, the component of momentum and velocity of the particle, its trajectory is given gyro-rotation in an external magnetic field after the departure of the effective potential well. Dependence of the dynamics of a particle interacting with the wave of the sign of the velocity of the charge along the wave front. We formulate the optimal conditions of the relativistic particle acceleration wave packet, indicate the possibility of again (after a number gyro-turnover) charge trapping wave with an additional relativistic acceleration.

Double layers are not particle accelerators

International Nuclear Information System (INIS)

Bryant, D.A.; Bingham, R.; Angelis, U. de.

1991-02-01

It is pointed out that the continuing advocacy of electrostatic double layers as particle accelerators in the aurora and other space and astrophysical plasmas is fundamentally unsound. It is suggested furthermore that there is little reason to invoke static or quasi-static electric fields as the cause of auroral electron acceleration. Stochastic acceleration by electrostatic wave turbulence appears to present a natural explanation for this and for electron acceleration in other space and astrophysical plasmas. (author)

Transverse phase space diagnostics for ionization injection in laser plasma acceleration using permanent magnetic quadrupoles

Science.gov (United States)

Li, F.; Nie, Z.; Wu, Y. P.; Guo, B.; Zhang, X. H.; Huang, S.; Zhang, J.; Cheng, Z.; Ma, Y.; Fang, Y.; Zhang, C. J.; Wan, Y.; Xu, X. L.; Hua, J. F.; Pai, C. H.; Lu, W.; Mori, W. B.

2018-04-01

We report the transverse phase space diagnostics for electron beams generated through ionization injection in a laser-plasma accelerator. Single-shot measurements of both ultimate emittance and Twiss parameters are achieved by means of permanent magnetic quadrupole. Beams with emittance of μm rad level are obtained in a typical ionization injection scheme, and the dependence on nitrogen concentration and charge density is studied experimentally and confirmed by simulations. A key feature of the transverse phase space, matched beams with Twiss parameter α T ≃ 0, is identified according to the measurement. Numerical simulations that are in qualitative agreement with the experimental results reveal that a sufficient phase mixing induced by an overlong injection length leads to the matched phase space distribution.

Collisionless shocks in space plasmas structure and accelerated particles

CERN Document Server

Burgess, David

2015-01-01

Shock waves are an important feature of solar system plasmas, from the solar corona out to the edge of the heliosphere. This engaging introduction to collisionless shocks in space plasmas presents a comprehensive review of the physics governing different types of shocks and processes of particle acceleration, from fundamental principles to current research. Motivated by observations of planetary bow shocks, interplanetary shocks and the solar wind termination shock, it emphasises the physical theory underlying these shock waves. Readers will develop an understanding of the complex interplay between particle dynamics and the electric and magnetic fields that explains the observations of in situ spacecraft. Written by renowned experts in the field, this up-to-date text is the ideal companion for both graduate students new to heliospheric physics and researchers in astrophysics who wish to apply the lessons of solar system shocks to different astrophysical environments.

Accelerator requirments for strategic defense

International Nuclear Information System (INIS)

Gullickson, R.L.

1987-01-01

The authors discuss how directed energy applications require accelerators with high brightness and large gradients to minimize size and weight for space systems. Several major directed energy applications are based upon accelerator technology. The radio-frequency linear accelerator is the basis for both space-based neutral particle beam (NPB) and free electron laser (FEL) devices. The high peak current of the induction linac has made it a leading candidate for ground based free electron laser applications

Accelerator structure for a charged particle linear accelerator working in standing wave mode

International Nuclear Information System (INIS)

Tran, D.T.; Tronc, Dominique.

1977-01-01

Charged particle accelerators generally include a pre-grouping or pre-accelerating structure associated with the accelerator structure itself. But pre-grouping or pre-accelerating structures of known type (Patent application No. 70 39261 for example) present electric and dimensional characteristics that rule them out for accelerators working at high frequencies (C or X bands for example), since the distance separating the interaction spaces becomes very small in this case. The accelerator structure mentioned in this invention can be used to advantage for such accelerators [fr

Perception of tilt (somatogravic illusion) in response to sustained linear acceleration during space flight

Science.gov (United States)

Clement, G.; Moore, S. T.; Raphan, T.; Cohen, B.

2001-01-01

During the 1998 Neurolab mission (STS-90), four astronauts were exposed to interaural and head vertical (dorsoventral) linear accelerations of 0.5 g and 1 g during constant velocity rotation on a centrifuge, both on Earth and during orbital space flight. Subjects were oriented either left-ear-out or right-ear-out (Gy centrifugation), or lay supine along the centrifuge arm with their head off-axis (Gz centrifugation). Pre-flight centrifugation, producing linear accelerations of 0.5 g and 1 g along the Gy (interaural) axis, induced illusions of roll-tilt of 20 degrees and 34 degrees for gravito-inertial acceleration (GIA) vector tilts of 27 degrees and 45 degrees , respectively. Pre-flight 0.5 g and 1 g Gz (head dorsoventral) centrifugation generated perceptions of backward pitch of 5 degrees and 15 degrees , respectively. In the absence of gravity during space flight, the same centrifugation generated a GIA that was equivalent to the centripetal acceleration and aligned with the Gy or Gz axes. Perception of tilt was underestimated relative to this new GIA orientation during early in-flight Gy centrifugation, but was close to the GIA after 16 days in orbit, when subjects reported that they felt as if they were 'lying on side'. During the course of the mission, inflight roll-tilt perception during Gy centrifugation increased from 45 degrees to 83 degrees at 1 g and from 42 degrees to 48 degrees at 0.5 g. Subjects felt 'upside-down' during in-flight Gz centrifugation from the first in-flight test session, which reflected the new GIA orientation along the head dorsoventral axis. The different levels of in-flight tilt perception during 0.5 g and 1 g Gy centrifugation suggests that other non-vestibular inputs, including an internal estimate of the body vertical and somatic sensation, were utilized in generating tilt perception. Interpretation of data by a weighted sum of body vertical and somatic vectors, with an estimate of the GIA from the otoliths, suggests that

A new type of accelerator power supply based on voltage-type space vector PWM rectification technology

International Nuclear Information System (INIS)

Wu, Fengjun; Gao, Daqing; Shi, Chunfeng; Huang, Yuzhen; Cui, Yuan; Yan, Hongbin; Zhang, Huajian; Wang, Bin; Li, Xiaohui

2016-01-01

To solve the problems such as low input power factor, a large number of AC current harmonics and instable DC bus voltage due to the diode or thyristor rectifier used in an accelerator power supply, particularly in the Heavy Ion Research Facility in Lanzhou-Cooler Storage Ring (HIRFL-CSR), we designed and built up a new type of accelerator power supply prototype base on voltage-type space vector PWM (SVPWM) rectification technology. All the control strategies are developed in TMS320C28346, which is a digital signal processor from TI. The experimental results indicate that an accelerator power supply with a SVPWM rectifier can solve the problems above well, and the output performance such as stability, tracking error and ripple current meet the requirements of the design. The achievement of prototype confirms that applying voltage-type SVPWM rectification technology in an accelerator power supply is feasible; and it provides a good reference for design and build of this new type of power supply. - Highlights: • Applying SVPWM rectification technology in an accelerator power supply improves its grid-side performance. • New Topology and its control strategies make an accelerator power supply have bidirectional power flow ability. • Hardware and software of controller provide a good reference for design of this new type of power supply.

A new type of accelerator power supply based on voltage-type space vector PWM rectification technology

Energy Technology Data Exchange (ETDEWEB)

Wu, Fengjun, E-mail: wufengjun@impcas.ac.cn [Institute of Modern Physics, CAS, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Gao, Daqing; Shi, Chunfeng; Huang, Yuzhen [Institute of Modern Physics, CAS, Lanzhou 730000 (China); Cui, Yuan [Institute of Modern Physics, CAS, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Yan, Hongbin [Institute of Modern Physics, CAS, Lanzhou 730000 (China); Zhang, Huajian [Institute of Modern Physics, CAS, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Wang, Bin [University of Chinese Academy of Sciences, Beijing 100049 (China); Li, Xiaohui [Institute of Modern Physics, CAS, Lanzhou 730000 (China)

2016-08-01

To solve the problems such as low input power factor, a large number of AC current harmonics and instable DC bus voltage due to the diode or thyristor rectifier used in an accelerator power supply, particularly in the Heavy Ion Research Facility in Lanzhou-Cooler Storage Ring (HIRFL-CSR), we designed and built up a new type of accelerator power supply prototype base on voltage-type space vector PWM (SVPWM) rectification technology. All the control strategies are developed in TMS320C28346, which is a digital signal processor from TI. The experimental results indicate that an accelerator power supply with a SVPWM rectifier can solve the problems above well, and the output performance such as stability, tracking error and ripple current meet the requirements of the design. The achievement of prototype confirms that applying voltage-type SVPWM rectification technology in an accelerator power supply is feasible; and it provides a good reference for design and build of this new type of power supply. - Highlights: • Applying SVPWM rectification technology in an accelerator power supply improves its grid-side performance. • New Topology and its control strategies make an accelerator power supply have bidirectional power flow ability. • Hardware and software of controller provide a good reference for design of this new type of power supply.

Biological effects of several extreme space flight factors (acceleration, magnetically activated water) on mouse natural or modified radiosensitivity

International Nuclear Information System (INIS)

Datsov, E.R.

1979-01-01

Irradiated and Adeturon-protected mice were used to assess biological effects of several static (magnetically-activated water - MW) and dynamic (acceleration) factors of space flight. The study shows that increased gravitation, 20 G, 5 min, generated by a small radius centrifuge, increases static ability to work, while the number of peripheral blood cells decreases. Continuous exposure of mice to MW induces a decrease in dynamic ability to work, in comparison with the physiological controls, without substantial changes in other indices. Extreme factors in space flight (acceleration MW, radiation, radiation protector), alone or in combination, decrease the animal's growth rate. After administration of 200 mg/kg Adeturone, mouse dynamic ability to work increases, while its capabilities for adaptation and training are lowered, and pronounced leucocytosis is observed. MW, acceleration, or Adeturone pre-treatment of mice increases their survival and dynamic ability to work, following exposure to 600 R, when compared to irradiated animals, but decreases their capabilities for adaptation and training. Acceleration and Adeturone protect peripheral blood from radiation injury, while MW alone intensifies radiation cytopenia. Irradiation does not significantly modify the static ability to work, upon preceding exposure to MW or acceleration. In this case, Adeturone exerts protective effect. ME and Adeturone combined action results in increased survival rate and mean duration of life of irradiated animals, as compared to their single administration. Acceleration reduces MW, Adeturone and MW + Adeturone effect on survival. Peripheral blood parameters do not correlate with survival rates. Combined pre-treatment with two or three of the factors studied increases dynamic ability to work following irradiation, and in many cases the static ability as well. The combination of Adeturone and MW was the only one with negative effect on the static ability to work. (A.B.)

Gymnastics in Phase Space

Energy Technology Data Exchange (ETDEWEB)

Chao, Alexander Wu; /SLAC

2012-03-01

As accelerator technology advances, the requirements on accelerator beam quality become increasingly demanding. Facing these new demands, the topic of phase space gymnastics is becoming a new focus of accelerator physics R&D. In a phase space gymnastics, the beam's phase space distribution is manipulated and precision tailored to meet the required beam qualities. On the other hand, all realization of such gymnastics will have to obey accelerator physics principles as well as technological limitations. Recent examples of phase space gymnastics include Emittance exchanges, Phase space exchanges, Emittance partitioning, Seeded FELs and Microbunched beams. The emittance related topics of this list are reviewed in this report. The accelerator physics basis, the optics design principles that provide these phase space manipulations, and the possible applications of these gymnastics, are discussed. This fascinating new field promises to be a powerful tool of the future.

Equilibrium phase-space distributions and space charge limits in linacs

International Nuclear Information System (INIS)

Lysenko, W.P.

1977-10-01

Limits on beam current and emittance in proton and heavy ion linear accelerators resulting from space charge forces are calculated. The method involves determining equilibrium distributions in phase space using a continuous focusing, no acceleration, model in two degrees of freedom using the coordinates r and z. A nonlinear Poisson equation must be solved numerically. This procedure is a matching between the longitudinal and transverse directions to minimize the effect of longitudinal-transverse coupling which is believed to be the main problem in emittance growth due to space charge in linacs. Limits on the Clinton P. Anderson Meson Physics Facility (LAMPF) accelerator performance are calculated as an example. The beam physics is described by a few space charge parameters so that accelerators with different physical parameters can be compared in a natural way. The main result of this parameter study is that the requirement of a high-intensity beam is best fulfilled with a low-frequency accelerator whereas the requirement of a high-brightness beam is best fulfilled with a high-frequency accelerator

Airy Wave Packets Accelerating in Space-Time

Science.gov (United States)

Kondakci, H. Esat; Abouraddy, Ayman F.

2018-04-01

Although diffractive spreading is an unavoidable feature of all wave phenomena, certain waveforms can attain propagation invariance. A lesser-explored strategy for achieving optical self-similar propagation exploits the modification of the spatiotemporal field structure when observed in reference frames moving at relativistic speeds. For such an observer, it is predicted that the associated Lorentz boost can bring to a halt the axial dynamics of a wave packet of an arbitrary profile. This phenomenon is particularly striking in the case of a self-accelerating beam—such as an Airy beam—whose peak normally undergoes a transverse displacement upon free propagation. Here we synthesize an acceleration-free Airy wave packet that travels in a straight line by deforming its spatiotemporal spectrum to reproduce the impact of a Lorentz boost. The roles of the axial spatial coordinate and time are swapped, leading to "time diffraction" manifested in self-acceleration observed in the propagating Airy wave-packet frame.

Accelerator-Based Studies of Heavy Ion Interactions Relevant to Space Biomedicine

Science.gov (United States)

Miller, J.; Heilbronn, L.; Zeitlin, C.

1999-01-01

Evaluation of the effects of space radiation on the crews of long duration space missions must take into account the interactions of high energy atomic nuclei in spacecraft and planetary habitat shielding and in the bodies of the astronauts. These heavy ions (i.e. heavier than hydrogen), while relatively small in number compared to the total galactic cosmic ray (GCR) charged particle flux, can produce disproportionately large effects by virtue of their high local energy deposition: a single traversal by a heavy charged particle can kill or, what may be worse, severely damage a cell. Research into the pertinent physics and biology of heavy ion interactions has consequently been assigned a high priority in a recent report by a task group of the National Research Council. Fragmentation of the incident heavy ions in shielding or in the human body will modify an initially well known radiation field and thereby complicate both spacecraft shielding design and the evaluation of potential radiation hazards. Since it is impractical to empirically test the radiation transport properties of each possible shielding material and configuration, a great deal of effort is going into the development of models of charged particle fragmentation and transport. Accurate nuclear fragmentation cross sections (probabilities), either in the form of measurements with thin targets or theoretical calculations, are needed for input to the transport models, and fluence measurements (numbers of fragments produced by interactions in thick targets) are needed both to validate the models and to test specific shielding materials and designs. Fluence data are also needed to characterize the incident radiation field in accelerator radiobiology experiments. For a number of years, nuclear fragmentation measurements at GCR-like energies have been carried out at heavy ion accelerators including the LBL Bevalac, Saturne (France), the Synchrophasotron and Nuklotron (Dubna, Russia), SIS-18 (GSI, Germany), the

General accelerator physics. Proceedings. Vol. 2

International Nuclear Information System (INIS)

Bryant, P.; Turner, S.

1985-01-01

This course on accelerator physics is the first in a series of two, which is planned by the CERN Accelerator School. Starting at the level of a science graduate, this course covers mainly linear theory. The topics include: transverse and longitudinal beam dynamics, insertions, coupling, transition, dynamics of radiating particles, space-charge forces, neutralization, beam profiles, luminosity calculations in colliders, longitudinal phase-space stacking, phase-displacement acceleration, transfer lines, injection and extraction. Some more advanced topics are also introduced: coherent instabilities in coasting beams, general collective phenomena, quantum lifetime, and intra-beam scattering. The seminar programme is based on two themes: firstly, the sub-systems of an accelerator and, secondly, the uses to which accelerators are put. (orig.)

Accelerator system model (ASM): A unique tool in exploring accelerator driven transmutation technologies (ADTT) system trade space

Energy Technology Data Exchange (ETDEWEB)

Myers, T.J.; Favale, A.J.; Berwald, D.H.; Burger, E.C.; Paulson, C.C.; Peacock, M.A.; Piaszczyk, C.M.; Piechowiak, E.M.; Rathke, J.W. [Northrop Grumman Corp., Bethpage, NY (United States). Advanced Technology and Development Center

1997-09-01

To aid in the development and optimization of emerging Accelerator Driven Transmutation Technology (ADTT) concepts, the Northrop Grumman Corporation, working together with G.H. Gillespie Associates and Los Alamos National Laboratory has developed a computational tool which combines both accelerator physics layout/analysis capabilities with engineering analysis capabilities to create a standardized platform to compare and contrast accelerator system configurations. In this context, the accelerator system configuration includes not only the accelerating structures, but also the major support systems such as the vacuum, thermal control, RF power, and cryogenic subsystem (if superconducting accelerator operation is investigated) as well as estimates of the costs for enclosures (accelerating tunnel and RF halls). This paper presents an overview of the Accelerator System Model (ASM) code flow, as well as a discussion of the data and analysis upon which it is based. Also presented is material which addresses the development of the evaluation criteria employed by this code including a presentation of the economic analysis methods, and a discussion of the cost database employed. The paper concludes with examples depicting completed and planned trade studies for both normal and superconducting accelerator applications. 8 figs.

Monte Carlo simulation of a medical linear accelerator for generation of phase spaces

International Nuclear Information System (INIS)

Oliveira, Alex C.H.; Santana, Marcelo G.; Lima, Fernando R.A.; Vieira, Jose W.

2013-01-01

Radiotherapy uses various techniques and equipment for local treatment of cancer. The equipment most often used in radiotherapy to the patient irradiation are linear accelerators (Linacs) which produce beams of X-rays in the range 5-30 MeV. Among the many algorithms developed over recent years for evaluation of dose distributions in radiotherapy planning, the algorithms based on Monte Carlo methods have proven to be very promising in terms of accuracy by providing more realistic results. The MC methods allow simulating the transport of ionizing radiation in complex configurations, such as detectors, Linacs, phantoms, etc. The MC simulations for applications in radiotherapy are divided into two parts. In the first, the simulation of the production of the radiation beam by the Linac is performed and then the phase space is generated. The phase space contains information such as energy, position, direction, etc. og millions of particles (photos, electrons, positrons). In the second part the simulation of the transport of particles (sampled phase space) in certain configurations of irradiation field is performed to assess the dose distribution in the patient (or phantom). The objective of this work is to create a computational model of a 6 MeV Linac using the MC code Geant4 for generation of phase spaces. From the phase space, information was obtained to asses beam quality (photon and electron spectra and two-dimensional distribution of energy) and analyze the physical processes involved in producing the beam. (author)

Twisted Acceleration-Enlarged Newton-Hooke Hopf Algebras

International Nuclear Information System (INIS)

Daszkiewicz, M.

2010-01-01

Ten Abelian twist deformations of acceleration-enlarged Newton-Hooke Hopf algebra are considered. The corresponding quantum space-times are derived as well. It is demonstrated that their contraction limit τ → ∞ leads to the new twisted acceleration-enlarged Galilei spaces. (author)

Experimental studies of field-reversed configuration translation

Energy Technology Data Exchange (ETDEWEB)

Rej, D.J.; Armstrong, W.T.; Chrien, R.E.; Klingner, P.L.; Linford, R.K.; McKenna, K.F.; Sherwood, E.G.; Siemon, R.E.; Tuszewski, M.; Milroy, R.D.

1986-03-01

In the FRX-C/T experiment (Proceedings of the 9th Symposium for Engineering Problems of Fusion Research (IEEE, New York, 1981), p. 1751), field-reversed configuration (FRC) plasmas have been formed in, and launched from, a field-reversed theta-pinch source and subsequently trapped in an adjacent confinement region. No destructive instabilities or enhanced losses of poloidal flux, particles, or thermal energy are observed for FRC total trajectories of up to 16 m. The observed translation dynamics agree with two-dimensional magnetohydrodynamic (MHD) simulations. When translated into reduced external magnetic fields, FRC's are observed to accelerate, expand, and cool in partial agreement with adiabatic theory. The plasmas reflect from an external mirror and after each reflection, the axial kinetic energy is reduced by approximately 50%. Because of this reduction, FRC's are readily trapped without the need of pulsed gate magnet coils.

Modification of the magnetic field structure in the vicinity of the x-points by the strong mirror field for a field-reversed configuration (FRC) with the Thick Edge-Layer plasma

International Nuclear Information System (INIS)

Suzuki, Yukihisa; Okada, Shigefumi; Goto, Seiichi

2003-01-01

Modification of the magnetic field structure in the vicinity of the x-points and changes of the separatrix shape are investigated under the pressure effects due to an edge-layer plasma together with a mirror field by the two-dimensional (2-D) MHD equilibrium solutions of field-reversed configuration (FRC) obtained from the Grad-Shafranov equation. To explore the coupling pressure effects caused by edge-layer plasma and mirror field, the equilibrium calculations are performed by the combinations of several values of mirror ratio (R m ) and of edge-layer width (δ), respectively. A summary of results for present study is as follows. In the condition of weak mirror field (1.0 m m > 1.6, ψ=0 surface never opens up for any δ. These original results make it clear that large magnetic curvature produced by the strong mirror field enhances the magnetic stress around the x-point, so that the ends of FRC are effectively sustained by this enhanced magnetic stress, which counteracts the edge-layer plasma pressure effect. (author)

Particle acceleration near Halley's comet

International Nuclear Information System (INIS)

Somogyi, Antal

1987-01-01

Vega and Giotto space probes observed energetic ions of cometary origin near Halley's comet. The water molecules evaporating from the cometary nucleus were ionized by the solar UV radiation. These 'standing' ions were accelerated from 1 km/s to a few 1000 km/s. Present paper analyses the possible mechanisms of acceleration based on the data of TUENDE detector (constructed by CRIP, Hungary) working on board of Vega probes. The basic mechanism is the ExB Lorentz acceleration by interplanetary magnetic field and electric field induced by magnetic field frozen into solar wind plasma. It is followed by an acceleration caused by the adiabatic compression of the plasma at shock wave front. These processes can not explain the observed velocity of ions. It is shown that the second order Fermi acceleration which dissipates the ion distribution in the velocity space can lead to the observed velocities. The circumstances required to the occurrence of this process are present at the cometary environment. (D.G.) 2 figs

Status of MAPA (Modular Accelerator Physics Analysis) and the Tech-X Object-Oriented Accelerator Library

Science.gov (United States)

Cary, J. R.; Shasharina, S.; Bruhwiler, D. L.

1998-04-01

The MAPA code is a fully interactive accelerator modeling and design tool consisting of a GUI and two object-oriented C++ libraries: a general library suitable for treatment of any dynamical system, and an accelerator library including many element types plus an accelerator class. The accelerator library inherits directly from the system library, which uses hash tables to store any relevant parameters or strings. The GUI can access these hash tables in a general way, allowing the user to invoke a window displaying all relevant parameters for a particular element type or for the accelerator class, with the option to change those parameters. The system library can advance an arbitrary number of dynamical variables through an arbitrary mapping. The accelerator class inherits this capability and overloads the relevant functions to advance the phase space variables of a charged particle through a string of elements. Among other things, the GUI makes phase space plots and finds fixed points of the map. We discuss the object hierarchy of the two libraries and use of the code.

TeV/m nano-accelerator: Investigation on feasibility of CNT-channeling acceleration at Fermilab

Energy Technology Data Exchange (ETDEWEB)

Shin, Y. M. [Northern Illinois Univ., DeKalb, IL (United States); Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Lumpkin, A. H. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Thurman-Keup, R. M. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

2015-03-23

The development of high gradient acceleration and tight phase-space control of high power beams is a key element for future lepton and hadron colliders since the increasing demands for higher energy and luminosity significantly raise costs of modern HEP facilities. Atomic channels in crystals are known to consist of 10–100 V/Å potential barriers capable of guiding and collimating a high energy beam providing continuously focused acceleration with exceptionally high gradients (TeV/m). However, channels in natural crystals are only angstrom-size and physically vulnerable to high energy interactions, which has prevented crystals from being applied to high power accelerators. Carbon-based nano-crystals such as carbon-nanotubes (CNTs) and graphenes have a large degree of dimensional flexibility and thermo-mechanical strength, which could be suitable for channeling acceleration of MW beams. Nano-channels of the synthetic crystals can accept a few orders of magnitude larger phase-space volume of channeled particles with much higher thermal tolerance than natural crystals. This study presents the current status of CNT-channeling acceleration research at the Advanced Superconducting Test Accelerator (ASTA) in Fermilab.

Discretization of space and time: mass-energy relation, accelerating expansion of the Universe, Hubble constant

OpenAIRE

Roatta , Luca

2017-01-01

Assuming that space and time can only have discrete values, we obtain the expression of the gravitational potential energy that at large distance coincides with the Newtonian. In very precise circumstances it coincides with the relativistic mass-energy relation: this shows that the Universe is a black hole in which all bodies are subjected to an acceleration toward the border of the Universe itself. Since the Universe is a black hole with a fixed radius, we can obtain the density of the Unive...

Accelerators for energy

International Nuclear Information System (INIS)

Inoue, Makoto

2000-01-01

A particle accelerator is a device to consume energy but not to produce it. Then, the titled accelerator seems to mean an accelerator for using devices related to nuclear energy. For an accelerator combined to nuclear fissionable fuel, neutron sources are D-T type, (gamma, n) reaction using electron beam type spallation type, and so forth. At viewpoints of powers of incident beam and formed neutron, a spallation type source using high energy proton is told to be effective but others have some advantages by investigation on easy operability, easy construction, combustion with target, energy and directivity of neutron, and so forth. Here were discussed on an accelerator for research on accelerator driven energy system by dividing its researching steps, and on kind, energy, beam intensity, and so forth of an accelerator suitable for it. And, space electric charge effect at beam propagation direction controlled by beam intensity of cyclotron was also commented. (G.K.)

Vp x B acceleration

International Nuclear Information System (INIS)

Sugihara, Ryo.

1987-05-01

A unique particle acceleration by an electrostatic (ES) wave, a magnetosonic shock wave as well as an electromagnetic (EM) wave is reviewed. The principle of the acceleration is that when a charged particle is carried across an external magnetic field the charge feels a DC field (the Lorentz force) and is accelerated. The theory for the ES wave acceleration is experimentally verified thought it is semi-quantitative. The shock acceleration is extensively studied theoretically and in a particle simulation method and the application is extended to phenomena in interplanetary space. The EM wave acceleration is based on a trapping in a moving neutral sheet created by the wave magnetic field and the external magnetic field, and the particle can be accelerated indefinitely. A brief sketch on a slow-wave-structure for this acceleration will be given. (author)

Acceleration radiation in a compact space

International Nuclear Information System (INIS)

Copeland, E.J.; Davies, P.C.W.; Hinton, K.

1984-01-01

The response is studied of a uniformly accelerated model particle detector in a spacetime with compact spatial sections. The basic thermal character of the response re-emerges, in spite of the fact that the spacetime does not possess event horizons. The model also permits a study of detector response to twisted field states. (author)

High intensity circular proton accelerators

International Nuclear Information System (INIS)

Craddock, M.K.

1987-12-01

Circular machines suitable for the acceleration of high intensity proton beams include cyclotrons, FFAG accelerators, and strong-focusing synchrotrons. This paper discusses considerations affecting the design of such machines for high intensity, especially space charge effects and the role of beam brightness in multistage accelerators. Current plans for building a new generation of high intensity 'kaon factories' are reviewed. 47 refs

Comparing an accelerated 3D fast spin-echo sequence (CS-SPACE) for knee 3-T magnetic resonance imaging with traditional 3D fast spin-echo (SPACE) and routine 2D sequences

Energy Technology Data Exchange (ETDEWEB)

Altahawi, Faysal F.; Blount, Kevin J.; Omar, Imran M. [Northwestern University Feinberg School of Medicine, Department of Radiology, Chicago, IL (United States); Morley, Nicholas P. [Marshfield Clinic, Department of Radiology, Marshfield, WI (United States); Raithel, Esther [Siemens Healthcare GmbH, Erlangen (Germany)

2017-01-15

To compare a faster, new, high-resolution accelerated 3D-fast-spin-echo (3D-FSE) acquisition sequence (CS-SPACE) to traditional 2D and high-resolution 3D sequences for knee 3-T magnetic resonance imaging (MRI). Twenty patients received knee MRIs that included routine 2D (T1, PD ± FS, T2-FS; 0.5 x 0.5 x 3 mm{sup 3}; ∝10 min), traditional 3D FSE (SPACE-PD-FS; 0.5 x 0.5 x 0.5 mm{sup 3}; ∝7.5 min), and accelerated 3D-FSE prototype (CS-SPACE-PD-FS; 0.5 x 0.5 x 0.5 mm{sup 3}; ∝5 min) acquisitions on a 3-T MRI system (Siemens MAGNETOM Skyra). Three musculoskeletal radiologists (MSKRs) prospectively and independently reviewed the studies with graded surveys comparing image and diagnostic quality. Tissue-specific signal-to-noise ratios (SNR) and contrast-to-noise ratios (CNR) were also compared. MSKR-perceived diagnostic quality of cartilage was significantly higher for CS-SPACE than for SPACE and 2D sequences (p < 0.001). Assessment of diagnostic quality of menisci and synovial fluid was higher for CS-SPACE than for SPACE (p < 0.001). CS-SPACE was not significantly different from SPACE but had lower assessments than 2D sequences for evaluation of bones, ligaments, muscles, and fat (p ≤ 0.004). 3D sequences had higher spatial resolution, but lower overall assessed contrast (p < 0.001). Overall image quality from CS-SPACE was assessed as higher than SPACE (p = 0.007), but lower than 2D sequences (p < 0.001). Compared to SPACE, CS-SPACE had higher fluid SNR and CNR against all other tissues (all p < 0.001). The CS-SPACE prototype allows for faster isotropic acquisitions of knee MRIs over currently used protocols. High fluid-to-cartilage CNR and higher spatial resolution over routine 2D sequences may present a valuable role for CS-SPACE in the evaluation of cartilage and menisci. (orig.)

Acceleration of H, He, and heavy ions observed in the magnetosheath, magnetotail, and near-by interplanetary space

International Nuclear Information System (INIS)

Fan, C.Y.; Gloeckler, G.; Hovestadt, D.

1975-01-01

Pulses of electrons and ions composed of H, He, and heavier elements were observed in the magnetosheath, magnetotail, and near-by interplanetary space. From the spatial positions where these particles were detected and the ion flow directions we conclude that they were accelerated at the bow shock near the sub-solar point and in the near-earth region of the neutral sheet of the magnetotail. (orig.) [de

Theory of accelerated orbits and space charge effects in an AVF cyclotron

International Nuclear Information System (INIS)

Kleeven, W.J.G.M.

1988-01-01

In the first part of this thesis the influence of the accelerating electric field upon the motion of particles in a cyclotron is studied. A general relativistic Hamiltonian theory is derived which allows for a simultaneous study of the transverse and longitudinal motion as well as the coupling between both motions. It includes azimuthally varying magnetic fields and therefore describes phenomena which are due to the interfering influences of a given geometrical dee system with the azimuthally varying part of the magnetic field. As an example the electric gap crossing resonance is treated. The second part deals with space charge effects in a AVF cyclotron. The properties of the bunch, like the sizes, emittances and momentum spread, are represented in terms of second order moments of the phase space distribution function, and two sets of differential equations are derived which describe the time evolution of these moments under space charge conditions. The model takes into account the coupling between the longitudinal and radial motion, and the fact that the revolution frequency of the particles is independent of their energy. The analytical models developed can be applied to a given cyclotron by adopting the relevant parameters. Some calculations are presented for the small 3 MeV Iscochroneous Low Energy Cyclotron ILEC which is presently under construction at the Eindhoven University. Also some attention to the construction of this machine is given. (H.W.). 49 refs.; 37 figs

The electron accelerator Ridgetron

International Nuclear Information System (INIS)

Hayashizaki, N.; Hattori, T.; Odera, M.; Fujisawa, T.

1999-01-01

Many electron accelerators of DC or RF type have been widely used for electron beam irradiation (curing, crosslinking of polymers, sterilization of medical disposables, preservation of food, etc.). Regardless of the acceleration energy, the accelerators to be installed in industrial facilities, have to satisfy the requires of compact size, low power consumption and stable operation. The DC accelerator is realized very compact in the energy under 300 keV, however, it is large to prevent the discharge of an acceleration column in the energy over 300 keV. The RF electron accelerator Ridgetron has been developed to accelerate the continuous beam of the 0.5-10 MeV range in compact space. It is the first example as an electron accelerator incorporated a ridged RF cavity. A prototype system of final energy of 2.5 MeV has been studied to confirm the feasibility at present

Accelerated rotation with orbital angular momentum modes

CSIR Research Space (South Africa)

Schulze, C

2015-04-01

Full Text Available . As the angular acceleration takes place in a bounded space, the azimuthal degree of freedom, such fields accelerate periodically as they propagate. Notably, the amount of angular acceleration is not limited by paraxial considerations, may be tailored for large...

Large electrostatic accelerators

Energy Technology Data Exchange (ETDEWEB)

Jones, C.M.

1984-01-01

The increasing importance of energetic heavy ion beams in the study of atomic physics, nuclear physics, and materials science has partially or wholly motivated the construction of a new generation of large electrostatic accelerators designed to operate at terminal potentials of 20 MV or above. In this paper, the author briefly discusses the status of these new accelerators and also discusses several recent technological advances which may be expected to further improve their performance. The paper is divided into four parts: (1) a discussion of the motivation for the construction of large electrostatic accelerators, (2) a description and discussion of several large electrostatic accelerators which have been recently completed or are under construction, (3) a description of several recent innovations which may be expected to improve the performance of large electrostatic accelerators in the future, and (4) a description of an innovative new large electrostatic accelerator whose construction is scheduled to begin next year. Due to time and space constraints, discussion is restricted to consideration of only tandem accelerators.

Large electrostatic accelerators

International Nuclear Information System (INIS)

Jones, C.M.

1984-01-01

The increasing importance of energetic heavy ion beams in the study of atomic physics, nuclear physics, and materials science has partially or wholly motivated the construction of a new generation of large electrostatic accelerators designed to operate at terminal potentials of 20 MV or above. In this paper, the author briefly discusses the status of these new accelerators and also discusses several recent technological advances which may be expected to further improve their performance. The paper is divided into four parts: (1) a discussion of the motivation for the construction of large electrostatic accelerators, (2) a description and discussion of several large electrostatic accelerators which have been recently completed or are under construction, (3) a description of several recent innovations which may be expected to improve the performance of large electrostatic accelerators in the future, and (4) a description of an innovative new large electrostatic accelerator whose construction is scheduled to begin next year. Due to time and space constraints, discussion is restricted to consideration of only tandem accelerators

Focusing of geodesic congruences in an accelerated expanding Universe

International Nuclear Information System (INIS)

Albareti, F.D.; Cembranos, J.A.R.; Cruz-Dombriz, A. de la

2012-01-01

We study the accelerated expansion of the Universe through its consequences on a congruence of geodesics. We make use of the Raychaudhuri equation which describes the evolution of the expansion rate for a congruence of timelike or null geodesics. In particular, we focus on the space-time geometry contribution to this equation. By straightforward calculation from the metric of a Robertson-Walker cosmological model, it follows that in an accelerated expanding Universe the space-time contribution to the Raychaudhuri equation is positive for the fundamental congruence, favoring a non-focusing of the congruence of geodesics. However, the accelerated expansion of the present Universe does not imply a tendency of the fundamental congruence to diverge. It is shown that this is in fact the case for certain congruences of timelike geodesics without vorticity. Therefore, the focusing of geodesics remains feasible in an accelerated expanding Universe. Furthermore, a negative contribution to the Raychaudhuri equation from space-time geometry which is usually interpreted as the manifestation of the attractive character of gravity is restored in an accelerated expanding Robertson-Walker space-time at high speeds

Focusing of geodesic congruences in an accelerated expanding Universe

Energy Technology Data Exchange (ETDEWEB)

Albareti, F.D.; Cembranos, J.A.R. [Departamento de Física Teórica I, Universidad Complutense de Madrid, Ciudad Universitaria, E-28040 Madrid (Spain); Cruz-Dombriz, A. de la, E-mail: fdalbareti@estumail.ucm.es, E-mail: cembra@fis.ucm.es, E-mail: alvaro.delacruz-dombriz@uct.ac.za [Astrophysics, Cosmology and Gravity Centre (ACGC), University of Cape Town, 7701 Rondebosch, Cape Town (South Africa)

2012-12-01

We study the accelerated expansion of the Universe through its consequences on a congruence of geodesics. We make use of the Raychaudhuri equation which describes the evolution of the expansion rate for a congruence of timelike or null geodesics. In particular, we focus on the space-time geometry contribution to this equation. By straightforward calculation from the metric of a Robertson-Walker cosmological model, it follows that in an accelerated expanding Universe the space-time contribution to the Raychaudhuri equation is positive for the fundamental congruence, favoring a non-focusing of the congruence of geodesics. However, the accelerated expansion of the present Universe does not imply a tendency of the fundamental congruence to diverge. It is shown that this is in fact the case for certain congruences of timelike geodesics without vorticity. Therefore, the focusing of geodesics remains feasible in an accelerated expanding Universe. Furthermore, a negative contribution to the Raychaudhuri equation from space-time geometry which is usually interpreted as the manifestation of the attractive character of gravity is restored in an accelerated expanding Robertson-Walker space-time at high speeds.

Accelerators for research and applications

International Nuclear Information System (INIS)

Alonso, J.R.

1990-06-01

The newest particle accelerators are almost always built for extending the frontiers of research, at the cutting edge of science and technology. Once these machines are operating and these technologies mature, new applications are always found, many of which touch our lives in profound ways. The evolution of accelerator technologies will be discussed, with descriptions of accelerator types and characteristics. The wide range of applications of accelerators will be discussed, in fields such as nuclear science, medicine, astrophysics and space-sciences, power generation, airport security, materials processing and microcircuit fabrication. 13 figs

Illinois Accelerator Research Center

Science.gov (United States)

Kroc, Thomas K.; Cooper, Charlie A.

The Illinois Accelerator Research Center (IARC) hosts a new accelerator development program at Fermi National Accelerator Laboratory. IARC provides access to Fermi's state-of-the-art facilities and technologies for research, development and industrialization of particle accelerator technology. In addition to facilitating access to available existing Fermi infrastructure, the IARC Campus has a dedicated 36,000 ft2 Heavy Assembly Building (HAB) with all the infrastructure needed to develop, commission and operate new accelerators. Connected to the HAB is a 47,000 ft2 Office, Technology and Engineering (OTE) building, paid for by the state, that has office, meeting, and light technical space. The OTE building, which contains the Accelerator Physics Center, and nearby Accelerator and Technical divisions provide IARC collaborators with unique access to world class expertise in a wide array of accelerator technologies. At IARC scientists and engineers from Fermilab and academia work side by side with industrial partners to develop breakthroughs in accelerator science and translate them into applications for the nation's health, wealth and security.

High-energy inverse free-electron laser accelerator

International Nuclear Information System (INIS)

Courant, E.D.; Pellegrini, C.; Zakowicz, W.

1985-01-01

We study the inverse free electron laser (IFEL) accelerator and show that it can accelerate electrons to the few hundred GeV region with average acceleration rates of the order of 200 meV/m. Several possible accelerating structures are analyzed, and the effect of synchrotron radiation losses is studied. The longitudinal phase stability of accelerated particles is also analyzed. A Hamiltonian description, which takes into account the dissipative features of the IFEL accelerator, is introduced to study perturbations from the resonant acceleration. Adiabatic invariants are obtained and used to estimate the change of the electron phase space density during the acceleration process

The auroral electron accelerator

International Nuclear Information System (INIS)

Bryant, D.A.; Hall, D.S.

1989-01-01

A model of the auroral electron acceleration process is presented in which the electrons are accelerated resonantly by lower-hybrid waves. The essentially stochastic acceleration process is approximated for the purposes of computation by a deterministic model involving an empirically derived energy transfer function. The empirical function, which is consistent with all that is known of electron energization by lower-hybrid waves, allows many, possibly all, observed features of the electron distribution to be reproduced. It is suggested that the process occurs widely in both space and laboratory plasmas. (author)

CAIPIRINHA accelerated SPACE enables 10-min isotropic 3D TSE MRI of the ankle for optimized visualization of curved and oblique ligaments and tendons.

Science.gov (United States)

Kalia, Vivek; Fritz, Benjamin; Johnson, Rory; Gilson, Wesley D; Raithel, Esther; Fritz, Jan

2017-09-01

To test the hypothesis that a fourfold CAIPIRINHA accelerated, 10-min, high-resolution, isotropic 3D TSE MRI prototype protocol of the ankle derives equal or better quality than a 20-min 2D TSE standard protocol. Following internal review board approval and informed consent, 3-Tesla MRI of the ankle was obtained in 24 asymptomatic subjects including 10-min 3D CAIPIRINHA SPACE TSE prototype and 20-min 2D TSE standard protocols. Outcome variables included image quality and visibility of anatomical structures using 5-point Likert scales. Non-parametric statistical testing was used. P values ≤0.001 were considered significant. Edge sharpness, contrast resolution, uniformity, noise, fat suppression and magic angle effects were without statistical difference on 2D and 3D TSE images (p > 0.035). Fluid was mildly brighter on intermediate-weighted 2D images (p acceleration enables high-spatial resolution oblique and curved planar MRI of the ankle and visualization of ligaments, tendons and joints equally well or better than a more time-consuming anisotropic 2D TSE MRI. • High-resolution 3D TSE MRI improves visualization of ankle structures. • Limitations of current 3D TSE MRI include long scan times. • 3D CAIPIRINHA SPACE allows now a fourfold-accelerated data acquisition. • 3D CAIPIRINHA SPACE enables high-spatial-resolution ankle MRI within 10 min. • 10-min 3D CAIPIRINHA SPACE produces equal-or-better quality than 20-min 2D TSE.

ELECTROMAGNETIC SIMULATIONS OF LINEAR PROTON ACCELERATOR STRUCTURES USING DIELECTRIC WALL ACCELERATORS

International Nuclear Information System (INIS)

Nelson, S; Poole, B; Caporaso, G

2007-01-01

Proton accelerator structures for medical applications using Dielectric Wall Accelerator (DWA) technology allow for the utilization of high electric field gradients on the order of 100 MV/m to accelerate the proton bunch. Medical applications involving cancer therapy treatment usually desire short bunch lengths on the order of hundreds of picoseconds in order to limit the extent of the energy deposited in the tumor site (in 3D space, time, and deposited proton charge). Electromagnetic simulations of the DWA structure, in combination with injections of proton bunches have been performed using 3D finite difference codes in combination with particle pushing codes. Electromagnetic simulations of DWA structures includes these effects and also include the details of the switch configuration and how that switch time affects the electric field pulse which accelerates the particle beam

Collective ion acceleration

International Nuclear Information System (INIS)

Godfrey, B.B.; Faehl, R.J.; Newberger, B.S.; Shanahan, W.R.; Thode, L.E.

