Plans for longitudinal and transverse neutralized beam compression experiments, and initial results from solenoid transport experiments

International Nuclear Information System (INIS)

Seidl, P.A.; Armijo, J.; Baca, D.; Bieniosek, F.M.; Coleman, J.; Davidson, R.C.; Efthimion, P.C.; Friedman, A.; Gilson, E.P.; Grote, D.; Haber, I.; Henestroza, E.; Kaganovich, I.; Leitner, M.; Logan, B.G.; Molvik, A.W.; Rose, D.V.; Roy, P.K.; Sefkow, A.B.; Sharp, W.M.; Vay, J.L.; Waldron, W.L.; Welch, D.R.; Yu, S.S.

2007-01-01

This paper presents plans for neutralized drift compression experiments, precursors to future target heating experiments. The target-physics objective is to study warm dense matter (WDM) using short-duration (∼1 ns) ion beams that enter the targets at energies just above that at which dE/dx is maximal. High intensity on target is to be achieved by a combination of longitudinal compression and transverse focusing. This work will build upon recent success in longitudinal compression, where the ion beam was compressed lengthwise by a factor of more than 50 by first applying a linear head-to-tail velocity tilt to the beam, and then allowing the beam to drift through a dense, neutralizing background plasma. Studies on a novel pulse line ion accelerator were also carried out. It is planned to demonstrate simultaneous transverse focusing and longitudinal compression in a series of future experiments, thereby achieving conditions suitable for future WDM target experiments. Future experiments may use solenoids for transverse focusing of un-neutralized ion beams during acceleration. Recent results are reported in the transport of a high-perveance heavy ion beam in a solenoid transport channel. The principal objectives of this solenoid transport experiment are to match and transport a space-charge-dominated ion beam, and to study associated electron-cloud and gas effects that may limit the beam quality in a solenoid transport system. Ideally, the beam will establish a Brillouin-flow condition (rotation at one-half the cyclotron frequency). Other mechanisms that potentially degrade beam quality are being studied, such as focusing-field aberrations, beam halo, and separation of lattice focusing elements

Neutralized Drift Compression Experiment (NDCX) - II Quarterly Report

International Nuclear Information System (INIS)

Kwan, J.W.

2009-01-01

LBNL has received American Recovery and Reinvestment Act (ARRA) funding to construct a new accelerator at Lawrence Berkeley National Laboratory (LBNL) to significantly increase the energy on target, which will allow both the Heavy Ion Fusion (HIF) and Warm Dense Matter (WDM) research communities to explore scientific conditions that have not been available in any other device. For NDCX-II, a new induction linear accelerator (linac) will be constructed at Lawrence Berkeley National Laboratory (LBNL). NDCX-II will produce nano-second long ion beam bunches to hit thin foil targets. The final kinetic energy of the ions arriving at the target varies according to the ion mass. For atomic mass unit of 6 or 7 (Lithium ions), useful kinetic energies range from 1.5 to 5 or more MeV. The expected beam charge in the 1 ns (or shorter) pulse is about 20 nanoCoulombs. The pulse repetition rate will be about once or twice per minute (of course, target considerations will often reduce this rate). Our approach to building the NDCX-II ion accelerator is to make use of the available induction modules and 200 kV pulsers from the retired ATA electron linac at LLNL. Reusing this hardware will maximize the ion energy on target at a minimum cost. Some modification of the cells (e.g., reduce the bore diameter and replace with higher field pulsed solenoids) are needed in order to meet the requirements of this project. The NDCX-II project will include the following tasks: (1) Physics design to determine the required ion current density at the ion source, the injector beam optics, the layout of accelerator cells along the beam line, the voltage waveforms for beam acceleration and compression, the solenoid focusing, the neutralized drift compression and the final focus on target; (2) Engineering design and fabrication of the accelerator components, pulsed power system, diagnostic system, and control and data acquisition system; (3) Conventional facilities; and (4) Installation and integration

On stationary states of electron beams in drift space

International Nuclear Information System (INIS)

Kovalev, N.F.

2002-01-01

The article is devoted to studying the conditions of formation and existence of virtual cathodes. The problem on stationary states of the strongly magnetized electron beams in the homogeneous drift channels is discussed. The problem on the planar and coaxial moduli of the drift spaces is considered. The possibility of existing the virtual cathodes in the coaxial tubular beams by the injection currents, smaller than the threshold ones is highly proved. The inaccuracy of results of a number of works, studying the properties of the virtual cathodes in the strongly magnetized electron beams, is shown [ru

Beam test of a large area silicon drift detector

International Nuclear Information System (INIS)

Castoldi, A.; Chinnici, S.; Gatti, E.; Longoni, A.; Palma, F.; Sampietro, M.; Rehak, P.; Ballocchi, G.; Kemmer, J.; Holl, P.; Cox, P.T.; Giacomelli, P.; Vacchi, A.

1992-01-01

The results from the tests of the first large area (4 x 4 cm 2 ) planar silicon drift detector prototype in a pion beam are reported. The measured position resolution in the drift direction is (σ=40 ± 10)μm

The Single Pass RF Driver: Final beam compression

Energy Technology Data Exchange (ETDEWEB)

Burke, Robert, E-mail: rjburke@fusionpowercorporation.com

2014-01-01

The Single Pass RF Driver (SPRFD) compacts the beam from the linac without storage rings by manipulations that take advantage of the multiplicity of isotopes (16), the preserved µbunch structure, and increased total linac current. Magnetic switches on a first set of delay lines rearrange the internal structure of the various isotopic beams. A second set of delay lines sets the relative timing of the 16 isotopic beam sections so they will telescope at the pellet, in one of multiple fusion chambers, e.g. 10. Shortening each isotopic beam section uses preservation of the µbunch structure up to the final ∼2 km drift before final focus. Just before the final drift, differential acceleration of the µbunches in each isotopic beam section (128 total) launches an axial collapse, referred to as the “Slick”. The µbunches interpenetrate as their centers of mass move toward each other and individual µbunches lengthen due to their momentum spread. In longitudinal phase space they slide over one another as they lengthen in time and slim down in instantaneous energy spread. The permissible amount of µbunch lengthening is set by the design pulse shape at the pellet, which varies for different groups of isotopes. In narrow bands of ranges according to the role for each isotope group in the pellet, the ranges extend from 1 to 10 g/cm{sup 2} to drive the cylinder barrel and thin hemispherical end caps, to heat the ∼0.5 g/cm{sup 2}ρR fast ignition zone, and to improve the quasi-sphericity of the compression of the fast ignition zones at the pellet's ends. Because the µbunch–µbunch momentum differences are correlated, time-ramped beamline transport elements close after the differential accelerator are used to correct the associated shifts of focal point. Beam neutralization is needed after the differential acceleration until adjacent bunches begin to overlap. Concurrent collapse of each isotope and telescoping of the 16 isotopes cause the current in each beamline

The Single Pass RF Driver: Final beam compression

International Nuclear Information System (INIS)

Burke, Robert

2014-01-01

The Single Pass RF Driver (SPRFD) compacts the beam from the linac without storage rings by manipulations that take advantage of the multiplicity of isotopes (16), the preserved µbunch structure, and increased total linac current. Magnetic switches on a first set of delay lines rearrange the internal structure of the various isotopic beams. A second set of delay lines sets the relative timing of the 16 isotopic beam sections so they will telescope at the pellet, in one of multiple fusion chambers, e.g. 10. Shortening each isotopic beam section uses preservation of the µbunch structure up to the final ∼2 km drift before final focus. Just before the final drift, differential acceleration of the µbunches in each isotopic beam section (128 total) launches an axial collapse, referred to as the “Slick”. The µbunches interpenetrate as their centers of mass move toward each other and individual µbunches lengthen due to their momentum spread. In longitudinal phase space they slide over one another as they lengthen in time and slim down in instantaneous energy spread. The permissible amount of µbunch lengthening is set by the design pulse shape at the pellet, which varies for different groups of isotopes. In narrow bands of ranges according to the role for each isotope group in the pellet, the ranges extend from 1 to 10 g/cm 2 to drive the cylinder barrel and thin hemispherical end caps, to heat the ∼0.5 g/cm 2 ρR fast ignition zone, and to improve the quasi-sphericity of the compression of the fast ignition zones at the pellet's ends. Because the µbunch–µbunch momentum differences are correlated, time-ramped beamline transport elements close after the differential accelerator are used to correct the associated shifts of focal point. Beam neutralization is needed after the differential acceleration until adjacent bunches begin to overlap. Concurrent collapse of each isotope and telescoping of the 16 isotopes cause the current in each beamline to rise

Li+ alumino-silicate ion source development for the Neutralized Drift Compression Experiment (NDCX)

Energy Technology Data Exchange (ETDEWEB)

Roy, Prabir K.; Greenway, Wayne G.; Kwan, Joe W.; Seidl, Peter A.; Waldron, William L.; Wu, James K.

2010-10-01

We report results on lithium alumino-silicate ion source development in preparation for warmdense-matter heating experiments on the new Neutralized Drift Compression Experiment (NDCXII). The practical limit to the current density for a lithium alumino-silicate source is determined by the maximum operating temperature that the ion source can withstand before running into problems of heat transfer, melting of the alumino-silicate material, and emission lifetime. Using small prototype emitters, at a temperature of ~;;1275 oC, a space-charge-limited Li+ beam current density of J ~;;1 mA/cm2 was obtained. The lifetime of the ion source was ~;;50 hours while pulsing at a rate of 0.033 Hz with a pulse duration of 5-6 mu s.

Li+ alumino-silicate ion source development for the Neutralized Drift Compression Experiment (NDCX)

International Nuclear Information System (INIS)

Roy, Prabir K.; Greenway, Wayne G.; Kwan, Joe W.; Seidl, Peter A.; Waldron, William L.; Wu, James K.

2010-01-01

We report results on lithium alumino-silicate ion source development in preparation for warm-dense-matter heating experiments on the new Neutralized Drift Compression Experiment (NDCX-II). The practical limit to the current density for a lithium alumino-silicate source is determined by the maximum operating temperature that the ion source can withstand before running into problems of heat transfer, melting of the alumino-silicate material, and emission lifetime. Using small prototype emitters, at a temperature of ∼1275 C, a space-charge-limited Li + beam current density of J ∼1 mA/cm 2 was obtained. The lifetime of the ion source was ∼50 hours while pulsing at a rate of 0.033 Hz with a pulse duration of 5-6 (micro) s.

Compressed beam directed particle nuclear energy generator

International Nuclear Information System (INIS)

Salisbury, W.W.