1977-01-01

Progress achieved in the understanding and development of collective ion acceleration is presented. Extensive analytic and computational studies of slow cyclotron wave growth on an electron beam in a helix amplifier were performed. Research included precise determination of linear coupling between beam and helix, suppression of undesired transients and end effects, and two-dimensional simulations of wave growth in physically realizable systems. Electrostatic well depths produced exceed requirements for the Autoresonant Ion Acceleration feasibility experiment. Acceleration of test ions to modest energies in the troughs of such waves was also demonstrated. Smaller efforts were devoted to alternative acceleration mechanisms. Langmuir wave phase velocity in Converging Guide Acceleration was calculated as a function of the ratio of electron beam current to space-charge limiting current. A new collective acceleration approach, in which cyclotron wave phase velocity is varied by modulation of electron beam voltage, is proposed. Acceleration by traveling Virtual Cathode or Localized Pinch was considered, but appears less promising. In support of this research, fundamental investigations of beam propagation in evacuated waveguides, of nonneutral beam linear eigenmodes, and of beam stability were carried out. Several computer programs were developed or enhanced. Plans for future work are discussed

Linear induction accelerators

International Nuclear Information System (INIS)

Briggs, R.J.

1986-06-01

The development of linear induction accelerators has been motivated by applications requiring high-pulsed currents of charged particles at voltages exceeding the capability of single-stage, diode-type accelerators and at currents too high for rf accelerators. In principle, one can accelerate charged particles to arbitrarily high voltages using a multi-stage induction machine, but the 50-MeV, 10-kA Advanced Test Accelerator (ATA) at LLNL is the highest voltage machine in existence at this time. The advent of magnetic pulse power systems makes sustained operation at high-repetition rates practical, and this capability for high-average power is very likely to open up many new applications of induction machines in the future. This paper surveys the US induction linac technology with primary emphasis on electron machines. A simplified description of how induction machines couple energy to the electron beam is given, to illustrate many of the general issues that bound the design space of induction linacs

Intrinsic space charge resonances and the space charge limit

International Nuclear Information System (INIS)

Parzen, G.

1990-01-01

A study has been done of the dependence of the space charge limit on the choice of ν-values using a simulation program. This study finds a strong dependence of the space charge limit on the location of the ν-values relative to the intrinsic space charge resonances, which are driven by the space charge forces due to the beam itself. Four accelerators were studied. For some of these accelerators the study suggest that the space charge limit can be increased by about a factor of 2 proper choice of the ν-values. The lower order 1/2 and 1/4 intrinsic resonances appear to be the important resonances. There is some evidence for effects due to the 1/6 and 1/8 intrinsic resonances, particularly for larger synchrotrons. 5 figs

CAS CERN Accelerator School: Fourth general accelerator physics course

International Nuclear Information System (INIS)

Turner, S.

1991-01-01

The fourth CERN Accelerator School (CAS) basic course on General Accelerator Physics was given at KFA, Juelich, from 17 to 28 September 1990. Its syllabus was based on the previous similar courses held at Gif-sur-Yvette in 1984, Aarhus 1986, and Salamanca 1988, and whose proceedings were published as CERN Reports 85-19, 87-10, and 89-05, respectively. However, certain topics were treated in a different way, improved or extended, while new subjects were introduced. All of these appear in the present proceedings, which include lectures or seminars on the history and applications of accelerators, phase space and emittance, chromaticity, beam-beam effects, synchrotron radiation, radiation damping, tune measurement, transition, electron cooling, the designs of superconducting magnets, ring lattices, conventional RF cavities and ring RF systems, and an introduction to cyclotrons. (orig.)

Dynamics and acceleration in linear structures

International Nuclear Information System (INIS)

Le Duff, J.

1985-06-01

Basic methods of linear acceleration are reviewed. Both cases of non relativistic and ultra relativistic particles are considered. Induction linac, radiofrequency quadrupole are mentioned. Fundamental parameters of accelerating structures are recalled; they are transit time factor, shunt impedance, quality factor and stored energy, phase velocity and group velocity, filling time, space harmonics in loaded waveguides. Energy gain in linear accelerating structures is considered through standing wave structures and travelling wave structures. Then particle dynamics in linear accelerators is studied: longitudinal motion, transverse motion and dynamics in RFQ

Maximum Acceleration Recording Circuit

Science.gov (United States)

Bozeman, Richard J., Jr.

1995-01-01

Coarsely digitized maximum levels recorded in blown fuses. Circuit feeds power to accelerometer and makes nonvolatile record of maximum level to which output of accelerometer rises during measurement interval. In comparison with inertia-type single-preset-trip-point mechanical maximum-acceleration-recording devices, circuit weighs less, occupies less space, and records accelerations within narrower bands of uncertainty. In comparison with prior electronic data-acquisition systems designed for same purpose, circuit simpler, less bulky, consumes less power, costs and analysis of data recorded in magnetic or electronic memory devices. Circuit used, for example, to record accelerations to which commodities subjected during transportation on trucks.

A comparison between the effect of zirconia-coated FRC and glass fiber posts on the fracture resistance of endodontically treated teeth

Directory of Open Access Journals (Sweden)

Ezatollah Jalalian

2014-04-01

Full Text Available   Background and Aims : The root fracture resistance of endodontically treated teeth depends on the types of posts. The aim of this study was to compare the effect of two types of bonded non-metallic posts with different elasticity modulus on the fracture resistance of endodontically treated teeth under compressive loads.   Materials and Methods: In this in vitro experimental study, 20 fresh extracted mandibular premolars were selected and sectioned adjacent to the CEJ and then were endodontically treated. The specimens were randomly divided into two groups (n=10. After post space preparations, the fiber RTD Light posts (R.T.D, France and zirconia coated fiber posts (ICE light, Danville were cemented into the root canals. Composite resin (Lumiglass R.T.D, France cores were built up. Aluminium foil was used to mimic the PDL, and the specimens were embedded in acrylic resin and tested in a Universal Testing Machine. A compressive load was applied at a 90 degree angle until fracture at a crosshead speed of 1mm/min. Data were analyzed using one-way ANOVA and T test .   Results: The mean fracture resistance of R.T.D group was (1083.11 ± 156.74 (N and the mean of ICE light group was (865.18 ± 106.24 (N. The highest mean fracture resistance was observed in RTD fiberglass and a statistically significant difference was observed between the two groups (P<0.001.   Conclusion: FRC posts with zirconia coating due to unfavorable fractures of the teeth should be used with caution, and thus, fiber posts are preferred.

Commissioning the GTA accelerator

International Nuclear Information System (INIS)

Sander, O.R.; Atkins, W.H.; Bolme, G.O.; Bowling, S.; Brown, S.; Cole, R.; Gilpatrick, J.D.; Garnett, R.; Guy, F.W.; Ingalls, W.B.; Johnson, K.F.; Kerstiens, D.; Little, C.; Lohsen, R.A.; Lloyd, S.; Lysenko, W.P.; Mottershead, C.T.; Neuschaefer, G.; Power, J.; Rusthoi, D.P.; Sandoval, D.P. Stevens, R.R. Jr.; Vaughn, G.; Wadlinger, E.A.; Yuan, V.; Connolly, R.; Weiss, R.; Saadatmand, K.

1992-01-01

The Ground Test Accelerator (GTA) is supported by the Strategic Defense command as part of their Neutral Particle Beam (NPB) program. Neutral particles have the advantage that in space they are unaffected by the earth's magnetic field and travel in straight lines unless they enter the earth's atmosphere and become charged by stripping. Heavy particles are difficult to stop and can probe the interior of space vehicles; hence, NPB can function as a discriminator between warheads and decoys. We are using GTA to resolve the physics and engineering issues related to accelerating, focusing, and steering a high-brightness, high-current H - beam and then neutralizing it. Our immediate goal is to produce a 24-MeV, 50mA device with a 2% duty factor

Analogies between Kruskal space and de Sitter space

International Nuclear Information System (INIS)

Rindler, W.

1986-01-01

Kruskal space is the analytical completion of Schwarzschild space and it consists of two outside and two inside Schwarzchild regions. Under suppression of the two angular coordinates, this space is usually diagrammed in terms of the Kruskal coordinates, μ,upsilon, much like Minkowski space is in terms of x, y. In particular, radial light paths correspond to +- 45 0 lines, the hyperbolas of μ/sup 2/ - upsilon/sup 2/ = a/sup 2/ represent uniformly accelerated particles (these being at rest in outer Schwarzschild space), and Lorentz transformations in μ, upsilon map the space into itself. Hermann Weyl first gave the analytic completion of de Sitter space as a hyper-hyperboloid μ/sub 1//sup 2/ + μ/sub 2//sup 2/ + μ/sub 3//sup 2/ + μ/sub 4//sup 2/ - upsilon/sup 2/ = a/sup 2/ in five-dimensional Minkowski space, which also contains two outside inside de Sitter regions. In a Weyl diagram, μ/sub 3/ and μ/sub 4/ are suppressed. There are many analogies: Lorentz transformations in μ/sub i/, upsilon map Weyl space into itself, the +- 45 0 generators are light paths, timelike plane hyperbolic sections are uniformly accelerated particles, and the horizon structure relative to each free worldline is analogous to the absolute horizon structure in Kruskal space

Coincident ion acceleration and electron extraction for space propulsion using the self-bias formed on a set of RF biased grids bounding a plasma source

International Nuclear Information System (INIS)

Rafalskyi, D; Aanesland, A

2014-01-01

We propose an alternative method to accelerate ions in classical gridded ion thrusters and ion sources such that co-extracted electrons from the source may provide beam space charge neutralization. In this way there is no need for an additional electron neutralizer. The method consists of applying RF voltage to a two-grid acceleration system via a blocking capacitor. Due to the unequal effective area of the two grids in contact with the plasma, a dc self-bias is formed, rectifying the applied RF voltage. As a result, ions are continuously accelerated within the grid system while electrons are emitted in brief instants within the RF period when the RF space charge sheath collapses. This paper presents the first experimental results and a proof-of-principle. Experiments are carried out using the Neptune thruster prototype which is a gridded Inductively Coupled Plasma (ICP) source operated at 4 MHz, attached to a larger beam propagation chamber. The RF power supply is used both for the ICP discharge (plasma generation) and powering the acceleration grids via a capacitor for ion acceleration and electron extraction without any dc power supplies. The ion and electron energies, particle flux and densities are measured using retarding field energy analyzers (RFEA), Langmuir probes and a large beam target. The system operates in Argon and N 2 . The dc self-bias is found to be generated within the gridded extraction system in all the range of operating conditions. Broad quasi-neutral ion-electron beams are measured in the downstream chamber with energies up to 400 eV. The beams from the RF acceleration method are compared with classical dc acceleration with an additional external electron neutralizer. It is found that the two acceleration techniques provide similar performance, but the ion energy distribution function from RF acceleration is broader, while the floating potential of the beam is lower than for the dc accelerated beam. (paper)

LeRC rail accelerators: test designs and diagnostic techniques

International Nuclear Information System (INIS)

Zana, L.M.; Kerslake, W.R.; Sturman, J.C.; Wang, S.Y.; Terdan, F.F.

1984-01-01

The feasibility of using rail accelerators for various in-space and to-space propulsion applications was investigated. A 1 meter, 24 sq mm bore accelerator was designed with the goal of demonstrating projectile velocities of 15 km/sec using a peak current of 200 kA. A second rail accelerator, 1 meter long with a 156.25 sq mm bore, was designed with clear polycarbonate sidewalls to permit visual observation of the plasma arc. A study of available diagnostic techniques and their application to the rail accelerator is presented. Specific topics of discussion include the use of interferometry and spectroscopy to examine the plasma armature as well as the use of optical sensors to measure rail displacement during acceleration. Standard diagnostics such as current and voltage measurements are also discussed. 15 references

Space lattice focusing on the way to extremely low accelerated beam divergence

CERN Document Server

Kushin, V V

1999-01-01

It is widely known the multiple channel acceleration is the most adequate way to save initial beam parameters due to the possibility of decreasing Coulomb forces in intensive input beams. To keep beam initial emittance and divergence for high enough specific value of the injection ion beam during acceleration the input beam should be split on multiple beams and every the micro beam must be screened from each other as much as possible. On the other hand, it is very much desirable to keep the total macro beam rather compact transversally and try to accelerate all the micro beams within the same accelerator structure at the same RF field. Attempts to use conventional quadruple focusing channels both RF and electrostatic for multiple beam acceleration usually lead to extremely complicate and bulky construction of the structure. We suppose multiple beam linac channels with alternating phase focusing (APF) as more adequate for the purpose while they are limited by less values of beam capture into acceleration proce...

LOO: a low-order nonlinear transport scheme for acceleration of method of characteristics

International Nuclear Information System (INIS)

Li, Lulu; Smith, Kord; Forget, Benoit; Ferrer, Rodolfo

2015-01-01

This paper presents a new physics-based multi-grid nonlinear acceleration method: the low-order operator method, or LOO. LOO uses a coarse space-angle multi-group method of characteristics (MOC) neutron transport calculation to accelerate the fine space-angle MOC calculation. LOO is designed to capture more angular effects than diffusion-based acceleration methods through a transport-based low-order solver. LOO differs from existing transport-based acceleration schemes in that it emphasizes simplified coarse space-angle characteristics and preserves physics in quadrant phase-space. The details of the method, including the restriction step, the low-order iterative solver and the prolongation step are discussed in this work. LOO shows comparable convergence behavior to coarse mesh finite difference on several two-dimensional benchmark problems while not requiring any under-relaxation, making it a robust acceleration scheme. (author)

Ion optics for accelerators

International Nuclear Information System (INIS)

Enge, H.A.

1974-01-01

A review is given of ion-optic devices used in particle accelerators, including electrostatic lenses, magnetic quadrupoles, and deflecting magnets. Tube focusing in dc accelerators is also treated, and a novel scheme for shaping the electrodes to produce strong focusing is described. The concepts of emittance (phase space) and emittance conservation are briefly discussed. Chromatic and spatial aberrations are introduced, and it is shown how they can be calculated and sometimes substantially reduced. Some examples are given

Analysis of the dependence of surfatron acceleration of electrons by an electromagnetic wave in space plasma on the particle momentum along the wave front

Energy Technology Data Exchange (ETDEWEB)

Erokhin, A. N., E-mail: nerokhin@mx.iki.rssi.ru [People’s Friendship University of Russia (Russian Federation); Zol’nikova, N. N. [Russian Academy of Sciences, Space Research Institute (Russian Federation); Erokhin, N. S. [People’s Friendship University of Russia (Russian Federation)

2016-01-15

Based on the numerical solution of the nonlinear nonstationary second-order equation for the wave phase on the particle trajectory, the dynamics of surfatron acceleration of electrons by an electromagnetic wave propagating across the external magnetic field in space plasma is analyzed as a function of the electron momentum along the wave front. Numerical calculations show that, for strongly relativistic initial values of the electron momentum component along the wave front g{sub y}(0) (the other parameters of the problem being the same), electrons are trapped into the regime of ultrarelativistic surfatron acceleration within a certain interval of the initial wave phase Ψ(0) on the particle trajectory. It is assumed in the calculations that vertical bar Ψ(0) vertical bar ≤ π. For strongly relativistic values of g{sub y}(0), electrons are immediately trapped by the wave for 19% of the initial values of the phase Ψ(0) (favorable phases). For the rest of the values of Ψ(0), trapping does not occur even at long times. This circumstance substantially simplifies estimations of the wave damping due to particle acceleration in subsequent calculations. The dynamics of the relativistic factor and the components of the electron velocity and momentum under surfatron acceleration is also analyzed. The obtained results are of interest for the development of modern concepts of possible mechanisms of generation of ultrarelativistic particle fluxes in relatively calm space plasma, as well as for correct interpretation of observational data on the fluxes of such particles and explanation of possible reasons for the deviation of ultrarelativistic particle spectra detected in the heliosphere from the standard power-law scalings and the relation of these variations to space weather and large-scale atmospheric processes similar to tropical cyclones.

Analysis of the dependence of surfatron acceleration of electrons by an electromagnetic wave in space plasma on the particle momentum along the wave front

International Nuclear Information System (INIS)

Erokhin, A. N.; Zol’nikova, N. N.; Erokhin, N. S.

2016-01-01

Based on the numerical solution of the nonlinear nonstationary second-order equation for the wave phase on the particle trajectory, the dynamics of surfatron acceleration of electrons by an electromagnetic wave propagating across the external magnetic field in space plasma is analyzed as a function of the electron momentum along the wave front. Numerical calculations show that, for strongly relativistic initial values of the electron momentum component along the wave front g y (0) (the other parameters of the problem being the same), electrons are trapped into the regime of ultrarelativistic surfatron acceleration within a certain interval of the initial wave phase Ψ(0) on the particle trajectory. It is assumed in the calculations that vertical bar Ψ(0) vertical bar ≤ π. For strongly relativistic values of g y (0), electrons are immediately trapped by the wave for 19% of the initial values of the phase Ψ(0) (favorable phases). For the rest of the values of Ψ(0), trapping does not occur even at long times. This circumstance substantially simplifies estimations of the wave damping due to particle acceleration in subsequent calculations. The dynamics of the relativistic factor and the components of the electron velocity and momentum under surfatron acceleration is also analyzed. The obtained results are of interest for the development of modern concepts of possible mechanisms of generation of ultrarelativistic particle fluxes in relatively calm space plasma, as well as for correct interpretation of observational data on the fluxes of such particles and explanation of possible reasons for the deviation of ultrarelativistic particle spectra detected in the heliosphere from the standard power-law scalings and the relation of these variations to space weather and large-scale atmospheric processes similar to tropical cyclones

High-powered pulsed-ion-beam acceleration and transport

Energy Technology Data Exchange (ETDEWEB)

Humphries, S. Jr.; Lockner, T.R.

1981-11-01

The state of research on intense ion beam acceleration and transport is reviewed. The limitations imposed on ion beam transport by space charge effects and methods available for neutralization are summarized. The general problem of ion beam neutralization in regions free of applied electric fields is treated. The physics of acceleration gaps is described. Finally, experiments on multi-stage ion acceleration are summarized.

High-powered pulsed-ion-beam acceleration and transport

International Nuclear Information System (INIS)

Humphries, S. Jr.; Lockner, T.R.

1981-11-01

The state of research on intense ion beam acceleration and transport is reviewed. The limitations imposed on ion beam transport by space charge effects and methods available for neutralization are summarized. The general problem of ion beam neutralization in regions free of applied electric fields is treated. The physics of acceleration gaps is described. Finally, experiments on multi-stage ion acceleration are summarized

Computer simulation of dynamic processes on accelerators

International Nuclear Information System (INIS)

Kol'ga, V.V.

1979-01-01

The problems of computer numerical investigation of motion of accelerated particles in accelerators and storages, an effect of different accelerator systems on the motion, determination of optimal characteristics of accelerated charged particle beams are considered. Various simulation representations are discussed which describe the accelerated particle dynamics, such as the enlarged particle method, the representation where a great number of discrete particle is substituted for a field of continuously distributed space charge, the method based on determination of averaged beam characteristics. The procedure is described of numerical studies involving the basic problems, viz. calculation of closed orbits, establishment of stability regions, investigation of resonance propagation determination of the phase stability region, evaluation of the space charge effect the problem of beam extraction. It is shown that most of such problems are reduced to solution of the Cauchy problem using a computer. The ballistic method which is applied to solution of the boundary value problem of beam extraction is considered. It is shown that introduction into the equation under study of additional members with the small positive regularization parameter is a general idea of the methods for regularization of noncorrect problems [ru

Laser-controlled collective ion accelerator

International Nuclear Information System (INIS)

O'Shea, P.G.; Destler, W.W.; Rodgers, J.; Segalov, Z.

1986-01-01

We report first results from a new collective accelerator experiment in which a laser-controlled channel of ionization is used to control the propagation of the potential well at the front of an intense relativistic electron beam injected at currents above the space-charge limit. The controlled acceleration of protons at the rate of 40 MeV/m over a distance of 45 cm is reported, in good agreement with experimental design values

Applications of proton and deuteron accelerators

Energy Technology Data Exchange (ETDEWEB)

Todd, A.M.M. (Grumman Corporate Research Center, Princeton, NJ (United States))

1993-06-01

Applications of positive and negative hydrogen and deuterium ion accelerators beyond basic research are increasing. Large scale proposed national laboratory/industrial projects include the Accelerator Production of Tritium (APT) which will utilize protons, and the International Fusion Material Irradiation Facility (IFMIF) which will accelerate a deuteron beam into a lithium target. At the small scale end, radio-frequency quadrupole (RFQ) accelerator based systems have been built for neutron activation analysis and for applications such as explosive detection. At an intermediate scale, the Loma Linda proton therapy accelerator is now successfully treating a full schedule of patients, and more than half a dozen such hospital based units are under active study world-wide. At this same scale, there are also several ongoing negative ion, military accelerator projects which include the Continuous Wave Deuterium Demonstrator (CWDD) and the Neutral Particle Beam Space Experiment (NPBSE). These respective deuterium and hydrogen accelerators, which have not been previously described, are the focus of this paper. (orig.)

ACCELERATION PHASES OF A SOLAR FILAMENT DURING ITS ERUPTION

International Nuclear Information System (INIS)

Song, H. Q.; Chen, Y.; Fu, H.; Zhang, J.; Cheng, X.; LI, G.

2015-01-01

Filament eruptions often lead to coronal mass ejections (CMEs), which can affect critical technological systems in space and on the ground when they interact with the geo-magnetosphere at high speeds. Therefore, it is important to investigate the acceleration mechanisms of CMEs in solar/space physics. Based on observations and simulations, the resistive magnetic reconnection and the ideal instability of magnetic flux ropes have been proposed to accelerate CMEs. However, it remains uncertain whether both of them play a comparable role during a particular eruption. It has been extremely difficult to separate their contributions as they often work in a close time sequence during one fast acceleration phase. Here we report an intriguing filament eruption event, which shows two apparently separated fast acceleration phases and provides us an excellent opportunity to address the issue. Through analyzing the correlations between velocity (acceleration) and soft (hard) X-ray profiles, we suggest that the instability and magnetic reconnection make a major contribution during the first and second fast acceleration phases, respectively. Further, we find that both processes have a comparable contribution to the filament acceleration in this event

Photocathodes in accelerator applications

International Nuclear Information System (INIS)

Fraser, J.S.; Sheffield, R.L.; Gray, E.R.; Giles, P.M.; Springer, R.W.; Loebs, V.A.

1987-01-01

Some electron accelerator applications require bursts of short pulses at high microscopic repetition rates and high peak brightness. A photocathode, illuminated by a mode-locked laser, is well suited to filling this need. The intrinsic brightness of a photoemitter beam is high; experiments are under way at Los Alamos to study the brightness of short bunches with high space charge after acceleration. A laser-illuminated Cs 3 Sb photoemitter is located in the first rf cavity of an injector linac. Diagnostics include a pepper-pot emittance analyzer, a magnetic spectrometer, and a streak camera

Accelerator physics and modeling: Proceedings

International Nuclear Information System (INIS)

Parsa, Z.

1991-01-01

This report contains papers on the following topics: Physics of high brightness beams; radio frequency beam conditioner for fast-wave free-electron generators of coherent radiation; wake-field and space-charge effects on high brightness beams. Calculations and measured results for BNL-ATF; non-linear orbit theory and accelerator design; general problems of modeling for accelerators; development and application of dispersive soft ferrite models for time-domain simulation; and bunch lengthening in the SLC damping rings

Self-accelerating parabolic cylinder waves in 1-D

Energy Technology Data Exchange (ETDEWEB)

Yuce, C., E-mail: cyuce@anadolu.edu.tr

2016-11-25

Highlights: • We find a new class of self-accelerating waves. • We show that parabolic cylinder waves self-accelerates in a parabolic potential. • We discuss that truncated parabolic cylinder waves propagates large distance without almost being non-diffracted in free space. - Abstract: We introduce a new self-accelerating wave packet solution of the Schrodinger equation in one dimension. We obtain an exact analytical parabolic cylinder wave for the inverted harmonic potential. We show that truncated parabolic cylinder waves exhibits their accelerating feature.

CAS CERN Accelerator School. 5. Advanced accelerator physics course. Proceedings. Vol. 2

International Nuclear Information System (INIS)

Turner, S.

1995-01-01

The fifth CERN Accelerator School (CAS) advanced course on Accelerator Physics was given at the Paradise Hotel, Rhodes, Greece from 20 September to 1 October 1993. Its syllabus was based on the previous similar courses held at Oxford 1985, Berlin 1987, Uppsala 1989 and Noordwijkerhout 1991, and whose proceedings were published as CERN Reports 97-03, 89-01, 90-04 and 92-01, respectively. The present volumes are intended to replace and to bring up to date all the material in earlier publications. They contain not only all the lectures given in the Rhodes course but a number of important contributions to previous courses which are thought to be essential for a complete understanding of all aspects of the design and construction of particle accelerators at an advanced level. They include sections on Hamiltonian equations and accelerator optics, chromaticity and dynamic beam aperture, particle tracking, the kinetic theory, longitudinal beam optics, coherent instabilities, beam-beam dynamics, intra-beam scattering, beam cooling, Schottky noise, beam radiation, neutralisation, beam polarisation, radio-frequency quadrupoles, as well as chapters on space charge, superconducting magnets, crystal bending, beam-beam measurement and accelerator medical applications. (orig.)

CAS CERN Accelerator School. 5. Advanced accelerator physics course. Proceedings. Vol. 1

Energy Technology Data Exchange (ETDEWEB)

Turner, S [ed.

1995-11-22

The fifth CERN Accelerator School (CAS) advanced course on Accelerator Physics was given at the Paradise Hotel, Rhodes, Greece from 20 September to 1 October 1993. Its syllabus was based on the previous similar courses held at Oxford 1985, Berlin 1987, Uppsala 1989 and Noordwijkerhout 1991, and whose proceedings were published as CERN Reports 87-03, 89-01, 90-04 and 92-01, respectively. The present volumes are intended to replace and to bring up to date all the material in earlier publications. They contain not only all the lectures given in the Rhodes course but a number of important contributions to previous courses which are thought to be essential for a complete understanding of all aspects of the design and construction of particle accelerators at an advanced level. They include sections on Hamiltonian equations and accelerator optics, chromaticity and dynamic beam aperture, particle tracking, the kinetic theory, longitudinal beam optics, coherent instabilities, beam-beam dynamics, intra-beam scattering, beam cooling, Schottky noise, beam radiation, neutralisation, beam polarisation, radio-frequency quadrupoles, as well as chapters on space charge, superconducting magnets, crystal bending, beam-beam measurement and accelerator medical applications. (orig.).

CAS CERN Accelerator School. 5. Advanced accelerator physics course. Proceedings. Vol. 1

International Nuclear Information System (INIS)

Turner, S.

1995-01-01

The fifth CERN Accelerator School (CAS) advanced course on Accelerator Physics was given at the Paradise Hotel, Rhodes, Greece from 20 September to 1 October 1993. Its syllabus was based on the previous similar courses held at Oxford 1985, Berlin 1987, Uppsala 1989 and Noordwijkerhout 1991, and whose proceedings were published as CERN Reports 87-03, 89-01, 90-04 and 92-01, respectively. The present volumes are intended to replace and to bring up to date all the material in earlier publications. They contain not only all the lectures given in the Rhodes course but a number of important contributions to previous courses which are thought to be essential for a complete understanding of all aspects of the design and construction of particle accelerators at an advanced level. They include sections on Hamiltonian equations and accelerator optics, chromaticity and dynamic beam aperture, particle tracking, the kinetic theory, longitudinal beam optics, coherent instabilities, beam-beam dynamics, intra-beam scattering, beam cooling, Schottky noise, beam radiation, neutralisation, beam polarisation, radio-frequency quadrupoles, as well as chapters on space charge, superconducting magnets, crystal bending, beam-beam measurement and accelerator medical applications. (orig.)

CAS CERN Accelerator School. 5. Advanced accelerator physics course. Proceedings. Vol. 2

Energy Technology Data Exchange (ETDEWEB)

Turner, S [ed.

1995-11-22

The fifth CERN Accelerator School (CAS) advanced course on Accelerator Physics was given at the Paradise Hotel, Rhodes, Greece from 20 September to 1 October 1993. Its syllabus was based on the previous similar courses held at Oxford 1985, Berlin 1987, Uppsala 1989 and Noordwijkerhout 1991, and whose proceedings were published as CERN Reports 97-03, 89-01, 90-04 and 92-01, respectively. The present volumes are intended to replace and to bring up to date all the material in earlier publications. They contain not only all the lectures given in the Rhodes course but a number of important contributions to previous courses which are thought to be essential for a complete understanding of all aspects of the design and construction of particle accelerators at an advanced level. They include sections on Hamiltonian equations and accelerator optics, chromaticity and dynamic beam aperture, particle tracking, the kinetic theory, longitudinal beam optics, coherent instabilities, beam-beam dynamics, intra-beam scattering, beam cooling, Schottky noise, beam radiation, neutralisation, beam polarisation, radio-frequency quadrupoles, as well as chapters on space charge, superconducting magnets, crystal bending, beam-beam measurement and accelerator medical applications. (orig.).

Accelerator mass spectrometry for radiocarbon dating

International Nuclear Information System (INIS)

Bronk, C.R.

1987-01-01

Accelerator mass spectrometry (AMS) has been used routinely for radiocarbon measurements for several years. This thesis describes theoretical work to understand the reasons for low accuracy and range and offers practical solutions. The production and transport of the ions used in the measurements are found to be the most crucial stages in the process. The theories behind ion production by sputtering are discussed and applied to the specific case of carbon sputtered by caesium. Experimental evidence is also examined in relation to the theories. The phenomena of space charge and lens aberrations are discussed along with the interaction between ion beams and gas molecules in the vacuum. Computer programs for calculating phase space transformations are then described; these are designed to help investigations of the effects of space charge and aberrations on AMS measurements. Calculations using these programs are discussed in relation both to measured ion beam profiles in phase space and to the current dependent transmission of ions through the Oxford radiocarbon accelerator. Improvements have been made to this accelerator and these are discussed in the context of the calculations. C - ions are produced directly from carbon dioxide at the Middleton High Intensity Sputter Source. Experiments to evaluate the performance of such a source are described and detailed design criteria established. An ion source designed and built specifically for radiocarbon measurements using carbon dioxide is described. Experiments to evaluate its performance and investigate the underlying physical processes are discussed. (author)

Using the FLUKA Monte Carlo Code to Simulate the Interactions of Ionizing Radiation with Matter to Assist and Aid Our Understanding of Ground Based Accelerator Testing, Space Hardware Design, and Secondary Space Radiation Environments

Science.gov (United States)

Reddell, Brandon

2015-01-01

Designing hardware to operate in the space radiation environment is a very difficult and costly activity. Ground based particle accelerators can be used to test for exposure to the radiation environment, one species at a time, however, the actual space environment cannot be duplicated because of the range of energies and isotropic nature of space radiation. The FLUKA Monte Carlo code is an integrated physics package based at CERN that has been under development for the last 40+ years and includes the most up-to-date fundamental physics theory and particle physics data. This work presents an overview of FLUKA and how it has been used in conjunction with ground based radiation testing for NASA and improve our understanding of secondary particle environments resulting from the interaction of space radiation with matter.

Tissue Engineering of Cartilage on Ground-Based Facilities

Science.gov (United States)

Aleshcheva, Ganna; Bauer, Johann; Hemmersbach, Ruth; Egli, Marcel; Wehland, Markus; Grimm, Daniela

2016-06-01

Investigations under simulated microgravity offer the opportunity for a better understanding of the influence of altered gravity on cells and the scaffold-free three-dimensional (3D) tissue formation. To investigate the short-term influence, human chondrocytes were cultivated for 2 h, 4 h, 16 h, and 24 h on a 2D Fast-Rotating Clinostat (FRC) in DMEM/F-12 medium supplemented with 10 % FCS. We detected holes in the vimentin network, perinuclear accumulations of vimentin after 2 h, and changes in the chondrocytes shape visualised by F-actin staining after 4 h of FRC-exposure. Scaffold-free cultivation of chondrocytes for 7 d on the Random Positioning Machine (RPM), the FRC and the Rotating Wall Vessel (RWV) resulted in spheroid formation, a phenomenon already known from spaceflight experiments with chondrocytes (MIR Space Station) and thyroid cancer cells (SimBox/Shenzhou-8 space mission). The experiments enabled by the ESA-CORA-GBF programme gave us an optimal opportunity to study gravity-related cellular processes, validate ground-based facilities for our chosen cell system, and prepare long-term experiments under real microgravity conditions in space

Ultrasound Instrumentation for Beam Diagnostics and Accelerating Structures Control

CERN Document Server

Moiseev, V I

2005-01-01

Sensitive elements and electronics for ultrasound measurements at conducting walls of beam pipes and accelerating structures are described. Noise protected instrumentation provides ultrasound spectra analysis in a wide frequency range up to 5 MHz.In circular accelerators, ultrasound fields in conducting walls of beam pipe represent the space-time characteristics of circulating beams. In accelerating structures, real high power operation modes of structure can be studied by outer ultrasound monitors. The experimental results at KSRS accelerators are discussed.

Ion accelerator based on plasma vircator

CERN Document Server

Onishchenko, I N

2001-01-01

The conception of a collective ion accelerator is proposed to be developed in the frameworks of STCU project 1569 (NSC KIPT, Ukraine) in coordination with the ISTC project 1629 (VNIEF, Russia). The main processes of acceleration are supposed to be consisted of two stages.First one is the plasma assistance virtual cathode (VC) in which plasma ions are accelerated in a potential well of VC. Along with ion acceleration the relaxation oscillations, caused by diminishing the potential well due to ion compensation, arise that provides the low-frequency (inverse ion transit time) temporal modulation of an intense relativistic electron beam (IREB) current. At the second stage temporally modulated IREB is injected into the spatially periodic magnetic field. The further ion acceleration is realized by the slow space charge wave that arises in IREB due to its simultaneous temporal and spatial modulation.

[Class III surgical patients facilitated by accelerated osteogenic orthodontic treatment].

Science.gov (United States)

Wu, Jia-qi; Xu, Li; Liang, Cheng; Zou, Wei; Bai, Yun-yang; Jiang, Jiu-hui

2013-10-01

To evaluate the treatment time and the anterior and posterior teeth movement pattern as closing extraction space for the Class III surgical patients facilitated by accelerated osteogenic orthodontic treatment. There were 10 skeletal Class III patients in accelerated osteogenic orthodontic group (AOO) and 10 patients in control group. Upper first premolars were extracted in all patients. After leveling and alignment (T2), corticotomy was performed in the area of maxillary anterior teeth to accelerate space closing.Study models of upper dentition were taken before orthodontic treatment (T1) and after space closing (T3). All the casts were laser scanned, and the distances of the movement of incisors and molars were digitally measured. The distances of tooth movement in two groups were recorded and analyzed. The alignment time between two groups was not statistically significant. The treatment time in AOO group from T2 to T3 was less than that in the control group (less than 9.1 ± 4.1 months). The treatment time in AOO group from T1 to T3 was less than that in the control group (less than 6.3 ± 4.8 months), and the differences were significant (P 0.05). Accelerated osteogenic orthodontic treatment could accelerate space closing in Class III surgical patients and shorten preoperative orthodontic time. There were no influence on the movement pattern of anterior and posterior teeth during pre-surgical orthodontic treatment.

Space Launch System Accelerated Booster Development Cycle

Science.gov (United States)

Arockiam, Nicole; Whittecar, William; Edwards, Stephen

2012-01-01

With the retirement of the Space Shuttle, NASA is seeking to reinvigorate the national space program and recapture the public s interest in human space exploration by developing missions to the Moon, near-earth asteroids, Lagrange points, Mars, and beyond. The would-be successor to the Space Shuttle, NASA s Constellation Program, planned to take humans back to the Moon by 2020, but due to budgetary constraints was cancelled in 2010 in search of a more "affordable, sustainable, and realistic" concept2. Following a number of studies, the much anticipated Space Launch System (SLS) was unveiled in September of 2011. The SLS core architecture consists of a cryogenic first stage with five Space Shuttle Main Engines (SSMEs), and a cryogenic second stage using a new J-2X engine3. The baseline configuration employs two 5-segment solid rocket boosters to achieve a 70 metric ton payload capability, but a new, more capable booster system will be required to attain the goal of 130 metric tons to orbit. To this end, NASA s Marshall Space Flight Center recently released a NASA Research Announcement (NRA) entitled "Space Launch System (SLS) Advanced Booster Engineering Demonstration and/or Risk Reduction." The increased emphasis on affordability is evident in the language used in the NRA, which is focused on risk reduction "leading to an affordable Advanced Booster that meets the evolved capabilities of SLS" and "enabling competition" to "enhance SLS affordability. The purpose of the work presented in this paper is to perform an independent assessment of the elements that make up an affordable and realistic path forward for the SLS booster system, utilizing advanced design methods and technology evaluation techniques. The goal is to identify elements that will enable a more sustainable development program by exploring the trade space of heavy lift booster systems and focusing on affordability, operability, and reliability at the system and subsystem levels5. For this study

Cosmic Accelerators: Engines of the Extreme Universe

Energy Technology Data Exchange (ETDEWEB)

Funk, Stefan

2009-06-23

The universe is home to numerous exotic and beautiful phenomena, some of which can generate almost inconceivable amounts of energy. While the night sky appears calm, it is populated by colossal explosions, jets from supermassive black holes, rapidly rotating neutron stars, and shock waves of gas moving at supersonic speeds. These accelerators in the sky boost particles to energies far beyond those we can produce on earth. New types of telescopes, including the Fermi Gamma-ray Space Telescope orbiting in space, are now discovering a host of new and more powerful accelerators. Please come and see how these observations are revising our picture of the most energetic phenomena in the universe.

Magnetic Diagnostics on the Magnetized Shock Experiment (MSX)

Science.gov (United States)

Hutchinson, T. M.; Weber, T. E.; Boguski, J. C.; Intrator, T. P.; Smith, R. J.; Dunn, J. P.

2013-10-01

The Magnetized Shock Experiment (MSX) at Los Alamos National Laboratory was built to investigate the physics of high-Alfvénic, supercritical, magnetized shocks through the acceleration and subsequent stagnation of a Field Reversed Configuration (FRC) plasmoid against a magnetic mirror and/or plasma target. An array of high-bandwidth, multi-axis, robust, internal magnetic probes has been constructed to characterize flux compression ratios, instability formation, and turbulent macro-scale features of the post-shock plasma. The mirror magnet is mounted on a linear translation stage, providing a capability to axially move the shock layer through the probe field of view. An independent, external probe array also provides conventional information on the FRC shape, velocity, and total pressure during the formation and acceleration phases. Probe design, characterization, configuration, and initial results are presented. This work is supported by the DOE OFES and NNSA under LANS contract DE-AC52-06NA25369. LA-UR-13-25189.

Multi-Scale CNT-Based Reinforcing Polymer Matrix Composites for Lightweight Structures

Science.gov (United States)

Eberly, Daniel; Ou, Runqing; Karcz, Adam; Skandan, Ganesh; Mather, Patrick; Rodriguez, Erika

2013-01-01

Reinforcing critical areas in carbon polymer matrix composites (PMCs), also known as fiber reinforced composites (FRCs), is advantageous for structural durability. Since carbon nanotubes (CNTs) have extremely high tensile strength, they can be used as a functional additive to enhance the mechanical properties of FRCs. However, CNTs are not readily dispersible in the polymer matrix, which leads to lower than theoretically predicted improvement in mechanical, thermal, and electrical properties of CNT composites. The inability to align CNTs in a polymer matrix is also a known issue. The feasibility of incorporating aligned CNTs into an FRC was demonstrated using a novel, yet commercially viable nanofiber approach, termed NRMs (nanofiber-reinforcing mats). The NRM concept of reinforcement allows for a convenient and safe means of incorporating CNTs into FRC structural components specifically where they are needed during the fabrication process. NRMs, fabricated through a novel and scalable process, were incorporated into FRC test panels using layup and vacuum bagging techniques, where alternating layers of the NRM and carbon prepreg were used to form the reinforced FRC structure. Control FRC test panel coupons were also fabricated in the same manner, but comprised of only carbon prepreg. The FRC coupons were machined to size and tested for flexural, tensile, and compression properties. This effort demonstrated that FRC structures can be fabricated using the NRM concept, with an increased average load at break during flexural testing versus that of the control. The NASA applications for the developed technologies are for lightweight structures for in-space and launch vehicles. In addition, the developed technologies would find use in NASA aerospace applications such as rockets, aircraft, aircraft/spacecraft propulsion systems, and supporting facilities. The reinforcing aspect of the technology will allow for more efficient joining of fiber composite parts, thus offering

Alternating phase focussing including space charge

International Nuclear Information System (INIS)

Cheng, W.H.; Gluckstern, R.L.

1992-01-01

Longitudinal stability can be obtained in a non-relativistic drift tube accelerator by traversing each gap as the rf accelerating field rises. However, the rising accelerating field leads to a transverse defocusing force which is usually overcome by magnetic focussing inside the drift tubes. The radio frequency quadrupole is one way of providing simultaneous longitudinal and transverse focusing without the use of magnets. One can also avoid the use of magnets by traversing alternate gaps between drift tubes as the field is rising and falling, thus providing an alternation of focussing and defocusing forces in both the longitudinal and transverse directions. The stable longitudinal phase space area is quite small, but recent efforts suggest that alternating phase focussing (APF) may permit low velocity acceleration of currents in the 100-300 ma range. This paper presents a study of the parameter space and a test of crude analytic predictions by adapting the code PARMILA, which includes space charge, to APF. 6 refs., 3 figs

Acceleration of a high-current single bunch in a linear accelerator

International Nuclear Information System (INIS)

Takeda, Seishi

1984-01-01

Some problems associated with the feasibility of an electron-positron linear collider with colliding energy of about 1x1 TeV are discussed. The first problem is related to the generation of high-current single bunch. A quasi-relativistic electron beam from an electron gun is injected into one bucket of the accelerating fields, in opposition to the longitudinal defocusing due to the space-charge effect. For generating a high-current single bunch, the beam bunching by means of the velocity modulation with a subharmonic prebuncher (SHPB) is indispensable. Three existing second generation single bunch electron linear accelerators (SLC, ANL and ISLR-Osaka Univ.) are briefly described. The results of the simulation of subharmonic-bunching is also reported. The second problem is associated with the physics of accelerating high-current single bunch. The longitudinal and transverse wake fields generated by a bunch-cavity interaction and the energy spread of the single bunch are analyzed and discussed. (Aoki, K.)

Theoretical and numerical study of the acceleration of particles in the separated sector cyclotrons (SSC's) at the large national heavy ion accelerator (GANIL)

International Nuclear Information System (INIS)

Chabert, A.; Gendreau, G.; Sauret, J.; Cardin, L.

The ideal machine is first considered, and the following topics are covered: (1) characteristics of accelerator cavities; (2) flat-topping; (3) the traverse of one acceleration interval; (4) the energy gain during the crossing of a cavity; and (5) beam injection conditions. A study is given of the coupling, including space charge forces, phase compression, and the effect of the angular opening of the accelerator cavities. The tolerances on the beam injection parameters and on the accelerator system are discussed

Control of electron injection and acceleration in laser-wakefield accelerators

International Nuclear Information System (INIS)

Guillaume, E.

2015-01-01

Laser-plasma accelerators provide a promising compact alternative to conventional accelerators. Plasma waves with extremely strong electric fields are generated when a high intensity laser is focused into an underdense gas target. Electrons that are trapped in these laser-driven plasma waves can be accelerated up to energies of a few GeVs. Despite their great potential, laser-wakefield accelerators face some issues, regarding notably the stability and reproducibility of the beam when electrons are injected in the accelerating structure. In this manuscript, different techniques of electron injection are presented and compared, notably injection in a sharp density gradient and ionization injection. It is shown that combining these two methods allows for the generation of stable and tunable electron beams. We have also studied a way to manipulate the electron bunch in the phase-space in order to accelerate the bunch beyond the dephasing limit. Such a technique was used with quasi-monoenergetic electron beams to enhance their energy. Moreover, the origin of the evolution of the angular momentum of electrons observed experimentally was investigated. Finally, we demonstrated experimentally a new method - the laser-plasma lens - to strongly reduce the divergence of the electron beam. This laser-plasma lens consists of a second gas jet placed at the exit of the accelerator. The laser pulse drives a wakefield in this second jet whose focusing forces take advantage to reduce the divergence of the trailing electron bunch. A simple analytical model describing the principle is presented, underlining the major importance of the second jet length, density and distance from the first jet. Experimental demonstration of the laser-plasma lens shows a divergence reduction by a factor of 2.6 for electrons up to 300 MeV, in accordance with the model predictions

Phase space measurements at non-accessible point on the beam path of an accelerator facility

International Nuclear Information System (INIS)

Hassan, A.

2004-01-01

The optimization of beam lines for particles extracted from accelerator facilities requires the knowledge of beam parameters. A method for the measurement of phase space and beam intensity distribution is represented. This method depends on the setting of quadrupole lenses that allows the imaging of beam profiles at arbitrary positions along the beam path on the same multi-wire proportional chamber, where the intensity distribution can be evaluated. The necessary focusing powers for a certain imaging task are calculated in a thin lens approximation. The corresponding focusing power for thick quadrupole lenses are calculated using the PC transport program. A comparison of the calculated focusing powers for thin and thick lenses reveals deviations at the highest field strengths, due to saturation effect. The position of the beam waist in normal and angular space is directly calculated and visualized. The horizontal and vertical waist positions are found to be rather independent of the beam energy. Extensive calculation was done to study the effect of a reduced aperture on the maximum beam emittances aa x and aa y of the extracted particles. The main result shows that the maximum emittance passing through depends on the waist distant and the diameter of the reduced aperture. (orig.)

Effect of Accelerated Aging on Color Change of Direct and Indirect Fiber-Reinforced Composite Restorations

Directory of Open Access Journals (Sweden)

Masomeh Hasani Tabatabaei

2016-10-01

Full Text Available Objectives: The aim of this study was to assess the effect of artificial accelerated aging (AAA on color change of direct and indirect fiber-reinforced composite (FRC restorations.Materials and Methods: Direct (Z250 and indirect (Gradia composite resins were reinforced with glass (GF and polyethylene fibers (PF based on the manufacturers’ instructions. Forty samples were fabricated and divided into eight groups (n=5. Four groups served as experimental groups and the remaining four served as controls. Color change (∆E and color parameters (∆L*, ∆a*, ∆b* were read at baseline and after AAA based on the CIELAB system. Three-way ANOVA and Tukey’s test were used for statistical analysis.Results: Significant differences were found in ΔE, ΔL*, Δa* and Δb* among the groups after AAA (P<0.05. Most of the studied samples demonstrated an increase in lightness and a red-yellow shift after AAA.Conclusions: The obtained ∆E values were unacceptable after AAA (∆E≥ 3.3. All indirect samples showed a green-blue shift with a reduction in lightness except for Gradia/PF+ NuliteF.Keywords: Aging; Composite Resins; Color

Distributed coupling high efficiency linear accelerator

Science.gov (United States)

Tantawi, Sami G.; Neilson, Jeffrey

2016-07-19

A microwave circuit for a linear accelerator includes multiple monolithic metallic cell plates stacked upon each other so that the beam axis passes vertically through a central acceleration cavity of each plate. Each plate has a directional coupler with coupling arms. A first coupling slot couples the directional coupler to an adjacent directional coupler of an adjacent cell plate, and a second coupling slot couples the directional coupler to the central acceleration cavity. Each directional coupler also has an iris protrusion spaced from corners joining the arms, a convex rounded corner at a first corner joining the arms, and a corner protrusion at a second corner joining the arms.

Late time acceleration of the 3-space in a higher dimensional steady state universe in dilaton gravity

International Nuclear Information System (INIS)

Akarsu, Özgür; Dereli, Tekin

2013-01-01

We present cosmological solutions for (1+3+n)-dimensional steady state universe in dilaton gravity with an arbitrary dilaton coupling constant w and exponential dilaton self-interaction potentials in the string frame. We focus particularly on the class in which the 3-space expands with a time varying deceleration parameter. We discuss the number of the internal dimensions and the value of the dilaton coupling constant to determine the cases that are consistent with the observed universe and the primordial nucleosynthesis. The 3-space starts with a decelerated expansion rate and evolves into accelerated expansion phase subject to the values of w and n, but ends with a Big Rip in all cases. We discuss the cosmological evolution in further detail for the cases w = 1 and w = ½ that permit exact solutions. We also comment on how the universe would be conceived by an observer in four dimensions who is unaware of the internal dimensions and thinks that the conventional general relativity is valid at cosmological scales

Late time acceleration of the 3-space in a higher dimensional steady state universe in dilaton gravity

Science.gov (United States)

Akarsu, Özgür; Dereli, Tekin

2013-02-01

We present cosmological solutions for (1+3+n)-dimensional steady state universe in dilaton gravity with an arbitrary dilaton coupling constant w and exponential dilaton self-interaction potentials in the string frame. We focus particularly on the class in which the 3-space expands with a time varying deceleration parameter. We discuss the number of the internal dimensions and the value of the dilaton coupling constant to determine the cases that are consistent with the observed universe and the primordial nucleosynthesis. The 3-space starts with a decelerated expansion rate and evolves into accelerated expansion phase subject to the values of w and n, but ends with a Big Rip in all cases. We discuss the cosmological evolution in further detail for the cases w = 1 and w = ½ that permit exact solutions. We also comment on how the universe would be conceived by an observer in four dimensions who is unaware of the internal dimensions and thinks that the conventional general relativity is valid at cosmological scales.

Single-particle dynamics - RF acceleration

International Nuclear Information System (INIS)

Montague, B.W.

1977-01-01

In this paper the rf acceleration of both synchronous and non-synchronous particles is discussed and a simple linearized equation of small amplitude synchrotron oscillations is derived. Phase stability, the hamiltonian for synchrotron oscillations, oscillation amplitudes and adiabatic damping are then briefly discussed. The final sections of the paper contain a description of the basic principles of rf beam stacking in the longitudinal phase space of intersecting Storage Rings and a description of phase displacement acceleration which inspite of certain disadvantages, remains an attractive technique for proton storage rings. (B.D.)

Limitations of heavy ion synchrotron acceleration for inertial fusion

International Nuclear Information System (INIS)

Berley, D.; Danby, G.T.

1977-01-01

The potential benefits from heavy ion inertial fusion motivate the rapid development of a program to test the principle. To define the program, accelerator parameters which have not hitherto been commonly considered must be studied interactively with basic questions of space charge limitations and charge exchange. Beam lifetime and power output efficiency may ultimately lead to a linear accelerator as the choice for an ignition device. For proof of principle, however, at power levels way beyond present inertial fusion experience, synchrotrons may have applicability at lower cost. The power and energy which can be delivered by the accelerating system to the reaction chamber are limited by space charge defocussing and intra beam charge exchange scattering, both of which are beam density dependent. These put constraints on linac injector energy, synchrotron aperture, synchrotron magnetic rigidity, acceleration time, ion species and charge to mass ratio. The accelerator system considered is classical. A linear accelerator injects into a synchrotron which accelerates the ion beam to the full energy delivered to the target. The maximum energy deliverable by a synchrotron is treated in section I. The targetting parameters and the energy gained through synchrotron acceleration completely determine the synchrotron aperture. These are discussed in sections II and III. The ion range in material is treated in section IV. The problem of intrabeam scattering is considered in section V. Finally, in section VI is a discussion of examples to meet specified goals

An embedded acceleration measurement capability for EXPRESS Rack Payloads

International Nuclear Information System (INIS)

Foster, William M. II; Sutliff, Thomas J.

2000-01-01

The International Space Station provides a microgravity environment allowing long duration studies to be made on phenomena masked by the presence of earth's gravitational effects. Studies are also enabled in areas requiring a substantial decrease in steady-state and vibratory acceleration environments. In anticipation microgravity science experiments being targeted for EXPRESS (EXpedite the PRocessing of Experiments to Space Station) Racks, a capability has been provided to simplify and conduct a consistent measurement of the microgravity environment for payloads. The Space Acceleration Measurement System-II (SAMS-II) project has collaborated with the EXPRESS Rack Project to embed an electronics unit within the four EXPRESS Racks equipped with Active Rack Isolation Systems (ARIS). Each SAMS-II unit provides a standardized means for payload acceleration measurements to be acquired. Access to this capability is via front panel connections similar to those of power, data and water cooling provided for EXPRESS payloads. Furthermore, an International Subrack Interface Standard (ISIS) drawer configuration has been developed to provide measurement capability to the non-ARIS equipped EXPRESS Racks, as well as to other ISIS-configured racks, for non-isolated experimental measurement needs. This paper describes the SAMS-II acceleration measurement capabilities provided to ISS users and, in particular, to the EXPRESS Rack community

Current understanding of SEP acceleration and propagation

International Nuclear Information System (INIS)

Klecker, B

2013-01-01

The solar energetic particle (SEP) populations of electrons and ions are highly variable in space and time, in intensity, energy, and composition. Over the last ∼20 years advanced instrumentation onboard many spacecraft (e.g. ACE, Coronas, GOES, Hinode, RHESSI, SAMPEX, SDO, SOHO, STEREO, TRACE, Ulysses, Yokoh, to name a few) extended our ability to explore the characteristics of solar energetic particles by in-situ measurements in interplanetary space and by observing their source characteristics near the Sun by remote-sensing observation of electromagnetic emission over a wide frequency range. These measurements provide crucial information for understanding the sources of the particle populations and the acceleration and propagation processes involved. We are now able to measure intensity-time profiles and anisotropies, energy spectra, elemental and isotopic abundances, and the ionic charge of particles over an extended energy range of 0.01 to several 100 MeV/nuc and for a large dynamic range of particle intensities. Furthermore, multi-spacecraft in-situ observations at different solar longitudes and latitudes provide new insight into the acceleration and propagation processes of SEPs near the Sun and in interplanetary space. In this paper we present an overview of SEP observations, their implications for SEP acceleration and propagation processes, and discuss open questions.

Second Symposium on ''Current trends in international fusion research: review and assessment''. Chairman's summary of session

International Nuclear Information System (INIS)

Post, R.F.

1998-01-01

This session began with a keynote speech by B. Coppi of M.I.T., entitled: ''Physics of Fusion Burning Plasmas, Ignition, and Relevant Technology Issues.'' It continued with a second paper on the tokamak approach to fusion, presented by E. Mazzucato of the Princeton Plasma Physics Laboratory, entitled ''High Confinement Plasma Confinement Regime in TFTR Configurations with Reversed Magnetic Shear.'' The session continued with three talks discussing various aspects of the so-called ''Field Reversed Configuration'' (FRC), and concluded with a talk on a more general topic. The first of the three FRC papers, presented by J. Slough of the University of Washington, was entitled ''FRC Reactor for Deep Space Propulsion.'' This paper was followed by a paper by S. Goto of the Plasma Physics Laboratory of Osaka University in Japan, entitled ''Experimental Initiation of Field-Reversed Configuration (FRC) Toward Helium-3 Fusion.'' The third of the FRC papers, authored by H. Mimoto and Y. Tomito of the National Institute for Fusion Science, Nagoya, Japan, and presented by Y. Tomita was entitled ''Helium-3 Fusion Based on a Field-Reversed Configuration.'' The session was concluded with a paper presented by D. Ryutov of the Lawrence Livermore National Laboratory entitled: ''A User Facility for Research on Fusion Systems with Dense Plasmas.''

Compact RF ion source for industrial electrostatic ion accelerator

Energy Technology Data Exchange (ETDEWEB)

Kwon, Hyeok-Jung, E-mail: hjkwon@kaeri.re.kr; Park, Sae-Hoon; Kim, Dae-Il; Cho, Yong-Sub [Korea Multi-purpose Accelerator Complex, Korea Atomic Energy Research Institute, Gyeongsangbukdo 38180 (Korea, Republic of)

2016-02-15

Korea Multi-purpose Accelerator Complex is developing a single-ended electrostatic ion accelerator to irradiate gaseous ions, such as hydrogen and nitrogen, on materials for industrial applications. ELV type high voltage power supply has been selected. Because of the limited space, electrical power, and robust operation, a 200 MHz RF ion source has been developed. In this paper, the accelerator system, test stand of the ion source, and its test results are described.

Compact RF ion source for industrial electrostatic ion accelerator

Science.gov (United States)

Kwon, Hyeok-Jung; Park, Sae-Hoon; Kim, Dae-Il; Cho, Yong-Sub

2016-02-01

Korea Multi-purpose Accelerator Complex is developing a single-ended electrostatic ion accelerator to irradiate gaseous ions, such as hydrogen and nitrogen, on materials for industrial applications. ELV type high voltage power supply has been selected. Because of the limited space, electrical power, and robust operation, a 200 MHz RF ion source has been developed. In this paper, the accelerator system, test stand of the ion source, and its test results are described.

Nonlinear Alfvén waves, discontinuities, proton perpendicular acceleration, and magnetic holes/decreases in interplanetary space and the magnetosphere: intermediate shocks?

Directory of Open Access Journals (Sweden)

B. T. Tsurutani

2005-01-01

Full Text Available Alfvén waves, discontinuities, proton perpendicular acceleration and magnetic decreases (MDs in interplanetary space are shown to be interrelated. Discontinuities are the phase-steepened edges of Alfvén waves. Magnetic decreases are caused by a diamagnetic effect from perpendicularly accelerated (to the magnetic field protons. The ion acceleration is associated with the dissipation of phase-steepened Alfvén waves, presumably through the Ponderomotive Force. Proton perpendicular heating, through instabilities, lead to the generation of both proton cyclotron waves and mirror mode structures. Electromagnetic and electrostatic electron waves are detected as well. The Alfvén waves are thus found to be both dispersive and dissipative, conditions indicting that they may be intermediate shocks. The resultant 'turbulence' created by the Alfvén wave dissipation is quite complex. There are both propagating (waves and nonpropagating (mirror mode structures and MDs byproducts. Arguments are presented to indicate that similar processes associated with Alfvén waves are occurring in the magnetosphere. In the magnetosphere, the 'turbulence' is even further complicated by the damping of obliquely propagating proton cyclotron waves and the formation of electron holes, a form of solitary waves. Interplanetary Alfvén waves are shown to rapidly phase-steepen at a distance of 1AU from the Sun. A steepening rate of ~35 times per wavelength is indicated by Cluster-ACE measurements. Interplanetary (reverse shock compression of Alfvén waves is noted to cause the rapid formation of MDs on the sunward side of corotating interaction regions (CIRs. Although much has been learned about the Alfvén wave phase-steepening processfrom space plasma observations, many facets are still not understood. Several of these topics are discussed for the interested researcher. Computer simulations and theoretical developments will be particularly useful in making further progress in

Plasma based charged-particle accelerators

International Nuclear Information System (INIS)

Bingham, R; Mendonca, J T; Shukla, P K

2004-01-01

Studies of charged-particle acceleration processes remain one of the most important areas of research in laboratory, space and astrophysical plasmas. In this paper, we present the underlying physics and the present status of high gradient and high energy plasma accelerators. We will focus on the acceleration of charged particles to relativistic energies by plasma waves that are created by intense laser and particle beams. The generation of relativistic plasma waves by intense lasers or electron beams in plasmas is important in the quest for producing ultra-high acceleration gradients for accelerators. With the development of compact short pulse high brightness lasers and electron positron beams, new areas of studies for laser/particle beam-matter interactions is opening up. A number of methods are being pursued vigorously to achieve ultra-high acceleration gradients. These include the plasma beat wave accelerator mechanism, which uses conventional long pulse (∼100 ps) modest intensity lasers (I ∼ 10 14 -10 16 W cm -2 ), the laser wakefield accelerator (LWFA), which uses the new breed of compact high brightness lasers ( 10 18 W cm -2 , the self-modulated LWFA concept, which combines elements of stimulated Raman forward scattering, and electron acceleration by nonlinear plasma waves excited by relativistic electron and positron bunches. In the ultra-high intensity regime, laser/particle beam-plasma interactions are highly nonlinear and relativistic, leading to new phenomena such as the plasma wakefield excitation for particle acceleration, relativistic self-focusing and guiding of laser beams, high-harmonic generation, acceleration of electrons, positrons, protons and photons. Fields greater than 1 GV cm -1 have been generated with particles being accelerated to 200 MeV over a distance of millimetre. Plasma wakefields driven by positron beams at the Stanford Linear Accelerator Center facility have accelerated the tail of the positron beam. In the near future

Proton linear accelerators: A theoretical and historical introduction

International Nuclear Information System (INIS)

Lapostolle, P.M.

1989-07-01

From the beginning, the development of linear accelerators has followed a number of different directions. This report surveys the basic ideas and general principles of such machines, pointing out the problems that have led to the various improvements, with the hope that it may also aid further progress. After a brief historical survey, the principal aspects of accelerator theory are covered in some detail: phase stability, focusing, radio-frequency accelerating structures, the detailed calculation of particle dynamics, and space-charge effects at high intensities. These developments apply essentially to proton and ion accelerators, and only the last chapter deals with a few aspects relative to electrons. 134 refs

Space charge effects in proton linear accelerators

International Nuclear Information System (INIS)

Prome, Michel

1971-01-01

Space charge difficulties are relatively well known because of the inconveniences they cause, but the physical mechanisms by which they operate are obscure; an attempt was made to explain some of these mechanisms. The method chosen involves a numerical simulation of the beam; computer programs describing beam dynamics with space charge are presented; they are used to check results obtained elsewhere. A series of experiments was performed demonstrating that coupling phenomena produce an equalization of r. m. s. velocities in the 3 directions; new quantity (sort of hyper-emittance) is introduced: its growth between the input and output of a given linac is proportional to the beam intensity. (author) [fr

Pierce electrodes for a multigap accelerating system

International Nuclear Information System (INIS)

Davydenko, V.I.; Ivanov, A.A.; Kotelnikov, I.A.; Tiunov, M.A.

2007-01-01

A well-known Pierce's solution that allows to focus a beam of charged particles using properly shaped electrodes outside the beam is generalized to the case of multigap accelerating system. Simple parametric formulae for Pierce electrodes are derived for an accelerating system with current density, limited either by space charge or by emitting property of the cathode. As an example of general approach, Pierce electrodes shape is analyzed for a system with two accelerating gaps. It is shown that precise Pierce's solution exists if acceleration rate within second gap is lower than within first gap. In the opposite case quasi-Pierce solution can be implemented using non-equipotential electrode between the gaps, and guidelines, based on numerical simulations, for the design of equipotential focusing electrodes are given

Accelerated Test Method for Corrosion Protective Coatings

Data.gov (United States)

National Aeronautics and Space Administration — This project seeks to develop a new accelerated corrosion test method that predicts the long-term corrosion protection performance of spaceport structure coatings as...

Direct observation of the phase space footprint of a painting injection in the Rapid Cycling Synchrotron at the Japan Proton Accelerator Research Complex

Directory of Open Access Journals (Sweden)

P. K. Saha

2009-04-01

Full Text Available The 3 GeV Rapid Cycling Synchrotron (RCS at Japan Proton Accelerator Research Complex is nearly at the operational stage with regard to the beam commissioning aspects. Recently, the design painting injection study has been commenced with the aim of high output beam power at the extraction. In order to observe the phase space footprint of the painting injection, a method was developed utilizing a beam position monitor (BPM in the so-called single pass mode. The turn-by-turn phase space coordinates of the circulating beam directly measured using a pair of BPMs entirely positioned in drift space, and the calculated transfer matrices from the injection point to the pair of BPMs with several successive turns were used together in order to obtain the phase space footprint of the painting injection. There are two such pairs of BPMs placed in two different locations in the RCS, the results from which both agreed and were quite consistent with what was expected.

Direct observation of the phase space footprint of a painting injection in the Rapid Cycling Synchrotron at the Japan Proton Accelerator Research Complex

Science.gov (United States)

Saha, P. K.; Shobuda, Y.; Hotchi, H.; Hayashi, N.; Takayanagi, T.; Harada, H.; Irie, Y.

2009-04-01

The 3 GeV Rapid Cycling Synchrotron (RCS) at Japan Proton Accelerator Research Complex is nearly at the operational stage with regard to the beam commissioning aspects. Recently, the design painting injection study has been commenced with the aim of high output beam power at the extraction. In order to observe the phase space footprint of the painting injection, a method was developed utilizing a beam position monitor (BPM) in the so-called single pass mode. The turn-by-turn phase space coordinates of the circulating beam directly measured using a pair of BPMs entirely positioned in drift space, and the calculated transfer matrices from the injection point to the pair of BPMs with several successive turns were used together in order to obtain the phase space footprint of the painting injection. There are two such pairs of BPMs placed in two different locations in the RCS, the results from which both agreed and were quite consistent with what was expected.

Whole Device Modeling of Compact Tori: Stability and Transport Modeling of C-2W

Science.gov (United States)

Dettrick, Sean; Fulton, Daniel; Lau, Calvin; Lin, Zhihong; Ceccherini, Francesco; Galeotti, Laura; Gupta, Sangeeta; Onofri, Marco; Tajima, Toshiki; TAE Team

2017-10-01

Recent experimental evidence from the C-2U FRC experiment shows that the confinement of energy improves with inverse collisionality, similar to other high beta toroidal devices, NSTX and MAST. This motivated the construction of a new FRC experiment, C-2W, to study the energy confinement scaling at higher electron temperature. Tri Alpha Energy is working towards catalysing a community-wide collaboration to develop a Whole Device Model (WDM) of Compact Tori. One application of the WDM is the study of stability and transport properties of C-2W using two particle-in-cell codes, ANC and FPIC. These codes can be used to find new stable operating points, and to make predictions of the turbulent transport at those points. They will be used in collaboration with the C-2W experimental program to validate the codes against C-2W, mitigate experimental risk inherent in the exploration of new parameter regimes, accelerate the optimization of experimental operating scenarios, and to find operating points for future FRC reactor designs.

Particle Acceleration and Fractional Transport in Turbulent Reconnection

Science.gov (United States)

Isliker, Heinz; Pisokas, Theophilos; Vlahos, Loukas; Anastasiadis, Anastasios

2017-11-01

We consider a large-scale environment of turbulent reconnection that is fragmented into a number of randomly distributed unstable current sheets (UCSs), and we statistically analyze the acceleration of particles within this environment. We address two important cases of acceleration mechanisms when particles interact with the UCS: (a) electric field acceleration and (b) acceleration by reflection at contracting islands. Electrons and ions are accelerated very efficiently, attaining an energy distribution of power-law shape with an index 1-2, depending on the acceleration mechanism. The transport coefficients in energy space are estimated from test-particle simulation data, and we show that the classical Fokker-Planck (FP) equation fails to reproduce the simulation results when the transport coefficients are inserted into it and it is solved numerically. The cause for this failure is that the particles perform Levy flights in energy space, while the distributions of the energy increments exhibit power-law tails. We then use the fractional transport equation (FTE) derived by Isliker et al., whose parameters and the order of the fractional derivatives are inferred from the simulation data, and solving the FTE numerically, we show that the FTE successfully reproduces the kinetic energy distribution of the test particles. We discuss in detail the analysis of the simulation data and the criteria that allow one to judge the appropriateness of either an FTE or a classical FP equation as a transport model.

Particle Acceleration and Fractional Transport in Turbulent Reconnection

Energy Technology Data Exchange (ETDEWEB)

Isliker, Heinz; Pisokas, Theophilos; Vlahos, Loukas [Department of Physics, Aristotle University of Thessaloniki, GR-52124 Thessaloniki (Greece); Anastasiadis, Anastasios [Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing, National Observatory of Athens, GR-15236 Penteli (Greece)

2017-11-01

We consider a large-scale environment of turbulent reconnection that is fragmented into a number of randomly distributed unstable current sheets (UCSs), and we statistically analyze the acceleration of particles within this environment. We address two important cases of acceleration mechanisms when particles interact with the UCS: (a) electric field acceleration and (b) acceleration by reflection at contracting islands. Electrons and ions are accelerated very efficiently, attaining an energy distribution of power-law shape with an index 1–2, depending on the acceleration mechanism. The transport coefficients in energy space are estimated from test-particle simulation data, and we show that the classical Fokker–Planck (FP) equation fails to reproduce the simulation results when the transport coefficients are inserted into it and it is solved numerically. The cause for this failure is that the particles perform Levy flights in energy space, while the distributions of the energy increments exhibit power-law tails. We then use the fractional transport equation (FTE) derived by Isliker et al., whose parameters and the order of the fractional derivatives are inferred from the simulation data, and solving the FTE numerically, we show that the FTE successfully reproduces the kinetic energy distribution of the test particles. We discuss in detail the analysis of the simulation data and the criteria that allow one to judge the appropriateness of either an FTE or a classical FP equation as a transport model.

Analysis of beam acceleration and instability on TWRR accelerator structure in PNC by beam-cavity interaction

Energy Technology Data Exchange (ETDEWEB)

Toyama, Shin`ichi [Power Reactor and Nuclear Fuel Development Corp., Oarai, Ibaraki (Japan). Oarai Engineering Center

1998-07-01

It is important for high current accelerators to estimate the contribution of the space charge effect to keep the beam off its beak up (BBU). The CW electron linac is designed in order to study BBU experimentally. The design is primary on the consideration which type of accelerator structure is suitable to reduce the BBU threshold, and how to observe and control BBU when it appears. The contribution of beam charge for the acceleration characteristics is surveyed by means of the comparison between traveling wave and standing wave structures in this report. At first, the characteristics of both traveling wave and standing wave structures are calculated analytically and the conversion efficiency and accelerator gain are presented. The merits and drawbacks are also mentioned concerning with unit accelerator length. Next, the choice of RF frequency on energy conversion is mentioned as independent matter of the types of accelerator structure. After that, the characteristics of TWRR are described as the advanced accelerator structure compared with above structures. The effect of longitudinal induced field is estimated by means of the loss parameter. The result from the analysis shows that the unit accelerator length is 1 m to get high conversion ratio from RF to beam power and that the BBU for transverse component is small. Therefore, total BBU is expected small in the accelerator, for transverse BBU is already expected small in previous reports. (author)

Beam energy reduction in an acceleration gap

International Nuclear Information System (INIS)

Rhee, M.J.

1990-01-01

The subject of high-current accelerators has recently attracted considerable attention. The high-current beam accompanies a substantial amount of field energy in the space between the beam and the drift tube wall, as it propagates through a conducting drift tube of accelerator system. While such a beam is being accelerated in a gap, this field energy is subject to leak through the opening of the gap. The amount of energy lost in the gap is replenished by the beam at the expense of its kinetic energy. In this paper, the authors present a simple analysis of field energy loss in an acceleration gap for a relativistic beam for which beam particle velocity equals to c. It is found that the energy loss, which in turn reduces the beam kinetic energy, is ΔV = IZ 0 : the beam current times the characteristic impedance of the acceleration gap. As a result, the apparent acceleration voltage of the gap is reduced from the applied voltage by ΔV. This effect, especially for generation of high-current beam accelerated by a multigap accelerator, appears to be an important design consideration. The energy reduction mechanism and a few examples are presented

Present status of TIARA electrostatic accelerator facility

Energy Technology Data Exchange (ETDEWEB)

Tajima, Satoshi; Takada, Isao; Mizuhashi, Kiyoshi; Saito, Yuichi; Uno, Sadanori; Okoshi, Kiyonori; Ishii, Yasuyuki; Nakajima, Yoshinori; Sakai, Takuro [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

1996-12-01

The electrostatic accelerator, 3 MV tandem accelerator, 3 MV single end accelerator and 400 kV ion implantation equipment, which were installed in Takasaki Ion Irradiation Research Facility (TIARA) of Japan Atomic Energy Research Institute, have been used for the research on the advanced utilization of radiation mainly in material science by ion beam. The utilization is open to other researchers, and in fiscal year 1995, about 40% was the utilization by outsiders. The number of the experimental subjects adopted in fiscal year 1995 was 47, and the fields of research were space and environment materials, nuclear fusion reactor materials, new functional materials, biotechnology and base technology. The operation time in fiscal year 1995 was 1201, 1705 and 1505 hours for the tandem accelerator, single end accelerator and ion implantation equipment, respectively. The methods of experiment are reported. The troubles occurred in the tandem accelerator and single end accelerator are reported. As the diversification of beam utilization in the tandem accelerator, the utilizations of high energy molecular ions, low energy negative ions, multivalent ions by post stripper and low intensity ions by mesh attenuator have been attempted. These utilizations are described. (K.I.)

Advanced Beamline Design for Fermilab's Advanced Superconducting Test Accelerator

Energy Technology Data Exchange (ETDEWEB)

Prokop, Christopher [Northern Illinois Univ., DeKalb, IL (United States)

2014-01-01

The Advanced Superconducting Test Accelerator (ASTA) at Fermilab is a new electron accelerator currently in the commissioning stage. In addition to testing superconducting accelerating cavities for future accelerators, it is foreseen to support a variety of Advanced Accelerator R&D (AARD) experiments. Producing the required electron bunches with the expected flexibility is challenging. The goal of this dissertation is to explore via numerical simulations new accelerator beamlines that can enable the advanced manipulation of electron bunches. The work especially includes the design of a low-energy bunch compressor and a study of transverse-to-longitudinal phase space exchangers.

Space Mechanisms Lessons Learned and Accelerated Testing Studies

Science.gov (United States)

Fusaro, Robert L.

1997-01-01

A number of mechanism (mechanical moving component) failures and anomalies have recently occurred on satellites. In addition, more demanding operating and life requirements have caused mechanism failures or anomalies to occur even before some satellites were launched (e.g., during the qualification testing of GOES-NEXT, CERES, and the Space Station Freedom Beta Joint Gimbal). For these reasons, it is imperative to determine which mechanisms worked in the past and which have failed so that the best selection of mechanically moving components can be made for future satellites. It is also important to know where the problem areas are so that timely decisions can be made on the initiation of research to develop future needed technology. To chronicle the life and performance characteristics of mechanisms operating in a space environment, a Space Mechanisms Lessons Learned Study was conducted. The work was conducted by the NASA Lewis Research Center and by Mechanical Technologies Inc. (MTI) under contract NAS3-27086. The expectation of the study was to capture and retrieve information relating to the life and performance of mechanisms operating in the space environment to determine what components had operated successfully and what components had produced anomalies.

Successful betatron acceleration of kiloampere electron rings in RECE-Christa

International Nuclear Information System (INIS)

Taggart, D.P.; Parker, M.R.; Hopman, H.J.; Jayakumar, R.; Fleischmann, H.H.

1984-01-01

This paper reports on betatron acceleration experiments using the space-charge-neutralized electron rings in the RECE-Christa device. Magnetic probe and x-ray-absorption measurements indicate that electron ring currents of up to 2 kA were accelerated to 3.3 +- 0.3 MeV without indication of instabilities. A similar neutralization and acceleration method also appears applicable to electron rings generated in B/sub theta/-free configurations

The medical implications of space tourism.

Science.gov (United States)

Tarzwell, R

2000-06-01

Commercial space travel may soon be a reality. If so, microgravity, high acceleration, and radiation exposure, all known hazards, will be accessible to the general public. Therefore, space tourism has medical implications. Even though the first flights will feature space exposure times of only a few minutes, the potential may someday exist for exposure times long enough to warrant careful consideration of the potential hazards to the space-faring public. The effects of acceleration and microgravity exposure are well known on the corps of astronauts and cosmonauts. The effects of space radiation are partially known on astronauts, but much remains to be discovered. However, there are problems using astronaut data to make inferences about the general public. Astronauts are not necessarily representative of the general public, since they are highly fit, highly screened individuals. Astronaut data can tell us very little about the potential hazards of microgravity in pediatric, obstetric and geriatric populations, all of whom are potential space tourists. Key issues in standard setting will be determining acceptable limits of pre-existing disease and inferring medical standards from mission profiles. It will not be a trivial task drafting minimal medical standards for commercial space travel. It will require the collaboration of space medicine physicians, making the best guesses possible, based on limited amounts of data, with limited applicability. A helpful departure point may be the USAF Class 3 medical standard, applicable to NASA payload specialists. It is time to begin preliminary discussions toward defining those standards. acceleration, aerospace medicine, medical standards, microgravity, radiation, space, space tourism, environmental hazards, environmental medicine.

Electron acceleration in the bubble regime

Energy Technology Data Exchange (ETDEWEB)

Jansen, Oliver

2014-02-03

The bubble regime of laser-wakefield acceleration has been studied over the recent years as an important alternative to classical accelerators. Several models and theories have been published, in particular a theory which provides scaling laws for acceleration parameters such as energy gain and acceleration length. This thesis deals with numerical simulations within the bubble regime, their comparison to these scaling laws and data obtained from experiments, as well as some specific phenomenona. With a comparison of the scaling laws with numerical results a parameter scan was able to show a large parameter space in which simulation and theory agree. An investigation of the limits of this parameter space revealed boundaries to other regimes, especially at very high (a{sub 0} > 100) and very low laser amplitudes (a{sub 0} < 4). Comparing simulation data with data from experiments concerning laser pulse development and electron energies, it was found that experimental results can be adequately reproduced using the Virtual-Laser-Plasma-Laboratory code. In collaboration with the Institut fuer Optik und Quantenelektronik at the Friedrich-Schiller University Jena synchrotron radiation emitted from the inside of the bubble was investigated. A simulation of the movement of the electrons inside the bubble together with time dependent histograms of the emitted radiation helped to prove that the majority of radiation created during a bubble acceleration originates from the inside of the bubble. This radiation can be used to diagnose the amplitude of oscillation of the trapped electrons. During a further study it was proven that the polarisation of synchrotron radiation from a bubble contains information about the exact oscillation direction. This oscillation was successfully controlled by using either a laser pulse with a tilted pulse front or an asymmetric laser pulse. First results of ongoing studies concerning injecting electrons into an existing bubble and a scheme called

Electron acceleration by turbulent plasmoid reconnection

Science.gov (United States)

Zhou, X.; Büchner, J.; Widmer, F.; Muñoz, P. A.

2018-04-01

In space and astrophysical plasmas, like in planetary magnetospheres, as that of Mercury, energetic electrons are often found near current sheets, which hint at electron acceleration by magnetic reconnection. Unfortunately, electron acceleration by reconnection is not well understood yet, in particular, acceleration by turbulent plasmoid reconnection. We have investigated electron acceleration by turbulent plasmoid reconnection, described by MHD simulations, via test particle calculations. In order to avoid resolving all relevant turbulence scales down to the dissipation scales, a mean-field turbulence model is used to describe the turbulence of sub-grid scales and their effects via a turbulent electromotive force (EMF). The mean-field model describes the turbulent EMF as a function of the mean values of current density, vorticity, magnetic field as well as of the energy, cross-helicity, and residual helicity of the turbulence. We found that, mainly around X-points of turbulent reconnection, strongly enhanced localized EMFs most efficiently accelerated electrons and caused the formation of power-law spectra. Magnetic-field-aligned EMFs, caused by the turbulence, dominate the electron acceleration process. Scaling the acceleration processes to parameters of the Hermean magnetotail, electron energies up to 60 keV can be reached by turbulent plasmoid reconnection through the thermal plasma.

COMPASS, the COMmunity Petascale project for Accelerator Science and Simulation, a board computational accelerator physics initiative

International Nuclear Information System (INIS)

Cary, J.R.; Spentzouris, P.; Amundson, J.; McInnes, L.; Borland, M.; Mustapha, B.; Ostroumov, P.; Wang, Y.; Fischer, W.; Fedotov, A.; Ben-Zvi, I.; Ryne, R.; Esarey, E.; Geddes, C.; Qiang, J.; Ng, E.; Li, S.; Ng, C.; Lee, R.; Merminga, L.; Wang, H.; Bruhwiler, D.L.; Dechow, D.; Mullowney, P.; Messmer, P.; Nieter, C.; Ovtchinnikov, S.; Paul, K.; Stoltz, P.; Wade-Stein, D.; Mori, W.B.; Decyk, V.; Huang, C.K.; Lu, W.; Tzoufras, M.; Tsung, F.; Zhou, M.; Werner, G.R.; Antonsen, T.; Katsouleas, T.; Morris, B.

2007-01-01

Accelerators are the largest and most costly scientific instruments of the Department of Energy, with uses across a broad range of science, including colliders for particle physics and nuclear science and light sources and neutron sources for materials studies. COMPASS, the Community Petascale Project for Accelerator Science and Simulation, is a broad, four-office (HEP, NP, BES, ASCR) effort to develop computational tools for the prediction and performance enhancement of accelerators. The tools being developed can be used to predict the dynamics of beams in the presence of optical elements and space charge forces, the calculation of electromagnetic modes and wake fields of cavities, the cooling induced by comoving beams, and the acceleration of beams by intense fields in plasmas generated by beams or lasers. In SciDAC-1, the computational tools had multiple successes in predicting the dynamics of beams and beam generation. In SciDAC-2 these tools will be petascale enabled to allow the inclusion of an unprecedented level of physics for detailed prediction

A practical guide to modern high energy particle accelerators

International Nuclear Information System (INIS)

Holmes, S.D.

1987-10-01

The purpose of these lectures is to convey an understanding of how particle accelerators work and why they look the way they do. The approach taken is physically intuitive rather than mathematically rigorous. The emphasis is on the description of proton circular accelerators and colliders. Linear accelerators are mentioned only in passing as sources of protons for higher energy rings. Electron accelerators/storage rings and antiproton sources are discussed only by way of brief descriptions of the features which distinguish them from proton accelerators. The basics of how generic accelerators work are discussed, focusing on descriptions of what sets the overall scale, single particle dynamics and stability, and descriptions of the phase space of the particle beam, the information thus presented is then used to go through the exercise of designing a Superconducting Super Collider

European accelerator facilities for single event effects testing

Energy Technology Data Exchange (ETDEWEB)

Adams, L; Nickson, R; Harboe-Sorensen, R [ESA-ESTEC, Noordwijk (Netherlands); Hajdas, W; Berger, G

1997-03-01

Single event effects are an important hazard to spacecraft and payloads. The advances in component technology, with shrinking dimensions and increasing complexity will give even more importance to single event effects in the future. The ground test facilities are complex and expensive and the complexities of installing a facility are compounded by the requirement that maximum control is to be exercised by users largely unfamiliar with accelerator technology. The PIF and the HIF are the result of experience gained in the field of single event effects testing and represent a unique collaboration between space technology and accelerator experts. Both facilities form an essential part of the European infrastructure supporting space projects. (J.P.N.)

The advantages of orthogonal acceleration in ICP time-of-flight mass spectrometry

International Nuclear Information System (INIS)

Gaal, Andrew

2004-01-01

The OptiMass 8000 incorporates an orthogonal acceleration time-of-flight mass spectrometer. A general schematic of the instrument is given. The continuous ion beam is chopped by an orthogonal accelerator. A push out pulse supply is coupled to the accelerator for providing repetitive push-out voltages at a frequency of 30 kHz. The ion packets that are sliced out of the beam then travel within the field free space towards the SMARTGATE ion blanker. Orthogonal accelerator parameters are set to enable temporal-spatial focusing at the SMARTGATE ion blanker, so that iso-mass ion packets are resolved in time. Any ion packets of unwanted specie are ejected from the direction of travel by supplying pulsed voltages onto the deflection plates of the SMARTGATE. The ions to be measured are let through SMARTGATE and travel further down the field free space, to enter the ion reflectron. The ion reflectron increases the resolution of the mass spectrometer by means of temporal-energy focussing. After reflection, the ions travel within the field free space towards the discrete-dynode detector. In comparison to other acceleration geometries used in elemental time-of-flight mass spectrometry the OptiMass 8000 orthogonal acceleration geometry ultimately leads to superior resolution. As the energy spread is about 3 orders of magnitude lower in the time-of-flight direction for an oaTOFMS in comparison to an on-axis system, aberration acquired in the initial stages of acceleration are much lower. As a result the orthogonal acceleration scheme provides superior resolution at the first spatial focus point and the detector. The orthogonal acceleration time-of-flight analyzer of the OptiMass 8000 is able to provide resolution of at least 1800 at mass 238. (author)

Linear accelerator with x-ray absorbing insulators

International Nuclear Information System (INIS)

Rose, P.H.

1975-01-01

Annular insulators for supporting successive annular electrodes in a linear accelerator have embedded x-ray absorbing shield structures extending around the accelerating path. The shield members are disposed to intercept x-ray radiation without disrupting the insulative effect of the insulator members. In preferred forms, the structure comprises a plurality of annular members of heavy metal disposed in an x-ray blocking array, spaced from each other by the insulating substance of the insulator member. (auth)

Beam dynamics studies of the Heavy Ion Fusion Accelerator injector

International Nuclear Information System (INIS)

Henestroza, E.; Yu, S.S.; Eylon, S.

1995-04-01

A driver-scale injector for the Heavy Ion Fusion Accelerator project has been built at LBL. This machine has exceeded the design goals of high voltage (> 2 MV), high current (> 0.8 A of K + ) and low normalized emittance (< 1 π mm-mr). The injector consists of a 750 keV diode pre-injector followed by an electrostatic quadrupole accelerator (ESQ) which provides strong (alternating gradient) focusing for the space-charge dominated beam and simultaneously accelerates the ions to 2 MeV. The fully 3-D PIC code WARP together with EGUN and POISSON were used to design the machine and analyze measurements of voltage, current and phase space distributions. A comparison between beam dynamics characteristics as measured for the injector and corresponding computer calculations will be presented

Modeling of Particle Acceleration at Multiple Shocks Via Diffusive Shock Acceleration: Preliminary Results

Science.gov (United States)

Parker, L. N.; Zank, G. P.