1985-01-01

This invention relates to the generation of energy from the fusion of atomic nuclei which are caused to travel towards each other along collision courses, orbiting in common paths having common axes and equal radii. High velocity fusible ion beams are directed along head-on circumferential collision paths in an annular zone wherein beam compression by electrostatic focusing greatly enhances head-on fusion-producing collisions. In one embodiment, a steady radial electric field is imposed on the beams to compress the beams and reduce the radius of the spiral paths for enhancing the particle density. Beam compression is achieved through electrostatic focusing to establish and maintain two opposing beams in a reaction zone

Optimized simultaneous transverse and longitudinal focusing of intense ion beam pulses for warm dense matter applications

International Nuclear Information System (INIS)

Sefkow, Adam B.; Davidson, Ronald C.; Kaganovich, Igor D.; Gilson, Erik P.; Roy, Prabir K.; Seidl, Peter A.; Yu, Simon S.; Welch, Dale R.; Rose, David V.; Barnard, John J.

2007-01-01

Intense, space-charge-dominated ion beam pulses for warm dense matter and heavy ion fusion applications must undergo simultaneous transverse and longitudinal bunch compression in order to meet the requisite beam intensities desired at the target. The longitudinal compression of an ion bunch is achieved by imposing an initial axial velocity tilt on the drifting beam and subsequently neutralizing its space-charge and current in a drift region filled with high-density plasma. The Neutralized Drift Compression Experiment (NDCX) at Lawrence Berkeley National Laboratory has measured a sixty-fold longitudinal current compression of an intense ion beam with pulse duration of a few nanoseconds, in agreement with simulations and theory. A strong solenoid is modeled near the end of the drift region in order to transversely focus the beam to a sub-millimeter spot size coincident with the longitudinal focal plane. The charge and current neutralization provided by the background plasma is critical in determining the total achievable transverse and longitudinal compression of the beam pulse. Numerical simulations show that the current density of an NDCX ion beam can be compressed over a few meters by factors greater than 10 5 with peak beam density in excess of 10 14 cm -3 . The peak beam density sets a lower bound on the local plasma density required near the focal plane for optimal beam compression, since the simulations show stagnation of the compression when n beam >n plasma . Beam-plasma interactions can also have a deleterious effect on the compression physics and lead to the formation of nonlinear wave excitations in the plasma. Simulations that optimize designs for the simultaneous transverse and longitudinal focusing of an NDCX ion beam for future warm dense matter experiments are discussed

Image compression for the silicon drift detectors in the ALICE experiment

International Nuclear Information System (INIS)

Werbrouck, A.; Tosello, F.; Rivetti, A.; Mazza, G.; De Remigis, P.; Cavagnino, D.; Alberici, G.

2001-01-01

We describe an algorithm for the zero suppression and data compression for the Silicon Drift Detectors (SDD) in the ALICE experiment. The algorithm operates on 10-bit linear data streams from the SDDs by applying a 10 bit to 8-bit non-linear compression followed by a data reduction based on a two-threshold discrimination and a two-dimensional analysis along both the drift time and the anodes. The proposed scheme allows for a better understanding of the neighborhoods of the SDD signal clusters, thus improving their reconstructability, and also provides a statistical monitoring of the background characteristics for each SDD anode. The entire algorithm is purely combinatorial and thus can be executed in pipeline, without additional clock cycles, during the SDD readout. The hardware coding together with the methods for the expansion to the original 10-bit values in the offline analysis and for the background monitoring are presented

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.)

Dynamics of heavy ion beams during longitudinal compression

International Nuclear Information System (INIS)

Ho, D.D.M.; Bangerter, R.O.; Lee, E.P.; Brandon, S.; Mark, J.W.K.

1987-01-01

Heavy ion beams with initially uniform line charge density can be compressed longitudinally by an order of magnitude in such a way that the compressed beam has uniform line charge density and velocity-tilt profiles. There are no envelope mismatch oscillations during compression. Although the transverse temperature varies along the beam and also varies with time, no substantial longitudinal and transverse emittance growth has been observed. Scaling laws for beam radius and transport system parameters are given

SU-F-T-279: Impact of Beam Energy Drifts On IMRT Delivery Accuracy

International Nuclear Information System (INIS)

Goddu, S; Kamal, G; Herman, A; Edwards, S; Cai, B; Yaddanapudi, S; Oddiraju, S; Rangaraj, D; Mutic, S

2016-01-01

Purpose: According to TG-40 percent-depth-dose (PDD) tolerance is ±2% but TG-142 is ±1%. Now the question is, which one is relevant in IMRT era? The primary objective of this study is to evaluate dosimetric impact of beam-energy-drifts on IMRT-delivery. Methods: Beam-energy drifts were simulated by adjusting Linac’s bending-magnet-current (BMC) followed by tuning the pulse-forming network and adjusting gun-current. PDD change of −0.6% and +1.2% were tested. Planar-dosimetry measurements were performed using an ionization-chamber-array in solid-water phantoms. Study includes 10-head-and-neck and 3-breast cancer patients. en-face beam-deliveries were also tested at 1.3cm and 5.3cm depths. Composite and single-field dose-distributions were compared against the plans to determine %Gamma pass-rates (%GPRs). For plan dose comparisons, changes in %Gamma pass-rates (cPGPRs) were computed/reported to exclude the differences between dose-computation and delivery. Dose distributions of the drifted-energies were compared against their baseline measurements to determine the% GPRs. A Gamma criteria of 3%/3mm was considered for plan-dose comparisons while 3%/1mm used for measured dose intercomparisons. Results: For composite-dose delivery, average cPGPRs were 0.41%±2.48% and −2.54%±3.65% for low-energy (LE) and high-energy (HE) drifts, respectively. For measured dose inter-comparisons, the average%GPRs were 98.4%±2.2% (LE-drift) and 95.8%±4.0 (HE-drift). The average %GPR of 92.6%±4.3% was noted for the worst-case scenario comparing LE-drift to HE-drift. All en-face beams at 5.3 cm depth have cPGPRs within ±4% of the baseline-energy measurements. However, greater variations were noted for 1.3cm depth. Average %GPRs for drifted energies were >99% at 5.3cm and >97% at 1.3cm depths. However, for the worst-case scenario (LE-drift to HE-drift) these numbers dropped to 95.2% at 5.3cm and 93.1% at 1.3cm depths. Conclusion: The dosimetric impact of beam-energy drifts was

Free-beam soliton self-compression in air

Science.gov (United States)

Voronin, A. A.; Mitrofanov, A. V.; Sidorov-Biryukov, D. A.; Fedotov, A. B.; Pugžlys, A.; Panchenko, V. Ya; Shumakova, V.; Ališauskas, S.; Baltuška, A.; Zheltikov, A. M.

2018-02-01

We identify a physical scenario whereby soliton transients generated in freely propagating laser beams within the regions of anomalous dispersion in air can be compressed as a part of their free-beam spatiotemporal evolution to yield few-cycle mid- and long-wavelength-infrared field waveforms, whose peak power is substantially higher than the peak power of the input pulses. We show that this free-beam soliton self-compression scenario does not require ionization or laser-induced filamentation, enabling high-throughput self-compression of mid- and long-wavelength-infrared laser pulses within a broad range of peak powers from tens of gigawatts up to the terawatt level. We also demonstrate that this method of pulse compression can be extended to long-range propagation, providing self-compression of high-peak-power laser pulses in atmospheric air within propagation ranges as long as hundreds of meters, suggesting new ways towards longer-range standoff detection and remote sensing.

Long plasma source for heavy ion beam charge neutralization

International Nuclear Information System (INIS)

Efthimion, Philip C.; Gilson, Erik P.; Grisham, Larry; Davidson, Ronald C.; Grant Logan, Larry B.; Seidl, Peter A.; Waldron, William

2009-01-01

Plasmas are a source of unbound electrons for charge neutralizing intense heavy ion beams to focus them to a small spot size and compress their axial length. The plasma source should operate at low neutral pressures and without strong externally applied fields. To produce long plasma columns, sources based upon ferroelectric ceramics with large dielectric coefficients have been developed. The source utilizes the ferroelectric ceramic BaTiO 3 to form metal plasma. The drift tube inner surface of the Neutralized Drift Compression Experiment (NDCX) is covered with ceramic material. High voltage (∼8 kV) is applied between the drift tube and the front surface of the ceramics. A BaTiO 3 source comprised of five 20-cm-long sources has been tested and characterized, producing relatively uniform plasma in the 5x10 10 cm -3 density range. The source was integrated into the NDCX device for charge neutralization and beam compression experiments, and yielded current compression ratios ∼120. Present research is developing multi-meter-long and higher density sources to support beam compression experiments for high-energy-density physics applications.

Resolution and drift measurements on the Advanced Photon Source beam position monitors

International Nuclear Information System (INIS)

Chung, Y.; Kahana, E.

1994-01-01

The resolution and long-term drift of the Advanced Photon Source (APS) beam position monitor (BPM) electronics were measured using the charged particle beams in the ESRF storage ring with various beam current and configurations (single bunch, 8 and 16 equally spaced bunches, and 1/3-fill). The energy of the stored electrons was 6 GeV. The integrated BPM electronics system as used for this work is capable of measuring the beam position on a turn-by-turn basis, which can be accumulated for N turns (N = 2 n , n = 1, 2, ... , 11). Estimation of the BPM resolution apart from the low-frequency beam motion was made by measuring the standard deviation in the measured beam position with different Ns. The analysis of the results indicates a BPM resolution of 18/√ N [μm] for the APS storage ring, which is equivalent to 0.07 μm/√Hz. For the miniature insertion device BPM with 2.8 times higher sensitivity, the resolution will be 0.02 μm/√Hz. The long-term drift of the BPM electronics independent of the actual beam motion was measured at 2 μm/hr, which settled after approximately 1.5 hours. This drift can be attributed mainly to the temperature effect. Comparison of the results with the laboratory measurements shows good agreement. Implication of the BPM resolution limit on the proposed global and local beam position feedback systems for the APS storage ring will also be discussed

Neutral-beam requirements for compression-boosted ignited tokamak plasmas

International Nuclear Information System (INIS)

Cohn, D.R.; Jassby, D.L.; Kreischer, K.

1977-12-01

Neutral-beam energies of 200 to 500-keV D 0 may be required to insure adequate penetration into the center of ignition-sized tokamak plasmas. However, the beam energy requirement can be reduced by using a start-up scenario in which the final plasma is formed by major-radius compression of a beam-heated plasma whose density-radius product, na, is determined by satisfactory neutral-beam penetration. ''Compression boosting'' is attractive only for plasmas in which ntau/sub E/ increases with na, because a major-radius compression C increases na by C 3 / 2 . The dependence on C of beam energy and beam power for plasmas which obey ''empirical scaling laws'' of the type ntau/sub E/ varies as (na) 2 is analyzed. The dependences on C of stored magnetic energy and TF-coil power dissipation are also determined. It is found that a compression ratio of 1.5 to attain the ignited plasma permits adequate penetration by 150-keV D 0 beams

Approaching maximal performance of longitudinal beam compression in induction accelerator drivers

International Nuclear Information System (INIS)

Mark, J.W.K.; Ho, D.D.M.; Brandon, S.T.; Chang, C.L.; Drobot, A.T.; Faltens, A.; Lee, E.P.; Krafft, G.A.