2013-12-01

Successful forecasting of energetic particle events in space weather models require algorithms for correctly predicting the spectrum of ions accelerated from a background population of charged particles. We present preliminary results from a model that diffusively accelerates particles at multiple shocks. Our basic approach is related to box models (Protheroe and Stanev, 1998; Moraal and Axford, 1983; Ball and Kirk, 1992; Drury et al., 1999) in which a distribution of particles is diffusively accelerated inside the box while simultaneously experiencing decompression through adiabatic expansion and losses from the convection and diffusion of particles outside the box (Melrose and Pope, 1993; Zank et al., 2000). We adiabatically decompress the accelerated particle distribution between each shock by either the method explored in Melrose and Pope (1993) and Pope and Melrose (1994) or by the approach set forth in Zank et al. (2000) where we solve the transport equation by a method analogous to operator splitting. The second method incorporates the additional loss terms of convection and diffusion and allows for the use of a variable time between shocks. We use a maximum injection energy (Emax) appropriate for quasi-parallel and quasi-perpendicular shocks (Zank et al., 2000, 2006; Dosch and Shalchi, 2010) and provide a preliminary application of the diffusive acceleration of particles by multiple shocks with frequencies appropriate for solar maximum (i.e., a non-Markovian process).

Hardware Accelerated Sequence Alignment with Traceback

Directory of Open Access Journals (Sweden)

Scott Lloyd

2009-01-01

in a timely manner. Known methods to accelerate alignment on reconfigurable hardware only address sequence comparison, limit the sequence length, or exhibit memory and I/O bottlenecks. A space-efficient, global sequence alignment algorithm and architecture is presented that accelerates the forward scan and traceback in hardware without memory and I/O limitations. With 256 processing elements in FPGA technology, a performance gain over 300 times that of a desktop computer is demonstrated on sequence lengths of 16000. For greater performance, the architecture is scalable to more processing elements.

An overview of collective effects in circular and linear accelerators

International Nuclear Information System (INIS)

Ruth, R.D.

1989-04-01

The purpose of both linear and circular accelerator is, of course, to accelerate beams of charged particles. In order to do this it is necessary not only to accelerate particles but also to confine them transversely so that they remain in the vacuum environment. Originally, as accelerators were developed, the intensity of the beams was rather low and so the external fields could be applied without regard to the effects of the space-charge forces of the beams. However, as the demand for high intensity increased, collective effects that are due to the space-charge forces became increasingly important. In order to control a beam of particles we apply external fields. These focus the beam transversely and accelerate it and focus it longitudinally. In addition to these externally applied fields a particle within the beam feels a field due to the charge and current of all the other particles in the beam. By collective effects, we mean all those modifications to the beam behavior which are due to these beam-induced forces. The first two major topics discussed are linear and circular accelerators. In the linear accelerator case, we will consider as examples only electron linacs that have relatively high energy and so particles will have ν ≅ c. For circular accelerators we'll consider both protons and electrons or their anti-particles. The next two topics are single bunches and multi-bunches. In both linear accelerators and circular accelerators the particles have a bunched character because they are accelerated by an RF system, and the RF has a natural wavelength. The next two topics arise from the natural separation of longitudinal and transverse effects. 40 refs., 30 figs., 1 tab

Optical diagnostics on the Magnetized Shock Experiment (MSX)

Science.gov (United States)

Boguski, J. C.; Weber, T. E.; Intrator, T. P.; Smith, R. J.; Dunn, J. P.; Hutchinson, T. M.; Gao, K. W.

2013-10-01

The Magnetized Shock Experiment (MSX) at Los Alamos National Laboratory was built to investigate the physics of high Alfvén Mach number, supercritical, magnetized shocks through the acceleration and subsequent stagnation of a Field Reversed Configuration (FRC) plasmoid against a magnetic mirror and/or plasma target. A suite of optical diagnostics has recently been fielded on MSX to characterize plasma conditions during the formation, acceleration, and stagnation phases of the experiment. CCD-backed streak and framing cameras, and a fiber-based visible light array, provide information regarding FRC shape, velocity, and instability growth. Time-resolved narrow and broadband spectroscopy provides information on pre-shock plasma temperature, impurity levels, shock location, and non-thermal ion distributions within the shock region. Details of the diagnostic design, configuration, and characterization will be presented along with initial results. This work is supported by the Center for Magnetic Self Organization, DoE OFES and NNSA under LANS contract DE-AC52-06NA25369. Approved for public release: LA-UR- 13-25190.

The transmission theory of electrostatic analyzer in six dimensional phase space and the concept design of a supersensitive mass spectrometer beam line for HI-13 tandem accelerator

International Nuclear Information System (INIS)

Guan Xialing; Cao Qingxi; Zhang Jie; Ye Jingping

1986-01-01

It follows from the motion equations of charged particle in curvilinear coordinates system that the transfer matrix of electrostatic analyzer was derived in six dimensional phase space. In accordance with these matrixes, the concept design of the supersensitive mass spectrometer beam line for HI-13 tandem accelerator was calculated

Quasi-stable injection channels in a wakefield accelerator

CERN Document Server

Wiltshire-Turkay, Mara; Pukhov, Alexander

2016-01-01

Particle-driven plasma-wakefield acceleration is a promising alternative to conventional electron acceleration techniques, potentially allowing electron acceleration to energies orders of magnitude higher than can currently be achieved. In this work we investigate the dependence of the energy gain on the position at which electrons are injected into the wake. Test particle simulations show previously unobserved complex structure in the parameter space, with quasi-stable injection channels forming for particles injected in narrow regions away from the centre of the wake. The result is relevant to the planning and tuning of experiments making use of external injection.

Moments method in the theory of accelerators

International Nuclear Information System (INIS)

Perel'shtejn, Eh.A.

1984-01-01

The moments method is widely used for solution of different physical and calculation problems in the theory of accelerators, magnetic optics and dynamics of high-current beams. Techniques using moments of the second order-mean squape characteristics of charged particle beams is shown to be most developed. The moments method is suitable and sometimes even the only technique applicable for solution of computerized problems on optimization of accelerating structures, beam transport channels, matching and other systems with accout of a beam space charge

Optimization of negative ion accelerators

International Nuclear Information System (INIS)

Pamela, J.

1991-01-01

We have started to study negative ion extraction and acceleration systems in view of designing a 1 MeV D - accelerator. This study is being made with a two-Dimensional code that has been specifically developed in our laboratory and validated by comparison to three sets of experimental data. We believe that the criteria for negative ion accelerator design optimization should be: (i) to provide the best optics; (ii) to reduce the power load on the extraction grid; (iii) to allow operation with low electric fields in order to reduce the problem of breakdowns. We show some results of optics calculations performed for two systems that will be operational in the next months: the CEA-JAERI collaboration at Cadarache and the european DRAGON experiment at Culham. Extrapolations to higher energies of 500 to 1100 keV have also been conducted. All results indicate that the overall accelerator length, whatever be the number of gaps, is constrained by space charge effects (Child-Langmuir). We have combined this constraint with high-voltage hold-off empirical laws. As a result, it appears that accelerating 10 mA/cm 2 of D - at 1 MeV with good optics, as required for NET or ITER, is close to the expected limit of high-voltage hold-off

Injection and extraction techniques in circular accelerators

International Nuclear Information System (INIS)

Tang Jingyu

2008-01-01

Injection and extraction are usually the key systems in circular accelerators. They play important roles in transferring the beam from one stage acceleration to the other or to experimental stations. It is also in the injection and extraction regions where beam losses happen mostly. Due to the tight space and to reduce the perturbation to the circulating orbit, the devices are usually designed to meet special requirements such as compactness, small stray field, fast rise time or fall time, etc. Usual injection and extraction devices include septum magnets, kicker magnets, electrostatic deflectors, slow bump magnets and strippers. In spite of different accelerators and specification for the injection and extraction devices, many techniques are shared in the design and manufacturing. This paper gives a general review on the techniques employed in the major circular accelerators in China. (authors)

Preliminary design of a 10 MV ion accelerator

International Nuclear Information System (INIS)

Fessenden, T.J.; Celata, C.M.; Faltens, A.

1986-06-01

At the low energy end of an induction linac HIF driver the beam current is limited by our ability to control space charge by a focusing system. As a consequence, HIF induction accelerator designs feature simultaneous acceleration of many beams in parallel within a single accelerator structure. As the speed of the beams increase, the focusing system changes from electrostatic to magnetic quadrupoles with a corresponding increase in the maximum allowable current. At that point the beams are merged thereby decreasing the cost of the subsequent accelerator structure. The LBL group is developing an experiment to study the physics of merging and of focusing ion beams. In the design, parallel beams of ions (C + , Al + , or Al ++ ) are accelerated to several MV and merged transversely. The merged beams are then further accelerated and the growth in transverse and longitudinal emittance is determined for comparison with theory. The apparatus will then be used to study the problems associated with focusing ion beams to a small spot. Details of the accelerator design and considerations of the physics of combining beams are presented

Overview of Phase Space Manipulations of Relativistic Electron Beams

Energy Technology Data Exchange (ETDEWEB)

Xiang, Dao; /SLAC

2012-08-31

Phase space manipulation is a process to rearrange beam's distribution in 6-D phase space. In this paper, we give an overview of the techniques for tailoring beam distribution in 2D, 4D, and 6D phase space to meet the requirements of various applications. These techniques become a new focus of accelerator physics R&D and very likely these advanced concepts will open up new opportunities in advanced accelerators and the science enabled by them.

Overview of Phase Space Manipulations of Relativistic Electron Beams

International Nuclear Information System (INIS)

Xiang, Dao

2012-01-01

Phase space manipulation is a process to rearrange beam's distribution in 6-D phase space. In this paper, we give an overview of the techniques for tailoring beam distribution in 2D, 4D, and 6D phase space to meet the requirements of various applications. These techniques become a new focus of accelerator physics R and D and very likely these advanced concepts will open up new opportunities in advanced accelerators and the science enabled by them.

Heavy-ion fusion accelerator research, 1985

International Nuclear Information System (INIS)

1986-10-01

A plan for exploring the physics and technology of induction linac development is discussed which involves a series of increasingly sophisticated experiments. The first is the single-beam transport experiment, which has explored the physics of a single space-charge-dominated beam. Second is the multiple-beam experiment in which four independent beams will be transported and accelerated through a multigap accelerating structure. The single-beam transport experiment is described, and some results are given of stability studies and instrumentation studies. The design and fabrication of the multi-beam experiment are described, as well as results of a first round of experiments in which beam-current amplification was observed. Concurrent theoretical work, resulting in a variety of acce-leration schedules and sets of associated voltage waveforms required to implement the experiments, is also reported

Electrostatic quadrupole focused particle accelerating assembly with laminar flow beam

International Nuclear Information System (INIS)

Maschke, A. W.

1985-01-01

A charged particle accelerating assembly provided with a predetermined ratio of parametric structural characteristics and with related operating voltages applied to each of its linearly spaced focusing and accelerating quadrupoles, thereby to maintain a particle beam traversing the electrostatic fields of the quadrupoles in the assembly in an essentially laminar flow throughout the assembly

NONLINEAR ACCELERATOR LATTICES WITH ONE AND TWO ANALYTIC INVARIANTS

International Nuclear Information System (INIS)

Danilov, Viatcheslav V.

2010-01-01

Integrable systems appeared in physics long ago at the onset of classical dynamics with examples being Kepler s and other famous problems. Unfortunately, the majority of nonlinear problems turned out to be nonintegrable. In accelerator terms, any 2D nonlinear map produces a chaotic motion and a complex network of stable and unstable resonances with the unit probability. Nevertheless, in the proximity of an integrable system the full volume of such a chaotic network is small. Thus, the integrable nonlinear motion in accelerators has the potential to introduce a large betatron tune spread to suppress instabilities and to mitigate space charge effects with relatively small resonances and particle loss. To create such an accelerator lattice one has to find magnetic and electrtic field combinations leading to a stable integrable motion. This paper presents families of lattices with one invariant where bounded motion can be easily created in large volumes of the phase space. In addition, it presents 3 families of integrable nonlinear accelerator lattices, relizable with longitudinal-coordinate-dependent magnetic or electric fields with the stable nonlinear motion, which can be solved in terms of separable variables.

STOCHASTIC PARTICLE ACCELERATION IN TURBULENCE GENERATED BY MAGNETOROTATIONAL INSTABILITY

Energy Technology Data Exchange (ETDEWEB)

Kimura, Shigeo S.; Toma, Kenji [Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Sendai 980-8578 (Japan); Suzuki, Takeru K.; Inutsuka, Shu-ichiro, E-mail: shigeo@astr.tohoku.ac.jp [Department of Physics, Nagoya University, Nagoya, Aichi 464-8602 (Japan)

2016-05-10

We investigate stochastic particle acceleration in accretion flows. It is believed that magnetorotational instability (MRI) generates turbulence inside accretion flows and that cosmic rays (CRs) are accelerated by the turbulence. We calculate equations of motion for CRs in the turbulent fields generated by MRI with the shearing box approximation and without back reaction to the field. Our results show that the CRs randomly gain or lose their energy through interaction with the turbulent fields. The CRs diffuse in the configuration space anisotropically: the diffusion coefficient in the direction of the unperturbed flow is about 20 times higher than the Bohm coefficient, while those in the other directions are only a few times higher than the Bohm. The momentum distribution is isotropic and its evolution can be described by the diffusion equation in momentum space where the diffusion coefficient is a power-law function of the CR momentum. We show that the shear acceleration works efficiently for energetic particles. We also cautiously note that in the shearing box approximation, particles that cross the simulation box many times along the radial direction undergo unphysical runaway acceleration by the Lorentz transformation, which needs to be taken into account with special care.

Two-stage light-gas magnetoplasma accelerator for hypervelocity impact simulation

International Nuclear Information System (INIS)

Khramtsov, P P; Vasetskij, V A; Makhnach, A I; Grishenko, V M; Chernik, M Yu; Shikh, I A; Doroshko, M V

2016-01-01

The development of macroparticles acceleration methods for high-speed impact simulation in a laboratory is an actual problem due to increasing of space flights duration and necessity of providing adequate spacecraft protection against micrometeoroid and space debris impacts. This paper presents results of experimental study of a two-stage light- gas magnetoplasma launcher for acceleration of a macroparticle, in which a coaxial plasma accelerator creates a shock wave in a high-pressure channel filled with light gas. Graphite and steel spheres with diameter of 2.5-4 mm were used as a projectile and were accelerated to the speed of 0.8-4.8 km/s. A launching of particle occurred in vacuum. For projectile velocity control the speed measuring method was developed. The error of this metod does not exceed 5%. The process of projectile flight from the barrel and the process of a particle collision with a target were registered by use of high-speed camera. The results of projectile collision with elements of meteoroid shielding are presented. In order to increase the projectile velocity, the high-pressure channel should be filled with hydrogen. However, we used helium in our experiments for safety reasons. Therefore, we can expect that the range of mass and velocity of the accelerated particles can be extended by use of hydrogen as an accelerating gas. (paper)

Two-stage light-gas magnetoplasma accelerator for hypervelocity impact simulation

Science.gov (United States)

Khramtsov, P. P.; Vasetskij, V. A.; Makhnach, A. I.; Grishenko, V. M.; Chernik, M. Yu; Shikh, I. A.; Doroshko, M. V.

2016-11-01

The development of macroparticles acceleration methods for high-speed impact simulation in a laboratory is an actual problem due to increasing of space flights duration and necessity of providing adequate spacecraft protection against micrometeoroid and space debris impacts. This paper presents results of experimental study of a two-stage light- gas magnetoplasma launcher for acceleration of a macroparticle, in which a coaxial plasma accelerator creates a shock wave in a high-pressure channel filled with light gas. Graphite and steel spheres with diameter of 2.5-4 mm were used as a projectile and were accelerated to the speed of 0.8-4.8 km/s. A launching of particle occurred in vacuum. For projectile velocity control the speed measuring method was developed. The error of this metod does not exceed 5%. The process of projectile flight from the barrel and the process of a particle collision with a target were registered by use of high-speed camera. The results of projectile collision with elements of meteoroid shielding are presented. In order to increase the projectile velocity, the high-pressure channel should be filled with hydrogen. However, we used helium in our experiments for safety reasons. Therefore, we can expect that the range of mass and velocity of the accelerated particles can be extended by use of hydrogen as an accelerating gas.

Accelerator development at Bates

International Nuclear Information System (INIS)

Sargent, C.P.

1983-01-01

The past year has seen the completion of a major expansion of the Bates Accelerator Laboratory. A second experimental hall, South Hall, and several magnetic spectrometers have been constructed. The accelerator's maximum energy has been raised from 400 to 750 MeV by means of beam recirculation. A current two-year project for the fabrication of an additional RF transmitter plus a 30% increase in RF peak power capability will increase energy further to ca. 1 GeV. During the same period pulse-to-pulse beam sharing between the high-resolution spectrometer area and South Hall will become available. In January 1981 the Laboratory submitted their ''Proposal for a Long-Range Expansion Program'' to DOE-NSF. The proposed development consists of three stages. Stage I calls for the addition of a pulse stretcher ring to furnish a CW beam to the South Hall beam lines. Additional experimental space for internal target experiments and photon tagging research are also included. Stage II increases the accelerator energy to 2.1 GeV (at 140 microamps) by means of a five-pass head-to-tail recirculator. Stage III is, at this time, a plan rather than a proposal. It increases accelerator energy to 4 GeV by extending the accelerator length and power and adds another pulse stretcher ring and three new experimental areas for the higher energy work. This paper discusses each of these stages in detail and recommends their funding and scheduling

DC and RF ion accelerators for MeV energies

International Nuclear Information System (INIS)

Urbanus, W.H.

1990-01-01

This thesis deals with the transport and acceleration of intense ion beams in single-ended Van de Graaff accelerators and the multiple beam rf accelerator MEQALAC (Multiple Electrostatic Quadrupole Array Linear Accelerator). Ch. 2 discusses several beam-envelope calculation techniques and describes the ion-optical components of a 1 MV, high-current, heavy-ion implantation facility and a 2 MV facility for analyzing purposes. The X-ray level of these accelerators is kept low, such that no shielding is needed, by keeping the energy of the secondary electrons sufficiently low, which is accomplished by a suppression system of small permanent magnets built in the acceleration tubes (ch. 3). Ch.'s 4,5 and 6 cover various aspects of stage II of the MEQALAC project. This stage deals with the parallel acceleration of four high-current N + beams from 40 keV to 1 MeV. Acceleration takes place in 32 rf gaps which are part of a modified interdigital H-resonator. In between the accelerating gaps, small electrostatic quadrupoles are mounted, which oppose the space charge forces of the intense ion beams. The lenses are arranged in a periodic focusing structure. A bucket-type plasma ion source is used, which produces both N + and N 2 + ions. In between the ion source and the MEQALAC section, a Low Energy Beam Transport (LEBT) section is mounted which provides for the drift space for a buncher. The latter device transforms the extracted dc beams into bunched beams which are accepted by the MEQALAC section. In ch. 4 the transport of ion beams that contain both N + and N 2 + ions, so-called mixed beams, through the LEBT section is discussed and equations for the current limit of a mixed beam are derived. Bunching of mixed N + , N 2 + beams is discussed in ch. 5. Multichannel acceleration of N + ions with the MEQALAC is discussed in ch. 6. (author). 122 refs.; 67 figs.; 1 tab

Matching sub-fs electron bunches for laser-driven plasma acceleration at SINBAD

Energy Technology Data Exchange (ETDEWEB)

Zhu, J., E-mail: jun.zhu@desy.de [Deutsches Elektronen-Synchrotron, DESY, Hamburg (Germany); Universität Hamburg, Hamburg (Germany); Assmann, R.W.; Dorda, U.; Marchetti, B. [Deutsches Elektronen-Synchrotron, DESY, Hamburg (Germany)

2016-09-01

We present theoretical and numerical studies of matching sub-femtosecond space-charge-dominated electron bunch into the Laser-plasma Wake Field Accelerator (LWFA) foreseen at the SINBAD facility. The longitudinal space-charge (SC) effect induced growths of the energy spread and longitudinal phase-space chirp are major issues in the matching section, which will result in bunch elongation, emittance growth and spot size dilution. In addition, the transverse SC effect would lead to a mismatch of the beam optics if it were not compensated for. Start-to-end simulations and preliminary optimizations were carried out in order to understand the achievable beam parameters at the entrance of the plasma accelerator.

Equipartitioning in linear accelerators

International Nuclear Information System (INIS)

Jameson, R.A.

1982-01-01

Emittance growth has long been a concern in linear accelerators, as has the idea that some kind of energy balance, or equipartitioning, between the degrees of freedom, would ameliorate the growth. M. Prome observed that the average transverse and longitudinal velocity spreads tend to equalize as current in the channel is increased, while the sum of the energy in the system stays nearly constant. However, only recently have we shown that an equipartitioning requirement on a bunched injected beam can indeed produce remarkably small emittance growth. The simple set of equations leading to this condition are outlined. At the same time, Hofmann has investigated collective instabilities in transported beams and has identified thresholds and regions in parameter space where instabilities occur. Evidence is presented that shows transport system boundaries to be quite accurate in computer simulations of accelerating systems. Discussed are preliminary results of efforts to design accelerators that avoid parameter regions where emittance is affected by the instabilities identified by Hofmann. These efforts suggest that other mechanisms are present. The complicated behavior of the RFQ linac in this framework also is shown

Functional scintigraphy of pulmonary ventilation with 133Xe in juvenile scoliosis

International Nuclear Information System (INIS)

Grau, M.; Leisner, B.; Rohloff, R.; Fink, U.; Moser, E.; Matzen, K.A.; Haeusinger, K.; Muenchen Univ.; Muenchen Univ.

1981-01-01

Twenty children with severe scoliosis underwent spirometry, chest X-ray and 133 Xe ventilation studies before surgical correction by the Harrington operation. By means of functional scintigraphy the relative distribution of the functional residual capacity (FRC) and the wash-out curves (3 min-retention without background correction, mean time constant, effectivity index after background correction) were analysed quantitatively. The chest X-ray and the single-breath-phase of the ventilation study remained mostly unchanged, whereas the shifting of the FRC distribution towards the lung of the concave side indicated in all cases a regional ventilation restriction of the convex side. In addition the analysis of the wash-out curves showed a regional impairment of the alveolar ventilation of the convex side which exceeded the shifting of FRC distribution. Even in the cases with normal spirometric values all scintigraphic parameters were slightly pathological, probably due to the decreased lung function caused by the scoliosis. The effectivity index taking into account the respiration frequency, the tidal volume, the FRC and the dead space, was found to be the most accurate and sensitive parameter for the evaluation of regional ventilation impairment. (orig.) [de

Accelerated Aging Experiments for Capacitor Health Monitoring and Prognostics

Data.gov (United States)

National Aeronautics and Space Administration — This paper discusses experimental setups for health monitoring and prognostics of electrolytic capacitors under nominal operation and accelerated aging conditions....

NASA FACILITY FOR THE STUDY OF SPACE RADIATION EFFECTS

Energy Technology Data Exchange (ETDEWEB)

Johnson, David R.

1963-04-15

Information on the energies andd fluxes of trapped electrons and protons in space is summarized, and the Space Radiation Effects Laboratory being constructed to simulate most of the space particulate-energy spectrum is described. A 600-Mev proton synchrocyclotron of variable energy and electron accelerators of 1 to 10 Mev will be included. The accelerator characteristics and the arrangement of the experimental and support buildings, particularly the beam facilities, are discussed; and the planned activities of the laboratory are given. (D.C.W.)

Beam collimation and transport of laser-accelerated protons by a solenoid field

Energy Technology Data Exchange (ETDEWEB)

Harres, K; Alber, I; Guenther, M; Nuernberg, F; Otten, A; Schuetrumpf, J; Roth, M [Technische Universitaet Darmstadt, Institut fuer Kernphysik, Schlossgartenstrasse 9, 64289 Darmstadt (Germany); Tauschwitz, A; Bagnoud, V [GSI - Hemholtzzentrum fur Schwerionenforschung GmbH, Plasmaphysik and PHELIX, Planckstrasse 1, 64291 Darmstadt (Germany); Daido, H; Tampo, M [Photo Medical Research Center, JAEA, 8-1 Umemidai, Kizugawa-city, Kyoto, 619-0215 (Japan); Schollmeier, M, E-mail: k.harres@gsi.d [Sandia National Laboratories, Albuquerque NM 87185 (United States)

2010-08-01

A pulsed high field solenoid was used in a laser-proton acceleration experiment to collimate and transport the proton beam that was generated at the irradiation of a flat foil by a high intensity laser pulse. 10{sup 12} particles at an energy of 2.3 MeV could be caught and transported over a distance of more than 240 mm. Strong space charge effects occur, induced by the high field of the solenoid that forces all co-moving electrons down the the solenoid's axis, building up a strong negative space charge that interacts with the proton beam. This leads to an aggregation of the proton beam around the solenoid's axis and therefore to a stronger focusing effect. The collimation and transport of laser-accelerated protons is the first step to provide these unique beams for further applications like post-acceleration by conventional accelerator structures.

Beam collimation and transport of laser-accelerated protons by a solenoid field

International Nuclear Information System (INIS)

Harres, K; Alber, I; Guenther, M; Nuernberg, F; Otten, A; Schuetrumpf, J; Roth, M; Tauschwitz, A; Bagnoud, V; Daido, H; Tampo, M; Schollmeier, M

2010-01-01

A pulsed high field solenoid was used in a laser-proton acceleration experiment to collimate and transport the proton beam that was generated at the irradiation of a flat foil by a high intensity laser pulse. 10 12 particles at an energy of 2.3 MeV could be caught and transported over a distance of more than 240 mm. Strong space charge effects occur, induced by the high field of the solenoid that forces all co-moving electrons down the the solenoid's axis, building up a strong negative space charge that interacts with the proton beam. This leads to an aggregation of the proton beam around the solenoid's axis and therefore to a stronger focusing effect. The collimation and transport of laser-accelerated protons is the first step to provide these unique beams for further applications like post-acceleration by conventional accelerator structures.

Charged particle accelerators for inertial fusion energy

International Nuclear Information System (INIS)

Humphries, S. Jr.

1991-01-01

The long history of successful commercial applications of charged-particle accelerators is largely a result of initiative by private industry. The Department of Energy views accelerators mainly as support equipment for particle physicists rather than components of an energy generation program. In FY 91, the DOE spent over 850 M$ on building and supporting accelerators for physics research versus 5 M$ on induction accelerators for fusion energy. The author believes this emphasis is skewed. One must address problems of long-term energy sources to preserve the possibility of basic research by future generations. In this paper, the author reviews the rationale for accelerators as inertial fusion drivers, emphasizing that these devices provide a viable path of fusion energy from viewpoints of both physics and engineering. In this paper, he covered the full range of accelerator fusion applications. Because of space limitations, this paper concentrates on induction linacs for ICF, an approach singled out in recent reports by the National Academy of Sciences and the Fusion Policy Advisory Committee as a promising path to long-term fusion power production. Review papers by Cook, Leung, Franzke, Hofmann and Reiser in these proceedings give details on light ion fusion and RF accelerator studies

Hardware-Accelerated Simulated Radiography

International Nuclear Information System (INIS)

Laney, D; Callahan, S; Max, N; Silva, C; Langer, S.; Frank, R

2005-01-01

We present the application of hardware accelerated volume rendering algorithms to the simulation of radiographs as an aid to scientists designing experiments, validating simulation codes, and understanding experimental data. The techniques presented take advantage of 32-bit floating point texture capabilities to obtain solutions to the radiative transport equation for X-rays. The hardware accelerated solutions are accurate enough to enable scientists to explore the experimental design space with greater efficiency than the methods currently in use. An unsorted hexahedron projection algorithm is presented for curvilinear hexahedral meshes that produces simulated radiographs in the absorption-only regime. A sorted tetrahedral projection algorithm is presented that simulates radiographs of emissive materials. We apply the tetrahedral projection algorithm to the simulation of experimental diagnostics for inertial confinement fusion experiments on a laser at the University of Rochester

Electric rail gun application to space propulsion

International Nuclear Information System (INIS)

Barber, J.P.

1979-01-01

The paper examines the possibility of using the DC electric gun principles as a space vehicle propulsion system, capable of producing intermediate thrust levels. The application of an electromagnetic launch technique, called the DC electric rail gun, to the space propulsion concept of O'Neill, is examined. It is determined that the DC electric rail gun offers very high projectile accelerations and a very significant potential for reducing the size and mass of a reaction motor for space application. A detailed description of rail gun principles is given and some simple expressions for the accelerating force, gun impedance, power supply requirements, and system performance are discussed

Formation and acceleration of uniformly filled ellipsoidal electron bunches obtained via space-charge-driven expansion from a cesium-telluride photocathode

Directory of Open Access Journals (Sweden)

P. Piot

2013-01-01

Full Text Available We report the experimental generation, acceleration, and characterization of a uniformly filled electron bunch obtained via space-charge-driven expansion (often referred to as “blow-out regime” in an L-band (1.3-GHz radiofrequency photoinjector. The beam is photoemitted from a cesium-telluride semiconductor photocathode using a short (<200  fs ultraviolet laser pulse. The produced electron bunches are characterized with conventional diagnostics and the signatures of their ellipsoidal character are observed. We especially demonstrate the production of ellipsoidal bunches with charges up to ∼0.5  nC corresponding to a ∼20-fold increase compared to previous experiments with metallic photocathodes.

SOLVING BY PARALLEL COMPUTATION THE POISSON PROBLEM FOR HIGH INTENSITY BEAMS IN CIRCULAR ACCELERATORS

International Nuclear Information System (INIS)

LUCCIO, A.U.; DIMPERIO, N.L.; SAMULYAK, R.; BEEB-WANG, J.

2001-01-01

Simulation of high intensity accelerators leads to the solution of the Poisson Equation, to calculate space charge forces in the presence of acceleration chamber walls. We reduced the problem to ''two-and-a-half'' dimensions for long particle bunches, characteristic of large circular accelerators, and applied the results to the tracking code Orbit

Choice of initial operating parameters for high average current linear accelerators

International Nuclear Information System (INIS)

Batchelor, K.

1976-01-01

In designing an accelerator for high currents it is evident that beam losses in the machine must be minimized, which implies well matched beams, and that adequate acceptance under severe space charge conditions must be met. This paper investigates the input parameters to an Alvarez type drift-tube accelerator resulting from such factors

Generation and transport of laser accelerated ion beams

Energy Technology Data Exchange (ETDEWEB)

Schmidt, Peter; Boine-Frankenheim, Oliver [Technische Univ. Darmstadt (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Kornilov, Vladimir; Spaedtke, Peter [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Collaboration: LIGHT-Collaboration

2013-07-01

Currently the LIGHT- Project (Laser Ion Generation, Handling and Transport) is performed at the GSI Helmholtzzentrum fuer Schwerionenforschung GmbH Darmstadt. Within this project, intense proton beams are generated by laser acceleration, using the TNSA mechanism. After the laser acceleration the protons are transported through the beam pipe by a pulsed power solenoid. To study the transport a VORPAL 3D simulation is compared with CST simulation. A criterion as a function of beam parameters was worked out, to rate the importance of space charge. Furthermore, an exemplary comparison of the solenoid with a magnetic quadrupole-triplet was carried out. In the further course of the LIGHT-Project, it is planned to generate ion beams with higher kinetic energies, using ultra-thin targets. The acceleration processes that can appear are: RPA (Radiation Pressure Acceleration) and BOA (Break-Out Afterburner). Therefore the transport of an ion distribution will be studied, as it emerges from a RPA acceleration.

Beam dynamics simulation of a double pass proton linear accelerator

Directory of Open Access Journals (Sweden)

Kilean Hwang

2017-04-01

Full Text Available A recirculating superconducting linear accelerator with the advantage of both straight and circular accelerator has been demonstrated with relativistic electron beams. The acceleration concept of a recirculating proton beam was recently proposed [J. Qiang, Nucl. Instrum. Methods Phys. Res., Sect. A 795, 77 (2015NIMAER0168-900210.1016/j.nima.2015.05.056] and is currently under study. In order to further support the concept, the beam dynamics study on a recirculating proton linear accelerator has to be carried out. In this paper, we study the feasibility of a two-pass recirculating proton linear accelerator through the direct numerical beam dynamics design optimization and the start-to-end simulation. This study shows that the two-pass simultaneous focusing without particle losses is attainable including fully 3D space-charge effects through the entire accelerator system.

The acceleration and propagation of solar energetic particles

International Nuclear Information System (INIS)

Dalla, Silvia

2004-01-01

During flares and coronal mass ejections at the Sun, ions and electrons can be accelerated to high energies. They can escape from the solar corona into interplanetary space, and be detected by instruments on board spacecraft. This paper will review measurements of these solar energetic particles (SEPs) and models of their acceleration and propagation.It is generally agreed that SEP flux enhancements fall into two distinct classes: the so-called impulsive events, thought to originate in solar flares, and gradual events, thought to be the result of acceleration at the shock driven through the corona and interplanetary space by coronal mass ejections. A fundamental assumption of this model for SEPs is that particles' guiding centers propagate essentially parallel to the interplanetary magnetic field lines, and cross-field particle diffusion is negligible.The recent passage of the Ulysses spacecraft over the solar poles provided the first ever measurements of SEPs out of the ecliptic plane. Analysis of these data has revealed several fundamental differences with respect to the near-ecliptic measurements, such as large delays in particle arrival and in fluxes reaching their peak value. It will be shown that the current model of SEP acceleration and propagation does not account for the Ulysses results, which would more easily be explained by efficient cross-field diffusion of energetic particles

Relativity and accelerator engineering

International Nuclear Information System (INIS)

Geloni, Gianluca; Kocharyan, Vitali; Saldin, Evgeni

2017-09-01

From a geometrical viewpoint, according to the theory of relativity, space and time constitute a four-dimensional continuum with pseudo-Euclidean structure. This has recently begun to be a practically important statement in accelerator physics. An X-ray Free Electron Laser (XFEL) is in fact the best, exciting example of an engineering system where improvements in accelerator technology makes it possible to develop ultrarelativistic macroscopic objects with an internal fine structure, and the theory of relativity plays an essential role in their description. An ultrarelativistic electron bunch modulated at nanometer-scale in XFELs has indeed a macroscopic finite-size of order of 10 μm. Its internal, collective structure is characterized in terms of a wave number vector. Here we will show that a four-dimensional geometrical approach, unusual in accelerator physics, is needed to solve problems involving the emission of radiation from an ultrarelativistic modulated electron beam accelerating along a curved trajectory. We will see that relativistic kinematics enters XFEL physics in a most fundamental way through the so-called Wigner rotation of the modulation wave number vector, which is closely associated to the relativity of simultaneity. If not taken into account, relativistic kinematics effects would lead to a strong qualitative disagreement between theory and experiments. In this paper, several examples of relativistic kinematics effects, which are important for current and future XFEL operation, are studied. The theory of relativity is applied by providing details of the clock synchronization procedure within the laboratory frame. This approach, exploited here but unusual in literature, is rather ''practical'', and should be acceptable to accelerator physicists.

Analytic mappings: a new approach in particle production by accelerated observers

International Nuclear Information System (INIS)

Sanchez, N.

1982-01-01

This is a summary of the authors recent results about physical consequences of analytic mappings in the space-time. Classically, the mapping defines an accelerated frame. At the quantum level it gives rise to particle production. Statistically, the real singularities of the mapping have associated temperatures. This concerns a new approach in Q.F.T. as formulated in accelerated frames. It has been considered as a first step in the understanding of the deep connection that could exist between the structure (geometry and topology) of the space-time and thermodynamics, mainly motivated by the works of Hawking since 1975. (Auth.)

Spinor Field Nonlinearity and Space-Time Geometry

Science.gov (United States)

Saha, Bijan

2018-03-01

Within the scope of Bianchi type VI,VI0,V, III, I, LRSBI and FRW cosmological models we have studied the role of nonlinear spinor field on the evolution of the Universe and the spinor field itself. It was found that due to the presence of non-trivial non-diagonal components of the energy-momentum tensor of the spinor field in the anisotropic space-time, there occur some severe restrictions both on the metric functions and on the components of the spinor field. In this report we have considered a polynomial nonlinearity which is a function of invariants constructed from the bilinear spinor forms. It is found that in case of a Bianchi type-VI space-time, depending of the sign of self-coupling constants, the model allows either late time acceleration or oscillatory mode of evolution. In case of a Bianchi VI 0 type space-time due to the specific behavior of the spinor field we have two different scenarios. In one case the invariants constructed from bilinear spinor forms become trivial, thus giving rise to a massless and linear spinor field Lagrangian. This case is equivalent to the vacuum solution of the Bianchi VI 0 type space-time. The second case allows non-vanishing massive and nonlinear terms and depending on the sign of coupling constants gives rise to accelerating mode of expansion or the one that after obtaining some maximum value contracts and ends in big crunch, consequently generating space-time singularity. In case of a Bianchi type-V model there occur two possibilities. In one case we found that the metric functions are similar to each other. In this case the Universe expands with acceleration if the self-coupling constant is taken to be a positive one, whereas a negative coupling constant gives rise to a cyclic or periodic solution. In the second case the spinor mass and the spinor field nonlinearity vanish and the Universe expands linearly in time. In case of a Bianchi type-III model the space-time remains locally rotationally symmetric all the time

Susceptibility of materials processing experiments to low-level accelerations

Science.gov (United States)

Naumann, R. J.

1981-01-01

The types of material processing experiments being considered for shuttle can be grouped into four categories: (1) contained solidification experiment; (2) quasicontainerless experiments; (3) containerless experiments; and (4) fluids experiments. Low level steady acceleration, compensated and uncompensated transient accelerations, and rotation induced flow factors that must be considered in the acceleration environment of a space vehicle whose importance depends on the type of experiment being performed. Some control of these factors may be exercised by the location and orientation of the experiment relative to shuttle and by the orbit vehicle attitude chosen for mission. The effects of the various residual accelerations can have serious consequence to the control of the experiment and must be factored into the design and operation of the apparatus.

Dusty-Plasma Particle Accelerator

Science.gov (United States)

Foster, John E.

2005-01-01

A dusty-plasma apparatus is being investigated as means of accelerating nanometer- and micrometer-sized particles. Applications for the dusty-plasma particle accelerators fall into two classes: Simulation of a variety of rapidly moving dust particles and micrometeoroids in outer-space environments that include micrometeoroid streams, comet tails, planetary rings, and nebulae and Deposition or implantation of nanoparticles on substrates for diverse industrial purposes that could include hardening, increasing thermal insulation, altering optical properties, and/or increasing permittivities of substrate materials. Relative to prior apparatuses used for similar applications, dusty-plasma particle accelerators offer such potential advantages as smaller size, lower cost, less complexity, and increased particle flux densities. A dusty-plasma particle accelerator exploits the fact that an isolated particle immersed in plasma acquires a net electric charge that depends on the relative mobilities of electrons and ions. Typically, a particle that is immersed in a low-temperature, partially ionized gas, wherein the average kinetic energy of electrons exceeds that of ions, causes the particle to become negatively charged. The particle can then be accelerated by applying an appropriate electric field. A dusty-plasma particle accelerator (see figure) includes a plasma source such as a radio-frequency induction discharge apparatus containing (1) a shallow cup with a biasable electrode to hold the particles to be accelerated and (2) a holder for the substrate on which the particles are to impinge. Depending on the specific design, a pair of electrostatic-acceleration grids between the substrate and discharge plasma can be used to both collimate and further accelerate particles exiting the particle holder. Once exposed to the discharge plasma, the particles in the cup quickly acquire a negative charge. Application of a negative voltage pulse to the biasable electrode results in the

Electron accelerator for tunneling through hard rock

International Nuclear Information System (INIS)

Avery, R.T.; Keefe, D.

1975-10-01

Earlier work demonstrated that intense sub-microsecond bursts of energetic electrons cause significant pulverization and spalling of a variety of rock types. The spall debris generally consists of sand, dust, and small flakes. If carried out at rapid repetition rate, this can lead to a promising technique for increasing the speed and reducing the cost of underground excavation of tunnels, mines, and storage spaces. The conceptual design features of a Pulsed Electron Tunnel Excavator capable of tunneling approximately ten times faster than conventional drill/blast methods are presented, with primary emphasis on the electron accelerator and only a brief description of the tunneling aspects. Of several candidate types of accelerators, a linear induction accelerator producing electron pulses (5 MV, 5 kA, 1.0 μs = 25 kJ) at a 360 Hz rate was selected for the conceptual example. This provides the required average electron beam power output of 9 MW. The feasibility of such an accelerator is discussed

Electron accelerator for tunneling through hard rock

International Nuclear Information System (INIS)

Avery, R.T.; Keefe, D.

1975-01-01

Earlier work demonstrated that intense sub-microsecond bursts of energetic electrons cause significant pulverization and spalling of a variety of rock types. The spall debris generally consists of sand, dust, and small flakes. If carried out at rapid repetition rate, this can lead to a promising technique for increasing the speed and reducing the cost of underground excavation of tunnels, mines, and storage spaces. The conceptual design features of a Pulsed Electron Tunnel Excavator capable of tunneling approximately ten times faster than conventional drill/blast methods are presented with primary emphasis on the electron accelerator and only a brief description of the tunneling aspects. Of several candidate types of accelerators, a linear induction accelerator producing electron pulses (5 MV, 5 kA, 1.0 μs = 25 kJ) at a 360 Hz rate was selected for the conceptual example. This provides the required average electron beam power output of 9 MW. The feasibility of such an accelerator is discussed

Particle acceleration by coronal and interplanetary shock waves

International Nuclear Information System (INIS)

Pesses, M.E.