1986-01-01

Longitudinal beam compression occurs before final focus and fusion chamber beam transport and is a key process determining initial conditions for final focus hardware. Determining the limits for maximal performance of key accelerator components is an essential element of the effort to reduce driver costs. Studies directed towards defining the limits of final beam compression including considerations such as maximal available compression, effects of longitudinal dispersion and beam emittance, combining pulse-shaping with beam compression to reduce the total number of beam manipulators, etc., are given. Several possible techniques are illustrated for utilizing the beam compression process to provide the pulse shapes required by a number of targets. Without such capabilities to shape the pulse, an additional factor of two or so of beam energy would be required by the targets

Resolution and drift measurements on the advanced photon source beam position monitor

International Nuclear Information System (INIS)

Chung, Y.; Kahana, E.

1995-01-01

The resolution and long-term drift of the Advanced Photon Source (APS) beam position monitor (BPM) electronics were measured using the charged particle beams in the ESRF storage ring with various beam current and configurations (single bunch, 8 and 16 equally spaced bunches, and 1/3-fill). The energy of the stored electrons was 6 GeV. The integrated BPM electronics system as used for this work is capable of measuring the beam position on a turn-by-turn basis, which can be accumulated for N turns (N=2 n , n=1,2,...,11) . Estimation of the BPM resolution apart from the low-frequency beam motion was made by measuring the standard deviation in the measured beam position with different Ns. The analysis of the results indicates a BPM resolution of 18/√N [μm] for the APS storage ring, which is equivalent to 0.07 μm/√Hz. For the miniature insertion device BPM with 2.8 times higher sensitivity, the resolution will be 0.02 μm/√Hz. The long-term drift of the BPM electronics independent of the actual beam motion was measured at 2 μm/hr, which settled after approximately 1.5 hours. This drift can be attributed mainly to the temperature effect. Comparison of the results with the laboratory measurements shows good agreement. Implication of the BPM resolution limit on the proposed global and local beam position feedback systems for the APS storage ring will also be discussed. copyright 1995 American Institute of Physics

Approaching maximal performance of longitudinal beam compression in induction accelerator drivers

International Nuclear Information System (INIS)

Mark, J.W.K.; Ho, D.D.M.; Brandon, S.T.; Chang, C.L.; Drobot, A.T.; Faltens, A.; Lee, E.P.; Krafft, G.A.

1986-01-01

Longitudinal beam compression is an integral part of the US induction accelerator development effort for heavy ion fusion. Producing maximal performance for key accelerator components is an essential element of the effort to reduce driver costs. We outline here initial studies directed towards defining the limits of final beam compression including considerations such as: maximal available compression, effects of longitudinal dispersion and beam emittance, combining pulse-shaping with beam compression to reduce the total number of beam manipulations, etc. The use of higher ion charge state Z greater than or equal to 3 is likely to test the limits of the previously envisaged beam compression and final focus hardware. A more conservative approach is to use additional beamlets in final compression and focus. On the other end of the spectrum of choices, alternate approaches might consider new final focus with greater tolerances for systematic momentum and current variations. Development of such final focus concepts would also allow more compact (and hopefully cheaper) hardware packages where the previously separate processes of beam compression, pulse-shaping and final focus occur as partially combined and nearly concurrent beam manipulations

'Electron compression' of beam-beam footprint in the Tevatron

International Nuclear Information System (INIS)

Shiltsev, V.; Finley, D.A.

1997-08-01

The beam-beam interaction in the Tevatron collider sets some limits on bunch intensity and luminosity. These limits are caused by a tune spread in each bunch which is mostly due to head-on collisions, but there is also a bunch-to-bunch tune spread due to parasitic collisions in multibunch operation. We describe a counter-traveling electron beam which can be used to eliminate these effects, and present general considerations and physics limitations of such a device which provides 'electron compression' of the beam-beam footprint in the Tevatron

Estimates of post-acceleration longitudinal bunch compression

International Nuclear Information System (INIS)

Judd, D.L.

1977-01-01

A simple analytic method is developed, based on physical approximations, for treating transient implosive longitudinal compression of bunches of heavy ions in an accelerator system for ignition of inertial-confinement fusion pellet targets. Parametric dependences of attainable compressions and of beam path lengths and times during compression are indicated for ramped pulsed-gap lines, rf systems in storage and accumulator rings, and composite systems, including sections of free drift. It appears that for high-confidence pellets in a plant producing 1000 MW of electric power the needed pulse lengths cannot be obtained with rings alone unless an unreasonably large number of them are used, independent of choice of rf harmonic number. In contrast, pulsed-gap lines alone can meet this need. The effects of an initial inward compressive drift and of longitudinal emittance are included

Electron beam acceleration and compression for short wavelength FELs

International Nuclear Information System (INIS)

Raubenheimer, T.O.

1994-11-01

A single pass UV or X-ray FEL will require a low emittance electron beam with high peak current and relatively high beam energy, a few hundred MeV to many GeV. To achieve the necessary peak current and beam energy, the beams must be bunch compressed and they must be accelerated in long transport lines where dispersive and wakefield emittance dilutions are important. In this paper, we will describe the sources and significance of the dilutions during acceleration, bunch compression, and transport through the undulator. In addition, we will discuss sources of jitter, especially effects arising from the bunch compressions, and the possible cancellation techniques

Coulomb-Driven Relativistic Electron Beam Compression.

Science.gov (United States)

Lu, Chao; Jiang, Tao; Liu, Shengguang; Wang, Rui; Zhao, Lingrong; Zhu, Pengfei; Xiang, Dao; Zhang, Jie

2018-01-26

Coulomb interaction between charged particles is a well-known phenomenon in many areas of research. In general, the Coulomb repulsion force broadens the pulse width of an electron bunch and limits the temporal resolution of many scientific facilities such as ultrafast electron diffraction and x-ray free-electron lasers. Here we demonstrate a scheme that actually makes use of the Coulomb force to compress a relativistic electron beam. Furthermore, we show that the Coulomb-driven bunch compression process does not introduce additional timing jitter, which is in sharp contrast to the conventional radio-frequency buncher technique. Our work not only leads to enhanced temporal resolution in electron-beam-based ultrafast instruments that may provide new opportunities in probing material systems far from equilibrium, but also opens a promising direction for advanced beam manipulation through self-field interactions.

Coulomb-Driven Relativistic Electron Beam Compression

Science.gov (United States)

Lu, Chao; Jiang, Tao; Liu, Shengguang; Wang, Rui; Zhao, Lingrong; Zhu, Pengfei; Xiang, Dao; Zhang, Jie

2018-01-01

Coulomb interaction between charged particles is a well-known phenomenon in many areas of research. In general, the Coulomb repulsion force broadens the pulse width of an electron bunch and limits the temporal resolution of many scientific facilities such as ultrafast electron diffraction and x-ray free-electron lasers. Here we demonstrate a scheme that actually makes use of the Coulomb force to compress a relativistic electron beam. Furthermore, we show that the Coulomb-driven bunch compression process does not introduce additional timing jitter, which is in sharp contrast to the conventional radio-frequency buncher technique. Our work not only leads to enhanced temporal resolution in electron-beam-based ultrafast instruments that may provide new opportunities in probing material systems far from equilibrium, but also opens a promising direction for advanced beam manipulation through self-field interactions.

Evaluation of a wavelet-based compression algorithm applied to the silicon drift detectors data of the ALICE experiment at CERN

International Nuclear Information System (INIS)

Falchieri, Davide; Gandolfi, Enzo; Masotti, Matteo

2004-01-01

This paper evaluates the performances of a wavelet-based compression algorithm applied to the data produced by the silicon drift detectors of the ALICE experiment at CERN. This compression algorithm is a general purpose lossy technique, in other words, its application could prove useful even on a wide range of other data reduction's problems. In particular the design targets relevant for our wavelet-based compression algorithm are the following ones: a high-compression coefficient, a reconstruction error as small as possible and a very limited execution time. Interestingly, the results obtained are quite close to the ones achieved by the algorithm implemented in the first prototype of the chip CARLOS, the chip that will be used in the silicon drift detectors readout chain

Longitudinal beam compression for heavy-ion inertial fusion

International Nuclear Information System (INIS)

Ho, D.D.M.; Brandon, S.T.

1991-01-01

A scheme is described for compressing a heavy-ion beam longitudinally in such a way that the compressed pulse has uniform line-charge density and longitudinal momentum. Attaining these conditions will be important in the final focusing of a beam on a small fuel capsule in an inertial confinement fusion reactor. The longitudinal dynamics can be approximately described by a one-dimensional (1-D) fluid model for charged particles. Recognizing the similarity between the 1-D charged particle equations of motion and the 1-D equations for ideal-gas flow permits us to calculate the evolution of the line-charge density and velocity profile using self-similar solutions and the method of characteristics, developed for unsteady supersonic gas dynamics, for different regions along the beam. Simple physical arguments show that although the longitudinal and transverse temperatures vary along the beam following the adiabatic laws, no substantial longitudinal and transverse emittance growth is to be expected. Particle-in-cell simulations confirm all the physical arguments. The compressed beam has negligible longitudinal momentum spread and can therefore avoid chromatic aberrations in final focus. (author) 24 refs., 5 figs., 1 tab

Test beam results of Silicon Drift Detector prototypes for the ALICE experiment

Energy Technology Data Exchange (ETDEWEB)

Nouais, D.; Bonvicini, V.; Busso, L.; Cerello, P.; Giubellino, P.; Gregorio, A.; Hernandez-Montoya, R.; Idzik, M.; Kolojvari, A.; Mazza, G.; Montano, L. M.; Nilsen, B.S.; Petta, C.; Randazzo, N.; Rashevsky, A.; Reito, S.; Rivetti, A.; Tosello, F.; Trzaska, W.H.; Vacchi, A

1999-08-01

We report preliminary beam test results of linear Silicon Drift Detector prototypes for the ALICE experiment. Linearity, resolution, charge transport and collection, and efficiency have been studied using a minimum ionizing particle beam for a very large area detector prototype read out with the OLA preamplifier/shaper and for another detector read out using a new transimpedance amplifier with a non linear response.

Test beam results of silicon drift detector prototypes for the ALICE experiment

CERN Document Server

Nouais, D; Busso, L; Cerello, P G; Giubellino, P; Gregorio, A; Hernández-Montoya, R; Idzik, M; Kolojvari, A A; Mazza, G; Montaño-Zetina, L M; Nilsson, B S; Petta, C; Randazzo, N; Rashevsky, A; Reito, S; Rivetti, A; Tosello, F; Trzaska, W H; Vacchi, A

1999-01-01

We report preliminary beam test results of linear silicon drift detector prototypes for the ALICE experiment. Linearity, resolution, charge transport and collection, and efficiency have been studied using a minimum ionizing particle beam for a very large area detector prototype read out with the OLA preamplifier/shaper and for another detector read out using a new transimpedance amplifier with a nonlinear response. (14 refs).

Use beam steering dipoles to minimize aberrations associated with off-centered transit through the induction bunching module. Design an improved NDCX-I drift compression section to make best use of the new bunching module to optimize planned initial NDCX-I target experiments

International Nuclear Information System (INIS)

HIFS-VNL; Seidl, Peter; Seidl, P.; Barnard, J.; Bieniosek, F.; Coleman, J.; Grote, D.; Leitner, M.; Gilson, E.; Logan, B.G.; Lund, S.; Lidia, S.; Ni, P.; Ogata, D.; Roy, P.; Waldron, W.; Welch, D.; Wooton, C.

2008-01-01

This milestone has been met by: (1) calculating steering solutions and implementing them in the experiment using the three pairs of crossed magnetic dipoles installed in between the matching solenoids, S1-S4. We have demonstrated the ability to center the beam position and angle to < 1 mm and < 1 mrad upstream of the induction bunching module (IBM) gap, compared to uncorrected beam offsets of several millimeters and milli-radians. (2) Based on LSP and analytic study, the new IBM, which has twice the volt-seconds of our first IBM, should be accompanied by a longer drift compression section in order to achieve a predicted doubling of the energy deposition on future warm-dense matter targets. This will be accomplished by constructing a longer ferro-electric plasma source. (3) Because the bunched current is a function of the longitudinal phase space and emittance of the beam entering the IBM we have characterized the longitudinal phase space with a high-resolution energy analyzer

Beam collimation and energy spectrum compression of laser-accelerated proton beams using solenoid field and RF cavity

Energy Technology Data Exchange (ETDEWEB)

Teng, J.; Gu, Y.Q., E-mail: tengjian@mail.ustc.edu.cn; Zhu, B.; Hong, W.; Zhao, Z.Q.; Zhou, W.M.; Cao, L.F.

2013-11-21

This paper presents a new method of laser produced proton beam collimation and spectrum compression using a combination of a solenoid field and a RF cavity. The solenoid collects laser-driven protons efficiently within an angle that is smaller than 12 degrees because it is mounted few millimeters from the target, and collimates protons with energies around 2.3 MeV. The collimated proton beam then passes through a RF cavity to allow compression of the spectrum. Particle-in-cell (PIC) simulations demonstrate the proton beam transport in the solenoid and RF electric fields. Excellent energy compression and collection efficiency of protons are presented. This method for proton beam optimization is suitable for high repetition-rate laser acceleration proton beams, which could be used as an injector for a conventional proton accelerator.

Beam collimation and energy spectrum compression of laser-accelerated proton beams using solenoid field and RF cavity

Science.gov (United States)

Teng, J.; Gu, Y. Q.; Zhu, B.; Hong, W.; Zhao, Z. Q.; Zhou, W. M.; Cao, L. F.

2013-11-01

This paper presents a new method of laser produced proton beam collimation and spectrum compression using a combination of a solenoid field and a RF cavity. The solenoid collects laser-driven protons efficiently within an angle that is smaller than 12 degrees because it is mounted few millimeters from the target, and collimates protons with energies around 2.3 MeV. The collimated proton beam then passes through a RF cavity to allow compression of the spectrum. Particle-in-cell (PIC) simulations demonstrate the proton beam transport in the solenoid and RF electric fields. Excellent energy compression and collection efficiency of protons are presented. This method for proton beam optimization is suitable for high repetition-rate laser acceleration proton beams, which could be used as an injector for a conventional proton accelerator.

Beam collimation and energy spectrum compression of laser-accelerated proton beams using solenoid field and RF cavity

International Nuclear Information System (INIS)

Teng, J.; Gu, Y.Q.; Zhu, B.; Hong, W.; Zhao, Z.Q.; Zhou, W.M.; Cao, L.F.

2013-01-01

This paper presents a new method of laser produced proton beam collimation and spectrum compression using a combination of a solenoid field and a RF cavity. The solenoid collects laser-driven protons efficiently within an angle that is smaller than 12 degrees because it is mounted few millimeters from the target, and collimates protons with energies around 2.3 MeV. The collimated proton beam then passes through a RF cavity to allow compression of the spectrum. Particle-in-cell (PIC) simulations demonstrate the proton beam transport in the solenoid and RF electric fields. Excellent energy compression and collection efficiency of protons are presented. This method for proton beam optimization is suitable for high repetition-rate laser acceleration proton beams, which could be used as an injector for a conventional proton accelerator

Beam Aborts in PEP-II Rings and Lingering Drift Chamber Currents

International Nuclear Information System (INIS)

Meshkat, N.

2004-01-01

The BABAR detector at SLAC was designed to study CP-violation in B-meson decays from electron-positron collisions in the PEP-II electron-positron storage rings. Background radiation in the High Energy Ring (HER) and Low Energy Ring (LER) of PEP-II has the potential to damage the sensitive equipment in the BABAR detector. As a result, the beams in the HER and LER can be aborted to prevent such damage. In the span of a few microseconds, the HER and LER currents drop from, for example, 1450 micro Amps and 2300 micro Amps, respectively, to zero. At this time the voltage in the Drift Chamber is rapidly ramped down from a potential of 1930 V to a safe potential of 800 V, thus we would expect the currents in the Drift Chamber to quickly go to zero once the beams are aborted. However, we observe an average 15 second delay in the measured time it takes for all current in the Drift Chamber to fall below 1 micro Amp. This delay has been hypothesized as an instrumentation issue and not as a physical phenomenon. The specific sources of this error are still not completely known, but analysis suggests that it results from the interplay of the CAEN High Voltage supplies and the EPICS system and/or limitations within those systems

Enhanced collective focusing of intense neutralized ion beam pulses in the presence of weak solenoidal magnetic fields

International Nuclear Information System (INIS)

Dorf, Mikhail A.; Davidson, Ronald C.; Kaganovich, Igor D.; Startsev, Edward A.

2012-01-01

The design of ion drivers for warm dense matter and high energy density physics applications and heavy ion fusion involves transverse focusing and longitudinal compression of intense ion beams to a small spot size on the target. To facilitate the process, the compression occurs in a long drift section filled with a dense background plasma, which neutralizes the intense beam self-fields. Typically, the ion bunch charge is better neutralized than its current, and as a result a net self-pinching (magnetic) force is produced. The self-pinching effect is of particular practical importance, and is used in various ion driver designs in order to control the transverse beam envelope. In the present work we demonstrate that this radial self-focusing force can be significantly enhanced if a weak (B ∼ 100 G) solenoidal magnetic field is applied inside the neutralized drift section, thus allowing for substantially improved transport. It is shown that in contrast to magnetic self-pinching, the enhanced collective self-focusing has a radial electric field component and occurs as a result of the overcompensation of the beam charge by plasma electrons, whereas the beam current becomes well-neutralized. As the beam leaves the neutralizing drift section, additional transverse focusing can be applied. For instance, in the neutralized drift compression experiments (NDCX) a strong (several Tesla) final focus solenoid is used for this purpose. In the present analysis we propose that the tight final focus in the NDCX experiments may possibly be achieved by using a much weaker (few hundred Gauss) magnetic lens, provided the ion beam carries an equal amount of co-moving neutralizing electrons from the preceding drift section into the lens. In this case the enhanced focusing is provided by the collective electron dynamics strongly affected by a weak applied magnetic field.

Drifting solutions with elliptic symmetry for the compressible Navier-Stokes equations with density-dependent viscosity

International Nuclear Information System (INIS)

An, Hongli; Yuen, Manwai

2014-01-01

In this paper, we investigate the analytical solutions of the compressible Navier-Stokes equations with dependent-density viscosity. By using the characteristic method, we successfully obtain a class of drifting solutions with elliptic symmetry for the Navier-Stokes model wherein the velocity components are governed by a generalized Emden dynamical system. In particular, when the viscosity variables are taken the same as Yuen [M. W. Yuen, “Analytical solutions to the Navier-Stokes equations,” J. Math. Phys. 49, 113102 (2008)], our solutions constitute a generalization of that obtained by Yuen. Interestingly, numerical simulations show that the analytical solutions can be used to explain the drifting phenomena of the propagation wave like Tsunamis in oceans

Electron beam generation in z-pinch discharges

Energy Technology Data Exchange (ETDEWEB)

Vikhrev, V.V.; Baronova, E.O. [Kurchatov Inst., Moscow (Russian Federation). Russian Research Center

1997-12-31

Numerical modelling of the process of electron beam generation in z-pinch discharges are presented. The proposed model represents the electron beam generation under turbulent plasma conditions. Strong current distribution inhomogeneity in the plasma column and the zigzag drift current motion through the plasma have accounted for the adequate generation process investigation. Electron beam is generated near the maximum of compression and it is not related with the current break effect. (author)

Analysis of axial compressive loaded beam under random support excitations

Science.gov (United States)

Xiao, Wensheng; Wang, Fengde; Liu, Jian

2017-12-01

An analytical procedure to investigate the response spectrum of a uniform Bernoulli-Euler beam with axial compressive load subjected to random support excitations is implemented based on the Mindlin-Goodman method and the mode superposition method in the frequency domain. The random response spectrum of the simply supported beam subjected to white noise excitation and to Pierson-Moskowitz spectrum excitation is investigated, and the characteristics of the response spectrum are further explored. Moreover, the effect of axial compressive load is studied and a method to determine the axial load is proposed. The research results show that the response spectrum mainly consists of the beam's additional displacement response spectrum when the excitation is white noise; however, the quasi-static displacement response spectrum is the main component when the excitation is the Pierson-Moskowitz spectrum. Under white noise excitation, the amplitude of the power spectral density function decreased as the axial compressive load increased, while the frequency band of the vibration response spectrum increased with the increase of axial compressive load.

2-D emittance equation with acceleration and compression

International Nuclear Information System (INIS)

Hahn, K.D.; Smith, L.