1982-01-01

Utilizing many years of observation from deep space and near-earth spacecraft a theoretical understanding has evolved on how ions and electrons are accelerated in interplanetary shock waves. This understanding is now being applied to solar flare-induced shock waves propagating through the solar atmosphere. Such solar flare phenomena as gamma-ray line and neutron emissions, interplanetary energetic electron and ion events, and Type II and moving Type IV radio bursts appear understandable in terms of particle acceleration in shock waves

Accelerated Optimization in the PDE Framework: Formulations for the Active Contour Case

KAUST Repository

Yezzi, Anthony; Sundaramoorthi, Ganesh

2017-01-01

Following the seminal work of Nesterov, accelerated optimization methods have been used to powerfully boost the performance of first-order, gradient-based parameter estimation in scenarios where second-order optimization strategies are either inapplicable or impractical. Not only does accelerated gradient descent converge considerably faster than traditional gradient descent, but it also performs a more robust local search of the parameter space by initially overshooting and then oscillating back as it settles into a final configuration, thereby selecting only local minimizers with a basis of attraction large enough to contain the initial overshoot. This behavior has made accelerated and stochastic gradient search methods particularly popular within the machine learning community. In their recent PNAS 2016 paper, Wibisono, Wilson, and Jordan demonstrate how a broad class of accelerated schemes can be cast in a variational framework formulated around the Bregman divergence, leading to continuum limit ODE's. We show how their formulation may be further extended to infinite dimension manifolds (starting here with the geometric space of curves and surfaces) by substituting the Bregman divergence with inner products on the tangent space and explicitly introducing a distributed mass model which evolves in conjunction with the object of interest during the optimization process. The co-evolving mass model, which is introduced purely for the sake of endowing the optimization with helpful dynamics, also links the resulting class of accelerated PDE based optimization schemes to fluid dynamical formulations of optimal mass transport.

Accelerated Optimization in the PDE Framework: Formulations for the Active Contour Case

KAUST Repository

Yezzi, Anthony

2017-11-27

Following the seminal work of Nesterov, accelerated optimization methods have been used to powerfully boost the performance of first-order, gradient-based parameter estimation in scenarios where second-order optimization strategies are either inapplicable or impractical. Not only does accelerated gradient descent converge considerably faster than traditional gradient descent, but it also performs a more robust local search of the parameter space by initially overshooting and then oscillating back as it settles into a final configuration, thereby selecting only local minimizers with a basis of attraction large enough to contain the initial overshoot. This behavior has made accelerated and stochastic gradient search methods particularly popular within the machine learning community. In their recent PNAS 2016 paper, Wibisono, Wilson, and Jordan demonstrate how a broad class of accelerated schemes can be cast in a variational framework formulated around the Bregman divergence, leading to continuum limit ODE\\'s. We show how their formulation may be further extended to infinite dimension manifolds (starting here with the geometric space of curves and surfaces) by substituting the Bregman divergence with inner products on the tangent space and explicitly introducing a distributed mass model which evolves in conjunction with the object of interest during the optimization process. The co-evolving mass model, which is introduced purely for the sake of endowing the optimization with helpful dynamics, also links the resulting class of accelerated PDE based optimization schemes to fluid dynamical formulations of optimal mass transport.

The neutron dose equivalent around high energy medical electron linear accelerators

Directory of Open Access Journals (Sweden)

Poje Marina

2014-01-01

Full Text Available The measurement of neutron dose equivalent was made in four dual energy linear accelerator rooms. Two of the rooms were reconstructed after decommissioning of 60Co units, so the main limitation was the space. The measurements were performed by a nuclear track etched detectors LR-115 associated with the converter (radiator that consist of 10B and with the active neutron detector Thermo BIOREM FHT 742. The detectors were set at several locations to evaluate the neutron ambient dose equivalent and/or neutron dose rate to which medical personnel could be exposed. Also, the neutron dose dependence on collimator aperture was analyzed. The obtained neutron dose rates outside the accelerator rooms were several times smaller than the neutron dose rates inside the accelerator rooms. Nevertheless, the measured neutron dose equivalent was not negligible from the aspect of the personal dosimetry with almost 2 mSv a year per person in the areas occupied by staff (conservative estimation. In rooms with 15 MV accelerators, the neutron exposure to the personnel was significantly lower than in the rooms having 18 MV accelerators installed. It was even more pronounced in the room reconstructed after the 60Co decommissioning. This study confirms that shielding from the neutron radiation should be considered when building vaults for high energy linear accelerators, especially when the space constraints exist.

Vertical orbit excursion fixed field alternating gradient accelerators

Directory of Open Access Journals (Sweden)

Stephen Brooks

2013-08-01

Full Text Available Fixed field alternating gradient (FFAG accelerators with vertical orbit excursion (VFFAGs provide a promising alternative design for rings with fixed-field superconducting magnets. They have a vertical magnetic field component that increases with height in the vertical aperture, yielding a skew quadrupole focusing structure. Scaling-type VFFAGs are found with fixed tunes and no intrinsic limitation on momentum range. This paper presents the first multiparticle tracking of such machines. Proton driver rings to accelerate the 800 MeV beam from the ISIS synchrotron are presented, in terms of both magnet field geometry and longitudinal behavior during acceleration with space charge. The 12 GeV ring produces an output power of at least 2.18 MW. Possible applications of VFFAGs to waste transmutation, hadron therapy, and energy-recovery electron accelerators are also discussed.

Effects of hyperbolic rotation in Minkowski space on the modeling of plasma accelerators in a Lorentz boosted frame

International Nuclear Information System (INIS)

Vay, J.-L.; Geddes, C. G. R.; Cormier-Michel, E.; Grote, D. P.

2011-01-01

The effects of hyperbolic rotation in Minkowski space resulting from the use of Lorentz boosted frames of calculation on laser propagation in plasmas are analyzed. Selection of a boost frame at the laser group velocity is shown to alter the laser spectrum, allowing the use of higher boost velocities. The technique is applied to simulations of laser driven plasma wakefield accelerators, which promise much smaller machines and whose development requires detailed simulations that challenge or exceed current capabilities. Speedups approaching the theoretical optima are demonstrated, producing the first direct simulations of stages up to 1 TeV. This is made possible by a million times speedup thanks to a frame boost with a relativistic factor γ b as high as 1300, taking advantage of the rotation to mitigate an instability that limited previous work.

Laser-pump/X-ray-probe experiments with electrons ejected from a Cu(111) target: space-charge acceleration.

Science.gov (United States)

Schiwietz, G; Kühn, D; Föhlisch, A; Holldack, K; Kachel, T; Pontius, N

2016-09-01

A comprehensive investigation of the emission characteristics for electrons induced by X-rays of a few hundred eV at grazing-incidence angles on an atomically clean Cu(111) sample during laser excitation is presented. Electron energy spectra due to intense infrared laser irradiation are investigated at the BESSY II slicing facility. Furthermore, the influence of the corresponding high degree of target excitation (high peak current of photoemission) on the properties of Auger and photoelectrons liberated by a probe X-ray beam is investigated in time-resolved pump and probe measurements. Strong electron energy shifts have been found and assigned to space-charge acceleration. The variation of the shift with laser power and electron energy is investigated and discussed on the basis of experimental as well as new theoretical results.

Simulation of the Plasma Meniscus with and without Space Charge using Triode Extraction System

International Nuclear Information System (INIS)

Abdel Rahman, M.M.; EI-Khabeary, H.

2007-01-01

In this work simulation of the singly charged argon ion trajectories for a variable plasma meniscus is studied with and without space charge for the triode extraction system by using SIMION 3D (Simulation of Ion Optics in Three Dimensions) version 7 personal computer program. Tbe influence of acceleration voltage applied to tbe acceleration electrode of the triode extraction system on the shape of the plasma meniscus has been determined. The plasma electrode is set at +5000 volt and the acceleration voltage applied to the acceleration electrode is varied from -5000 volt to +5000 volt. In the most of the concave and convex plasma shapes ion beam emittance can be calculated by using separate standard deviations of positions and elevations angles. Ion beam emittance as a function of the curvature of the plasma meniscus for different plasma shapes ( flat concave and convex ) without space change at acceleration voltage varied from -5000 volt to +5000 volt applied to the acceleration electrode of the triode extraction system has been investigated. Tbe influence of the extraction gap on ion beam emittance for a plasma concave shape of 3.75 mm without space charge at acceleration voltage, V a cc = -2000 volt applied to the acceleration electrode of the triode extraction system has been determined. Also the influence of space charge on ion beam emittance for variable plasma meniscus at acceleration voltage, V a cc = - 2000 volt applied to the acceleration electrode of. the triode extraction system has been studied

Simulation of the plasma meniscus with and without space charge using triode extraction system

International Nuclear Information System (INIS)

Rahman, M.M.Abdel; El-Khabeary, H.

2009-01-01

In this work, simulation of the singly charged argon ion trajectories for a variable plasma meniscus is studied with and without space charge for the triode extraction system by using SIMION 3D (Simulation of Ion Optics in Three Dimensions) version 7 personal computer program. The influence of acceleration voltage applied to the acceleration electrode of the triode extraction system on the shape of the plasma meniscus has been determined. The plasma electrode is set at +5000 volt and the acceleration voltage applied to the acceleration electrode is varied from -5000 volt to +5000 volt. In the most of the concave and convex plasma shapes, ion beam emittance can be calculated by using separate standard deviations of positions and elevations angles. Ion beam emittance as a function of the curvature of the plasma meniscus for different plasma shapes ( flat, concave and convex ) without space charge at acceleration voltage varied from -5000 volt to +5000 volt applied to the acceleration electrode of the triode extraction system has been investigated. The influence of the extraction gap on ion beam emittance for a plasma concave shape of 3.75 mm without space charge at acceleration voltage, V acc = -2000 volt applied to the acceleration electrode of the triode extraction system has been determined. Also the influence of space charge on ion beam emittance for variable plasma meniscus at acceleration voltage, V acc = -2000 volt applied to the acceleration electrode of the triode extraction system has been studied. (author)

A feasibility study of space-charge neutralized ion induction linacs: Final report

International Nuclear Information System (INIS)

Slutz, S.A.; Primm, P.; Renk, T.; Johnson, D.J.

1997-03-01

Applications for high current (> 1 kA) ion beams are increasing. They include hardening of material surfaces, transmutation of radioactive waste, cancer treatment, and possibly driving fusion reactions to create energy. The space-charge of ions limits the current that can be accelerated in a conventional ion linear accelerator (linac). Furthermore, the accelerating electric field must be kept low enough to avoid the generation and acceleration of counter-streaming electrons. These limitations have resulted in ion accelerator designs that employ long beam lines and would be expensive to build. Space-charge neutralization and magnetic insulation of the acceleration gaps could substantially reduce these two limitations, but at the expense of increasing the complexity of the beam physics. We present theory and experiments to determine the degree of charge-neutralization that can be achieved in various environments found in ion accelerators. Our results suggest that, for high current applications, space-charge neutralization could be used to improve on the conventional ion accelerator technology. There are two basic magnetic field geometries that can be used to insulate the accelerating gaps, a radial field or a cusp field. We will present studies related to both of these geometries. We shall also present numerical simulations of open-quotes multicuspclose quotes accelerator that would deliver potassium ions at 400 MeV with a total beam power of approximately 40 TW. Such an accelerator could be used to drive fusion

Accelerator research studies. Progress report

International Nuclear Information System (INIS)

1983-07-01

The major goal of this project is to study the effects that lead to emittance growth and limitation of beam current and brightness in periodic focusing systems (including linear accelerators). This problem is of great importance for all accelerator applications requiring high intensity beams with small emittance such as heavy ion fusion, spallation neutron sources and high energy physics. In the latter case, future machines must not only provide higher energies (in the range of 10 to 100 TeV), but also higher luminosities than the existing facilities. This implies considerably higher phase-space density of the particle beam produced by the injector linac, i.e., the detrimental emittance growth and concurrent beam loss observed in existing linacs must be avoided

Impurity production and acceleration in CTIX

Energy Technology Data Exchange (ETDEWEB)

Buchenauer, D. [Sandia National Laboratories, MS-9161, P.O. Box 969, Livermore, CA 94550 (United States)], E-mail: dabuche@sandia.gov; Clift, W.M. [Sandia National Laboratories, MS-9161, P.O. Box 969, Livermore, CA 94550 (United States); Klauser, R.; Horton, R.D. [CTIX Group, University of California at Davis, Davis, CA 95616 (United States); Howard, S.J. [General Fusion Inc., Burnaby, BC V5A 3H4 (Canada); Brockington, S.J. [HyperV Technologies Corp., Chantilly, VA 20151 (United States); Evans, R.W.; Hwang, D.Q. [CTIX Group, University of California at Davis, Davis, CA 95616 (United States)

2009-06-15

The Compact Toroid Injection Experiment (CTIX) produces a high density, high velocity hydrogen plasma that maintains its configuration in free space on a MHD resistive time scale. In order to study the production and acceleration of impurities in the injector, several sets of silicon collector probes were exposed to spheromak-like CT's exiting the accelerator. Elemental analysis by Auger Electron Spectroscopy indicated the presence of O, Al, Fe, and Cu in films up to 200 A thickness (1000 CT interactions). Using a smaller number of CT interactions (10-20), implantation of Fe and Cu was measured by Auger depth profiling. The amount of impurities was found to increase with accelerating voltage and number of CT interactions while use of a solenoidal field reduced the amount. Comparison of the implanted Fe and Cu with TRIM simulations indicated that the impurities were traveling more slowly than the hydrogen CT.

A new electrostatic accelerator: the vivitron

International Nuclear Information System (INIS)

1982-07-01

The 35 MV electrostatic accelerator described in the present document operates according to Van de Graaff tandem type accelerator principles. This new accelerator has appreciable advantages over the classical machines built up to today: 1) reduced radial dimensions, and in consequence, a lower overall cast for identical or even lower limiting electric field values; 2) a significantly reduced stored electrical energy distributed in a homogeneous and better controlled way over the interelectrode space; 3) the use of discrete electrodes rather than classical intermediate screens enabling the advantages of direct electrical vision between the vessel and the high-tension electrode (voltage measurements and regulation by the Corona effect) to be retained. The reduced surface area of these electrodes improving both their characteristics when a voltage is applied and the mechanical behavior of the system; 4) a ''light'' internal structure enabling a horizontal machine to be envisaged [fr

High-gradient compact linear accelerator

Science.gov (United States)

Carder, Bruce M.

1998-01-01

A high-gradient linear accelerator comprises a solid-state stack in a vacuum of five sets of disc-shaped Blumlein modules each having a center hole through which particles are sequentially accelerated. Each Blumlein module is a sandwich of two outer conductive plates that bracket an inner conductive plate positioned between two dielectric plates with different thicknesses and dielectric constants. A third dielectric core in the shape of a hollow cylinder forms a casing down the series of center holes, and it has a dielectric constant different that the two dielectric plates that sandwich the inner conductive plate. In operation, all the inner conductive plates are charged to the same DC potential relative to the outer conductive plates. Next, all the inner conductive plates are simultaneously shorted to the outer conductive plates at the outer diameters. The signal short will propagate to the inner diameters at two different rates in each Blumlein module. A faster wave propagates quicker to the third dielectric core across the dielectric plates with the closer spacing and lower dielectric constant. When the faster wave reaches the inner extents of the outer and inner conductive plates, it reflects back outward and reverses the field in that segment of the dielectric core. All the field segments in the dielectric core are then in unipolar agreement until the slower wave finally propagates to the third dielectric core across the dielectric plates with the wider spacing and higher dielectric constant. During such unipolar agreement, particles in the core are accelerated with gradients that exceed twenty megavolts per meter.

The peculiarities of particle dynamics in the Fermi acceleration scheme

International Nuclear Information System (INIS)

Buts, V.A.

2015-01-01

With examples of discrete and distributed mathematical models of the Fermi acceleration mechanism, a usefulness, or even necessity, of taking into account of singular solutions is demonstrated. Also the role is shown of those parts of phase space where the uniqueness theorem conditions to form the dynamics of physical systems are broken. It was found that the dynamics of particles in discrete and distributed mathematical schemes of Fermi acceleration can be significantly different. The difference is due to the fact that the distributed model takes into account the effects of phase space where conditions do not correspond to those necessary for application of the uniqueness theorem. The role of singular solutions is under discussion as well.

Beam front accelerators

International Nuclear Information System (INIS)

Reiser, M.

1982-01-01

An intense relativistic electron beam cannot propagate in a metal drift tube when the current exceeds the space charge limit. Very high charge density and electric field gradients (10 2 to 10 3 MV/m) develop at the beam front and the electrons are reflected. When a neutral gas or a plasma is present, collective acceleration of positive ions occur, and the resulting charge neutralization enables the beam to propagate. Experimental results, theoretical understanding, and schemes to achieve high ion energies by external control of the beam front velocity will be reviewed

Studies of polarized beam acceleration and Siberian Snakes

International Nuclear Information System (INIS)

Lee, S.Y.

1992-01-01

We studied depolarization mechanisms of polarized proton acceleration in high energy accelerators with snakes and found that the perturbed spin tune due to the imperfection resonance plays an important role in beam depolarization at snake resonances. We also found that even order snake resonances exist in the overlapping intrinsic and imperfection resonances. Due to the perturbed spin tune of imperfection resonances, each snake resonance splits into two. Thus the available betatron tune space becomes smaller. Some constraints on polarized beam colliders were also examined

CHARACTERISATION OF THE ALICE ACCELERATOR AS AN INJECTOR FOR THE EMMA NS-FFAG

CERN Document Server

Garland, J M; McKenzie, J W; Muratori, B D

2010-01-01

EMMA (ElectronModel with Many Applications) is the first proof-of-principle non-scaling FFAG accelerator and is presently under construction at Daresbury Laboratory in the UK. To probe different parts of the bunch phase space during the acceleration from 10 to 20 MeV (which requires rapid resonance crossing), electron bunches are needed with sufficiently small emittance. To understand the phase space painting into the 3000 mm-mrad EMMA acceptance, we have modelled ALICE (Accelerators and Lasers in Combined Experiments) - which acts as an injector for EMMA - using GPT and compared the estimated emittances with measurements made with a variety of screen-based methods. Although the emittances are not yet as small as desired, we obtain reasonable agreement between simulation and measurement.

Saha equation in Rindler space

Indian Academy of Sciences (India)

Sanchari De

2017-05-31

May 31, 2017 ... scenario, the flat local geometry is called the Rindler space. For an illustration, let us consider two reference ... the local acceleration of the frame. To investigate Saha equation in a uniformly acceler- ... the best of our knowledge, the study of Saha equa- tion in Rindler space has not been reported earlier.

Case Studies in Space Charge and Plasma Acceleration of Charged Beams

CERN Document Server

Bazzani, A; Londrillo, P; Sinigardi, S; Turchetti, G

2014-01-01

Plasma acceleration with electron or proton driver beams is a challenging opportunity for high energy physics. An energy doubling experiment with electron drivers was successfully performed at SLAC and a key experiment AWAKE with proton drivers is on schedule at CERN. Simulations play an important role in choosing the best experimental conditions and in interpreting the results. The Vlasov equation is the theoretical tool to describe the interaction of a driver particle beam or a driver laser pulse with a plasma. Collective effects, such as tune shift and mismatch instabilities, appear in high intensity standard accelerators and are described by the Poisson-Vlasov equation. In the paper we review the Vlasov equation in electrostatic and fully electromagnetic case. The general framework of variational principles is used to derive the equation, the local form of the balance equations and related conservation laws. In the electrostatic case we remind the analytic Kapchinskij-Vladimirskij (K-V) model and we propo...

Improving the growth of Ge/Si islands by modulating the spacing between screen and accelerator grids in ion beam sputtering deposition system

International Nuclear Information System (INIS)

Yang, Jie; Zhao, Bo; Wang, Chong; Qiu, Feng; Wang, Rongfei; Yang, Yu

2016-01-01

Highlights: • Ge islands were prepared by ion beam sputtering with different grid-to-grid gaps. • Ge islands with larger sizes and low density are observed in 1-mm-spaced samples. • The island growth was determined by sputter energy and the quality of Si buffer. • The crystalline volume fraction of buffer must be higher than 72% to grow islands. - Abstract: Ge islands were fabricated on Si buffer layer by ion beam sputtering deposition with a spacing between the screen and accelerator grids of either 1 mm or 2 mm. The Si buffer layer exhibits mixed-phase microcrystallinity for samples grown with 1 mm spacing and crystallinity for those with 2 mm spacing. Ge islands are larger and less dense than those grown on the crystalline buffer because of the selective growth mechanism on the microcrystalline buffer. Moreover, the nucleation site of Ge islands formed on the crystalline Si buffer is random. Ge islands grown at different grid-to-grid gaps are characterized by two key factors, namely, divergence half angle of ion beam and crystallinity of buffer layer. High grid-to-grid spacing results in small divergence half angle, thereby enhancing the sputtering energy and redistribution of sputtered atoms. The crystalline volume fraction of the microcrystalline Si buffer was obtained based on the integrated intensity ratio of Raman peaks. The islands show decreased density with decreasing crystalline volume fraction and are difficult to observe at crystalline volume fractions lower than 72%.

Improving the growth of Ge/Si islands by modulating the spacing between screen and accelerator grids in ion beam sputtering deposition system

Energy Technology Data Exchange (ETDEWEB)

Yang, Jie; Zhao, Bo [Institute of Optoelectronic Information Materials, School of Materials Science and Engineering, Yunnan University, Kunming 650091 (China); Yunnan Key Laboratory for Micro/Nano Materials and Technology, Yunnan University, Kunming 650091 (China); Wang, Chong, E-mail: cwang@mail.sitp.ac.cn [Institute of Optoelectronic Information Materials, School of Materials Science and Engineering, Yunnan University, Kunming 650091 (China); Yunnan Key Laboratory for Micro/Nano Materials and Technology, Yunnan University, Kunming 650091 (China); Qiu, Feng; Wang, Rongfei [Institute of Optoelectronic Information Materials, School of Materials Science and Engineering, Yunnan University, Kunming 650091 (China); Yunnan Key Laboratory for Micro/Nano Materials and Technology, Yunnan University, Kunming 650091 (China); Yang, Yu, E-mail: yuyang@ynu.edu.cn [Institute of Optoelectronic Information Materials, School of Materials Science and Engineering, Yunnan University, Kunming 650091 (China); Yunnan Key Laboratory for Micro/Nano Materials and Technology, Yunnan University, Kunming 650091 (China)

2016-11-15

Highlights: • Ge islands were prepared by ion beam sputtering with different grid-to-grid gaps. • Ge islands with larger sizes and low density are observed in 1-mm-spaced samples. • The island growth was determined by sputter energy and the quality of Si buffer. • The crystalline volume fraction of buffer must be higher than 72% to grow islands. - Abstract: Ge islands were fabricated on Si buffer layer by ion beam sputtering deposition with a spacing between the screen and accelerator grids of either 1 mm or 2 mm. The Si buffer layer exhibits mixed-phase microcrystallinity for samples grown with 1 mm spacing and crystallinity for those with 2 mm spacing. Ge islands are larger and less dense than those grown on the crystalline buffer because of the selective growth mechanism on the microcrystalline buffer. Moreover, the nucleation site of Ge islands formed on the crystalline Si buffer is random. Ge islands grown at different grid-to-grid gaps are characterized by two key factors, namely, divergence half angle of ion beam and crystallinity of buffer layer. High grid-to-grid spacing results in small divergence half angle, thereby enhancing the sputtering energy and redistribution of sputtered atoms. The crystalline volume fraction of the microcrystalline Si buffer was obtained based on the integrated intensity ratio of Raman peaks. The islands show decreased density with decreasing crystalline volume fraction and are difficult to observe at crystalline volume fractions lower than 72%.

Sun Radio Interferometer Space Experiment (SunRISE)

Science.gov (United States)

Kasper, Justin C.; SunRISE Team

2018-06-01

The Sun Radio Interferometer Space Experiment (SunRISE) is a NASA Heliophysics Explorer Mission of Opportunity currently in Phase A. SunRISE is a constellation of spacecraft flying in a 10-km diameter formation and operating as the first imaging radio interferometer in space. The purpose of SunRISE is to reveal critical aspects of solar energetic particle (SEP) acceleration at coronal mass ejections (CMEs) and transport into space by making the first spatially resolved observations of coherent Type II and III radio bursts produced by electrons accelerated at CMEs or released from flares. SunRISE will focus on solar Decametric-Hectometric (DH, 0.1 space before major SEP events, but cannot be seen on Earth due to ionospheric absorption. This talk will describe SunRISE objectives and implementation. Presented on behalf of the entire SunRISE team.

Relativity and accelerator engineering

Energy Technology Data Exchange (ETDEWEB)

Geloni, Gianluca [European XFEL GmbH, Schenefeld (Germany); Kocharyan, Vitali; Saldin, Evgeni [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

2017-09-15

From a geometrical viewpoint, according to the theory of relativity, space and time constitute a four-dimensional continuum with pseudo-Euclidean structure. This has recently begun to be a practically important statement in accelerator physics. An X-ray Free Electron Laser (XFEL) is in fact the best, exciting example of an engineering system where improvements in accelerator technology makes it possible to develop ultrarelativistic macroscopic objects with an internal fine structure, and the theory of relativity plays an essential role in their description. An ultrarelativistic electron bunch modulated at nanometer-scale in XFELs has indeed a macroscopic finite-size of order of 10 μm. Its internal, collective structure is characterized in terms of a wave number vector. Here we will show that a four-dimensional geometrical approach, unusual in accelerator physics, is needed to solve problems involving the emission of radiation from an ultrarelativistic modulated electron beam accelerating along a curved trajectory. We will see that relativistic kinematics enters XFEL physics in a most fundamental way through the so-called Wigner rotation of the modulation wave number vector, which is closely associated to the relativity of simultaneity. If not taken into account, relativistic kinematics effects would lead to a strong qualitative disagreement between theory and experiments. In this paper, several examples of relativistic kinematics effects, which are important for current and future XFEL operation, are studied. The theory of relativity is applied by providing details of the clock synchronization procedure within the laboratory frame. This approach, exploited here but unusual in literature, is rather ''practical'', and should be acceptable to accelerator physicists.

Fast space travel by vacuum zero-point field perturbations

International Nuclear Information System (INIS)

Froning, H. D. Jr.

1999-01-01

Forces acting upon an accelerating vehicle that is 'warping' its surrounding space are estimated, using the techniques of computational gas/fluid dynamics. Disturbances corresponding to perturbation of spacetime metric and vacuum zero-point fields by electromagnetic discharges are modeled as changes in the electric permittivity and magnetic permeability characteristics of the vacuum of space. And it is assumed that resistance to acceleration (vehicle inertia) is, in part, a consequence of zero-point radiation pressure field anisotropy in the warped space region surrounding the craft. The paper shows that resistance to vehicle acceleration can be diminished by spacetime warping that increases light propagation speed within the warped region. If sufficient warping is achieved, ship speed is slower than light speed within the region that surrounds it-even if it is moving faster-than-light with respect to earth

Classical mechanics in non-commutative phase space

International Nuclear Information System (INIS)

Wei Gaofeng; Long Chaoyun; Long Zhengwen; Qin Shuijie

2008-01-01

In this paper the laws of motion of classical particles have been investigated in a non-commutative phase space. The corresponding non-commutative relations contain not only spatial non-commutativity but also momentum non-commutativity. First, new Poisson brackets have been defined in non-commutative phase space. They contain corrections due to the non-commutativity of coordinates and momenta. On the basis of this new Poisson brackets, a new modified second law of Newton has been obtained. For two cases, the free particle and the harmonic oscillator, the equations of motion are derived on basis of the modified second law of Newton and the linear transformation (Phys. Rev. D, 2005, 72: 025010). The consistency between both methods is demonstrated. It is shown that a free particle in commutative space is not a free particle with zero-acceleration in the non-commutative phase space, but it remains a free particle with zero-acceleration in non-commutative space if only the coordinates are non-commutative. (authors)

Incorporating space charge in the transverse phase-space matching and tomography at PITZ

Energy Technology Data Exchange (ETDEWEB)

Kourkafas, Georgios

2015-11-15

The ever-expanding achievements in the field of particle accelerators push their specifications to very demanding levels. The performance of many modern applications depends on their ability to be operated with high bunch charges confined in small volumes. However, the consequence of increased intensity is strong space-charge forces, which perplex the beam manipulation and undermine the beam quality. As a result, reliable methods are needed to control and measure the accelerated particles under these extraordinary conditions. The phase space tomography is a diagnostic technique which can reveal details of the transverse beam parameters for a wide range of intensities and energies, with minimal influence from the machine instabilities, in a quasi non-destructive way. The accuracy of this method relies on the precise knowledge and control of the particle dynamics under the influence of space charge in different stages of the measurement. On the one hand, the matching of the beam to the measurement's design transverse parameters requires a procedure which efficiently compensates the effects of space charge. Depending on the structure of the magnetic lattice, different aspects of these effects prevail, therefore different strategies have to be developed. On the other hand, the impact of the space-charge forces on the phase-space transformations during the data acquisition has to be included in the model which is used for the tomographic reconstruction. The aim of this thesis is to provide and test time-efficient solutions for the incorporation of space charge in the transverse beam matching and phase space tomography.

Incorporating space charge in the transverse phase-space matching and tomography at PITZ

International Nuclear Information System (INIS)

Kourkafas, Georgios

2015-11-01

The ever-expanding achievements in the field of particle accelerators push their specifications to very demanding levels. The performance of many modern applications depends on their ability to be operated with high bunch charges confined in small volumes. However, the consequence of increased intensity is strong space-charge forces, which perplex the beam manipulation and undermine the beam quality. As a result, reliable methods are needed to control and measure the accelerated particles under these extraordinary conditions. The phase space tomography is a diagnostic technique which can reveal details of the transverse beam parameters for a wide range of intensities and energies, with minimal influence from the machine instabilities, in a quasi non-destructive way. The accuracy of this method relies on the precise knowledge and control of the particle dynamics under the influence of space charge in different stages of the measurement. On the one hand, the matching of the beam to the measurement's design transverse parameters requires a procedure which efficiently compensates the effects of space charge. Depending on the structure of the magnetic lattice, different aspects of these effects prevail, therefore different strategies have to be developed. On the other hand, the impact of the space-charge forces on the phase-space transformations during the data acquisition has to be included in the model which is used for the tomographic reconstruction. The aim of this thesis is to provide and test time-efficient solutions for the incorporation of space charge in the transverse beam matching and phase space tomography.

Evaluation of parameters for particles acceleration by the zero-point field of quantum electrodynamics

Science.gov (United States)

Rueda, A.

1985-01-01

That particles may be accelerated by vacuum effects in quantum field theory has been repeatedly proposed in the last few years. A natural upshot of this is a mechanism for cosmic rays (CR) primaries acceleration. A mechanism for acceleration by the zero-point field (ZPE) when the ZPE is taken in a realistic sense (in opposition to a virtual field) was considered. Originally the idea was developed within a semiclassical context. The classical Einstein-Hopf model (EHM) was used to show that free isolated electromagnrtically interacting particles performed a random walk in phase space and more importantly in momentum space when submitted to the perennial action of the so called classical electromagnrtic ZPE.

Evaluation of parameters for particles acceleration by the zero-point field of quantum electrodynamics

International Nuclear Information System (INIS)

Rueda, A.

1985-01-01

That particles may be accelerated by vacuum effects in quantum field theory has been repeatedly proposed in the last few years. A natural upshot of this is a mechanism for cosmic rays (CR) primaries acceleration. A mechanism for acceleration by the zero-point field (ZPE) when the ZPE is taken in a realistic sense (in opposition to a virtual field) was considered. Originally the idea was developed within a semiclassical context. The calssical Einstein-Hopf model (EHM) was used to show that free isolated electromagnrtically interacting particles performed a random walk in phase space and more importantly in momentum space when submitted to the perennial action of the so called classical electromagnetic ZPE

Motion sickness and otolith sensitivity - A pilot study of habituation to linear acceleration

Science.gov (United States)

Potvin, A. R.; Sadoff, M.; Billingham, J.

1977-01-01

Astronauts, particularly in Skylab flights, experienced varying degrees of motion sickness lasting 3-5 days. One possible mechanism for this motion sickness adaptation is believed to be a reduction in otolith sensitivity with an attendant reduction in sensory conflict. In an attempt to determine if this hypothesis is valid, a ground-based pilot study was conducted on a vertical linear accelerator. The extent of habituation to accelerations which initially produced motion sickness was evaluated, along with the possible value of habituation training to minimize the space motion sickness problem. Results showed that habituation occurred for 6 of the 8 subjects tested. However, in tests designed to measure dynamic and static otolith function, no significant differences between pre- and post-habituation tests were observed. Cross habituation effects to a standard Coriolis acceleration test were not significant. It is unlikely that ground-based pre-habituation to linear accelerations of the type examined would alter susceptibility to space motion sickness.

Laser acceleration in vacuum with an open iris-loaded waveguide

International Nuclear Information System (INIS)

Xie, Ming

1997-05-01

An open iris-loaded waveguide structure is considered for laser acceleration of highly relativistic particle in vacuum. Complete characterization of all eigenmodes are given in analytical form for the structure. In particular the dominant radially polarized TM mode is evaluated in detail for laser acceleration. The entire parameter space is searched and it is found that below the laser damage threshold of the structure an acceleration gradient around 1 GV/m can be obtained over a phase slippage length of 10s of cm with TWs laser in the wavelength range from 1 to 10 μm

Accelerator physics analysis with an integrated toolkit

International Nuclear Information System (INIS)

Holt, J.A.; Michelotti, L.; Satogata, T.

1992-08-01

Work is in progress on an integrated software toolkit for linear and nonlinear accelerator design, analysis, and simulation. As a first application, ''beamline'' and ''MXYZPTLK'' (differential algebra) class libraries, were used with an X Windows graphics library to build an user-friendly, interactive phase space tracker which, additionally, finds periodic orbits. This program was used to analyse a theoretical lattice which contains octupoles and decapoles to find the 20th order, stable and unstable periodic orbits and to explore the local phase space structure

Influence functionals and the accelerating detector

International Nuclear Information System (INIS)

Anglin, J.R.

1993-01-01

The influence functional is derived for a massive scalar field in the ground state, coupled to a uniformly accelerating DeWitt monopole detector in (D+1)-dimensional Minkowski space. This confirms the local nature of the Unruh effect, and provides an exact solution to the problem of the accelerating detector without invoking a nonstandard quantization. A directional detector is presented which is efficiently decohered by the scalar field vacuum, and which illustrates an important difference between the quantum mechanics of inertial and noninertial frames. From the results of these calculations, some comments are made regarding the possibility of establishing a quantum equivalence principle, so that the Hawking effect might be derived from the Unruh effect

Current Fragmentation and Particle Acceleration in Solar Flares

Science.gov (United States)

Cargill, P. J.; Vlahos, L.; Baumann, G.; Drake, J. F.; Nordlund, Å.

2012-11-01

Particle acceleration in solar flares remains an outstanding problem in plasma physics and space science. While the observed particle energies and timescales can perhaps be understood in terms of acceleration at a simple current sheet or turbulence site, the vast number of accelerated particles, and the fraction of flare energy in them, defies any simple explanation. The nature of energy storage and dissipation in the global coronal magnetic field is essential for understanding flare acceleration. Scenarios where the coronal field is stressed by complex photospheric motions lead to the formation of multiple current sheets, rather than the single monolithic current sheet proposed by some. The currents sheets in turn can fragment into multiple, smaller dissipation sites. MHD, kinetic and cellular automata models are used to demonstrate this feature. Particle acceleration in this environment thus involves interaction with many distributed accelerators. A series of examples demonstrate how acceleration works in such an environment. As required, acceleration is fast, and relativistic energies are readily attained. It is also shown that accelerated particles do indeed interact with multiple acceleration sites. Test particle models also demonstrate that a large number of particles can be accelerated, with a significant fraction of the flare energy associated with them. However, in the absence of feedback, and with limited numerical resolution, these results need to be viewed with caution. Particle in cell models can incorporate feedback and in one scenario suggest that acceleration can be limited by the energetic particles reaching the condition for firehose marginal stability. Contemporary issues such as footpoint particle acceleration are also discussed. It is also noted that the idea of a "standard flare model" is ill-conceived when the entire distribution of flare energies is considered.

Space-to-Space Power Beaming Enabling High Performance Rapid Geocentric Orbit Transfer

Science.gov (United States)

Dankanich, John W.; Vassallo, Corinne; Tadge, Megan

2015-01-01

The use of electric propulsion is more prevalent than ever, with industry pursuing all electric orbit transfers. Electric propulsion provides high mass utilization through efficient propellant transfer. However, the transfer times become detrimental as the delta V transitions from near-impulsive to low-thrust. Increasing power and therefore thrust has diminishing returns as the increasing mass of the power system limits the potential acceleration of the spacecraft. By using space-to-space power beaming, the power system can be decoupled from the spacecraft and allow significantly higher spacecraft alpha (W/kg) and therefore enable significantly higher accelerations while maintaining high performance. This project assesses the efficacy of space-to-space power beaming to enable rapid orbit transfer while maintaining high mass utilization. Concept assessment requires integrated techniques for low-thrust orbit transfer steering laws, efficient large-scale rectenna systems, and satellite constellation configuration optimization. This project includes the development of an integrated tool with implementation of IPOPT, Q-Law, and power-beaming models. The results highlight the viability of the concept, limits and paths to infusion, and comparison to state-of-the-art capabilities. The results indicate the viability of power beaming for what may be the only approach for achieving the desired transit times with high specific impulse.

Direct and accelerated parameter mapping using the unscented Kalman filter.

Science.gov (United States)

Zhao, Li; Feng, Xue; Meyer, Craig H

2016-05-01

To accelerate parameter mapping using a new paradigm that combines image reconstruction and model regression as a parameter state-tracking problem. In T2 mapping, the T2 map is first encoded in parameter space by multi-TE measurements and then encoded by Fourier transformation with readout/phase encoding gradients. Using a state transition function and a measurement function, the unscented Kalman filter can describe T2 mapping as a dynamic system and directly estimate the T2 map from the k-space data. The proposed method was validated with a numerical brain phantom and volunteer experiments with a multiple-contrast spin echo sequence. Its performance was compared with a conjugate-gradient nonlinear inversion method at undersampling factors of 2 to 8. An accelerated pulse sequence was developed based on this method to achieve prospective undersampling. Compared with the nonlinear inversion reconstruction, the proposed method had higher precision, improved structural similarity and reduced normalized root mean squared error, with acceleration factors up to 8 in numerical phantom and volunteer studies. This work describes a new perspective on parameter mapping by state tracking. The unscented Kalman filter provides a highly accelerated and efficient paradigm for T2 mapping. © 2015 Wiley Periodicals, Inc.

Neutron accelerator tube having improved ionization section

International Nuclear Information System (INIS)

Givens, W.W.

1982-01-01

A neutron accelerator tube is described having a target section, an ionization section, and a replenisher section for supplying accelerator gas to the ionization section. The ionization section is located between the target and the replenisher section and includes an ionization chamber adapted to receive accelerator gas from the replenisher section. The ionization section further includes spaced cathodes having opposed active surfaces exposed to the interior of the ionization chamber. An anode is located intermediate the cathodes whereby in response to an applied positive voltage, electrons created by field emission are transmitted between the opposed active surfaces of the cathodes and produce the emission of secondary electrons. The active surface of at least one of the cathodes is formulated of a material having a secondary electron emission factor of at least one cathode member located in the tube adjacent to th replenisher section may have a protuberant portion extending axially into the ionization chamber. The other cathode spaced from the first cathode member in the direction of the target has an aperture therein along the axis of the protuberant portion. An annular magnet extends around the exterior of the ionization chamber and envelops the anode member. Means are provided to establish a high permeability magnetic flux path extending outwardly from the opposed poles from the magnet to the active surfaces of the cathode members

Neutron accelerator tube having improved ionization section

International Nuclear Information System (INIS)

Givens, W.W.

1981-01-01

A neutron accelerator tube having a target section, an ionization section, and a replenisher section for supplying accelerator gas to the ionization section. The ionization section is located between the target and the replenisher section and includes an ionization chamber adapted to receive accelerator gas from the replenisher section. The ionization section further includes spaced cathodes having opposed active surfaces exposed to the interior of the ionization chamber. An anode is located intermediate the cathodes whereby in response to an applied positive voltage, electrons created by field emmission are transmitted between the opposed active surfaces of the cathodes and produce the emission of secondary electrons. The active surface of at least one of the cathodes is formulated of a material having a secondary electron emission factor of at least 2. One cathode member located in the tube adjacent to the replenisher section may have a protuberant portion extending axially into the ioization chamber. The other cathode spaced from the first cathode member in the direction of the target has an aperture therein along the axis of the protuberant portion. An annular magnet extends around the exterior of the ionization chamber and envelops the anode member. Means are provided to establish a high permeability magnetic flux path extending outwardly from the opposed poles from the magnet to the active surfaces of the cathode members

Main physical problems of superhigh energy accelerators

International Nuclear Information System (INIS)

Lapidus, L.I.

1979-01-01

A survey is given of the state and prospects for the scientific researches to be carried out at the largest charged particle accelerators now under construction. The fundamental problems of the elementary particle physics are considered which can be solved on the base of experiments at high-energy accelerators. The problems to be solved involve development of the theory of various quark number, accurate determination of the charged and neutral intermediate vector boson masses in the Weinberg-Salam theory, the problem of production of t-quark, W -+ - and Z deg bosons, Higgs mesons and investigation of their interactions, examination of quark and lepton spectra, studies on the effects of strong interactions. As a result of the investigations on hadrons at maximum momentum transfers, the data on space-time structure at short distances can be obtained. It is emphasized that there are no engineering barriers to the construction of such accelerators. The main problem lies in financial investment. A conclusion is drawn that the next generation of accelerators will be developed on the base of cooperation between many countries [ru

Accelerator complex for unstable beams at INS

International Nuclear Information System (INIS)

Tomizawa, M.; Arai, S.; Doi, M.; Katayama, T.; Niki, K.; Tokuda, N.; Yoshizawa, M.

1992-11-01

The construction of the prototype facility of the Exotic arena in the Japan Hadron Project (JHP) is started in 1992 at the Institute for Nuclear Study (INS), University of Tokyo. The purpose of this facility is to study the various technical problems of the Exotic arena, and to perform the experiment on nuclear and astrophysics with unstable nuclear beam. The unstable nuclei produced by bombarding a thick target with 40 MeV proton beam from the existing SF cyclotron are ionized in the ion sources, mass-analyzed by an ISOL, and transported to the accelerator complex. The accelerator complex consists of a split coaxial RFQ and an interdigital H type linac. The construction of accelerator will be completed in fiscal year 1994. The development of the SCRFQ and the IH linac which is suitable to the post-accelerator of the SCRFQ are reported. Charge stripper and the beam matching between the SCRFQ and the IH linac are explained. A buncher is necessary for the matching of longitudinal phase space between the SCRFQ and the IH linac. (K.I.)

Acceleration (Deceleration Model Supporting Time Delays to Refresh Data

Directory of Open Access Journals (Sweden)

José Gerardo Carrillo González

2018-04-01

Full Text Available This paper proposes a mathematical model to regulate the acceleration (deceleration applied by self-driving vehicles in car-following situations. A virtual environment is designed to test the model in different circumstances: (1 the followers decelerate in time if the leader decelerates, considering a time delay of up to 5 s to refresh data (vehicles position coordinates required by the model, (2 with the intention of optimizing space, the vehicles are grouped in platoons, where 3 s of time delay (to update data is supported if the vehicles have a centre-to-centre spacing of 20 m and a time delay of 1 s is supported at a spacing of 6 m (considering a maximum speed of 20 m/s in both cases, and (3 an algorithm is presented to manage the vehicles’ priority at a traffic intersection, where the model regulates the vehicles’ acceleration (deceleration and a balance in the number of vehicles passing from each side is achieved.