1988-10-01

Since both acceleration and compression are required for an Inertial Fusion Driver, the understanding of their effect on the beam quality, emittance, is important. This report attempts to generalize the usual emittance formula for the drifting beam to include these effects. The derivation of the 2-D emittance equation is carried out and a comparison with the particle code results is given. The 2-D emittance at a given axial location is reasonable to consider for a long beam, particularly with velocity tilt; transverse emittance averaged over the entire bunch is not a useful quantity. 6 refs., 2 figs., 1 tab

Electron beam charging of insulators: A self-consistent flight-drift model

International Nuclear Information System (INIS)

Touzin, M.; Goeuriot, D.; Guerret-Piecourt, C.; Juve, D.; Treheux, D.; Fitting, H.-J.

2006-01-01

Electron beam irradiation and the self-consistent charge transport in bulk insulating samples are described by means of a new flight-drift model and an iterative computer simulation. Ballistic secondary electron and hole transport is followed by electron and hole drifts, their possible recombination and/or trapping in shallow and deep traps. The trap capture cross sections are the Poole-Frenkel-type temperature and field dependent. As a main result the spatial distributions of currents j(x,t), charges ρ(x,t), the field F(x,t), and the potential slope V(x,t) are obtained in a self-consistent procedure as well as the time-dependent secondary electron emission rate σ(t) and the surface potential V 0 (t). For bulk insulating samples the time-dependent distributions approach the final stationary state with j(x,t)=const=0 and σ=1. Especially for low electron beam energies E 0 G of a vacuum grid in front of the target surface. For high beam energies E 0 =10, 20, and 30 keV high negative surface potentials V 0 =-4, -14, and -24 kV are obtained, respectively. Besides open nonconductive samples also positive ion-covered samples and targets with a conducting and grounded layer (metal or carbon) on the surface have been considered as used in environmental scanning electron microscopy and common SEM in order to prevent charging. Indeed, the potential distributions V(x) are considerably small in magnitude and do not affect the incident electron beam neither by retarding field effects in front of the surface nor within the bulk insulating sample. Thus the spatial scattering and excitation distributions are almost not affected

Source-to-target simulation of simultaneous longitudinal and transverse focusing of heavy ion beams

Directory of Open Access Journals (Sweden)

D. R. Welch

2008-06-01

Full Text Available Longitudinal bunching factors in excess of 70 of a 300-keV, 27-mA K^{+} ion beam have been demonstrated in the neutralized drift compression experiment [P. K. Roy et al., Phys. Rev. Lett. 95, 234801 (2005PRLTAO0031-900710.1103/PhysRevLett.95.234801] in rough agreement with particle-in-cell source-to-target simulations. A key aspect of these experiments is that a preformed plasma provides charge neutralization of the ion beam in the last one meter drift region where the beam perveance becomes large. The simulations utilize the measured ion source temperature, diode voltage, and induction-bunching-module voltage waveforms in order to determine the initial beam longitudinal phase space which is critical to accurate modeling of the longitudinal compression. To enable simultaneous longitudinal and transverse compression, numerical simulations were used in the design of the solenoidal focusing system that compensated for the impact of the applied velocity tilt on the transverse phase space of the beam. Complete source-to-target simulations, that include detailed modeling of the diode, magnetic transport, induction bunching module, and plasma neutralized transport, were critical to understanding the interplay between the various accelerator components in the experiment. Here, we compare simulation results with the experiment and discuss the contributions to longitudinal and transverse emittance that limit the final compression.

Reduction of cracking and shrinkage in compressed clay beams during dying

International Nuclear Information System (INIS)

Lakho, N.A.; Zardari, M.A.; Memon, N.A.

2016-01-01

Uncontrolled evaporation of moisture from compressed clay beams can cause surface cracks, resulting in reduction of strength. This paper presents various treatments applied to clay beams during the process of casting, compacting and drying in order to curtail the possibility of cracking and to decrease percentage of drying shrinkage. Following treatments were applied to the beams during casting and drying: (i) a steel plate and double layer of plastic sheet was provided between the beam and the plank, (ii) the beam was enveloped with a propylene fabric sheet during casting and (iii) beams were covered with plastic sheet during drying. Using these treatments, the clay beams were cast and compacted at various intensities of compaction. The results show that the drying shrinkage was reduced to minimum and the cracks were curtailed. The rate of drying shrinkage was decreased depending upon the level of compaction. Thus at the higher degree of compaction, more density of clay beams was achieved, which resulted in higher degree of compressive strength in baked and unbaked state. (author)

A beam test of a prototype of the BESIII drift chamber in magnetic field

International Nuclear Information System (INIS)

Liu, J.B.; Qin, Z.H.; Wu, L.H.; Chen, C.; Zhuang, B.A.; Chen, Y.B.; Jin, Y.; Liu, R.G.; Ma, X.Y.; Ma, Y.Y.; Tang, X.; Wang, L.; Xu, M.H.; Zhang, G.F.; Zhu, M.X.; Zhu, Q.M.

2006-01-01

A prototype of the BESIII drift chamber was tested with He/C 3 H 8 (60/40) gas mixture in a 1T magnetic field at the π-2 beam line of KEK 12GeV PS. The drift distance-time relationship was extracted for various conditions. The performance of the chamber, such as the spatial resolution, the dE/dx resolution and the cell efficiency, was studied in detail. The dE/dx was measured as a function of βγ to calculate the particle separation power. Based on the test results, the operating voltage of the BESIII drift chamber is optimized to be 2200V, resulting in a spatial resolution better than 110μm, a cell efficiency over 98%, a dE/dx resolution better than 5% and the 3σπ/K separation at a momentum exceeding 700MeV/c. These results confirm the validation of the physics design of the BESIII drift chamber

Drift tube alignment and beam emittance codes in use at the SuperHILAC

International Nuclear Information System (INIS)

Spence, D.A.

1974-01-01

Two Fortran-IV codes in use at the SuperHILAC are of significant value in optimizing the geometry of the accelerator and in evaluating the performance of the heavy ion beams. The first routine described is used to determine the existing root mean square deviation of the 210 internal drift tube quadrupoles fitted to a straight line or to a second-order quadratic. It then predicts the minimum number of drift tubes, and their identities, to be moved in order to attain a user-elected margin of error fit. Brief mention is made of the pulsed-wire alignment technique for the quadrupole positioning. The second program described is part of a data system which utilizes a PDP-8/I as a control device for the manipulation of beam-scanning hardware and a CDC-6600 in an off-line interactive mode which gives the user maximum versatility in treating the raw data and displaying the results of calculations. The code portrays the transverse beam emittance figures and their transmission through the accelerator and transport lines. Also discussed are future plans which include on-line data reduction and CRT display by the PDP-8/I to enable the operators to optimize the tuning of the HILAC. (U.S.)

Limiting currents of an unneutralized magnetized electron beam in a cylindrical drift tube

International Nuclear Information System (INIS)

Thompson, J.R.; Sloan, M.L.

1978-01-01

Results of an investigation of the steady state injection of a uniform unneutralized, magnetized, relativistic electron beam into a cylindrical drift tube are presented. The space-charge-limited current and the asymptotic kinetic energy of electrons on axis is determined both numerically and analytically as a function of the input kinetic energy (γ 0 -1) mc 2 and of the ratio of beam-to-wall radii. A previously cited ''interpolation formula'' is obtained in the pencil beam limit, but more accurate limiting current expressions are developed for other cases (such as the fat beam limit) where the interpolation formula is as much as 20% in error. The corresponding axial electron energy is also found to be significantly smaller than the previously cited value of (γ/sup 1/3/ 0 -1) mc 2 except in the strong pencil beam limit

Beam test results of the irradiated Silicon Drift Detector for ALICE

OpenAIRE

Kushpil, S.; Crescio, E.; Giubellino, P.; Idzik, M.; Kolozhvari, A.; Kushpil, V.; Martinez, M. I.; Mazza, G.; Mazzoni, A.; Meddi, F.; Nouais, D.; Petracek, V.; Piemonte, C.; Rashevsky, A.; Riccati, L.

2005-01-01

The Silicon Drift Detectors will equip two of the six cylindrical layers of high precision position sensitive detectors in the ITS of the ALICE experiment at LHC. In this paper we report the beam test results of a SDD irradiated with 1 GeV electrons. The aim of this test was to verify the radiation tolerance of the device under an electron fluence equivalent to twice particle fluence expected during 10 years of ALICE operation.

Symmetric compression of 'laser greenhouse' targets by a few laser beams

International Nuclear Information System (INIS)

Gus'kov, Sergei Yu; Demchenko, N N; Rozanov, Vladislav B; Stepanov, R V; Zmitrenko, N V; Caruso, A; Strangio, C

2003-01-01

The possibility of efficient and symmetric compression of a target with a low-density structured absorber by a few laser beams is considered. An equation of state is proposed for a porous medium, which takes into account the special features of the absorption of high-power nanosecond laser pulses. The open version of this target is shown to allow the use of ordinary Gaussian beams, requiring no special profiling of the absorber surface. The conditions are defined under which such targets can be compressed efficiently by only two laser beams (or beam clusters). Simulations show that for a 2.1-MJ laser pulse, a seven-fold gain for the target under study is achieved. (special issue devoted to the 80th anniversary of academician n g basov's birth)

Quasistationary model of high current relativistic electron beam. 2. The own magnetic field of relativistic electron beam in cylindrical Drift space

International Nuclear Information System (INIS)

Brenner, S.E.; Gandul', E.M.; Podkopaev, A.P.

1995-01-01

This paper is devoted to obtaining the components of own magnetic field of high current relativistic electron beam passing through the cylindrical drift space superconducting walls: the peculiarities of applied numerical scheme have been also described briefly. (author). 6 refs

DIAGNOSTICS FOR ION BEAM DRIVEN HIGH ENERGY DENSITY PHYSICS EXPERIMENTS

International Nuclear Information System (INIS)

Bieniosek, F.M.; Henestroza, E.; Lidia, S.; Ni, P.A.

2010-01-01

Intense beams of heavy ions are capable of heating volumetric samples of matter to high energy density. Experiments are performed on the resulting warm dense matter (WDM) at the NDCX-I ion beam accelerator. The 0.3 MeV, 30-mA K + beam from NDCX-I heats foil targets by combined longitudinal and transverse neutralized drift compression of the ion beam. Both the compressed and uncompressed parts of the NDCX-I beam heat targets. The exotic state of matter (WDM) in these experiments requires specialized diagnostic techniques. We have developed a target chamber and fielded target diagnostics including a fast multi-channel optical pyrometer, optical streak camera, laser Doppler-shift interferometer (VISAR), beam transmission diagnostics, and high-speed gated cameras. We also present plans and opportunities for diagnostic development and a new target chamber for NDCX-II.

Acceleration of beam ions during major radius compression in TFTR

International Nuclear Information System (INIS)

Wong, K.L.; Bitter, M.; Hammett, G.W.