The Extended Relativity Theory in Clifford Spaces

CERN Document Server

Castro, C

2004-01-01

A brief review of some of the most important features of the Extended Relativity theory in Clifford-spaces ( $C$-spaces) is presented whose " point" coordinates are noncommuting Clifford-valued quantities and which incoporate the lines, areas, volumes, .... degrees of freedom associated with the collective particle, string, membrane, ... dynamics of the $p$-loop histories (closed p-branes) living in target $D$-dimensional spacetime backgrounds. $C$-space Relativity naturally incoporates the ideas of an invariant length (Planck scale), maximal acceleration, noncommuting coordinates, supersymmetry, holography, superluminal propagation, higher derivative gravity with torsion and variable dimensions/signatures that allows to study the dynamics of all (closed ) p-branes, for all values of $ p $, in a unified footing. It resolves the ordering ambiguities in QFT and the problem of time in Cosmology. A discussion of the maximal-acceleration Relativity principle in phase-spaces follows along with the study of the inva...

Collective ion acceleration via laser controlled ionization channel

International Nuclear Information System (INIS)

Destler, W.W.; O'Shea, P.G.; Rodgers, J.; Segalov, Z.

1987-01-01

Initial results from a successful laser-controlled collective ion acceleration experiment at the University of Maryland are presented. In the experiment, positive ions are trapped in the potential well at the head of an intense relativistic electron beam injected at current levels above the space charge limit. Seed ions for acceleration are provided by puff valve injection of a neutral gas cloud localized to within 3 cm of the injection point. Control over the acceleration of the well and the ions is then achieved by means of a laser-generated ionization channel produced by passing the light from a Q-switched ruby laser through a series of partially and fully reflecting mirrors in such a way as to provide time-sequenced laser ionization of a target located on the drift tube wall. Using this system, controlled acceleration of protons at a rate of approximately 40 MV/m has been demonstrated over a distance of about 50 cm

Accelerator studies at cooler rings TARN and TARN II

International Nuclear Information System (INIS)

Katayama, Takeshi.

1992-07-01

Two ion cooler rings, TARN and TARN II were constructed and operated from 1975 to 1992 at the Institute for Nuclear Study, Univ. of Tokyo, for mainly accelerator studies concerning the beam accumulation, acceleration and cooling. The main subjects performed in these facilities were; 1) beam stacking in transverse and longitudinal phase spaces, 2) stochastic momentum cooling, 3) electron cooling, 4) synchrotron acceleration and 5) slow beam extraction. In the present paper, typical experimental results on these subjects, arc described as well as the basic physical idea underlying these experimental results. The technical details are out of scope of the present paper. They can be found in the other papers refered in the concerned section in the text. (author)

Cosmic ray acceleration by stellar wind. Simulation for heliosphere

International Nuclear Information System (INIS)

Petukhov, S.I.; Turpanov, A.A.; Nikolaev, V.S.

1985-01-01

The solar wind deceleration by the interstellar medium may result in the existence of the solar wind terminal shock. In this case a certain fraction of thermal particles after being heated at the shock would obtain enough energy to be injected to the regular acceleration process. An analytical solution for the spectrum in the frame of a simplified model that includes particle acceleration at the shock front and adiabatic cooling inside the stellar wind cavity has been derived. It is shown that the acceleration of the solar wind particles at the solar wind terminal shock is capable of providing the total flux, spectrum and radial gradients of the low-energy protons close to one observed in the interplanetary space

Issues to be verified by IFMIF prototype accelerator for engineering validation

International Nuclear Information System (INIS)

Sugimoto, M.; Imai, T.; Okumura, Y.; Nakayama, K.; Suzuki, S.; Saigusa, M.

2002-01-01

The validation of the accelerator technology providing the 250 mA/40 MeV continuous-wave (CW) deuteron beam with the required quality is a key issue to realize the international fusion materials irradiation facility (IFMIF). As the difficulty of high current accelerator generally comes from the low energy section due to space-charge effects, a prototype test of such a part is planned in the next development phase. The optimal choice of the prototype consists of a full-scale injector, a full-modelled radiofrequency quadrupole, and a short drift tube linear accelerator associated with a beam diagnostics/dump. Through prototype tests, the stable control of the CW accelerator at the various operational conditions will be addressed, and the technical risks of IFMIF accelerator construction can be significantly reduced

Beam manipulation techniques, nonlinear beam dynamics, and space charge effect in high energy high power accelerators

Energy Technology Data Exchange (ETDEWEB)

Lee, S. Y. [Indiana Univ., Bloomington, IN (United States)

2014-04-07

We had carried out a design of an ultimate storage ring with beam emittance less than 10 picometer for the feasibility of coherent light source at X-ray wavelength. The accelerator has an inherent small dynamic aperture. We study method to improve the dynamic aperture and collective instability for an ultimate storage ring. Beam measurement and accelerator modeling are an integral part of accelerator physics. We develop the independent component analysis (ICA) and the orbit response matrix method for improving accelerator reliability and performance. In collaboration with scientists in National Laboratories, we also carry out experimental and theoretical studies on beam dynamics. Our proposed research topics are relevant to nuclear and particle physics using high brightness particle and photon beams.

Searching for oscillations of atmospheric and accelerator neutrinos with GeNIUS

International Nuclear Information System (INIS)

Michael, Douglas G.

1994-01-01

A very large (17KT) fine-grained sampling calorimeter is discussed for use in studying contained events induced by atmospheric or accelerator neutrinos for the purpose of searching for neutrino oscillations. The ratio of neutral current to charged current events can be used to rule out a large region of the currently allowed parameter space with accelerator and atmospheric neutrinos providing complimentary measurements. ((orig.))

Bose–Einstein condensation in the Rindler space

Directory of Open Access Journals (Sweden)

Shingo Takeuchi

2015-11-01

Full Text Available Based on the Unruh effect, we calculate the critical acceleration of the Bose–Einstein condensation in a free complex scalar field at finite density in the Rindler space. Our model corresponds to an ideal gas performing constantly accelerating motion in a Minkowski space–time at zero-temperature, where the gas is composed of the complex scalar particles and it can be thought to be in a thermal-bath with the Unruh temperature. In the accelerating frame, the model will be in the Bose–Einstein condensation state at low acceleration; on the other hand, there will be no condensation at high acceleration by the thermal excitation brought into by the Unruh effect. Our critical acceleration is the one at which the Bose–Einstein condensation begins to appear in the accelerating frame when we decrease the acceleration gradually. To carry out the calculation, we assume that the critical acceleration is much larger than the mass of the particle.

Collective focusing ion accelerator

International Nuclear Information System (INIS)

Goldin, F.J.

1986-01-01

The principal subject of this dissertation is the trapping confinement of pure electron plasmas in bumpy toroidal magnetic fields, with particular attention given to the trapping procedure and the behavior of the plasma during the final equilibrium. The most important aspects of the equilibrium studied were the qualitative nature of the plasma configuration and motion and its density, distribution and stability. The motivation for this study was that an unneutralized cloud of electrons contained in a toroidal system, sufficiently dense and stable, may serve to electrostatically focus ions (against centrifugal and self space charge forces) in a cyclic ion accelerator. Such an accelerator, known as a Collective Focusing Ion Accelerator (CFIA) could be far smaller than conventional designs (which use external magnetic fields directly to focus the ions) due to the smaller gyro-radium of an electron in a magnetic field of given strength. The electron cloud generally drifted poloidally at a finite radius from the toroidal minor axis. As this would preclude focusing ions with such clouds, damping this motion was investigated. Finite resistance in the normally perfectly conductive vessel wall did this. In further preparation for a working CFIA, additional experiments studied the effect of ions on the stability of the electron cloud

Synergia CUDA: GPU-accelerated accelerator modeling package

International Nuclear Information System (INIS)

Lu, Q; Amundson, J

2014-01-01

Synergia is a parallel, 3-dimensional space-charge particle-in-cell accelerator modeling code. We present our work porting the purely MPI-based version of the code to a hybrid of CPU and GPU computing kernels. The hybrid code uses the CUDA platform in the same framework as the pure MPI solution. We have implemented a lock-free collaborative charge-deposition algorithm for the GPU, as well as other optimizations, including local communication avoidance for GPUs, a customized FFT, and fine-tuned memory access patterns. On a small GPU cluster (up to 4 Tesla C1070 GPUs), our benchmarks exhibit both superior peak performance and better scaling than a CPU cluster with 16 nodes and 128 cores. We also compare the code performance on different GPU architectures, including C1070 Tesla and K20 Kepler.

Induction accelerator development for heavy ion fusion

International Nuclear Information System (INIS)

Reginato, L.L.

1993-05-01

For approximately a decade, the Heavy Ion Fusion Accelerator Research (HIFAR) group at LBL has been exploring the use of induction accelerators with multiple beams as the driver for inertial fusion targets. Scaled experiments have investigated the transport of space charge dominated beams (SBTE), and the current amplification and transverse emittance control in induction linacs (MBE-4) with very encouraging results. In order to study many of the beam manipulations required by a driver and to further develop economically competitive technology, a proposal has been made in partnership with LLNL to build a 10 MeV accelerator and to conduct a series of experiments collectively called the Induction Linac System Experiments (ILSE). The major components critical to the ILSE accelerator are currently under development. We have constructed a full scale induction module and we have tested a number of amorphous magnetic materials developed by Allied Signal to establish an overall optimal design. The electric and magnetic quadrupoles critical to the transport and focusing of heavy ion beams are also under development The hardware is intended to be economically competitive for a driver without sacrificing any of the physics or performance requirements. This paper will concentrate on the recent developments and tests of the major components required by the ILSE accelerator

Induction accelerator development for heavy ion fusion

International Nuclear Information System (INIS)

Reginato, L.L.

1993-05-01

For approximately a decade, the Heavy Ion Fusion Accelerator Research (HIFAR) group at LBL has been exploring the use of induction accelerators with multiple beams as the driver for inertial fusion targets. Scaled experiments have investigated the transport of space charge dominated beams (SBTE), and the current amplification and transverse emittance control in induction linacs (MBE-4) with very encouraging results. In order to study many of the beam manipulations required by a driver and to further develop economically competitive technology, a proposal has been made in partnership with LLNL to build a 10 MeV accelerator and to conduct a series of experiments collectively called the Induction Linac System Experiments (ILSE).The major components critical to the ILSE accelerator are currently under development. We have constructed a full scale induction module and we have tested a number of amorphous magnetic materials developed by Allied Signal to establish an overall optimal design. The electric and magnetic quadrupoles critical to the transport and focusing of heavy ion beams are also under development. The hardware is intended to be economically competitive for a driver without sacrificing any of the physics or performance requirements. This paper will concentrate on the recent developments and tests of the major components required by the ILSE accelerator

Production, Characterization, and Acceleration of Optical Microbunches

Energy Technology Data Exchange (ETDEWEB)

Sears, Christopher M.S. [Stanford Univ., CA (United States)

2008-06-20

Optical microbunches with a spacing of 800 nm have been produced for laser acceleration research. The microbunches are produced using a inverse Free-Electron-Laser (IFEL) followed by a dispersive chicane. The microbunched electron beam is characterized by coherent optical transition radiation (COTR) with good agreement to the analytic theory for bunch formation. In a second experiment the bunches are accelerated in a second stage to achieve for the first time direct net acceleration of electrons traveling in a vacuum with visible light. This dissertation presents the theory of microbunch formation and characterization of the microbunches. It also presents the design of the experimental hardware from magnetostatic and particle tracking simulations, to fabrication and measurement of the undulator and chicane magnets. Finally, the dissertation discusses three experiments aimed at demonstrating the IFEL interaction, microbunch production, and the net acceleration of the microbunched beam. At the close of the dissertation, a separate but related research effort on the tight focusing of electrons for coupling into optical scale, Photonic Bandgap, structures is presented. This includes the design and fabrication of a strong focusing permanent magnet quadrupole triplet and an outline of an initial experiment using the triplet to observe wakefields generated by an electron beam passing through an optical scale accelerator.

Analysis of Higher Order Modes in Large Superconducting Radio Frequency Accelerating Structures

CERN Document Server

Galek, Tomasz; Brackebusch, Korinna; Van Rienen, Ursula

2015-01-01

Superconducting radio frequency cavities used for accelerating charged particle beams are commonly used in accelerator facilities around the world. The design and optimization of modern superconducting RF cavities requires intensive numerical simulations. Vast number of operational parameters must be calculated to ensure appropriate functioning of the accelerating structures. In this study, we primarily focus on estimation and behavior of higher order modes in superconducting RF cavities connected in chains. To calculate large RF models the state-space concatenation scheme, an efficient hybrid method, is employed.

Effect of increases in lung volume on clearance of aerosolized solute from human lungs

Energy Technology Data Exchange (ETDEWEB)

Marks, J.D.; Luce, J.M.; Lazar, N.M.; Wu, J.N.; Lipavsky, A.; Murray, J.F.

1985-10-01

To study the effect of increases in lung volume on solute uptake, we measured clearance of /sup 99m/Tc-diethylenetriaminepentaacetic acid (Tc-DTPA) at different lung volumes in 19 healthy humans. Seven subjects inhaled aerosols (1 micron activity median aerodynamic diam) at ambient pressure; clearance and functional residual capacity (FRC) were measured at ambient pressure (control) and at increased lung volume produced by positive pressure (12 cmH2O continuous positive airway pressure (CPAP)) or negative pressure (voluntary breathing). Six different subjects inhaled aerosol at ambient pressure; clearance and FRC were measured at ambient pressure and CPAP of 6, 12, and 18 cmH2O pressure. Six additional subjects inhaled aerosol at ambient pressure or at CPAP of 12 cmH2O; clearance and FRC were determined at CPAP of 12 cmH2O. According to the results, Tc-DTPA clearance from human lungs is accelerated exponentially by increases in lung volume, this effect occurs whether lung volume is increased by positive or negative pressure breathing, and the effect is the same whether lung volume is increased during or after aerosol administration. The effect of lung volume must be recognized when interpreting the results of this method.

Effect of increases in lung volume on clearance of aerosolized solute from human lungs

International Nuclear Information System (INIS)

Marks, J.D.; Luce, J.M.; Lazar, N.M.; Wu, J.N.; Lipavsky, A.; Murray, J.F.

1985-01-01

To study the effect of increases in lung volume on solute uptake, we measured clearance of /sup 99m/Tc-diethylenetriaminepentaacetic acid (Tc-DTPA) at different lung volumes in 19 healthy humans. Seven subjects inhaled aerosols (1 micron activity median aerodynamic diam) at ambient pressure; clearance and functional residual capacity (FRC) were measured at ambient pressure (control) and at increased lung volume produced by positive pressure [12 cmH 2 O continuous positive airway pressure (CPAP)] or negative pressure (voluntary breathing). Six different subjects inhaled aerosol at ambient pressure; clearance and FRC were measured at ambient pressure and CPAP of 6, 12, and 18 cmH 2 O pressure. Six additional subjects inhaled aerosol at ambient pressure or at CPAP of 12 cmH 2 O; clearance and FRC were determined at CPAP of 12 cmH 2 O. According to the results, Tc-DTPA clearance from human lungs is accelerated exponentially by increases in lung volume, this effect occurs whether lung volume is increased by positive or negative pressure breathing, and the effect is the same whether lung volume is increased during or after aerosol administration. The effect of lung volume must be recognized when interpreting the results of this method

Stability of anisotropic beams with space charge

International Nuclear Information System (INIS)

Hofmann, I.

1997-07-01

We calculate coherent frequencies and stability properties of anisotropic or ''non-equipartitioned'' beams with different focusing constants and emittances in the two transverse directions. Based on the self-consistent Vlasov-Poisson equations the dispersion relations of transverse multipole oscillations with quadrupolar, sextupolar and octupolar symmetry are solved numerically. The eigenfrequencies give the coherent space charge tune shift for linear or nonlinear resonances in circular accelerators. We find that for sufficiently large energy anisotropy some of the eigenmodes become unstable in the space-charge-dominated regime. The properties of these anisotropy instabilities are used to show that ''non-equipartitioned'' beams can be tolerated in high-current linear accelerators. It is only in beams with strongly space-charge-depressed betatron tunes where harmful instabilities leading to emittance exchange should be expected. (orig.)

Realtime tune measurements in slow-cycling accelerators

International Nuclear Information System (INIS)

Herrup, D.

1997-01-01

Measurement and control of the tunes, coupling, and chromaticities in storage rings is essential to efficient operation of these accelerators. Yet it has been very difficult to make reliable realtime measurements of these quantities. We have built and commissioned the microprocessor-based Generic Finite State Data Acquisition (GFSDA) system. GFSDA provides turn-by-turn data acquisition and analysis of accelerator signals in a way that can be easily related to accelerator operations. The microprocessor is capable of calculating FFTs and correlations in real time. Both the Fermilab Main Ring and Tevatron use open loop tune, chromaticity, and coupling control, and the GFSDA measurements can easily be used to improve the open loop tables. We can add realtime feedback control with simple extensions of the system. We have used this system to make tune measurements closely spaced in time over an entire Tevatron ramp cycle

Contributions to the 1999 particle accelerator conference

Energy Technology Data Exchange (ETDEWEB)

Bernard, M. [Laboratoire de l' Accelerateur Lineaire, 91 - Orsay (France); Fartoukh, S.; Jablonka, M.; Joly, J.M.; Lalot, M.; Magne, C.; Napoly, O. [CEA/Saclay, 91 - Gif sur Yvette (France); Baboi, N.; Schreiber, S.; Simrock, S.; Weise, H. [DESY, Hamburg (Germany)

2000-06-01

This document puts together the 10 contributions of the laboratory to the 1999 particle accelerator conference. The titles of the papers are: 1) Evidence for a strongly coupled dipole mode with insufficient damping in the first accelerating module of the TESLA test facility (TTF); 2) An alternative scheme for stiffening superconducting RF cavities by plasma spraying; 3) A laser triggered electron source for pulsed radiolysis; 4) A cure for the energy spread increasing related bunch lengthening in electron storage rings; 5) Single bunch longitudinal instabilities in proton storage rings; 6) Analytical investigation on the halo formation in space charge dominated beams; 7) Analytical investigation on the dynamic apertures of circular accelerators; 8) The intrinsic upper limit to the beam energy of an electron-positron circular collider; 9) Coaxial disc windows for a high power superconducting cavity input coupler; and 10) RF pulsed tests on 3 GHz niobium cavities.

Contributions to the 1999 particle accelerator conference

International Nuclear Information System (INIS)

Bernard, M.; Fartoukh, S.; Jablonka, M.; Joly, J.M.; Lalot, M.; Magne, C.; Napoly, O.; Baboi, N.; Schreiber, S.; Simrock, S.; Weise, H.

2000-06-01

This document puts together the 10 contributions of the laboratory to the 1999 particle accelerator conference. The titles of the papers are: 1) Evidence for a strongly coupled dipole mode with insufficient damping in the first accelerating module of the TESLA test facility (TTF); 2) An alternative scheme for stiffening superconducting RF cavities by plasma spraying; 3) A laser triggered electron source for pulsed radiolysis; 4) A cure for the energy spread increasing related bunch lengthening in electron storage rings; 5) Single bunch longitudinal instabilities in proton storage rings; 6) Analytical investigation on the halo formation in space charge dominated beams; 7) Analytical investigation on the dynamic apertures of circular accelerators; 8) The intrinsic upper limit to the beam energy of an electron-positron circular collider; 9) Coaxial disc windows for a high power superconducting cavity input coupler; and 10) RF pulsed tests on 3 GHz niobium cavities

Method and device for monochromatization of the internal accelerated particles beam in isochronous cyclotrons

International Nuclear Information System (INIS)

Enchevich, I.B.; Dinev, D.H.

1988-01-01

The invention assures a reduced size of the supplementary electrode which leads to economy of a material and a more effective use of the accelerator space, where the elements of an axial injection system of the cyclotron particles can be situated. The amplitude homogeneity of the supplementary accelerating field is also improved. To the main high-frequency field, covering the whole scope of the acceleration radiuses, an additional accelerating high-frequency field is introduced comprising a part of the scope of the acceleration radiuses. The frequency of this additional accelerating high frequency field is a third harmonics of the main field frequency. The device consists of a supplementary accelerating electrode, connected to an additional resonator and an additional exciting high-frequency generator. 2 cls., 7 figs

Nonlocality and Multipartite Entanglement in Asymptotically Flat Space-Times

International Nuclear Information System (INIS)

Moradi, Shahpoor; Amiri, Firouz

2016-01-01

We study the Bell's inequality and multipartite entanglement generation for initially maximally entangled states of free Dirac field in a non inertial frame and asymptotically flat Robertson–Walker space-time. For two qubit case, we show that the Bell's inequality always is violated as measured by the accelerated observers which are in the causally connected regions. On the other hand, for those observers in the causally disconnected regions inequality is not violated for any values of acceleration. The generated three qubit state from two qubit state due to acceleration of one parties has a zero 3-tangle. For a three qubit state, the inequality violated for measurements done by both causally connected and disconnected observers. Initially GHZ state with non zero 3-tangle, in accelerated frame, transformed to a four qubit state with vanishing 4-tangle value. On the other hand, for a W-state with zero 3-tangle, in non inertial frame, transformed to a four qubit state with a non-zero 4-tangle acceleration dependent. In an expanding space-time with asymptotically flat regions, for an initially maximally entangled state, the maximum value of violation of Bell's inequality in the far past decreased in the far future due to cosmological particle creation. For some initially maximally entangled states, the generated four qubit state due to expansion of space-time, has non vanishing 4-tangle. (paper)

Accelerator Based Neutron Beams for Neutron Capture Therapy

International Nuclear Information System (INIS)

Yanch, Jacquelyn C.

2003-01-01

The DOE-funded accelerator BNCT program at the Massachusetts Institute of Technology has resulted in the only operating accelerator-based epithermal neutron beam facility capable of generating significant dose rates in the world. With five separate beamlines and two different epithermal neutron beam assemblies installed, we are currently capable of treating patients with rheumatoid arthritis in less than 15 minutes (knee joints) or 4 minutes (finger joints) or irradiating patients with shallow brain tumors to a healthy tissue dose of 12.6 Gy in 3.6 hours. The accelerator, designed by Newton scientific Incorporated, is located in dedicated laboratory space that MIT renovated specifically for this project. The Laboratory for Accelerator Beam Applications consists of an accelerator room, a control room, a shielded radiation vault, and additional laboratory space nearby. In addition to the design, construction and characterization of the tandem electrostatic accelerator, this program also resulted in other significant accomplishments. Assemblies for generating epithermal neutron beams were designed, constructed and experimentally evaluated using mixed-field dosimetry techniques. Strategies for target construction and target cooling were implemented and tested. We demonstrated that the method of submerged jet impingement using water as the coolant is capable of handling power densities of up to 6 x 10(sup 7) W/m(sup 2) with heat transfer coefficients of 10(sup 6)W/m(sup 2)-K. Experiments with the liquid metal gallium demonstrated its superiority compared with water with little effect on the neutronic properties of the epithermal beam. Monoenergetic proton beams generated using the accelerator were used to evaluate proton RBE as a function of LET and demonstrated a maximum RBE at approximately 30-40 keV/um, a finding consistent with results published by other researchers. We also developed an experimental approach to biological intercomparison of epithermal beams and

An Accelerator Neutron Source for BNCT

Energy Technology Data Exchange (ETDEWEB)

Blue, Thomas, E

2006-03-14

The overall goal of this project was to develop an accelerator-based neutron source (ABNS) for Boron Neutron Capture Therapy (BNCT). Specifically, our goals were to design, and confirm by measurement, a target assembly and a moderator assembly that would fulfill the design requirements of the ABNS. These design requirements were 1) that the neutron field quality be as good as the neutron field quality for the reactor-based neutron sources for BNCT, 2) that the patient treatment time be reasonable, 3) that the proton current required to treat patients in reasonable times be technologially achievable at reasonable cost with good reliability, and accelerator space requirements which can be met in a hospital, and finally 4) that the treatment be safe for the patients.

An Accelerator Neutron Source for BNCT

International Nuclear Information System (INIS)

Blue, Thomas E.

2006-01-01

The overall goal of this project was to develop an accelerator-based neutron source (ABNS) for Boron Neutron Capture Therapy (BNCT). Specifically, our goals were to design, and confirm by measurement, a target assembly and a moderator assembly that would fulfill the design requirements of the ABNS. These design requirements were (1) that the neutron field quality be as good as the neutron field quality for the reactor-based neutron sources for BNCT, (2) that the patient treatment time be reasonable, (3) that the proton current required to treat patients in reasonable times be technologically achievable at reasonable cost with good reliability, and accelerator space requirements which can be met in a hospital, and finally (4) that the treatment be safe for the patients

Proceeding of the 11th meeting on linear accelerators

International Nuclear Information System (INIS)

Nakahara, Kazuo; Anami, Shozo; Takasaki, Eiichi

1986-08-01

The study group on linear accelerators has attained the period of 10 years. The worldwide change of social structure and economical condition during this period affected also linear accelerators. For a while, the new installation of linear accelerators was limited to Japan and China, and the state of standstill continued in Europe and America. Therefore, the large scale projects of electron-positron collision type accelerators started, and LEP of CERN and HERA of DESY in Europe and Linear Collider of SLAC in USA compete the lead together with TRISTAN in Japan. Large electron rings have become the type connecting CW linear accelerators with electromagnets in circular form unlike the conventional type. The developed type of superconducting CW linacs such as CEBAF in USA is planned. In the large accelerators hereafter of CW or pulse type, the RF system of high accuracy and large power output is the key to the success of projects, instead of individual accelerating spaces, high frequency sources, waveguides or controls. When the scale of projects exceeds a certain limit, those cannot be dealt with merely by the experience and means in the past. In this book, the gists of 62 presented papers and invited lectures are collected. (Kako, I.)

Steady state ion acceleration by a circularly polarized laser pulse

International Nuclear Information System (INIS)

Zhang Xiaomei; Shen Baifei; Cang Yu; Li Xuemei; Jin Zhangying; Wang Fengchao

2007-01-01

The steady state ion acceleration at the front of a cold solid target by a circularly polarized flat-top laser pulse is studied with one-dimensional particle-in-cell (PIC) simulation. A model that ions are reflected by a steady laser-driven piston is used by comparing with the electrostatic shock acceleration. A stable profile with a double-flat-top structure in phase space forms after ions enter the undisturbed region of the target with a constant velocity

Preliminary analysis of space mission applications for electromagnetic launchers

Science.gov (United States)

Miller, L. A.; Rice, E. E.; Earhart, R. W.; Conlon, R. J.

1984-01-01

The technical and economic feasibility of using electromagnetically launched EML payloads propelled from the Earth's surface to LEO, GEO, lunar orbit, or to interplanetary space was assessed. Analyses of the designs of rail accelerators and coaxial magnetic accelerators show that each is capable of launching to space payloads of 800 KG or more. A hybrid launcher in which EML is used for the first 2 KM/sec followed by chemical rocket stages was also tested. A cost estimates study shows that one to two EML launches per day are needed to break even, compared to a four-stage rocket. Development models are discussed for: (1) Earth orbital missions; (2) lunar base supply mission; (3) solar system escape mission; (4) Earth escape missions; (5) suborbital missions; (6) electromagnetic boost missions; and (7) space-based missions. Safety factors, environmental impacts, and EML systems analysis are discussed. Alternate systems examined include electrothermal thrustors, an EML rocket gun; an EML theta gun, and Soviet electromagnetic accelerators.

RIKEN accelerator progress report, vol. 36. January - December 2002

International Nuclear Information System (INIS)

Asahi, K.; Abe, T.; Ichihara, T.

2003-03-01

This issue of RIKEN Accelerator Progress Report reports research activities of the RIKEN Accelerator Research Facility (RARF) during the calendar year of 2002. The research programs have been coordinated in the framework of the project entitled Multidisciplinary Researches on Heavy Ion Science. The project involves a variety of fields such as: nuclear physics, nuclear astrophysics, atomic physics, nuclear chemistry, radiation biology, condensed matter physics in terms of accelerator or radiation application, plant mutation, material characterization, application to space science, accelerator physics and engineering, laser technology, and computational technology. These activities involved ten laboratories, five Centers involving seven divisions, the RIKEN-RAL (Rutherford-Appleton Laboratory) Center, and the RBRC (RIKEN-Brookhaven Research Center at Brookhaven National Laboratory), and more than 350 researchers from domestic and foreign institutions. Thirty-six universities and institutes from within Japan and 33 institutes from 10 countries are involved. (J.P.N.)

Scale-by-scale contributions to Lagrangian particle acceleration

Science.gov (United States)

Lalescu, Cristian C.; Wilczek, Michael

2017-11-01

Fluctuations on a wide range of scales in both space and time are characteristic of turbulence. Lagrangian particles, advected by the flow, probe these fluctuations along their trajectories. In an effort to isolate the influence of the different scales on Lagrangian statistics, we employ direct numerical simulations (DNS) combined with a filtering approach. Specifically, we study the acceleration statistics of tracers advected in filtered fields to characterize the smallest temporal scales of the flow. Emphasis is put on the acceleration variance as a function of filter scale, along with the scaling properties of the relevant terms of the Navier-Stokes equations. We furthermore discuss scaling ranges for higher-order moments of the tracer acceleration, as well as the influence of the choice of filter on the results. Starting from the Lagrangian tracer acceleration as the short time limit of the Lagrangian velocity increment, we also quantify the influence of filtering on Lagrangian intermittency. Our work complements existing experimental results on intermittency and accelerations of finite-sized, neutrally-buoyant particles: for the passive tracers used in our DNS, feedback effects are neglected such that the spatial averaging effect is cleanly isolated.

Compact toroid formation, compression, and acceleration

International Nuclear Information System (INIS)

Degnan, J.H.; Peterkin, R.E. Jr.; Baca, G.P.; Beason, J.D.; Bell, D.E.; Dearborn, M.E.; Dietz, D.; Douglas, M.R.; Englert, S.E.; Englert, T.J.; Hackett, K.E.; Holmes, J.H.; Hussey, T.W.; Kiuttu, G.F.; Lehr, F.M.; Marklin, G.J.; Mullins, B.W.; Price, D.W.; Roderick, N.F.; Ruden, E.L.; Sovinec, C.R.; Turchi, P.J.; Bird, G.; Coffey, S.K.; Seiler, S.W.; Chen, Y.G.; Gale, D.; Graham, J.D.; Scott, M.; Sommars, W.

1993-01-01

Research on forming, compressing, and accelerating milligram-range compact toroids using a meter diameter, two-stage, puffed gas, magnetic field embedded coaxial plasma gun is described. The compact toroids that are studied are similar to spheromaks, but they are threaded by an inner conductor. This research effort, named MARAUDER (Magnetically Accelerated Ring to Achieve Ultra-high Directed Energy and Radiation), is not a magnetic confinement fusion program like most spheromak efforts. Rather, the ultimate goal of the present program is to compress toroids to high mass density and magnetic field intensity, and to accelerate the toroids to high speed. There are a variety of applications for compressed, accelerated toroids including fast opening switches, x-radiation production, radio frequency (rf) compression, as well as charge-neutral ion beam and inertial confinement fusion studies. Experiments performed to date to form and accelerate toroids have been diagnosed with magnetic probe arrays, laser interferometry, time and space resolved optical spectroscopy, and fast photography. Parts of the experiment have been designed by, and experimental results are interpreted with, the help of two-dimensional (2-D), time-dependent magnetohydrodynamic (MHD) numerical simulations. When not driven by a second discharge, the toroids relax to a Woltjer--Taylor equilibrium state that compares favorably to the results of 2-D equilibrium calculations and to 2-D time-dependent MHD simulations. Current, voltage, and magnetic probe data from toroids that are driven by an acceleration discharge are compared to 2-D MHD and to circuit solver/slug model predictions. Results suggest that compact toroids are formed in 7--15 μsec, and can be accelerated intact with material species the same as injected gas species and entrained mass ≥1/2 the injected mass

Dynamics and transport of laser-accelerated particle beams

International Nuclear Information System (INIS)

Becker, Stefan

2010-01-01

The subject of this thesis is the investigation and optimization of beam transport elements in the context of the steadily growing field of laser-driven particle acceleration. The first topic is the examination of the free vacuum expansion of an electron beam at high current density. It could be shown that particle tracking codes which are commonly used for the calculation of space charge effects will generate substantial artifacts in the regime considered here. The artifacts occurring hitherto predominantly involve insufficient prerequisites for the Lorentz transformation, the application of inadequate initial conditions and non negligible retardation artifacts. A part of this thesis is dedicated to the development of a calculation approach which uses a more adequate ansatz calculating space charge effects for laser-accelerated electron beams. It can also be used to validate further approaches for the calculation of space charge effects. The next elements considered are miniature magnetic quadrupole devices for the focusing of charged particle beams. General problems involved with their miniaturization concern distorting higher order field components. If these distorting components cannot be controlled, the field of applications is very limited. In this thesis a new method for the characterization and compensation of the distorting components was developed, which might become a standard method when assembling these permanent magnet multipole devices. The newly developed characterization method has been validated at the Mainz Microtron (MAMI) electron accelerator. Now that we can ensure optimum performance, the first application of permanent magnet quadrupole devices in conjunction with laser-accelerated ion beams is presented. The experiment was carried out at the Z-Petawatt laser system at Sandia National Laboratories. A promising application for laser-accelerated electron beams is the FEL in a university-scale size. The first discussion of all relevant aspects

Dynamics and transport of laser-accelerated particle beams

Energy Technology Data Exchange (ETDEWEB)

Becker, Stefan

2010-04-19

The subject of this thesis is the investigation and optimization of beam transport elements in the context of the steadily growing field of laser-driven particle acceleration. The first topic is the examination of the free vacuum expansion of an electron beam at high current density. It could be shown that particle tracking codes which are commonly used for the calculation of space charge effects will generate substantial artifacts in the regime considered here. The artifacts occurring hitherto predominantly involve insufficient prerequisites for the Lorentz transformation, the application of inadequate initial conditions and non negligible retardation artifacts. A part of this thesis is dedicated to the development of a calculation approach which uses a more adequate ansatz calculating space charge effects for laser-accelerated electron beams. It can also be used to validate further approaches for the calculation of space charge effects. The next elements considered are miniature magnetic quadrupole devices for the focusing of charged particle beams. General problems involved with their miniaturization concern distorting higher order field components. If these distorting components cannot be controlled, the field of applications is very limited. In this thesis a new method for the characterization and compensation of the distorting components was developed, which might become a standard method when assembling these permanent magnet multipole devices. The newly developed characterization method has been validated at the Mainz Microtron (MAMI) electron accelerator. Now that we can ensure optimum performance, the first application of permanent magnet quadrupole devices in conjunction with laser-accelerated ion beams is presented. The experiment was carried out at the Z-Petawatt laser system at Sandia National Laboratories. A promising application for laser-accelerated electron beams is the FEL in a university-scale size. The first discussion of all relevant aspects

Time travel in Goedel's space

International Nuclear Information System (INIS)

Pfarr, J.

1981-01-01

An analysis is presented of the motion of test particles in Goedel's universe. Both geodesical and nongeodesical motions are considered; the accelerations for nongeodesical motions are given. Examples for closed timelike world lines are shown and the dynamical conditions for time travel in Goedel's space-time are discussed. It is shown that these conditions alone do not suffice to exclude time travel in Goedel's space-time. (author)

On-Chip Laser-Power Delivery System for Dielectric Laser Accelerators

Science.gov (United States)

Hughes, Tyler W.; Tan, Si; Zhao, Zhexin; Sapra, Neil V.; Leedle, Kenneth J.; Deng, Huiyang; Miao, Yu; Black, Dylan S.; Solgaard, Olav; Harris, James S.; Vuckovic, Jelena; Byer, Robert L.; Fan, Shanhui; England, R. Joel; Lee, Yun Jo; Qi, Minghao

2018-05-01

We propose an on-chip optical-power delivery system for dielectric laser accelerators based on a fractal "tree-network" dielectric waveguide geometry. This system replaces experimentally demanding free-space manipulations of the driving laser beam with chip-integrated techniques based on precise nanofabrication, enabling access to orders-of-magnitude increases in the interaction length and total energy gain for these miniature accelerators. Based on computational modeling, in the relativistic regime, our laser delivery system is estimated to provide 21 keV of energy gain over an acceleration length of 192 μ m with a single laser input, corresponding to a 108-MV/m acceleration gradient. The system may achieve 1 MeV of energy gain over a distance of less than 1 cm by sequentially illuminating 49 identical structures. These findings are verified by detailed numerical simulation and modeling of the subcomponents, and we provide a discussion of the main constraints, challenges, and relevant parameters with regard to on-chip laser coupling for dielectric laser accelerators.

Accelerating solutions of one-dimensional unsteady PDEs with GPU-based swept time-space decomposition

Science.gov (United States)

Magee, Daniel J.; Niemeyer, Kyle E.

2018-03-01

The expedient design of precision components in aerospace and other high-tech industries requires simulations of physical phenomena often described by partial differential equations (PDEs) without exact solutions. Modern design problems require simulations with a level of resolution difficult to achieve in reasonable amounts of time-even in effectively parallelized solvers. Though the scale of the problem relative to available computing power is the greatest impediment to accelerating these applications, significant performance gains can be achieved through careful attention to the details of memory communication and access. The swept time-space decomposition rule reduces communication between sub-domains by exhausting the domain of influence before communicating boundary values. Here we present a GPU implementation of the swept rule, which modifies the algorithm for improved performance on this processing architecture by prioritizing use of private (shared) memory, avoiding interblock communication, and overwriting unnecessary values. It shows significant improvement in the execution time of finite-difference solvers for one-dimensional unsteady PDEs, producing speedups of 2 - 9 × for a range of problem sizes, respectively, compared with simple GPU versions and 7 - 300 × compared with parallel CPU versions. However, for a more sophisticated one-dimensional system of equations discretized with a second-order finite-volume scheme, the swept rule performs 1.2 - 1.9 × worse than a standard implementation for all problem sizes.

The formation of kappa-distribution accelerated electron populations in solar flares

Energy Technology Data Exchange (ETDEWEB)

Bian, Nicolas H.; Stackhouse, Duncan J.; Kontar, Eduard P. [School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom); Emslie, A. Gordon, E-mail: n.bian@physics.gla.ac.uk, E-mail: d.stackhouse.1@research.gla.ac.uk, E-mail: eduard@astro.gla.ac.uk, E-mail: emslieg@wku.edu [Department of Physics and Astronomy, Western Kentucky University, Bowling Green, KY 42101 (United States)

2014-12-01

Driven by recent RHESSI observations of confined loop-top hard X-ray sources in solar flares, we consider stochastic acceleration of electrons in the presence of Coulomb collisions. If electron escape from the acceleration region can be neglected, the electron distribution function is determined by a balance between diffusive acceleration and collisions. Such a scenario admits a stationary solution for the electron distribution function that takes the form of a kappa distribution. We show that the evolution toward this kappa distribution involves a 'wave front' propagating forward in velocity space, so that electrons of higher energy are accelerated later; the acceleration timescales with energy according to τ{sub acc} ∼ E {sup 3/2}. At sufficiently high energies escape from the finite-length acceleration region will eventually dominate. For such energies, the electron velocity distribution function is obtained by solving a time-dependent Fokker-Planck equation in the 'leaky-box' approximation. Solutions are obtained in the limit of a small escape rate from an acceleration region that can effectively be considered a thick target.

On the choice of the adjusting mouth electrode profile at the input of a linear accelerator with space-uniform quadrupole focusing

International Nuclear Information System (INIS)

Balabin, A.I.; Kapchinskij, I.M.; Lipkin, I.M.

1983-01-01

Beam matching of an electrostatical injector with a linear accelerator is an important problem, since acceptance at the inlet of a linac with space-homogeneous quadrupole focusing (SHQF) does not remain constant but rotates with the frequency of an accelerating field. A possibility of transverse stationary beam matching with the SHQF at the inlet of the linac can be ensured to a considerable extent by means of an initial matching section (matching mouth) at the length of which focusing hardness varies according to a certain law. In this case the purpose of creating beam matching conditions practically independent of the phases of particles at the inlet into the mouth is attained. Transverse beam matching for different laws of focusing hardness variation along the non-modulated mouth is investigated. It is shown that for earlier suggested laws of hardness variation the matching conditions at the mouth inlet are critically dependent on the input phases of particles at high phase densities of the beam current j. Laws of hardness variation ensuring actual matching condition independence of the phases of particles up to j=2 A/cmxmrad (for protons) are suggested. A case of beam matching by means of the modulated mouth is also considered. Recommendations on mouth modulation laws are given

Collective acceleration of electrons and ions in a high current relativistic electron beam. Final report

International Nuclear Information System (INIS)

Nation, J.A.

1996-01-01

The original purpose of this research was an investigation into the use of slow space charge waves on weakly relativistic electron beams for ion acceleration. The work had three main objectives namely, the development of a suitable ion injector, the growth and study of the properties of slow space charge waves on an electron beam, and a combination of the two components parts into a suitable proof of principle demonstration of the wave accelerator. This work focusses on the first two of these objectives

Heavy accelerated nuclei in biomedical research

International Nuclear Information System (INIS)

Tobias, C.A.

1987-01-01

Accelerated atomic nuclei in physics accelerators have been used in basic biological research and in applied medical diagnostic and therapeutic studies for the past 50 years. The passage of single heavy particles through the cell nucleus is capable of producing multiple DNA double-strand scission and chromatin breaks. According to the Repair-Misrepair model, the high biological effectiveness of high-LET particles is due to misrepair and misrejoining of the breaks. The Bragg depth ionization effect allows heavy particles to deposit considerably more energy deep in tissue than at the surface, and this property has been used for great improvements in the radiation therapy of localized tumors. Recent advances in producing radioactive beams will allow verification of therapeutic administration of such beams. The radioactive beams also open a new field of Nuclear Medicine. There is increasing interest in building special biomedical light and heavy-ion accelerators. These will be used not only for therapy but also for diagnosis, for the study of radiation hazards in space flight, and for basic molecular and cellular understanding of the mechanisms of radiation effect

MGN V RSS LINE OF SIGHT ACCELERATION PROFILES V1.0

Data.gov (United States)

National Aeronautics and Space Administration — Line of Sight Acceleration Profile Data Records (LOSAPDR) consist of data from Doppler tracking of the orbiting spacecraft. The relative motion of the spacecraft and...

Laser accelerated protons captured and transported by a pulse power solenoid

OpenAIRE

Burris-Mog, T.; Harres, K.; Zielbauer, B.; Bagnoud, V.; Herrmannsdoerfer, T.; Roth, M.; Cowan, T. E.; Nürnberg, F.; Busold, S.; Bussmann, M.; Deppert, O.; Hoffmeister, G.; Joost, M.; Sobiella, M.; Tauschwitz, A.

2011-01-01

Using a pulse power solenoid, we demonstrate efficient capture of laser accelerated proton beams and the ability to control their large divergence angles and broad energy range. Simulations using measured data for the input parameters give inference into the phase-space and transport efficiencies of the captured proton beams. We conclude with results from a feasibility study of a pulse power compact achromatic gantry concept. Using a scaled target normal sheath acceleration spectrum, we prese...

Investigation of Microbunching Instabilities in Modern Recirculating Accelerators

Energy Technology Data Exchange (ETDEWEB)

Tsai, Cheng [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States)

2017-05-21

Particle accelerators are machines to accelerate and store charged particles, such as electrons or protons, to the energy levels for various scientific applications. A collection of charged particles usually forms a particle beam. There are three basic types of particle accelerators: linear accelerators (linac), storage-ring (or circular) accelerators, and recirculating accelerators. In a linac, particles are accelerated and pass through once along a linear or straight beamline. Storage-ring accelerators propel particles around a circular track and repetitively append the energy to the stored beam. The third type, also the most recent one in chronology, the recirculating accelerator, is designed to accelerate the particle beam in a short section of linac, circulate the beam, and then either continue to accelerate for energy boost or decelerate it for energy recovery. The beam properties of a linac machine are set at best by the initial particle sources. For storage rings, the beam equilibria are instead determined by the overall machine design. The modern recirculating machines share with linacs the advantages to both accelerate and preserve the beam with high beam quality, as well as efficiently reuse the accelerating components. The beamline design in such a machine configuration can however be much more complicated than that of linacs. As modern accelerators push toward the high-brightness or high-intensity frontier by demanding particles in a highly charged bunch (about nano-Coulomb per bunch) to concentrate in an ever-decreasing beam phase space (transverse normalized emittance about 1 μm and relative energy spread of the order of 10^-5 in GeV beam energy), the interaction amongst particles via their self-generated electromagnetic fields can potentially lead to coherent instabilities of the beam and thus pose significant challenges to the machine design and operation. In the past decade and a half, microbunching instability (MBI) has been one of the most

Beam-envelope calculations of space-charge loaded beams in MeV dc ion-implantation facilities

International Nuclear Information System (INIS)

Urbanus, W.H.; Bannenberg, J.G.; Doorn, S.; Saris, F.W.; Koudijs, R.; Dubbelman, P.; Koelewijn, W.

1989-01-01

MeV dc ion accelerators are being developed that can deliver a beam current up to several hundred micro-amperes. At the low-energy part of the accelerator, the beam transport is space-charge dominated rather than emittance dominated. A system of differential equations has been derived, based on the Kapchinski-Vladimirski equations, which describe the envelope of a space-charge loaded ion beam, taking a longitudinal electrical field in an accelerating tube into account. The equations have been used to design the accelerator of a high-current 1 MV heavy-ion implantation facility. Furthermore, the design of a 2 MV accelerator is presented, which is used for analyzing techniques such as RBS and PIXE. Both facilities are based on single-ended Van de Graaff accelerators. (orig.)

Advances of dense plasma physics with particle accelerators

Energy Technology Data Exchange (ETDEWEB)

Hoffmann, D.H.H.; Blazevic, A.; Rosmej, O.N.; Spiller, P.; Tahir, N.A.; Weyrich, K. [Gesellschaft fur Schwerionenforschung, GSI-Darmstadt, Plasmaphysik, Darmstadt (Germany); Hoffmann, D.H.H.; Dafni, T.; Kuster, M.; Roth, M.; Udrea, S.; Varentsov, D. [DarmstadtTechnische Univ., Institut fur Kernphysik (Germany); Jacoby, J. [Frankfurt Univ., Institut fur Angewandte Physik (Germany); Zioutas, K. [European Organization for Nuclear Research (CERN), Geneve (Switzerland); Patras Univ., Dept. of Physics (Greece); Sharkov, B.Y. [Institut for Theoretical and Experimental Physics ITEP, Moscow (Russian Federation)

2006-06-15

High intensity particle beams from accelerators induce high energy density states in bulk matter. The SIS-18 heavy ion synchrotron at GSI (Darmstadt, Germany) now routinely delivers intense Uranium beams that deposit about 1 kJ/g of specific energy in solid matter, e.g. solid lead. Due to the specific nature of the ion-matter interaction a volume of matter is heated uniformly with low gradients of temperature and pressure in the initial phase, depending on the pulse structure of the beam with respect to space and time. The new accelerator complex FAIR (Facility for Antiproton and ion Research) at GSI as well as beams from the CERN large hadron collider (LHC) will vastly extend the accessible parameter range for high energy density states. One special piece of accelerator equipment a superconducting high field dipole magnet, developed for the LHC at CERN is now serving as a key instrument to diagnose the dense plasma of the sun interior plasma, thus providing an extremely interesting combination of accelerator physics, plasma physics and particle physics. (authors)

Advances of dense plasma physics with particle accelerators

International Nuclear Information System (INIS)

Hoffmann, D.H.H.; Blazevic, A.; Rosmej, O.N.; Spiller, P.; Tahir, N.A.; Weyrich, K.; Hoffmann, D.H.H.; Dafni, T.; Kuster, M.; Roth, M.; Udrea, S.; Varentsov, D.; Jacoby, J.; Zioutas, K.; Sharkov, B.Y.

2006-01-01

High intensity particle beams from accelerators induce high energy density states in bulk matter. The SIS-18 heavy ion synchrotron at GSI (Darmstadt, Germany) now routinely delivers intense Uranium beams that deposit about 1 kJ/g of specific energy in solid matter, e.g. solid lead. Due to the specific nature of the ion-matter interaction a volume of matter is heated uniformly with low gradients of temperature and pressure in the initial phase, depending on the pulse structure of the beam with respect to space and time. The new accelerator complex FAIR (Facility for Antiproton and ion Research) at GSI as well as beams from the CERN large hadron collider (LHC) will vastly extend the accessible parameter range for high energy density states. One special piece of accelerator equipment a superconducting high field dipole magnet, developed for the LHC at CERN is now serving as a key instrument to diagnose the dense plasma of the sun interior plasma, thus providing an extremely interesting combination of accelerator physics, plasma physics and particle physics. (authors)

Leak detection of SF6 gas pressure vessel safety devices at BARC-TIFR Pelletron accelerator

International Nuclear Information System (INIS)

Ninawe, N.G.; Sharma, S.C.; Nair, J.P.; Sparrow, H.; Bolar, P.C.; Gudekar, P.V.; Mahapatra, S.; Vishwakarma, R.S.; Ramjilal; Matkar, U.V.; Gore, J.A.; Gupta, A.K.

2015-01-01

Pelletron accelerator is in operation since last more than 26 years. To achieve desired voltage gradient SF6 gas of about 20 tons is used to have 75-80 psig pressure in main accelerator tank. During accelerator tank maintenance gas is transferred to four storage tanks, kept in open space in the vicinity of sea. Recently refurbishment and retrofitting of four storage tanks was carried out which includes the installation of new drift space, rupture disc assembly, relief valves and manual valves along with civil and painting work. All components to be installed were tested for high pressure. Helium gas sniffer technique was used to check micro leaks for new joints for all components before installing for storage tanks. Subsequently, the tanks were tested up to 90 psig SF6 gradually in succession. No pressure drop was observed in storage tanks. This work was carried out as per recommendation of the then particle accelerator committee (PASC). (author)

Equipartitioning in linear accelerators

International Nuclear Information System (INIS)

Jameson, R.A.

1981-01-01

Emittance growth has long been a concern in linear accelerators, as has the idea that some kind of energy balance, or equipartitioning, between the degrees of freedom, would ameliorate the growth. M. Prome observed that the average transverse and longitudinal velocity spreads tend to equalize as current in the channel is increased, while the sum of the energy in the system stays nearly constant. However, only recently have we shown that an equipartitioning requirement on a bunched injected beam can indeed produce remarkably small emittance growth. The simple set of equations leading to this condition are outlined below. At the same time, Hofmann, using powerful analytical and computational methods, has investigated collective instabilities in transported beams and has identified thresholds and regions in parameter space where instabilities occur. This is an important generalization. Work that he will present at this conference shows that the results are essentially the same in r-z coordinates for transport systems, and evidence is presented that shows transport system boundaries to be quite accurate in computer simulations of accelerating systems also. Discussed are preliminary results of efforts to design accelerators that avoid parameter regions where emittance is affected by the instabilities identified by Hofmann. These efforts suggest that other mechanisms are present. The complicated behavior of the RFQ linac in this framework also is shown

Ion extraction capabilities of closely spaced grids

Science.gov (United States)

Rovang, D. C.; Wilbur, P. J.

1982-01-01

The ion extraction capabilities of accelerator systems with small screen hole diameters (less than 2.0 mm) are investigated at net-accelerating voltages of 100, 300, and 500 V. Results show that the impingement-limited perveance is not dramatically affected by reductions in screen hole diameter to 1.0 mm, but impingement-limited performance was found to be dependent on the grid separation distance, the discharge-to-total accelerating voltage ratio, and the net-to-total accelerating voltage ratio. Results obtained using small hole diameters and closely spaced grids indicate a new mode of grid operation where high current density operation can be achieved with a specified net acceleration voltage by operating the grids at a high rather than low net-to-total acceleration voltage. Beam current densities as high as 25 mA/sq cm were obtained using grids with 1.0 mm diameter holes operating at a net accelerating voltage of 500 V.

Annotated bibliography on high-intensity linear accelerators

International Nuclear Information System (INIS)

Jameson, R.A.; Roybal, E.U.

1978-01-01

A technical bibliography covering subjects important to the design of high-intensity beam transport systems and linear accelerators is presented. Space charge and emittance growth are stressed. Subject and author concordances provide cross-reference to detailed citations, which include an abstract and notes on the material. The bibliography resides in a computer database that can be searched for key words and phrases

Synergistic Effects of Ad-Libitum Low-Dose Fructose Drinking and Low-Dose Streptozotocin Treatment in Wistar Rats: A Mild Model of Type 2 Diabetes

Directory of Open Access Journals (Sweden)

Asie Sadeghi

2017-07-01

Full Text Available To develop a convenient animal model of T2D by pretreatment with low-dose 10% w/v fructose (FRC solution followed by the injection of low doses of streptozotocin (STZ in Wistar rats. For this 8-week experimental study; rats were first fed a standard chow ad-libitum diet and either tap water (n=40 or 10% w/v FRC solution (n=40 for 4 weeks. Next, rats in each category were randomly allocated to 4 subgroups (n=10 each of low-dose STZ (25,35, and 45 mg/kg. The final mean fasting blood sugar (FBG of FRC+STZ45 (197±55.87 mg/dl were significantly higher than that of the STZ45 (P=0.015 and FRC (P=0.019 groups. FRC+STZ45 showed the highest insulin resistance demonstrated by insulin tolerance test [area under the curve (AUC of insulin tolerance test; P<0.05]. AUC was not significantly different between the STZ45 and non-STZ groups and between FRC and non-FRC fed groups. Furthermore, FBG levels did not differ between FRC and non-FRC groups. Body weight measurement showed that the FRC+STZ45 group had the lowest body weight compared to all other groups. Our data provide the evidence that FRC and STZ45 synergistically could induce hyperglycemia and insulin resistance in Wistar rats. Here we presented a feasible model for initial forms of T2D by employing pretreatment with low-dose FRC solution and treatment with low-dose STZ.

Theory of factors limiting high gradient operation of warm accelerating structures

Energy Technology Data Exchange (ETDEWEB)

Nusinovich, Gregory S. [Univ. of Maryland, College Park, MD (United States)

2014-07-22

This report consists of two parts. In the first part we describe a study of the heating of microprotrusions on surfaces of accelerating structures. This ;process is believed to lead to breakdown in these structures. Our study revealed that for current accelerator parameters melting should not occur due to space charge limitations of the current emitted by a protrusion. The second part describes a novel concept to develop THz range sources based on harmonic cyclotron masers for driving future colliders. This work was stimulated by a recent request of SLAC to develop high power, high-efficiency sources of sub-THz radiation for future high-gradient accelerators.

Studies of the mirrortron ion accelerator concept and its application to heavy-ion drivers

International Nuclear Information System (INIS)

Post, R.F.; Schwager, L.A.; Dougless, S.R.; Jones, B.R.; Lambert, M.A.; Larson, D.L.

1991-01-01

The Mirrortron accelerator is a plasma-based ion accelerator concept that, when implemented, should permit both higher acceleration gradients and higher peak-current capabilities than is possible with conventional induction-type accelerators. Control over the acceleration and focussing of an accelerated beam should approach that achieved in vacuum-field-based ion accelerators. In the Mirrortron a low density (10 10 to 10 11 cm -3 ) ''hot electron'' plasma is confined by a long solenoidal magnetic field capped by ''mirrors''. Acceleration of prebunched ions is accomplished by activating a series of fast-pulsed mirror coils spaced along the acceleration tube. The hot electrons, being repelled by mirror action, leave the plasma ions behind to create a localized region of high electrical gradient (up to of order 100 MV/m). At the Laboratory an experiment and analyses to elucidate the concept and its scaling laws as applied to heavy-ion drivers are underway and will be described. 4 refs., 5 figs

Nonlinear transport of dynamic system phase space

International Nuclear Information System (INIS)

Xie Xi; Xia Jiawen

1993-01-01

The inverse transform of any order solution of the differential equation of general nonlinear dynamic systems is derived, realizing theoretically the nonlinear transport for the phase space of nonlinear dynamic systems. The result is applicable to general nonlinear dynamic systems, with the transport of accelerator beam phase space as a typical example

Modelling the reflective thermal contribution to the acceleration of the Pioneer spacecraft

International Nuclear Information System (INIS)

Francisco, F.; Bertolami, O.; Gil, P.J.S.; Páramos, J.

2012-01-01

We present an improved method to compute the radiative momentum transfer in the Pioneer 10 and 11 spacecraft that takes into account both diffusive and specular reflection. The method allows for more reliable results regarding the thermal acceleration of the deep-space probes, confirming previous findings. A parametric analysis is performed in order to set upper and lower bounds for the thermal acceleration and its evolution with time.

Modelling the reflective thermal contribution to the acceleration of the Pioneer spacecraft

Energy Technology Data Exchange (ETDEWEB)

Francisco, F., E-mail: frederico.francisco@ist.utl.pt [Instituto de Plasmas e Fusao Nuclear, Instituto Superior Tecnico, Universidade Tecnica de Lisboa, Av. Rovisco Pais 1, 1049-001 Lisboa (Portugal); Bertolami, O., E-mail: orfeu.bertolami@fc.up.pt [Departamento de Fisica e Astronomia, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto (Portugal); Instituto de Plasmas e Fusao Nuclear, Instituto Superior Tecnico, Universidade Tecnica de Lisboa, Av. Rovisco Pais 1, 1049-001 Lisboa (Portugal); Gil, P.J.S., E-mail: p.gil@dem.ist.utl.pt [Departamento de Engenharia Mecanica and IDMEC - Instituto de Engenharia Mecanica, Instituto Superior Tecnico, Universidade Tecnica de Lisboa, Av. Rovisco Pais 1, 1049-001 Lisboa (Portugal); Paramos, J., E-mail: paramos@ist.edu [Instituto de Plasmas e Fusao Nuclear, Instituto Superior Tecnico, Universidade Tecnica de Lisboa, Av. Rovisco Pais 1, 1049-001 Lisboa (Portugal)

2012-05-23

We present an improved method to compute the radiative momentum transfer in the Pioneer 10 and 11 spacecraft that takes into account both diffusive and specular reflection. The method allows for more reliable results regarding the thermal acceleration of the deep-space probes, confirming previous findings. A parametric analysis is performed in order to set upper and lower bounds for the thermal acceleration and its evolution with time.

Formation of spectrum of accelerated particles and the hydromagnetic turbulence in the variable magnetic field

International Nuclear Information System (INIS)

Savane, Y. Sy; Diaby, I.; Faza Barry, M.; Lomonossov, V.

2002-11-01

We study the acceleration of charged particles by the variable magnetic field. The study is based on the determination of spectrum of accelerated particles and the spectrum of hydro magnetic turbulence. We plan the self-consistent system of equation and we also find out the solution of the system for the spectrum of particles and hydro magnetic turbulence with the conditions of effective acceleration in the cosmic space of solar system. (author)

Brookhaven National Laboratory's Accelerator Test Facility: research highlights and plans

Science.gov (United States)

Pogorelsky, I. V.; Ben-Zvi, I.

2014-08-01

The Accelerator Test Facility (ATF) at Brookhaven National Laboratory has served as a user facility for accelerator science for over a quarter of a century. In fulfilling this mission, the ATF offers the unique combination of a high-brightness 80 MeV electron beam that is synchronized to a 1 TW picosecond CO2 laser. We unveil herein our plan to considerably expand the ATF's floor space with an upgrade of the electron beam's energy to 300 MeV and the CO2 laser's peak power to 100 TW. This upgrade will propel the ATF even further to the forefront of research on advanced accelerators and radiation sources, supporting the most innovative ideas in this field. We discuss emerging opportunities for scientific breakthroughs, including the following: plasma wakefield acceleration studies in research directions already active at the ATF; laser wakefield acceleration (LWFA), where the longer laser wavelengths are expected to engender a proportional increase in the beam's charge while our linac will assure, for the first time, the opportunity to undertake detailed studies of seeding and staging of the LWFA; proton acceleration to the 100-200 MeV level, which is essential for medical applications; and others.

Envelope method for determination of the ion linear accelerator acceptance

International Nuclear Information System (INIS)

Sharshanov, A.A.; Goncharenko, I.I.; Revutskij, E.I.

1974-01-01

The acceptance defined by the slit u 2 2 in space u, ν, z (u=coordinate of the accelerated particle in the direction perpendicular to the accelerator axis, ν=ratio of the transverse particle velocity component to the longitudinal component, z=accelerator axis, a=dimensions of slit) represents a convex curvilinear polygon with centre of symmetry at the origin of the co-ordinates. The sides of the polygon are sections of ellipses and straight lines, the ellipses being part of an envelope to the set of proto-types of all cross-sections of the slit in planes z=3, where 0<=xi<=z and z is the length of the accelerator, and the straight lines are tangents to the ends of the envelope. In the paper the equations of the ellipses forming the sides of the polygon are written using an elementary variable matrix of the accelerator structure, and the co-ordinates of the polygon apexes are found. A numerical value is derived for the area of the polygon for one transverse co-ordinate of the particular accelerator, the pre-stripping section of the LUMZI-10. (author)

Longitudinal Phase Space Tomography with Space Charge

CERN Document Server

Hancock, S; Lindroos, M

2000-01-01

Tomography is now a very broad topic with a wealth of algorithms for the reconstruction of both qualitative and quantitative images. In an extension in the domain of particle accelerators, one of the simplest algorithms has been modified to take into account the non-linearity of large-amplitude synchrotron motion. This permits the accurate reconstruction of longitudinal phase space density from one-dimensional bunch profile data. The method is a hybrid one which incorporates particle tracking. Hitherto, a very simple tracking algorithm has been employed because only a brief span of measured profile data is required to build a snapshot of phase space. This is one of the strengths of the method, as tracking for relatively few turns relaxes the precision to which input machine parameters need to be known. The recent addition of longitudinal space charge considerations as an optional refinement of the code is described. Simplicity suggested an approach based on the derivative of bunch shape with the properties of...

Composite resin reinforced with pre-tensioned fibers: a three-dimensional finite element study on stress distribution.

Science.gov (United States)

Jie, Lin; Shinya, Akikazu; Lassila, Lippo V J; Vallittu, Pekka K

2013-01-01

Pre-tensioned construction material is utilized in engineering applications of high strength demands. The purpose of this study was to evaluate the effect of the pre-tensioning fibers of fiber-reinforced composite (FRC) using three-dimensional finite element (FE) analysis. The 3D FE models of particulate composite resin (CR), FRC and composite resin reinforced with pre-tensioned fibers (PRE-T-FRC) were constructed. The uniaxial three-point bending test was simulated using FE analysis to calculate the principal stress distribution. In the FRC and PRE-T-FRC, stresses were higher than CR, and they were located in the fiber. However, the maximum principal stress value at the composite of PRE-T-FRC was lower than the FRC and CR. Composite resin reinforced with pre-tensioned fibers was advantageous for stress distribution and lowering the stress at the composite itself. Experimental studies on physical properties of pre-tensioned FRC are encouraged to be conducted.

A modified space charge routine for high intensity bunched beams

International Nuclear Information System (INIS)

Lapostolle, P.; Lombardi, A.M.; Tanke, E.; Valero, S.; Garnett, R.W.; Wangler, T.P.

1996-01-01

A new routine and a computer code (DYNAC) for the calculation of space charge densities in a new generation of linear accelerators for various industrial applications is presented. The new beam dynamics method used in this code, employs a set of quasi-Liouvillian equations, allowing beam dynamics computations in long and complex structures for electrons, as well as protons and ions. With this new beam dynamics method, the coordinates of particles are known at any position in the accelerating elements, allowing multistep space charge calculations. (K.A.)

Accelerator research studies. Progress report

International Nuclear Information System (INIS)

1984-06-01

Progress is reported in both experimental studies as well as theoretical understanding of the beam transport problem. Major highlights are: (a) the completion of the first channel section with 12 periods and two matching solenoids, (b) measurements of beam transmission and emittance in this 12-lens channel, (c) extensive analytical and numerical studies of the beam transport problem in collaboration with GSI (W. Germany), (d) detailed measurements and calculations of beam propagation through one lens with spherical aberration and space charge, and (e) completion of the emittance grids at the Rutherford-Appleton Laboratory. Our main objectives in Task B of our research program are: (a) study of collective acceleration of positive ions from a localized plasma source by an intense relativistic electron beam (IREB), (b) external control of the IREB beam front by a slow-wave structure to achieve higher ion energies - the Beam Front Accelerator (BFA) concept, (c) study of ion and electron acceleration and other applications of a plasma focus device, and (d) theoretical studies in support of (a) and (b). Our research in these areas has been oriented towards obtaining an improved understanding of the physical processes at work in these experiments and, subsequently, achieving improved performance for specific potential applications

Optimization and application of electron acceleration in relativistic laser plasmas

International Nuclear Information System (INIS)

Koenigstein, Thomas

2013-01-01

This thesis describes experiments and simulations of the acceleration of electrons to relativistic energies (toward γ e ∼ 10 3 ) by structures in plasmas which are generated by ultrashort (pulse length < 10 -14 s) laser pulses. The first part of this work discusses experiments in a parameter space where quasimonoenergetic electron bunches are generated in subcritical (gaseous) plasmas and compares them to analytical scalings. A primary concern in this work is to optimize the stability of the energy and the pointing of the electrons. The second part deals with acceleration of electrons along the surface of solid substrates by laser-plasma interaction. The measurements show good agreement with existing analytical scalings and dedicated numerical simulations. In the third part, two new concepts for multi-stage acceleration will be presented and parameterised by analytical considerations and numerical simulations. The first method uses electron pairs, as produced in the first part, to transfer energy from the first bunch to the second by means of a plasma wave. The second method utilizes a low intensity laser pulse in order to inject electrons from a neutral gas into the accelerating phase of a plasma wave. The final chapter proposes and demonstrates a first application that has been developed in collaboration with ESA. The use of electron beams with exponential energy distribution, as in the second part of this work, offers the potential to investigate the resistance of electronic components against space radiation exposure.

High intensity proton acceleration at the Brookhaven AGS -- An update

International Nuclear Information System (INIS)

Ahrens, L.; Alessi, J.; Blaskiewicz, M.

1997-01-01

The AGS accelerator complex is into its third year of 60+ x 10 12 (teraproton = Tp) per cycle operation. The hardware making up the complex as configured in 1997 is briefly mentioned. The present level of accelerator performance is discussed. This includes beam transfer efficiencies at each step in the acceleration process, i.e. losses; which are a serious issue at this intensity level. Progress made in understanding beam behavior at the Linac-to-Booster (LtB) injection, at the Booster-to-AGS (BtA) transfer as well as across the 450 ms AGS accumulation porch is presented. The state of transition crossing, with the gamma-tr jump is described. Coherent effects including those driven by space charge are important at all of these steps

Lecture Notes on Topics in Accelerator Physics

International Nuclear Information System (INIS)

Chao, Alex W.

2002-01-01

These are lecture notes that cover a selection of topics, some of them under current research, in accelerator physics. I try to derive the results from first principles, although the students are assumed to have an introductory knowledge of the basics. The topics covered are: (1) Panofsky-Wenzel and Planar Wake Theorems; (2) Echo Effect; (3) Crystalline Beam; (4) Fast Ion Instability; (5) Lawson-Woodward Theorem and Laser Acceleration in Free Space; (6) Spin Dynamics and Siberian Snakes; (7) Symplectic Approximation of Maps; (8) Truncated Power Series Algebra; and (9) Lie Algebra Technique for nonlinear Dynamics. The purpose of these lectures is not to elaborate, but to prepare the students so that they can do their own research. Each topic can be read independently of the others

Lecture Notes on Topics in Accelerator Physics

Energy Technology Data Exchange (ETDEWEB)

Chao, Alex W.

2002-11-15

These are lecture notes that cover a selection of topics, some of them under current research, in accelerator physics. I try to derive the results from first principles, although the students are assumed to have an introductory knowledge of the basics. The topics covered are: (1) Panofsky-Wenzel and Planar Wake Theorems; (2) Echo Effect; (3) Crystalline Beam; (4) Fast Ion Instability; (5) Lawson-Woodward Theorem and Laser Acceleration in Free Space; (6) Spin Dynamics and Siberian Snakes; (7) Symplectic Approximation of Maps; (8) Truncated Power Series Algebra; and (9) Lie Algebra Technique for nonlinear Dynamics. The purpose of these lectures is not to elaborate, but to prepare the students so that they can do their own research. Each topic can be read independently of the others.

RADON reconstruction in longitudinal phase space

International Nuclear Information System (INIS)

Mane, V.; Peggs, S.; Wei, J.

1997-01-01

Longitudinal particle motion in circular accelerators is typically monitoring by one dimensional (1-D) profiles. Adiabatic particle motion in two dimensional (2-D) phase space can be reconstructed with tomographic techniques, using 1-D profiles. A computer program RADON has been developed in C++ to process digitized mountain range data and perform the phase space reconstruction for the AGS, and later for Relativistic Heavy Ion Collider (RHIC)

FDTD method using for electrodynamic simulation of resonator accelerating structures

International Nuclear Information System (INIS)

Vorogushin, M.F.; Svistunov, Yu.A.; Chetverikov, I.O.; Malyshev, V.N.; Malyukhov, M.V.

2000-01-01

The finite difference method in the time area (FDTD) makes it possible to model both stationary and nonstationary processes, originating by the beam and field interaction. Possibilities of the method by modeling the fields in the resonant accelerating structures are demonstrated. The possibility of considering the transition processes is important besides the solution of the problem on determination of frequencies and distribution in the space of the resonators oscillations proper types. The program presented makes it possible to obtain practical results for modeling accelerating structures on personal computers [ru

Induction-accelerator heavy-ion fusion: Status and beam physics issues

International Nuclear Information System (INIS)

Friedman, A.

1996-01-01

Inertial confinement fusion driven by beams of heavy ions is an attractive route to controlled fusion. In the U.S., induction accelerators are being developed as open-quotes driversclose quotes for this process. This paper is divided into two main sections. In the first section, the concept of induction-accelerator driven heavy-ion fusion is briefly reviewed, and the U.S. program of experiments and theoretical investigations is described. In the second, a open-quotes taxonomyclose quotes of space-charge-dominated beam physics issues is presented, accompanied by a brief discussion of each area

Space trajectory calculation based on G-sensor

Science.gov (United States)

Xu, Biya; Zhan, Yinwei; Shao, Yang

2017-08-01

At present, without full use of the mobile phone around us, most of the research in human body posture recognition field is use camera or portable acceleration sensor to collect data. In this paper, G-sensor built-in mobile phone is use to collect data. After processing data with the way of moving average filter and acceleration integral, joint point's space three-dimensional coordinates can be abtained accurately.

Space Radiation Research at NASA

Science.gov (United States)

Norbury, John

2016-01-01

The harmful effects of space radiation on astronauts is one of the most important limiting factors for human exploration of space beyond low Earth orbit, including a journey to Mars. This talk will present an overview of space radiation issues that arise throughout the solar system and will describe research efforts at NASA aimed at studying space radiation effects on astronauts, including the experimental program at the NASA Space Radiation Laboratory at Brookhaven National Laboratory. Recent work on galactic cosmic ray simulation at ground based accelerators will also be presented. The three major sources of space radiation, namely geomagnetically trapped particles, solar particle events and galactic cosmic rays will be discussed as well as recent discoveries of the harmful effects of space radiation on the human body. Some suggestions will also be given for developing a space radiation program in the Republic of Korea.

The IFVE accelerating-storage complex (Present status)

International Nuclear Information System (INIS)

Balbekov, V.I.; Dmitrevski, Yu.P.; Kurnaev, O.V.

1979-01-01

A description of an accelerating-storage complex and the results of the development of its preliminary design are given. The first stage of the complex is a proton synchrotron with a standard electromagnet intended for storage and preliminary acceleration of protons to 400 GeV. Acceleration to 3 TeV will be provided by the second stage which is assumed to employ a superconducting magnet with 5 T. The existing 70 GeV synchrotron will be used as an injector. The magnetic structures of the first and second stages are identical. They include 180 FODO-type periods. Every period contains 12 dipoles and 2 quadrupole lenses. The accelerating devices should provide a total voltage amplitude of 12 MV or the superconducting ring. Three extraction modes are envisaged: a singleturn mode, a slow resonance extraction (during 30 s), and a fast resonance extraction of ten 1 ms pulses at 3 s intervals (6x10 13 protons per pulse). At present the preparation for testing 1 m long superconducting dipoles, HF systems, input and output devices is being completed. Measures aimed at suppressing the space charge effect are described. A possibility is investigated of obtaining 6 TeV by realizing proton-antiproton colliding beams in the complex by using the electron cooling method

Charged particle accelerator

Energy Technology Data Exchange (ETDEWEB)

Ress, T I; Nolde, G V

1974-11-25

A charged particle accelerator is described. It is made of an enclosure arranged for channeling a stream of charged particles along a predetermined path, and propelling means juxtaposed to the enclosure for generating a magnetic field moving in a predetermined direction with respect to each point of the path, the magnetic flux vector of that field being transverse to that path at every point, which gives the particles, along said path, a velocity connected to that of the mobile field by a predetermined relation. This can be applied to the fast production of chemical compounds, to the emission of neutrons and of thermal energy, and to the production of mechanical energy for propelling space ships.

Charged particle accelerator

International Nuclear Information System (INIS)

Ress, T.I.; Nolde, G.V.

1974-01-01

A charged particle accelerator is described. It is made of an enclosure arranged for channeling a stream of charged particles along a predetermined path, and propelling means juxtaposed to said enclosure for generating therein a magnetic field moving in a predetermined direction with respect to each point of said path, the magnetic flux vector of that field being transverse to that path at every point, which gives the particles, along said path, a velocity connected to that of the mobile field by a predetermined relation. This can be applied to the fast production of chemical compounds, to the emission of neutrons and of thermal energy, and to the production of mechanical energy for propelling space ships [fr

Ponderomotive ion acceleration in dense magnetized laser-irradiated thick target plasmas

Science.gov (United States)

Sinha, Ujjwal; Kaw, Predhiman

2012-03-01

When a circularly polarized laser pulse falls on an overdense plasma, it displaces the electrons via ponderomotive force creating a double layer. The double layer constitutes of an ion and electron sheath with in which the electrostatic field present is responsible for ion acceleration. In this paper, we have analyzed the effect a static longitudinal magnetic field has over the ion acceleration mechanism. The longitudinal magnetic field changes the plasma dielectric constant due to cyclotron effects which in turn enhances or reduces the ponderomotive force exerted by the laser depending on whether the laser is left or right circularly polarized. Also, the analysis of the ion space charge region present behind the ion sheath of the laser piston that undergoes coulomb explosion has been explored for the first time. We have studied the interaction of an incoming ion beam with the laser piston and the ion space charge. It has been found that the exploding ion space charge has the ability to act as an energy amplifier for incoming ion beams.

Plasma accelerators

International Nuclear Information System (INIS)

Bingham, R.; Angelis, U. de; Johnston, T.W.

1991-01-01

Recently attention has focused on charged particle acceleration in a plasma by a fast, large amplitude, longitudinal electron plasma wave. The plasma beat wave and plasma wakefield accelerators are two efficient ways of producing ultra-high accelerating gradients. Starting with the plasma beat wave accelerator (PBWA) and laser wakefield accelerator (LWFA) schemes and the plasma wakefield accelerator (PWFA) steady progress has been made in theory, simulations and experiments. Computations are presented for the study of LWFA. (author)

An extended car-following model considering the acceleration derivative in some typical traffic environments

Science.gov (United States)

Zhou, Tong; Chen, Dong; Liu, Weining

2018-03-01

Based on the full velocity difference and acceleration car-following model, an extended car-following model is proposed by considering the vehicle’s acceleration derivative. The stability condition is given by applying the control theory. Considering some typical traffic environments, the results of theoretical analysis and numerical simulation show the extended model has a more actual acceleration of string vehicles than that of the previous models in starting process, stopping process and sudden brake. Meanwhile, the traffic jams more easily occur when the coefficient of vehicle’s acceleration derivative increases, which is presented by space-time evolution. The results confirm that the vehicle’s acceleration derivative plays an important role in the traffic jamming transition and the evolution of traffic congestion.

Cancellation of differential accelerations for the LISA spacecraft

International Nuclear Information System (INIS)

Bender, Peter L

2006-01-01

The three spacecraft of the Laser Interferometer Space Antenna will form a nearly equilateral triangle with nominal side lengths of 5 million km. However, the arm lengths and the corner angles will vary by very roughly 1% over 5-10 years. Part of this variation is due to the nature of Kepler orbits around the Sun. But Sweetser (2006 Astrodynamics 2005, Advances in the Astronautical Sciences vol 123 (San Diego, CA: Univelt Inc.) pp 693-712) has shown recently that differential secular accelerations due to the Earth for the three spacecraft prevent the minimal variations from being preserved for more than 2 or 3 years. Based on Sweetser's results, it appears possible to cancel out the differential secular acceleration due to the Earth by applying forces to the two proof masses in each spacecraft. The applied acceleration is at most 2.1 x 10 -9 m s -2 . However, the directions of the required accelerations would have substantial components along the sides of the triangle, and thus the amplitudes of the applied forces would have to have very low noise, even at frequencies down to below 0.1 mHz

A physical process of the radial acceleration of disc galaxies

Science.gov (United States)

Wilhelm, Klaus; Dwivedi, Bhola N.

2018-03-01

An impact model of gravity designed to emulate Newton's law of gravitation is applied to the radial acceleration of disc galaxies. Based on this model (Wilhelm et al. 2013), the rotation velocity curves can be understood without the need to postulate any dark matter contribution. The increased acceleration in the plane of the disc is a consequence of multiple interactions of gravitons (called `quadrupoles' in the original paper) and the subsequent propagation in this plane and not in three-dimensional space. The concept provides a physical process that relates the fit parameter of the acceleration scale defined by McGaugh et al. (2016) to the mean free path length of gravitons in the discs of galaxies. It may also explain the gravitational interaction at low acceleration levels in MOdification of the Newtonian Dynamics (MOND, Milgrom 1983, 1994, 2015, 2016). Three examples are discussed in some detail: the spiral galaxies NGC 7814, NGC 6503 and M 33.

Handling and Transport of Oversized Accelerator Components and Physics Detectors

CERN Document Server

Prodon, S; Guinchard, M; Minginette, P

2006-01-01

For cost, planning and organisational reasons, it is often decided to install large pre-built accelerators components and physics detectors. As a result surface exceptional transports are required from the construction to the installation sites. Such heavy transports have been numerous during the LHC installation phase. This paper will describe the different types of transport techniques used to fit the particularities of accelerators and detectors components (weight, height, acceleration, planarity) as well as the measurement techniques for monitoring and the logistical aspects (organisation with the police, obstacles on the roads, etc). As far as oversized equipment is concerned, the lowering into the pit is challenging, as well as the transport in tunnel galleries in a very scare space and without handling means attached to the structure like overhead travelling cranes. From the PS accelerator to the LHC, handling systems have been developed at CERN to fit with these particular working conditions. This pap...

Plasma acceleration, injection, and loss

International Nuclear Information System (INIS)

McIlwain, C.E.

1988-01-01

The sudden and dramatic acceleration of charged particles seems to be a universal phenomenon which occurs in plasmas occupying a wide range of spatial scales. These accelerations are typically accompanied by intrusions of the energized plasma into adjacent regions of space. A physical understanding of these processes can only be obtained by carefully coordinated experimental and theoretical studies which are designed to let nature display what is happening without imposing limitations associated with existing paradigms. Studies of the Earth's magnetosphere are hampered by the lack of adequate sampling in space and time. The feature matching technique of building magnetic and electric field models can help compensate for the extreme sparseness of experimental data but many future studies will still require large numbers of spacecraft placed in carefully coordinated orbits. History shows that magnetospheric research has sometimes faltered while various attractive conjectures were explored, but that direct observations play the role of a strict teacher who has little concern for the egos of scientists. Presumably this teacher will also discard the author's pet notion: that the ignition' of portions of the auroral shell in association with Earth flares results in the heating of ionospheric particles (and some particles of solar origin) that are then convected inward to form the ring current. The author, of course, hopes that at least some aspects of this notion will survive and will help lead the way to a better understanding of the Earth's neighborhood

Studies of the plasma droplet accelerator scheme

International Nuclear Information System (INIS)

Mori, W.B.; Joshi, C.; Dawson, J.M.; Lee, K.; Forslund, D.W.; Kindel, J.M.

1985-01-01

In the plasma droplet accelerator scheme, proposed by R. Palmer, a sequence of liquid micro-spheres generated by a jet printer are ionized by an incoming intense laser. The hope is that the micro-spheres now acting as conducting balls will allow efficient coupling of the incoming laser radiation into an accelerating mode. Motivated by this the authors have carried out 2D, particle simulations in order to answer some of the plasma physics questions hitherto unaddressed. In particular they find that at least for laser intensities exceeding v 0 /c=0.03 (/sup ∼/10 13 w/cm 2 for a CO 2 laser), the incident laser light is rather efficiently absorbed in a hot electron distribution. Up to 70% of the incident energy can be absorbed by these electrons which rapidly expand and fill the vacuum space between the microspheres with a low density plasma. These results indicate that it is advisable to stay clear of plasma formation and thus put on an upper limit on the maximum surface fields that can be tolerated in the droplet-accelerator scheme

Studies of the plasma droplet accelerator scheme

International Nuclear Information System (INIS)

Mori, W.B.; Dawson, J.M.; Forslund, D.W.; Joshi, C.; Kindel, J.M.; Lee, K.

1985-01-01

In the plasma droplet accelerator scheme, proposed by R. Palmer, a sequence of liquid micro-spheres generated by a jet printer are ionized by an incoming intense laser. The hope is that the micro-spheres now acting as conducting balls will allow efficient coupling of the incoming laser radiation into an accelerating mode. Motivated by this we have carried out 2D, particle simulations in order to answer some of the plasma physics questions hitherto unaddressed. In particular we find that at least for laser intensities exceeding v /SUB o/ /c=0.03 ( about10 13 w/cm 2 for a CO 2 laser), the incident laser light is rather efficiently absorbed in a hot electron distribution. Up to 70% of the incident energy can be absorbed by these electrons which rapidly expand and fill the vacuum space between the microspheres with a low density plasma. These results indicate that it is advisable to stay clear of plasma formation and thus put on an upper limit on the maximum surface fields that can be tolerated in the droplet-accelerator scheme

Performance improvement of magnetized coaxial plasma gun by magnetic circuit on a bias coil

Science.gov (United States)

Edo, Takahiro; Matsumoto, Tadafumi; Asai, Tomohiko; Kamino, Yasuhiro; Inomoto, Michiaki; Gota, Hiroshi

2016-10-01

A magnetized coaxial plasmoid accelerator has been utilized for compact torus (CT) injection to refuel into fusion reactor core plasma. Recently, CT injection experiments have been conducted on the C-2/C-2U facility at Tri Alpha Energy. In the series of experiments successful refueling, i.e. increased particle inventory of field-reversed configuration (FRC) plasma, has been observed. In order to improve the performance of CT injector and to refuel in the upgraded FRC device, called C-2W, with higher confinement magnetic field, magnetic circuit consisting of magnetic material onto a bias magnetic coil is currently being tested at Nihon University. Numerical work suggests that the optimized bias magnetic field distribution realizes the increased injection velocity because of higher conversion efficiency of Lorenz self force to kinetic energy. Details of the magnetic circuit design as well as results of the test experiment and field calculations will be presented and discussed.

Cryogenic Beam Screens for High-Energy Particle Accelerators

CERN Document Server

Baglin, V; Tavian, L; van Weelderen, R

2013-01-01

Applied superconductivity has become a key enabling technology for high-energy particle accelerators, thus making them large helium cryogenic systems operating at very low temperature. The circulation of high-intensity particle beams in these machines generates energy deposition in the first wall through different processes. For thermodynamic efficiency, it is advisable to intercept these beam-induced heat loads, which may be large in comparison with cryostat heat in-leaks, at higher temperature than that of the superconducting magnets of the accelerator, by means of beam screens located in the magnet apertures. Beam screens may also be used as part of the ultra-high vacuum system of the accelerator, by sheltering the gas molecules cryopumped on the beam pipe from impinging radiation and thus avoiding pressure runaway. Space being extremely tight in the magnet apertures, cooling of the long, slender beam screens also raises substantial problems in cryogenic heat transfer and fluid flow. We present sizing rule...

Functional imaging of murine hearts using accelerated self-gated UTE cine MRI.

Science.gov (United States)

Motaal, Abdallah G; Noorman, Nils; de Graaf, Wolter L; Hoerr, Verena; Florack, Luc M J; Nicolay, Klaas; Strijkers, Gustav J

2015-01-01

We introduce a fast protocol for ultra-short echo time (UTE) Cine magnetic resonance imaging (MRI) of the beating murine heart. The sequence involves a self-gated UTE with golden-angle radial acquisition and compressed sensing reconstruction. The self-gated acquisition is performed asynchronously with the heartbeat, resulting in a randomly undersampled kt-space that facilitates compressed sensing reconstruction. The sequence was tested in 4 healthy rats and 4 rats with chronic myocardial infarction, approximately 2 months after surgery. As a control, a non-accelerated self-gated multi-slice FLASH sequence with an echo time (TE) of 2.76 ms, 4.5 signal averages, a matrix of 192 × 192, and an acquisition time of 2 min 34 s per slice was used to obtain Cine MRI with 15 frames per heartbeat. Non-accelerated UTE MRI was performed with TE = 0.29 ms, a reconstruction matrix of 192 × 192, and an acquisition time of 3 min 47 s per slice for 3.5 averages. Accelerated imaging with 2×, 4× and 5× undersampled kt-space data was performed with 1 min, 30 and 15 s acquisitions, respectively. UTE Cine images up to 5× undersampled kt-space data could be successfully reconstructed using a compressed sensing algorithm. In contrast to the FLASH Cine images, flow artifacts in the UTE images were nearly absent due to the short echo time, simplifying segmentation of the left ventricular (LV) lumen. LV functional parameters derived from the control and the accelerated Cine movies were statistically identical.