1985-09-01

Tangentially co-injected deuterium beam ions were accelerated from 82 keV up to 150 keV during a major radius compression experiment in TFTR. The ion energy spectra and the variation in fusion yield were in good agreement with Fokker-Planck code simulations. In addition, the plasma rotation velocity was observed to rise during compression

Beam test of a full-length prototype of the BESIII drift chamber with the readout electronics

International Nuclear Information System (INIS)

Qin, Z.H.; Chen, Y.B.; Sheng, H.Y.; Wu, L.H.; Liu, J.B.; Zhuang, B.A.; Jiang, X.S.; Zhao, Y.B.; Zhu, K.J.; Yan, Z.K.; Chen, C.; Xu, M.H.; Wang, L.; Ma, X.Y.; Tang, X.; Liu, R.G.; Jin, Y.; Zhu, Q.M.; Zhang, G.F.; Wu, Z.; Li, R.Y.; Zhao, P.P.; Dai, H.L.; Li, X.P.; Li, J.

2007-01-01

A full-length prototype of the BESIII drift chamber together with its readout electronics was built and a beam test was performed. Two different methods, namely 'single-threshold method' and 'double-threshold method' for timing measurement, were studied. Test results show that the BESIII drift chamber and its readout electronics can reach their design specifications. The 'double-threshold method' results in a better timing accuracy and noise suppression capabilities as compared with the 'single-threshold method'

Laboratory and test beam results from a large-area silicon drift detector

CERN Document Server

Bonvicini, V; Giubellino, P; Gregorio, A; Idzik, M; Kolojvari, A A; Montaño-Zetina, L M; Nouais, D; Petta, C; Rashevsky, A; Randazzo, N; Reito, S; Tosello, F; Vacchi, A; Vinogradov, L I; Zampa, N

2000-01-01

A very large-area (6.75*8 cm/sup 2/) silicon drift detector with integrated high-voltage divider has been designed, produced and fully characterised in the laboratory by means of ad hoc designed MOS injection electrodes. The detector is of the "butterfly" type, the sensitive area being subdivided into two regions with a maximum drift length of 3.3 cm. The device was also tested in a pion beam (at the CERN PS) tagged by means of a microstrip detector telescope. Bipolar VLSI front-end cells featuring a noise of 250 e/sup -/ RMS at 0 pF with a slope of 40 e/sup -//pF have been used to read out the signals. The detector showed an excellent stability and featured the expected characteristics. Some preliminary results will be presented. (12 refs).

Compact compressive arc and beam switchyard for energy recovery linac-driven ultraviolet free electron lasers

Science.gov (United States)

Akkermans, J. A. G.; Di Mitri, S.; Douglas, D.; Setija, I. D.

2017-08-01

High gain free electron lasers (FELs) driven by high repetition rate recirculating accelerators have received considerable attention in the scientific and industrial communities in recent years. Cost-performance optimization of such facilities encourages limiting machine size and complexity, and a compact machine can be realized by combining bending and bunch length compression during the last stage of recirculation, just before lasing. The impact of coherent synchrotron radiation (CSR) on electron beam quality during compression can, however, limit FEL output power. When methods to counteract CSR are implemented, appropriate beam diagnostics become critical to ensure that the target beam parameters are met before lasing, as well as to guarantee reliable, predictable performance and rapid machine setup and recovery. This article describes a beam line for bunch compression and recirculation, and beam switchyard accessing a diagnostic line for EUV lasing at 1 GeV beam energy. The footprint is modest, with 12 m compressive arc diameter and ˜20 m diagnostic line length. The design limits beam quality degradation due to CSR both in the compressor and in the switchyard. Advantages and drawbacks of two switchyard lines providing, respectively, off-line and on-line measurements are discussed. The entire design is scalable to different beam energies and charges.

The drive beam pulse compression system for the CLIC RF power source

CERN Document Server

Corsini, R

1999-01-01

The Compact LInear Collider (CLIC) is a high energy (0.5 to 5 TeV) e ± linear collider that uses a high- current electron beam (the drive beam) for 30 GHz RF power production by the Two-Beam Acceleration (TBA) method. Recently, a new cost­effective and efficient generation scheme for the drive beam has been developed. A fully­loaded normal­conducting linac operating at lower frequency (937 MHz) generates and accelerates the drive beam bunches, and a compression system composed of a delay­line and two combiner rings produces the proper drive beam time structure for RF power generation in the drive beam decelerator. In this paper, a preliminary design of the whole compression system is presented. In particular, the fundamental issue of preserving the bunch quality along the complex is studied and its impact on the beam parameters and on the various system components is assessed. A first design of the rings and delay­line lattice, including path length tuning chicanes, injection and extraction regions is a...

Investigations on KONUS beam dynamics using the pre-stripper drift tube linac at GSI

Science.gov (United States)

Xiao, C.; Du, X. N.; Groening, L.

2018-04-01

Interdigital H-mode (IH) drift tube linacs (DTLs) based on KONUS beam dynamics are very sensitive to the rf-phases and voltages at the gaps between tubes. In order to design these DTLs, a deep understanding of the underlying longitudinal beam dynamics is mandatory. The report presents tracking simulations along an IH-DTL using the PARTRAN and BEAMPATH codes together with MATHCAD and CST. Simulation results illustrate that the beam dynamics design of the pre-stripper IH-DTL at GSI is sensitive to slight deviations of rf-phase and gap voltages with impact to the mean beam energy at the DTL exit. Applying the existing geometrical design, rf-voltages, and rf-phases of the DTL were re-adjusted. In simulations this re-optimized design can provide for more than 90% of transmission of an intense 15 emA beam keeping the reduction of beam brilliance below 25%.

Extraction Compression and Acceleration of High Line Charge Density Ion Beams

CERN Document Server

Henestroza, Enrique; Grote, D P; Peters, Craig; Yu, Simon

2005-01-01

HEDP applications require high line charge density ion beams. An efficient method to obtain this type of beams is to extract a long pulse, high current beam from a gun at high energy, and let the beam pass through a decelerating field to compress it. The low energy beam bunch is loaded into a solenoid and matched to a Brillouin flow. The Brillouin equilibrium is independent of the energy if the relationship between the beam size (a), solenoid magnetic field strength (B) and line charge density is such that (Ba)2

SUNWARD PROPAGATING ALFVÉN WAVES IN ASSOCIATION WITH SUNWARD DRIFTING PROTON BEAMS IN THE SOLAR WIND

Energy Technology Data Exchange (ETDEWEB)

He, Jiansen; Pei, Zhongtian; Wang, Linghua; Tu, Chuanyi; Zhang, Lei [School of Earth and Space Sciences, Peking University, Beijing, 100871 (China); Marsch, Eckart [Institute for Experimental and Applied Physics, Christian-Albrechts-Universität zu Kiel, D-24118 Kiel (Germany); Salem, Chadi, E-mail: jshept@gmail.com [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States)

2015-06-01

Using measurements from the WIND spacecraft, here we report the observation of sunward propagating Alfvén waves (AWs) in solar wind that is magnetically disconnected from the Earth's bow shock. In the sunward magnetic field sector, we find a period lasting for more than three days in which there existed (during most time intervals) a negative correlation between the flow velocity and magnetic field fluctuations, thus indicating that the related AWs are mainly propagating sunward. Simultaneous observations of counter-streaming suprathermal electrons suggest that these sunward AWs may not simply be due to the deflection of an open magnetic field line. Moreover, no interplanetary coronal mass ejection appears to be associated with the counter-streaming suprathermal electrons. As the scale goes from the magnetohydrodynamic down to the ion kinetic regime, the wave vector of magnetic fluctuations usually becomes more orthogonal to the mean magnetic field direction, and the fluctuations become increasingly compressible, which are both features consistent with quasi-perpendicular kinetic AWs. However, in the case studied here, we find clear signatures of quasi-parallel sunward propagating ion-cyclotron waves. Concurrently, the solar wind proton velocity distribution reveals a sunward field-aligned beam that drifts at about the local Alfvén speed. This beam is found to run in the opposite direction of the normally observed (anti-sunward) proton beam, and is apparently associated with sunward propagating Alfvén/ion-cyclotron waves. The results and conclusions of this study enrich our knowledge of solar wind turbulence and foster our understanding of proton heating and acceleration within a complex magnetic field geometry.

Ferroelectric plasma source for heavy ion beam space charge neutralization

International Nuclear Information System (INIS)

Efthimion, Philip C.; Gilson, Erik P.; Davidson, Ronald C.; Grisham, Larry; Grant Logan, B.; Seidl, Peter A.; Waldron, William; Yu, Simon S.

2007-01-01

Plasmas are a source of unbound electrons for charge neutralizing intense heavy ion beams to allow them to focus to a small spot size and compress their axial pulse length. The plasma source should be able to operate at low neutral pressures and without strong externally applied electric or magnetic fields. To produce 1 m-long plasma columns, sources based upon ferroelectric ceramics with large dielectric coefficients are being developed. The sources utilize the ferroelectric ceramic BaTiO 3 to form metal plasma. The drift tube inner surface of the Neutralized Drift Compression Experiment (NDCX) will be covered with ceramic material, and high voltage (∼7 kV) will be applied between the drift tube and the front surface of the ceramics. A prototype ferroelectric source, 20 cm in length, has produced plasma densities of 5x10 11 cm -3 . It was integrated into the Neutralized Transport Experiment (NTX), and successfully charge neutralized the K + ion beam. A 1 m-long source comprised of five 20-cm-long sources has been tested. Simply connecting the five sources in parallel to a single pulse forming network power supply yielded non-uniform performance due to the time-dependent nature of the load that each of the five plasma sources experiences. Other circuit combinations have been considered, including powering each source by its own supply. The 1-m-long source has now been successfully characterized, producing relatively uniform plasma over the 1 m length of the source in the mid-10 10 cm -3 density range. This source will be integrated into the NDCX device for charge neutralization and beam compression experiments

Li+ alumino-silicate ion source development for the Neutralized Drift Compression Experiment (NDCX-II)

International Nuclear Information System (INIS)

Roy, P.K.; Greenway, W.; Kwan, J.W.; Seidl, P.A.; Waldron, W.