Proposal of experimental facilities for studies of nuclear data and radiation engineering in the Intense Proton Accelerator Project

CERN Document Server

Baba, M; Nagai, Y; Ishibashi, K

2003-01-01

A proposal is given on the facilities and experiments in the Intense Proton Accelerator Project (J-PARC) relevant to the nuclear data and radiation engineering, nuclear astrophysics, nuclear transmutation, accelerator technology and space technology and so on. (3 refs).

3D electromagnetic simulation of spatial autoresonance acceleration of electron beams

International Nuclear Information System (INIS)

Dugar-Zhabon, V D; Orozco, E A; González, J D

2016-01-01

The results of full electromagnetic simulations of the electron beam acceleration by a TE 112 linear polarized electromagnetic field through Space Autoresonance Acceleration mechanism are presented. In the simulations, both the self-sustaned electric field and selfsustained magnetic field produced by the beam electrons are included into the elaborated 3D Particle in Cell code. In this system, the space profile of the magnetostatic field maintains the electron beams in the acceleration regime along their trajectories. The beam current density evolution is calculated applying the charge conservation method. The full magnetic field in the superparticle positions is found by employing the trilinear interpolation of the mesh node data. The relativistic Newton-Lorentz equation presented in the centered finite difference form is solved using the Boris algorithm that provides visualization of the beam electrons pathway and energy evolution. A comparison between the data obtained from the full electromagnetic simulations and the results derived from the motion equation depicted in an electrostatic approximation is carried out. It is found that the self-sustained magnetic field is a factor which improves the resonance phase conditions and reduces the beam energy spread. (paper)

An improved 8 GeV beam transport system for the Fermi National Accelerator Laboratory

International Nuclear Information System (INIS)

Syphers, M.J.

1987-06-01

A new 8 GeV beam transport system between the Booster and Main Ring synchrotrons at the Fermi National Accelerator Laboratory is presented. The system was developed in an effort to improve the transverse phase space area occupied by the proton beam upon injection into the Main Ring accelerator. Problems with the original system are described and general methods of beamline design are formulated. Errors in the transverse properties of a beamline at the injection point of the second synchrotron and their effects on the region in transverse phase space occupied by a beam of particles are discussed. Results from the commissioning phase of the project are presented as well as measurements of the degree of phase space dilution generated by the transfer of 8 GeV protons from the Booster synchrotron to the Main Ring synchrotron

Beam-front dynamics and ion acceleration in drifting intense relativistic electron beams

International Nuclear Information System (INIS)

Alexander, K.F.; Hintze, W.

1976-01-01

Collective ion acceleration at the injection of a relativistic electron beam into a low-pressure gas or a plasma is discussed and its strong dependence on the beam-front dynamics is shown. A simple one-dimensional model taking explicitly into account the motion and ionizing action of the ions in the beam-front region is developed for the calculation of the beam drift velocity. The obtained pressure dependence is in good agreement with experimental data. The energy distribution is shown of the ions accelerated in the moving potential well of the space charge region. Scaling laws for the beam-front dynamics and ion acceleration are derived. (J.U.)

Space ventures and society long-term perspectives

Science.gov (United States)

Brown, W. M.

1985-01-01

A futuristic evaluation of mankind's potential long term future in space is presented. Progress in space will not be inhibited by shortages of the Earth's physical resources, since long term economic growth will be focused on ways to constrain industrial productivity by changing social values, management styles, or government competence. Future technological progress is likely to accelerate with an emphasis on international cooperation, making possible such large joint projects as lunar colonies or space stations on Mars. The long term future in space looks exceedingly bright even in relatively pessimistic scenarios. The principal driving forces will be technological progress, commercial and public-oriented satellites, space industrialization, space travel, and eventually space colonization.

Accelerator and Ion Beam Tradeoffs for Studies of Warm Dense Matter

International Nuclear Information System (INIS)

Barnard, J.J.; Briggs, R.J.; Callahan, D.A.; Davidson, R.C.; Friedman, A.; Grisham, L.; Lee, E.P.; Lee, R.W.; Logan, B.G.; Olson, C.L.; Rose, D.V.; Santhanam, P.; Sessler, A.M.; Staples, J.W.; Tabak, M.; Welch, D.R.; Wurtele, J.S.; Yu, S.S.

2006-01-01

One approach for heating a target to ''Warm Dense Matter'' conditions (similar, for example, to the interiors of giant planets or certain stages in inertial confinement fusion targets), is to use intense ion beams as the heating source (see refs.[6] and [7] and references therein for motivation and accelerator concepts). By consideration of ion beam phase-space constraints, both at the injector, and at the final focus, and consideration of simple equations of state and relations for ion stopping, approximate conditions at the target foil may be calculated. Thus, target temperature and pressure may be calculated as a function of ion mass, ion energy, pulse duration, velocity tilt, and other accelerator parameters. We connect some of these basic parameters to help search the extensive parameter space including ion mass, ion energy, total charge in beam pulse, beam emittance, target thickness and density

First muon acceleration using a radio-frequency accelerator

Directory of Open Access Journals (Sweden)

S. Bae

2018-05-01

Full Text Available Muons have been accelerated by using a radio-frequency accelerator for the first time. Negative muonium atoms (Mu^{-}, which are bound states of positive muons (μ^{+} and two electrons, are generated from μ^{+}’s through the electron capture process in an aluminum degrader. The generated Mu^{-}’s are initially electrostatically accelerated and injected into a radio-frequency quadrupole linac (RFQ. In the RFQ, the Mu^{-}’s are accelerated to 89 keV. The accelerated Mu^{-}’s are identified by momentum measurement and time of flight. This compact muon linac opens the door to various muon accelerator applications including particle physics measurements and the construction of a transmission muon microscope.

Acceleration Modes and Transitions in Pulsed Plasma Accelerators

Science.gov (United States)

Polzin, Kurt A.; Greve, Christine M.

2018-01-01

Pulsed plasma accelerators typically operate by storing energy in a capacitor bank and then discharging this energy through a gas, ionizing and accelerating it through the Lorentz body force. Two plasma accelerator types employing this general scheme have typically been studied: the gas-fed pulsed plasma thruster and the quasi-steady magnetoplasmadynamic (MPD) accelerator. The gas-fed pulsed plasma accelerator is generally represented as a completely transient device discharging in approximately 1-10 microseconds. When the capacitor bank is discharged through the gas, a current sheet forms at the breech of the thruster and propagates forward under a j (current density) by B (magnetic field) body force, entraining propellant it encounters. This process is sometimes referred to as detonation-mode acceleration because the current sheet representation approximates that of a strong shock propagating through the gas. Acceleration of the initial current sheet ceases when either the current sheet reaches the end of the device and is ejected or when the current in the circuit reverses, striking a new current sheet at the breech and depriving the initial sheet of additional acceleration. In the quasi-steady MPD accelerator, the pulse is lengthened to approximately 1 millisecond or longer and maintained at an approximately constant level during discharge. The time over which the transient phenomena experienced during startup typically occur is short relative to the overall discharge time, which is now long enough for the plasma to assume a relatively steady-state configuration. The ionized gas flows through a stationary current channel in a manner that is sometimes referred to as the deflagration-mode of operation. The plasma experiences electromagnetic acceleration as it flows through the current channel towards the exit of the device. A device that had a short pulse length but appeared to operate in a plasma acceleration regime different from the gas-fed pulsed plasma

Nonlinear theory of diffusive acceleration of particles by shock waves

Energy Technology Data Exchange (ETDEWEB)

Malkov, M.A. [University of California at San Diego, La Jolla, CA (United States)]. E-mail: mmalkov@ucsd.edu; Drury, L. O' C. [Dublin Institute for Advanced Studies, 5 Merrion Square, Dublin 2 (Ireland)

2001-04-01

Among the various acceleration mechanisms which have been suggested as responsible for the nonthermal particle spectra and associated radiation observed in many astrophysical and space physics environments, diffusive shock acceleration appears to be the most successful. We review the current theoretical understanding of this process, from the basic ideas of how a shock energizes a few reactionless particles to the advanced nonlinear approaches treating the shock and accelerated particles as a symbiotic self-organizing system. By means of direct solution of the nonlinear problem we set the limit to the test-particle approximation and demonstrate the fundamental role of nonlinearity in shocks of astrophysical size and lifetime. We study the bifurcation of this system, proceeding from the hydrodynamic to kinetic description under a realistic condition of Bohm diffusivity. We emphasize the importance of collective plasma phenomena for the global flow structure and acceleration efficiency by considering the injection process, an initial stage of acceleration and, the related aspects of the physics of collisionless shocks. We calculate the injection rate for different shock parameters and different species. This, together with differential acceleration resulting from nonlinear large-scale modification, determines the chemical composition of accelerated particles. The review concentrates on theoretical and analytical aspects but our strategic goal is to link the fundamental theoretical ideas with the rapidly growing wealth of observational data. (author)

Simulation and design of the photonic crystal microwave accelerating structure

International Nuclear Information System (INIS)

Song Ruiying; Wu Congfeng; He Xiaodong; Dong Sai

2007-01-01

The authors have derived the global band gaps for general two-dimensional (2D) photonic crystal microwave accelerating structures formed by square or triangular arrays of metal posts. A coordinate-space, finite-difference code was used to calculate the complete dispersion curves for the lattices. The fundamental and higher frequency global photonic band gaps were determined numerically. The structure formed by triangular arrays of metal posts with a missing rod at the center has advantages of higher-order-modes (HOM) suppression and main mode restriction under the condition of a/b<0.2. The relationship between the RF properties and the geometrical parameters have been studied for the 9.37 GHz photonic crystal accelerating structure. The Rs, Q, Rs/Q of the new structure may be comparable to the disk-loaded accelerating structure. (authors)

Accelerator development

International Nuclear Information System (INIS)

Anon.

1975-01-01

Because the use of accelerated heavy ions would provide many opportunities for new and important studies in nuclear physics and nuclear chemistry, as well as other disciplines, both the Chemistry and Physics Divisions are supporting the development of a heavy-ion accelerator. The design of greatest current interest includes a tandem accelerator with a terminal voltage of approximately 25 MV injecting into a linear accelerator with rf superconducting resonators. This combined accelerator facility would be capable of accelerating ions of masses ranging over the entire periodic table to an energy corresponding to approximately 10 MeV/nucleon. This approach, as compared to other concepts, has the advantages of lower construction costs, lower operating power, 100 percent duty factor, and high beam quality (good energy resolution, good timing resolution, small beam size, and small beam divergence). The included sections describe the concept of the proposed heavy-ion accelerator, and the development program aiming at: (1) investigation of the individual questions concerning the superconducting accelerating resonators; (2) construction and testing of prototype accelerator systems; and (3) search for economical solutions to engineering problems. (U.S.)

Focusing mechanisms in the Pulselac CU accelerator

International Nuclear Information System (INIS)

Johnson, D.J.; Lockner, T.R.

1986-06-01

The post-acceleration of a 400 keV, 10 kA proton beam by a 200 kV magnetically insulated gap is investigated. The deflection from self and applied E and B fields are measured and compared to calculated values. We find that the beam is inadequately space-charge neutralized without gas puffs in regions of applied-B field to allow efficient transport. The beam is also non-current neutralized in these regions leading to self-magnetic deflection. The applied-B field is used to focus the beam both directly as a solenoidal lens and indirectly by defining the equipotential surfaces in the accelerating gap. It is also pointed out how azimuthal asymmetries in the beam current density and cathode plasma cause beam self-field asymmetries that lead to emittance growth. 4 refs., 4 figs

Accelerator Technology: Geodesy and Alignment for Particle Accelerators

CERN Document Server

Missiaen, D

2013-01-01

This document is part of Subvolume C 'Accelerators and Colliders' of Volume 21 'Elementary Particles' of Landolt-Börnstein - Group I 'Elementary Particles, Nuclei and Atoms'. It contains the the Section '8.9 Geodesy and Alignment for Particle Accelerators' of the Chapter '8 Accelerator Technology' with the content: 8.9 Geodesy and Alignment for Particle Accelerators 8.9.1 Introduction 8.9.2 Reference and Co-ordinate Systems 8.9.3 Definition of the Beam Line on the Accelerator Site 8.9.4 Geodetic Network 8.9.5 Tunnel Preliminary Works 8.9.6 The Alignment References 8.9.7 Alignment of Accelerator Components 8.9.8 Permanent Monitoring and Remote Alignment of Low Beta Quadrupoles 8.9.9 Alignment of Detector Components

Plasma-gun-assisted field-reversed configuration formation in a conical θ-pinch

Energy Technology Data Exchange (ETDEWEB)

Weber, T. E., E-mail: tweber@lanl.gov; Intrator, T. P. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Smith, R. J. [Department of Aeronautics and Astronautics, University of Washington, Seattle, Washington 98195 (United States)

2015-04-15

Injection of plasma via an annular array of coaxial plasma guns during the pre-ionization phase of field-reversed configuration (FRC) formation is shown to catalyze the bulk ionization of a neutral gas prefill in the presence of a strong axial magnetic field and change the character of outward flux flow during field-reversal from a convective process to a much slower resistive diffusion process. This approach has been found to significantly improve FRC formation in a conical θ-pinch, resulting in a ∼350% increase in trapped flux at typical operating conditions, an expansion of accessible formation parameter space to lower densities and higher temperatures, and a reduction or elimination of several deleterious effects associated with the pre-ionization phase.

Plasma-gun-assisted field-reversed configuration formation in a conical θ-pinch

Science.gov (United States)

Weber, T. E.; Intrator, T. P.; Smith, R. J.

2015-04-01

Injection of plasma via an annular array of coaxial plasma guns during the pre-ionization phase of field-reversed configuration (FRC) formation is shown to catalyze the bulk ionization of a neutral gas prefill in the presence of a strong axial magnetic field and change the character of outward flux flow during field-reversal from a convective process to a much slower resistive diffusion process. This approach has been found to significantly improve FRC formation in a conical θ-pinch, resulting in a ˜350% increase in trapped flux at typical operating conditions, an expansion of accessible formation parameter space to lower densities and higher temperatures, and a reduction or elimination of several deleterious effects associated with the pre-ionization phase.

Investigation of advanced propulsion technologies: The RAM accelerator and the flowing gas radiation heater

Science.gov (United States)

Bruckner, A. P.; Knowlen, C.; Mattick, A. T.; Hertzberg, A.

1992-01-01

The two principal areas of advanced propulsion investigated are the ram accelerator and the flowing gas radiation heater. The concept of the ram accelerator is presented as a hypervelocity launcher for large-scale aeroballistic range applications in hypersonics and aerothermodynamics research. The ram accelerator is an in-bore ramjet device in which a projectile shaped like the centerbody of a supersonic ramjet is propelled in a stationary tube filled with a tailored combustible gas mixture. Combustion on and behind the projectile generates thrust which accelerates it to very high velocities. The acceleration can be tailored for the 'soft launch' of instrumented models. The distinctive reacting flow phenomena that have been observed in the ram accelerator are relevant to the aerothermodynamic processes in airbreathing hypersonic propulsion systems and are useful for validating sophisticated CFD codes. The recently demonstrated scalability of the device and the ability to control the rate of acceleration offer unique opportunities for the use of the ram accelerator as a large-scale hypersonic ground test facility. The flowing gas radiation receiver is a novel concept for using solar energy to heat a working fluid for space power or propulsion. Focused solar radiation is absorbed directly in a working gas, rather than by heat transfer through a solid surface. Previous theoretical analysis had demonstrated that radiation trapping reduces energy loss compared to that of blackbody receivers, and enables higher efficiencies and higher peak temperatures. An experiment was carried out to measure the temperature profile of an infrared-active gas and demonstrate the effect of radiation trapping. The success of this effort validates analytical models of heat transfer in this receiver, and confirms the potential of this approach for achieving high efficiency space power and propulsion.

Proposed second harmonic acceleration system for the intense pulsed neutron source rapid cycling synchrotron

International Nuclear Information System (INIS)

Norem, J.; Brandeberry, F.; Rauchas, A.

1983-01-01

The Rapid Cycling Synchrotron (RCS) of the Intense Pulsed Neutron Source (IPNS) operating at Argonne National Laboratory is presently producing intensities of 2 to 2.5 x 10 12 protons per pulse (ppp) with the addition of a new ion source. This intensity is close to the space charge limit of the machine, estimated at approx.3 x 10 12 ppp, depending somewhat on the available aperture. With the present good performance in mind, accelerator improvements are being directed at: (1) increasing beam intensities for neutron science; (2) lowering acceleration losses to minimize activation; and (3) gaining better control of the beam so that losses can be made to occur when and where they can be most easily controlled. On the basis of preliminary measurements, we are now proposing a third cavity for the RF systems which would provide control of the longitudinal bunch shape during the cycle which would permit raising the effective space charge limit of the accelerator and reducing losses

Choice of initial operating parameters for high average current linear accelerators

International Nuclear Information System (INIS)

Batchelor, K.

1976-01-01

Recent emphasis on alternative energy sources together with the need for intense neutron sources for testing of materials for CTR has resulted in renewed interest in high current (approximately 100 mA) c.w. proton and deuteron linear accelerators. In desinging an accelerator for such high currents, it is evident that beam losses in the machine must be minimized, which implies well matched beams, and that adequate acceptance under severe space charge conditions must be met. An investigation is presented of the input parameters to an Alvarez type drift-tube accelerator resulting from such factors. The analysis indicates that an accelerator operating at a frequency of 50 MHz is capable of accepting deuteron currents of about 0.4 amperes and proton currents of about 1.2 amperes. These values depend critically on the assumed values of beam emittance and on the ability to properly ''match'' this to the linac acceptance

Effluent Monitoring System Design for the Proton Accelerator Research Center of PEFP

International Nuclear Information System (INIS)

Kim, Jun Yeon; Mun, Kyeong Jun; Cho, Jang Hyung; Jo, Jeong Hee

2010-01-01

Since host site host site was selected Gyeong-ju city in January, 2006. we need design revision of Proton Accelerator research center to reflect on host site characteristics and several conditions. Also the IAC recommended maximization of space utilization and construction cost saving. After GA(General Arrangement) is made a decision, it is necessary to evaluate the radiation analysis of every controlled area in the proton accelerator research center such as accelerator tunnel, Klystron gallery, beam experimental hall, target rooms and ion beam application building to keep dose rate below the ALARA(As Low As Reasonably achievable) objective. Our staff has reviewed and made a shielding design of them. In this paper, According to accelerator operation mode and access conditions based on radiation analysis and shielding design, we made the exhaust system configuration of controlled area in the proton accelerator research center. Also, we installed radiation monitor and set its alarm value for each radiation area

Recirculating induction accelerators for inertial fusion: Prospects and status

International Nuclear Information System (INIS)

Friedman, A.; Barnard, J.J.; Cable, M.D.

1995-01-01

The US is developing the physics and technology of induction accelerators for heavy-ion beam-driven inertial fusion. The recirculating induction accelerator repeatedly passes beams through the same set of accelerating and focusing elements, thereby reducing both the length and gradient of the accelerator structure. This promises an attractive driver cost, if the technical challenges associated with recirculation can be met. Point designs for recirculator drivers were developed in a multi-year study by LLNL, LBNL, and FM Technologies, and that work is briefly reviewed here. To validate major elements of the recirculator concept, we are developing a small (4-5-m diameter) prototype recirculator which will accelerate a space-charge-dominated beam of K + ions through 15 laps, from 80 to 320 keV and from 2 to 8 mA. Transverse beam confinement is effected via permanent-magnet quadrupoles; bending is via electric dipoles. This ''Small Recirculator'' is being developed in a build-and-test sequence of experiments. An injector, matching section, and linear magnetic channel using seven half-lattice periods of permanent-magnet quadrupole lenses are operational. A prototype recirculator half-lattice period is being fabricated. This paper outlines the research program, and presents initial experimental results

W-band accelerator study in KEK

International Nuclear Information System (INIS)

Zhu Xiongwei; Nakajima, Kazuhisa

2001-01-01

In this paper, we summarize the W-band accelerator study in KEK. We present a design study on W-Band photocathode RF gun which is capable of generating and accelerating 300 pC electron bunch. The design system is made up of 91.392 GHz photocathode RF gun and 91.392 GHz traveling wave linac cells. Based on the numerical simulation using SUPERFISH and PARMELA and the conventional RF linac scaling law, the design will produce 300 pC at 1.74 MeV with bunch length 0.72 ps and normalized transverse emittance 0.55 mm mrad. We study the beam dynamics in high frequency and high gradient; due to the high gradient, the pondermotive effect plays an important role in beam dynamics; we found the pondermotive effect still exist with only the fundamental space harmonics (synchrotron mode) due to the coupling of the transverse and longitudinal motion

Radio frequency focused interdigital linear accelerator

Science.gov (United States)

Swenson, Donald A.; Starling, W. Joel

2006-08-29

An interdigital (Wideroe) linear accelerator employing drift tubes, and associated support stems that couple to both the longitudinal and support stem electromagnetic fields of the linac, creating rf quadrupole fields along the axis of the linac to provide transverse focusing for the particle beam. Each drift tube comprises two separate electrodes operating at different electrical potentials as determined by cavity rf fields. Each electrode supports two fingers, pointing towards the opposite end of the drift tube, forming a four-finger geometry that produces an rf quadrupole field distribution along its axis. The fundamental periodicity of the structure is equal to one half of the particle wavelength .beta..lamda., where .beta. is the particle velocity in units of the velocity of light and .lamda. is the free space wavelength of the rf. Particles are accelerated in the gaps between drift tubes. The particle beam is focused in regions inside the drift tubes.

The Study of Advanced Accelerator Physics Research at UCLA Using the ATF at BNL: Vacuum Acceleration by Laser of Free Electrons

International Nuclear Information System (INIS)

Cline, David B.

2016-01-01

An experiment was designed and data were taken to demonstrate that a tightly focused laser on vacuum can accelerate an electron beam in free space. The experiment was proof-of-principle and showed a clear effect for the laser beam off and on. The size of the effect was about 20% and was consistent over 30 laser and beam shots.

Beam envelope solution of a finite emittance beam including space charge and acceleration

International Nuclear Information System (INIS)

Larson, D.J.; Cole, F.T.; Mills, F.E.

1985-01-01

The intermediate-energy electron-cooling effort at the University of Wisconsin began as a collaboration with the University of California - Santa Barbara free electron laser group to measure the emittance of their test device. The measurement indicated that the optics of the FEL test device were extremely good; there was no emittance degradation throughout the system. For this reason, the electron gun for the electron-cooling effort has been designed to be optically identical to the UCSB gun designed by Hermannsfeldt of SLAC. The optics program used to investigate the gun behavior is EGUN, written by Hermannsfeldt. Because of the complicated problem of electron optics at the start of the Pelletron accelerating column, the first 120 kV of acceleration in the Pelletron is included in the gun optical study. At that point in the Pelletron, the electric field no longer has any significant radial component and the following optical treatment of the device is done

Accelerated high-frame-rate mouse heart cine-MRI using compressed sensing reconstruction.

Science.gov (United States)

Motaal, Abdallah G; Coolen, Bram F; Abdurrachim, Desiree; Castro, Rui M; Prompers, Jeanine J; Florack, Luc M J; Nicolay, Klaas; Strijkers, Gustav J

2013-04-01

We introduce a new protocol to obtain very high-frame-rate cinematographic (Cine) MRI movies of the beating mouse heart within a reasonable measurement time. The method is based on a self-gated accelerated fast low-angle shot (FLASH) acquisition and compressed sensing reconstruction. Key to our approach is that we exploit the stochastic nature of the retrospective triggering acquisition scheme to produce an undersampled and random k-t space filling that allows for compressed sensing reconstruction and acceleration. As a standard, a self-gated FLASH sequence with a total acquisition time of 10 min was used to produce single-slice Cine movies of seven mouse hearts with 90 frames per cardiac cycle. Two times (2×) and three times (3×) k-t space undersampled Cine movies were produced from 2.5- and 1.5-min data acquisitions, respectively. The accelerated 90-frame Cine movies of mouse hearts were successfully reconstructed with a compressed sensing algorithm. The movies had high image quality and the undersampling artifacts were effectively removed. Left ventricular functional parameters, i.e. end-systolic and end-diastolic lumen surface areas and early-to-late filling rate ratio as a parameter to evaluate diastolic function, derived from the standard and accelerated Cine movies, were nearly identical. Copyright © 2012 John Wiley & Sons, Ltd.

Cosmic ray acceleration in sources of the supersonic turbulence

International Nuclear Information System (INIS)

Bykov, A.M.; Toptygin, I.N.

1981-01-01

The mechanism of particle acceleration by the supersonic turbulence is studied. The supersonic turbulence is defined as an ensemble of large- and small-scale plasma motions, in which along with the ranges of smooth parameter variation there are randomly distributed shock wave fronts. Particle interaction with the large-scale turbulence is described by the transfer equation which is true at any relation between the Larmor radius and the transport length. The large-scale turbulence can accelerate particles only due to compressibility effects of the medium. The basic theoretical results concerning turbulence properties in compressed media are presented. Concrete physical conditions and the possibility of acceleration of cosmic rays in the interplanetary space, in the vicinity of suppergiant stars of the O and B class with a great loss of mass and strong stellar winds, in supernova remnants, in the interstellar medium and some extragalactic radio sources are considered [ru

An instability of the standard model of cosmology creates the anomalous acceleration without dark energy

Science.gov (United States)

Smoller, Joel; Temple, Blake; Vogler, Zeke

2017-11-01

We identify the condition for smoothness at the centre of spherically symmetric solutions of Einstein's original equations without the cosmological constant or dark energy. We use this to derive a universal phase portrait which describes general, smooth, spherically symmetric solutions near the centre of symmetry when the pressure p=0. In this phase portrait, the critical k=0 Friedmann space-time appears as a saddle rest point which is unstable to spherical perturbations. This raises the question as to whether the Friedmann space-time is observable by redshift versus luminosity measurements looking outwards from any point. The unstable manifold of the saddle rest point corresponding to Friedmann describes the evolution of local uniformly expanding space-times whose accelerations closely mimic the effects of dark energy. A unique simple wave perturbation from the radiation epoch is shown to trigger the instability, match the accelerations of dark energy up to second order and distinguish the theory from dark energy at third order. In this sense, anomalous accelerations are not only consistent with Einstein's original theory of general relativity, but are a prediction of it without the cosmological constant or dark energy.

An instability of the standard model of cosmology creates the anomalous acceleration without dark energy.

Science.gov (United States)

Smoller, Joel; Temple, Blake; Vogler, Zeke

2017-11-01

We identify the condition for smoothness at the centre of spherically symmetric solutions of Einstein's original equations without the cosmological constant or dark energy. We use this to derive a universal phase portrait which describes general, smooth, spherically symmetric solutions near the centre of symmetry when the pressure p =0. In this phase portrait, the critical k =0 Friedmann space-time appears as a saddle rest point which is unstable to spherical perturbations. This raises the question as to whether the Friedmann space-time is observable by redshift versus luminosity measurements looking outwards from any point. The unstable manifold of the saddle rest point corresponding to Friedmann describes the evolution of local uniformly expanding space-times whose accelerations closely mimic the effects of dark energy. A unique simple wave perturbation from the radiation epoch is shown to trigger the instability, match the accelerations of dark energy up to second order and distinguish the theory from dark energy at third order. In this sense, anomalous accelerations are not only consistent with Einstein's original theory of general relativity, but are a prediction of it without the cosmological constant or dark energy.

Neural Networks for Modeling and Control of Particle Accelerators

Science.gov (United States)

Edelen, A. L.; Biedron, S. G.; Chase, B. E.; Edstrom, D.; Milton, S. V.; Stabile, P.

2016-04-01

Particle accelerators are host to myriad nonlinear and complex physical phenomena. They often involve a multitude of interacting systems, are subject to tight performance demands, and should be able to run for extended periods of time with minimal interruptions. Often times, traditional control techniques cannot fully meet these requirements. One promising avenue is to introduce machine learning and sophisticated control techniques inspired by artificial intelligence, particularly in light of recent theoretical and practical advances in these fields. Within machine learning and artificial intelligence, neural networks are particularly well-suited to modeling, control, and diagnostic analysis of complex, nonlinear, and time-varying systems, as well as systems with large parameter spaces. Consequently, the use of neural network-based modeling and control techniques could be of significant benefit to particle accelerators. For the same reasons, particle accelerators are also ideal test-beds for these techniques. Many early attempts to apply neural networks to particle accelerators yielded mixed results due to the relative immaturity of the technology for such tasks. The purpose of this paper is to re-introduce neural networks to the particle accelerator community and report on some work in neural network control that is being conducted as part of a dedicated collaboration between Fermilab and Colorado State University (CSU). We describe some of the challenges of particle accelerator control, highlight recent advances in neural network techniques, discuss some promising avenues for incorporating neural networks into particle accelerator control systems, and describe a neural network-based control system that is being developed for resonance control of an RF electron gun at the Fermilab Accelerator Science and Technology (FAST) facility, including initial experimental results from a benchmark controller.

Transverse emittance studies of an induction accelerator of heavy ions

International Nuclear Information System (INIS)

Garvey, T.; Eylon, S.; Fessenden, T.J.; Hahn, K.; Henestroza, E.

1991-01-01

Current amplification of heavy ion beams is an integral feature of the induction linac approach to heavy ion fusion. As part of the Heavy Ion Fusion Accelerator Research program at LBL the authors have been studying the evolution of the transverse emittance of ion beams while they are undergoing current amplification, achieved by longitudinal bunch compression and acceleration. Experiments are conducted on MBE-4, a four beam Cs + induction linac. The space-charge dominated beams of MBE-4 are focused by electrostatic quadrupoles while they are accelerated from nominally 200 keV up to ∼ 1 MEV by 24 accelerating gaps. Initially the beams have currents of typically 4 mA to 10 mA per beam. Early experimental results showed a growth of the normalized emittance by a factor of 2 while the beam current was amplified by up to 9 times its initial value. The authors will discuss the results of recent experiments in which a mild bunch length compression rate, more typical of that required by a fusion driver, has shown that the normalized emittance can be maintained at its injection value (0.03 mm-mr) during acceleration

SINBAD—The accelerator R&D facility under construction at DESY

Energy Technology Data Exchange (ETDEWEB)

Dorda, U., E-mail: ulrich.dorda@desy.de [DESY, Hamburg & Zeuthen (Germany); Assmann, R.; Brinkmann, R.; Flöttmann, K.; Hartl, I.; Hüning, M.; Kärtner, F.; Fallahi, A.; Marchetti, B.; Nie, Y.; Osterhoff, J.; Schlarb, H.; Zhu, J. [DESY, Hamburg & Zeuthen (Germany); Maier, A.R. [University Hamburg (Germany)

2016-09-01

The SINBAD facility (Short INnovative Bunches and Accelerators at DESY) is a long-term dedicated accelerator research and development facility currently under construction at DESY. It will be located in the premises of the old DORIS accelerator complex and host multiple independent experiments cost-effectively accessing the same central infrastructure like a central high power laser. With the removal of the old DORIS accelerator being completed, the refurbishment of the technical infrastructure is currently starting up. The presently ongoing conversion of the area into the SINBAD facility and the currently foreseen layout is described. The first experiment will use a compact S-band linac for the production of ultra-short bunches at hundred MeV. Once established, one of the main usages will be to externally inject electrons into a laser-driven plasma wakefield accelerator to boost the energy to GeV-level while maintaining a usable beam quality, ultimately aiming to drive an FEL. The second experiment already under planning is the setup of an attosecond radiation source with advanced technology. Further usage of the available space and infrastructure is revised and national and international collaborations are being established.

2014 CERN Accelerator Schools: Plasma Wake Acceleration

CERN Multimedia

2014-01-01

A specialised school on Plasma Wake Acceleration will be held at CERN, Switzerland from 23-29 November, 2014.   This course will be of interest to staff and students in accelerator laboratories, university departments and companies working in or having an interest in the field of new acceleration techniques. Following introductory lectures on plasma and laser physics, the course will cover the different components of a plasma wake accelerator and plasma beam systems. An overview of the experimental studies, diagnostic tools and state of the art wake acceleration facilities, both present and planned, will complement the theoretical part. Topical seminars and a visit of CERN will complete the programme. Further information can be found at: http://cas.web.cern.ch/cas/PlasmaWake2014/CERN-advert.html http://indico.cern.ch/event/285444/

Accelerator and Ion Beam Tradeoffs for Studies of Warm Dense Matter

CERN Document Server

Barnard, John J; Callahan, Debra; Davidson, Ronald C; Friedman, Alex; Grant-Logan, B; Grisham, Larry; Lee, Edward; Lee, Richard; Olson, Craig; Rose, David; Santhanam, Parthiban; Sessler, Andrew M; Staples, John W; Tabak, Max; Welch, Dale; Wurtele, Jonathan; Yu, Simon

2005-01-01

One approach to heat a target to "Warm Dense Matter" conditions (similar, for example, to the interiors of giant planets or certain stages in Inertial Confinement Fusion targets), is to use intense ion beams as the heating source. By consideration of ion beam phase space constraints, both at the injector, and at the final focus, and consideration of simple equations of state, approximate conditions at a target foil may be calculated. Thus target temperature and pressure may be calculated as a function of ion mass, ion energy, pulse duration, velocity tilt, and other accelerator parameters. We examine the variation in target performance as a function of various beam and accelerator parameters, in the context of several different accelerator concepts, recently proposed for WDM studies.

Apparatus for neutralization of accelerated ions

International Nuclear Information System (INIS)

Fink, J.H.; Frank, A.M.

1979-01-01

Apparatus is described for neutralization of a beam of accelerated ions, such as hydrogen negative ions (H - ), using relatively efficient strip diode lasers which emit monochromatically at an appropriate wavelength (lambda = 8000 A for H - ions) to strip the excess electrons by photodetachment. A cavity, formed by two or more reflectors spaced apart, causes the laser beams to undergo multiple reflections within the cavity, thus increasing the efficiency and reducing the illumination required to obtain an acceptable percentage (approx. 85%) of neutralization

First Observation of Laser-Driven Acceleration of Relativistic Electrons in a Semi-Infinite Vacuum Space

CERN Document Server

Plettner, Tomas; Colby, Eric R; Cowan, Benjamin; Sears, Chris M S; Siemann, Robert; Smith, Todd I; Spencer, James

2005-01-01

We have observed acceleration of relativistic electrons in vacuum driven by a linearly polarized laser beam incident on a thin gold-coated reflective boundary. The observed energy modulation effect follows all the characteristics expected for linear acceleration caused by a longitudinal electric field. As predicted by the Lawson-Woodward theorem the laser driven modulation only appears in the presence of the boundary. It shows a linear dependence with the strength of the electric field of the laser beam and also it is critically dependent on the laser polarization. Finally, it appears to follow the expected angular dependence of the inverse transition radiation process.

Virtual Accelerator for Accelerator Optics Improvement

CERN Document Server

Yan Yi Ton; Decker, Franz Josef; Ecklund, Stanley; Irwin, John; Seeman, John; Sullivan, Michael K; Turner, J L; Wienands, Ulrich

2005-01-01

Through determination of all quadrupole strengths and sextupole feed-downs by fitting quantities derivable from precision orbit measurement, one can establish a virtual accelerator that matches the real accelerator optics. These quantities (the phase advances, the Green's functions, and the coupling eigen-plane ellipses tilt angles and axis ratios) are obtained by analyzing turn-by-turn Beam Position Monitor (BPM) data with a model-independent analysis (MIA). Instead of trying to identify magnet errors, a limited number of quadrupoles are chosen for optimized strength adjustment to improve the virtual accelerator optics and then applied to the real accelerator accordingly. These processes have been successfully applied to PEP-II rings for beta beating fixes, phase and working tune adjustments, and linear coupling reduction to improve PEP-II luminosity.

SU-E-T-512: Electromagnetic Simulations of the Dielectric Wall Accelerator

Energy Technology Data Exchange (ETDEWEB)

Uselmann, A; Mackie, T [University of Wisconsin and Morgridge Institute for Research, Madison, WI (United States)

2014-06-01

Purpose: To characterize and parametrically study the key components of a dielectric wall accelerator through electromagnetic modeling and particle tracking. Methods: Electromagnetic and particle tracking simulations were performed using a commercial code (CST Microwave Studio, CST Inc.) utilizing the finite integration technique. A dielectric wall accelerator consists of a series of stacked transmission lines sequentially fired in synchrony with an ion pulse. Numerous properties of the stacked transmission lines, including geometric, material, and electronic properties, were analyzed and varied in order to assess their impact on the transverse and axial electric fields. Additionally, stacks of transmission lines were simulated in order to quantify the parasitic effect observed in closely packed lines. Particle tracking simulations using the particle-in-cell method were performed on the various stacks to determine the impact of the above properties on the resultant phase space of the ions. Results: Examination of the simulation results show that novel geometries can shape the accelerating pulse in order to reduce the energy spread and increase the average energy of accelerated ions. Parasitic effects were quantified for various geometries and found to vary with distance from the end of the transmission line and along the beam axis. An optimal arrival time of an ion pulse relative to the triggering of the transmission lines for a given geometry was determined through parametric study. Benchmark simulations of single transmission lines agree well with published experimental results. Conclusion: This work characterized the behavior of the transmission lines used in a dielectric wall accelerator and used this information to improve them in novel ways. Utilizing novel geometries, we were able to improve the accelerating gradient and phase space of the accelerated particle bunch. Through simulation, we were able to discover and optimize design issues with the device at

The Near-Earth Space Radiation Environment

Science.gov (United States)

Xapsos, Michael

2008-01-01

This viewgraph presentation reviews the effects of the Near-Earth space radiation environment on NASA missions. Included in this presentation is a review of The Earth s Trapped Radiation Environment, Solar Particle Events, Galactic Cosmic Rays and Comparison to Accelerator Facilities.

Laser accelerated protons captured and transported by a pulse power solenoid

Directory of Open Access Journals (Sweden)

T. Burris-Mog

2011-12-01

Full Text Available Using a pulse power solenoid, we demonstrate efficient capture of laser accelerated proton beams and the ability to control their large divergence angles and broad energy range. Simulations using measured data for the input parameters give inference into the phase-space and transport efficiencies of the captured proton beams. We conclude with results from a feasibility study of a pulse power compact achromatic gantry concept. Using a scaled target normal sheath acceleration spectrum, we present simulation results of the available spectrum after transport through the gantry.

Beam collimation and transport of quasineutral laser-accelerated protons by a solenoid field

International Nuclear Information System (INIS)

Harres, K.; Alber, I.; Guenther, M.; Nuernberg, F.; Otten, A.; Schuetrumpf, J.; Roth, M.; Tauschwitz, A.; Bagnoud, V.; Daido, H.; Tampo, M.; Schollmeier, M.

2010-01-01

This article reports about controlling laser-accelerated proton beams with respect to beam divergence and energy. The particles are captured by a pulsed high field solenoid with a magnetic field strength of 8.6 T directly behind a flat target foil that is irradiated by a high intensity laser pulse. Proton beams with energies around 2.3 MeV and particle numbers of 10 12 could be collimated and transported over a distance of more than 300 mm. In contrast to the protons the comoving electrons are strongly deflected by the solenoid field. They propagate at a submillimeter gyroradius around the solenoid's axis which could be experimentally verified. The originated high flux electron beam produces a high space charge resulting in a stronger focusing of the proton beam than expected by tracking results. Leadoff particle-in-cell simulations show qualitatively that this effect is caused by space charge attraction due to the comoving electrons. The collimation and transport of laser-accelerated protons is the first step to provide these unique beams for further applications such as postacceleration by conventional accelerator structures.

Accelerator X-ray sources

International Nuclear Information System (INIS)

Talman, R.

2006-01-01

This is the first monograph to cover in-depth the production of brilliant x-ray beams in accelerators, with emphasis on fourth generation designs, such as energy recovery linacs (ERL), fast cycling storage rings, and free electron lasers (FEL). Going beyond existing treatments of the influence of synchroton radiation on accelerator operation, special emphasis is placed on the design of undulator-based beam lines, and the physics of undulator radiation. Starting from the unified treatment of electron and photon beams both as bunches of particles and as waves, the author proceeds to analyse the main components, from electron gun, through linac and arc lattice, to the x-ray beam line. Designs are given for both an ERL and a more conventional storage ring complex, and their anticipated properties are compared in detail. Space charge effects are analysed with emphasis on coherent synchrotron radiation and emittance dilution. Beam diagnostics using synchrotron radiation or laser wire (Compton scattering) are also analysed in detail. Written primarily for general, particle, and radiation physicists, the systematic treatment adopted by the work makes it equally suitable as an advanced textbook for young researchers. (orig.)

Linearization of the longitudinal phase space without higher harmonic field

Directory of Open Access Journals (Sweden)

Benno Zeitler

2015-12-01

Full Text Available Accelerator applications like free-electron lasers, time-resolved electron diffraction, and advanced accelerator concepts like plasma acceleration desire bunches of ever shorter longitudinal extent. However, apart from space charge repulsion, the internal bunch structure and its development along the beam line can limit the achievable compression due to nonlinear phase space correlations. In order to improve such a limited longitudinal focus, a correction by properly linearizing the phase space is required. At large scale facilities like Flash at Desy or the European Xfel, a higher harmonic cavity is installed for this purpose. In this paper, another method is described and evaluated: Expanding the beam after the electron source enables a higher order correction of the longitudinal focus by a subsequent accelerating cavity which is operated at the same frequency as the electron gun. The elaboration of this idea presented here is based on a ballistic bunching scheme, but can be extended to bunch compression based on magnetic chicanes. The core of this article is an analytic model describing this approach, which is verified by simulations, predicting possible bunch length below 1 fs at low bunch charge. Minimizing the energy spread down to σ_{E}/E<10^{-5} while keeping the bunch long is another interesting possibility, which finds applications, e.g., in time resolved transmission electron microscopy concepts.

Grounding and shielding in the accelerator environment

International Nuclear Information System (INIS)

Kerns, Q.

1991-01-01

Everyday features of the accelerator environment include long cable runs, high power and low level equipment sharing building space, stray electromagnetic fields and ground voltage differences between the sending and receiving ends of an installation. This paper pictures some Fermilab installations chosen to highlight significant features and presents practices, test methods and equipment that have been helpful in achieving successful shielding. Throughout the report are numbered statements aimed at summarizing good practices and avoiding pitfalls