2011-01-01

To heat targets to electron-volt temperatures for the study of warm dense matter with intense ion beams, low mass ions, such as lithium, have an energy loss peak (dE/dx) at a suitable kinetic energy. The Heavy Ion Fusion Sciences (HIFS) program at Lawrence Berkeley National Laboratory will carry out warm dense matter experiments using Li + ion beam with energy 1.2-4 MeV in order to achieve uniform heating up to 0.1-1 eV. The accelerator physics design of Neutralized Drift Compression Experiment (NDCX-II) has a pulse length at the ion source of about 0.5 (micro)s. Thus for producing 50 nC of beam charge, the required beam current is about 100 mA. Focusability requires a normalized (edge) emittance ∼2 π-mm-mrad. Here, lithium aluminosilicate ion sources, of β-eucryptite, are being studied within the scope of NDCX-II construction. Several small (0.64 cm diameter) lithium aluminosilicate ion sources, on 70%-80% porous tungsten substrate, were operated in a pulsed mode. The distance between the source surface and the mid-plane of the extraction electrode (1 cm diameter aperture) was 1.48 cm. The source surface temperature was at 1220 C to 1300 C. A 5-6 (micro)s long beam pulsed was recorded by a Faraday cup (+300 V on the collector plate and -300 V on the suppressor ring). Figure 1 shows measured beam current density (J) vs. V 3/2 . A space-charge limited beam density of ∼1 mA/cm 2 was measured at 1275 C temperature, after allowing a conditioning time of about ∼ 12 hours. Maximum emission limited beam current density of (ge) 1.8mA/cm 2 was recorded at 1300 C with 10-kV extractions. Figure 2 shows the lifetime of two typical sources with space-charge limited beam current emission at a lower extraction voltage (1.75 kV) and at temperature of 1265 ± 7 C. These data demonstrate a constant, space-charge limited beam current for 20-50 hours. The lifetime of a source is determined by the loss of lithium from the alumino-silicate material either as ions or as neutral

Validation of the Read Out Electronics for the CMS Muon Drift Chambers at Tests Beam in CERN/GIF

CERN Document Server

Fernández, C; Fouz-Iglesias, M C; Marin, J; Oller, J C; Willmott, C

2002-01-01

Part of the readout system for the CMS muon drift chambers has been tested in test beams at CERN/GIF. Read Out Board (ROB) and HPTD have been validated with signals from a real muon beam, with an structure and flux similar to LHC operating conditions and using one of the chambers produced in CIEMAT already located in the test beam area under normal gas and voltage conditions. (Author) 5 refs.

Ferroelectric Plasma Source for Heavy Ion Beam Charge Neutralization

CERN Document Server

Efthimion, Philip; Gilson, Erik P; Grisham, Larry; Logan, B G; Waldron, William; Yu, Simon

2005-01-01

Plasmas are employed as a medium for charge neutralizing heavy ion beams to allow them to focus to a small spot size. Calculations suggest that plasma at a density of 1-100 times the ion beam density and at a length ~ 0.1-1 m would be suitable. To produce 1 meter plasma, large-volume plasma sources based upon ferroelectric ceramics are being considered. These sources have the advantage of being able to increase the length of the plasma and operate at low neutral pressures. The source will utilize the ferroelectric ceramic BaTiO3 to form metal plasma. The drift tube inner surface of the Neutralized Drift Compression Experiment (NDCX) will be covered with ceramic. High voltage (~ 1-5 kV) is applied between the drift tube and the front surface of the ceramic by placing a wire grid on the front surface. A prototype ferroelectric source 20 cm long produced plasma densities ~ 5x1011 cm-3. The source was integrated into the experiment and successfully charge neutralized the K ion beam. Presently, the 1 meter source ...

Test beam analysis of the first CMS drift tube muon chamber

CERN Document Server

Albajar, C; Arce, P; Autermann, C; Bellato, M; Benettoni, M; Benvenuti, Alberto C; Bontenackels, M; Caballero, J; Cavallo, F R; Cerrada, M; Cirio, R; Colino, N; Conti, E; de la Cruz, B; Dal Corso, F; Dallavalle, G M; Fernández, C; Fernández de Troconiz, J; Fouz-Iglesias, M C; García-Abia, P; García-Raboso, A; Gasparini, F; Gasparini, U; Giacomelli, P; Gonella, F; Gulmini, M; Hebbeker, T; Hermann, S; Höpfner, K; Jiménez, I; Josa-Mutuberria, I; Lacaprara, S; Marcellini, S; Mariotti, C; Maron, G; Maselli, S; Meneguzzo, Anna Teresa; Monaco, V; Montanari, A; Montanari, C; Montecassiano, F; Navarria, Francesco Luigi; Odorici, F; Passaseo, M; Pegoraro, M; Peroni, C; Perrotta, A; Puerta, J; Reithler, H; Romero, A; Romero, L; Ronchese, P; Rossi, A; Rovelli, T; Sacchi, R; Sowa, M; Staiano, A; Toniolo, N; Torassa, E; Vaniev, V; Vanini, S; Ventura, Sandro; Villanueva, C; Willmott, C; Zotto, P L; Zumerle, G

2004-01-01

In October 2001 the first produced CMS Barrel Drift Tube (DT) Muon Chamber was tested at the CERN Gamma Irradiation Facility (GIF) using a muon beam. A Resistive Plate Chamber (RPC) was attached to the top of the DT chamber, and, for the first time, both detectors were operated coupled together. The performance of the DT chamber was studied for several operating conditions, and for gamma rates similar to the ones expected at LHC. In this paper we present the data analysis; the results are considered fully satisfactory.

Test beam analysis of the first CMS drift tube muon chamber

International Nuclear Information System (INIS)

Albajar, C.; Amapane, N.; Arce, P.; Autermann, C.; Bellato, M.; Benettoni, M.; Benvenuti, A.; Bontenackels, M.; Caballero, J.; Cavallo, F.R.; Cerrada, M.; Cirio, R.; Colino, N.; Conti, E.; Cruz, B. de la; Corso, F. dal; Dallavalle, G.M.; Fernandez, C.; Troconiz, J.F. de; Fouz, M.C.; Garcia-Abia, P.; Garcia-Raboso, A.; Gasparini, F.; Gasparini, U.; Giacomelli, P.; Gonella, F.; Gulmini, M.; Hebbeker, T.; Hermann, S.; Hoepfner, K.; Jimenez, I.; Josa, I.; Lacaprara, S.; Marcellini, S.; Mariotti, C.; Maron, G.; Maselli, S.; Meneguzzo, A.T.; Monaco, V.; Montanari, A.; Montanari, C.; Montecassiano, F.; Navarria, F.L.; Odorici, F.; Passaseo, M.; Pegoraro, M.; Peroni, C.; Perrotta, A.; Puerta, J.; Reithler, H.; Romero, A.; Romero, L.; Ronchese, P.; Rossi, A.; Rovelli, T.; Sacchi, R.; Sowa, M.; Staiano, A.; Toniolo, N.; Torassa, E.; Vaniev, V.; Vanini, S.; Ventura, S.; Villanueva, C.; Willmott, C.; Zotto, P.; Zumerle, G.

2004-01-01

In October 2001 the first produced CMS Barrel Drift Tube (DT) Muon Chamber was tested at the CERN Gamma Irradiation Facility (GIF) using a muon beam. A Resistive Plate Chamber (RPC) was attached to the top of the DT chamber, and, for the first time, both detectors were operated coupled together. The performance of the DT chamber was studied for several operating conditions, and for gamma rates similar to the ones expected at LHC. In this paper we present the data analysis; the results are considered fully satisfactory

Test beam analysis of the first CMS drift tube muon chamber

Energy Technology Data Exchange (ETDEWEB)

Albajar, C.; Amapane, N.; Arce, P.; Autermann, C.; Bellato, M.; Benettoni, M.; Benvenuti, A.; Bontenackels, M.; Caballero, J.; Cavallo, F.R.; Cerrada, M.; Cirio, R.; Colino, N.; Conti, E.; Cruz, B. de la; Corso, F. dal; Dallavalle, G.M.; Fernandez, C.; Troconiz, J.F. de E-mail: jorge.troconiz@uam.es; Fouz, M.C.; Garcia-Abia, P.; Garcia-Raboso, A.; Gasparini, F.; Gasparini, U.; Giacomelli, P.; Gonella, F.; Gulmini, M.; Hebbeker, T.; Hermann, S.; Hoepfner, K.; Jimenez, I.; Josa, I.; Lacaprara, S.; Marcellini, S.; Mariotti, C.; Maron, G.; Maselli, S.; Meneguzzo, A.T.; Monaco, V.; Montanari, A.; Montanari, C.; Montecassiano, F.; Navarria, F.L.; Odorici, F.; Passaseo, M.; Pegoraro, M.; Peroni, C.; Perrotta, A.; Puerta, J.; Reithler, H.; Romero, A.; Romero, L.; Ronchese, P.; Rossi, A.; Rovelli, T.; Sacchi, R.; Sowa, M.; Staiano, A.; Toniolo, N.; Torassa, E.; Vaniev, V.; Vanini, S.; Ventura, S.; Villanueva, C.; Willmott, C.; Zotto, P.; Zumerle, G

2004-06-11

In October 2001 the first produced CMS Barrel Drift Tube (DT) Muon Chamber was tested at the CERN Gamma Irradiation Facility (GIF) using a muon beam. A Resistive Plate Chamber (RPC) was attached to the top of the DT chamber, and, for the first time, both detectors were operated coupled together. The performance of the DT chamber was studied for several operating conditions, and for gamma rates similar to the ones expected at LHC. In this paper we present the data analysis; the results are considered fully satisfactory.

Simulation of integrated beam experiment designs

International Nuclear Information System (INIS)

Grote, D.P.; Sharp, W.M.

2004-01-01

Simulation of designs of an Integrated Beam Experiment (IBX) class accelerator have been carried out. These simulations are an important tool for validating such designs. Issues such as envelope mismatch and emittance growth can be examined in a self-consistent manner, including the details of injection, accelerator transitions, long-term transport, and longitudinal compression. The simulations are three-dimensional and time-dependent, and begin at the source. They continue up through the end of the acceleration region, at which point the data is passed on to a separate simulation of the drift compression. Results are be presented

Initial Measurements of CSR from a Bunch-Compressed Beam at APS

CERN Document Server

Lumpkin, Alex H; Borland, M; Sereno, N S

2005-01-01

The interest in bunch compression to generate higher peak current electron beams with low emittance continues in the free-electron laser (FEL) community. At the Advanced Photon source (APS) we have both an rf thermionic gun and an rf photocathode (PC) gun on the S-band linac. At the 150-MeV point in the linac, we have a flexible chicane bunch compressor whose four dipoles bend the beam in the horizontal plane. There is also a vertical bend dipole after the chicane that allows measurement of energy and horizontal beam size at the imaging screen station to study possible effects on emittance due to coherent synchrotron radiation (CSR) in the chicane. A far-infrared (FIR) coherent radiation monitor is located downstream of the chicane as well. We have begun recommissioning of this device with coherent transition radiation (CTR), but we also have directly observed CSR from the bunch-compressed beam as it transits the vertical dipole and goes into the down leg. The unique geometry allows simultaneous tracking of b...

Flexural torsional buckling of uniformly compressed beam-like structures

Science.gov (United States)

Ferretti, M.

2018-02-01

A Timoshenko beam model embedded in a 3D space is introduced for buckling analysis of multi-store buildings, made by rigid floors connected by elastic columns. The beam model is developed via a direct approach, and the constitutive law, accounting for prestress forces, is deduced via a suitable homogenization procedure. The bifurcation analysis for the case of uniformly compressed buildings is then addressed, and numerical results concerning the Timoshenko model are compared with 3D finite element analyses. Finally, some conclusions and perspectives are drawn.

Broad-band beam buncher

International Nuclear Information System (INIS)

Goldberg, D.A.; Flood, W.S.; Arthur, A.A.; Voelker, F.

1986-01-01

This patent describes a broad-band beam buncher. This beam buncher consists of: a housing adapted to be eacuated, an electron gun in the housing for producing a beam of electrons, buncher means in the housing forming a buncher cavity which has an entrance opening for receiving the electron beam and an exit opening through which the electron beam passes out of the buncher cavity, a drift tube electrode in the buncher cavity and disposed between the entrance opening and the exit opening with first and second gaps between the drift tube electrode and the entrance and exit openings, the drift tube electrode which has a first drift space through which the electron beam passes in traveling between the entrance and exit openings, modulating means for supplying an ultrahigh frequeny modulating signal to the drift tube electrode for producing velocity modulation of the electrons in the electron beam as the electrons pass through the buncher cavity and the drift tube electrode between the entrance opening and the exit opening, drift space means in the housing forming a second drift space for receiving the velocity modulated electron beam from the exit opening, the velocity modulated electron beam being bunched as it passes along the second drift space, the drift space means has a discharge opening through which the electron beam is discharged from the second drift space after being bunched therein, the modulating means containing a signal source for producing an ultrahigh frequency signal, a transmission line connected between the signal source and the drift tube electrode, and terminating means connected to the drift tube electrode for terminating the transmission line in approximately its characteristic impedance to afford a broad response band with minimum 6 variations therein

Tokamak heating by neutral beams and adiabatic compression

International Nuclear Information System (INIS)

Furth, H.P.

1973-08-01

''Realistic'' models of tokamak energy confinement strongly favor reactor operation at the maximum MHD-stable β-value, in order to maximize plasma density. Ohmic heating is unsuitable for this purpose. Neutral-beam heating plus compression is well suited; however, very large requirements on device size and injection power seem likely for a DT ignition experiment using a Maxwellian plasma. Results of the ATC experiment are reviewed, including Ohmic heating, neutral-beam heating, and production of two-energy-component plasmas (energetic deuteron population in deuterium ''target plasma''). A modest extrapolation of present ATC parameters could give zero-power conditions in a DT experiment of the two-energy-component type. (U.S.)

Conceptual design of bend, compression, and final focus components of ILSE [Induction Linac System Experiment

International Nuclear Information System (INIS)

Lee, E.P.; Fong, C.; Mukherjee, S.; Thur, W.

1989-03-01

The Induction Linac System Experiment (ILSE) includes a 180/degree/ bend system, drift compression line and a final focus, which test the analogous features of a heavy ion driver for inertial fusion. These components are novel in their transport of a space-charge-dominated ion beam with large head-to-tail velocity tilt. Their conceptual design is presented, including calculations of the beam envelope, momentum dispersion, and engineering design of magnets, vacuum system, diagnostics, alignment, and support. 3 refs., 5 figs

Test of a high resolution drift chamber prototype

International Nuclear Information System (INIS)

Comminchau, V.; Deutschmann, M.; Draheim, K.J.; Fritze, P.; Hangarter, K.; Hawelka, P.; Herten, U.; Tonutti, M.; Anderhub, H.; Fehlmann, J.; Hofer, H.; Klein, M.; Paradiso, J.A.; Schreiber, J.; Viertel, G.

1984-06-01

The performance of a drift chamber prototype for a colliding beam vertex detector in a test beam at DESY is described. At one (two) atmosphere gas pressure a spatial resolution of 40 μm (30 μm) per wire for one cm drift length was achieved with a 100 MHz Flash-ADC system. An excellent double track resolution of better than 300 μm over the full drift length of 5 cm can be estimated. (orig.)

Brookhaven National Laboratory electron beam test stand

International Nuclear Information System (INIS)

Pikin, A.; Alessi, J.; Beebe, E.; Kponou, A.; Prelec, K.; Snydstrup, L.

1998-01-01

The main purpose of the electron beam test stand (EBTS) project at the Brookhaven National Laboratory is to build a versatile device to develop technologies that are relevant for a high intensity electron beam ion source (EBIS) and to study the physics of ion confinement in a trap. The EBTS will have all the main attributes of EBIS: a 1-m-long, 5 T superconducting solenoid, electron gun, drift tube structure, electron collector, vacuum system, ion injection system, appropriate control, and instrumentation. Therefore it can be considered a short prototype of an EBIS for a relativistic heavy ion collider. The drift tube structure will be mounted in a vacuum tube inside a open-quotes warmclose quotes bore of a superconducting solenoid, it will be at room temperature, and its design will employ ultrahigh vacuum technology to reach the 10 -10 Torr level. The first gun to be tested will be a 10 A electron gun with high emission density and magnetic compression of the electron beam. copyright 1998 American Institute of Physics

Wellhead gas compression extends life of beam-pumped wells

International Nuclear Information System (INIS)

Sherry, M.J.; Fairchild, P.W.

1992-01-01

This paper reports that operators of marginal oil and gas wells often can avoid having to shut them in by compressing gas from the back side of the casing at the well head and delivering it into the flowline. This process can reduce the back pressure at the face of the producing formation, which allows additional oil and gas to be produced and extends the economical reserves. Small, low-horsepower stationary compressors or a walking beam compressor (WBC) may be used for this purpose. A portable compressor test unit recently has been employed to evaluate wells that are possible candidates for wellhead compression as another cost cutting measure

Target design for the cylindrical compression of matter driven by heavy ion beams

Energy Technology Data Exchange (ETDEWEB)

Piriz, A.R. [E. T. S. I. Industriales, Universidad de Castilla-La Mancha, 13071 Ciudad Real (Spain)]. E-mail: roberto.piriz@uclm.es; Temporal, M. [E. T. S. I. Industriales, Universidad de Castilla-La Mancha, 13071 Ciudad Real (Spain); Lopez Cela, J.J. [E. T. S. I. Industriales, Universidad de Castilla-La Mancha, 13071 Ciudad Real (Spain); Grandjouan, N. [LULI, UMR 7605, Ecole Polytechnique-CNRS-CEA-Universite Paris VI, Palaiseau (France); Tahir, N.A. [GSI Darmstadt, Plankstrasse 1, 64291 Darmstadt (Germany); Serna Moreno, M.C. [E. T. S. I. Industriales, Universidad de Castilla-La Mancha, 13071 Ciudad Real (Spain); Portugues, R.F. [E. T. S. I. Industriales, Universidad de Castilla-La Mancha, 13071 Ciudad Real (Spain); Hoffmann, D.H.H. [GSI Darmstadt, Plankstrasse 1, 64291 Darmstadt (Germany)

2005-05-21

The compression of a cylindrical sample of hydrogen contained in a hollow shell of Pb or Au has been analyzed in the framework of the experiments to be performed in the heavy ion synchrotron SIS100 to be constructed at the Gesellschaft fuer Schwerionenforschung (GSI) Darmstadt. The target implosion is driven by an intense beam of heavy ions with a ring-shaped focal spot. We report the results of a parametric study of the final state of the compressed hydrogen in terms of the target and beam parameters. We consider the generation of the annular heated region by means of a radio-frequency wobbler that rotates the beam at extremely high frequencies in order to accommodate symmetry constraints. We have also studied the hydrogen conditions that can be achieved with a non-rotating beam with Gaussian focal spot and the possibility to use a beam stopper as an alternative way to avoid the direct heating of the sample. Finally, we report the analysis of the hydrodynamic instabilities that affect the implosion and the mitigating effects of the elastoplastic properties of the shell.

Target design for the cylindrical compression of matter driven by heavy ion beams

International Nuclear Information System (INIS)

Piriz, A.R.; Temporal, M.; Lopez Cela, J.J.; Grandjouan, N.; Tahir, N.A.; Serna Moreno, M.C.; Portugues, R.F.; Hoffmann, D.H.H.

2005-01-01

The compression of a cylindrical sample of hydrogen contained in a hollow shell of Pb or Au has been analyzed in the framework of the experiments to be performed in the heavy ion synchrotron SIS100 to be constructed at the Gesellschaft fuer Schwerionenforschung (GSI) Darmstadt. The target implosion is driven by an intense beam of heavy ions with a ring-shaped focal spot. We report the results of a parametric study of the final state of the compressed hydrogen in terms of the target and beam parameters. We consider the generation of the annular heated region by means of a radio-frequency wobbler that rotates the beam at extremely high frequencies in order to accommodate symmetry constraints. We have also studied the hydrogen conditions that can be achieved with a non-rotating beam with Gaussian focal spot and the possibility to use a beam stopper as an alternative way to avoid the direct heating of the sample. Finally, we report the analysis of the hydrodynamic instabilities that affect the implosion and the mitigating effects of the elastoplastic properties of the shell

Performance of composite I-beams under axial compression and bending load modes

International Nuclear Information System (INIS)

Khalid, Y.A.; Ali, F.A.; Sahari, B.B.; Saad, E.M.A.

2005-01-01

An experimental and finite-element analyses for glass/epoxy composite I-beams have been carried out. Four, six, eight and 10 layers of woven fabric glass/epoxy composite I-beams were fabricated by a hand lay-up (molding) process. Quasi-static axial crushing and bending loading modes were used for this investigation. The load-displacement response was obtained and the energy absorption values were calculated for all the composite I-beams. Three tests were done for each composite I-beams type and each loading case for the results conformation. The second part of this study includes the elastic behavior of composite I-beams of the same dimensions and materials using finite-element analysis. The woven fabric glass/epoxy composite I-beams mechanical properties have been obtained from tensile tests. Results from this investigation show that the load required and the specific energy absorption for composite I-beams under axial compression load were higher than those for three and four point bending. On the other hand, the loads required for composite I-beams under four point bending were higher than those for three point bending, while the specific energy absorption for composite I-beams under three point bending were higher than those for four point bending. The first crushing loads difference between the experimental and finite-element results fell in the 3.6-10.92% range for axial compression tests, while fell in the 1.44-12.99% and 4.94-22.0% range for three and four point bending, respectively

Compression of pulsed electron beams for material tests

Science.gov (United States)

Metel, Alexander S.

2018-03-01

In order to strengthen the surface of machine parts and investigate behavior of their materials exposed to highly dense energy fluxes an electron gun has been developed, which produces the pulsed beams of electrons with the energy up to 300 keV and the current up to 250 A at the pulse width of 100-200 µs. Electrons are extracted into the accelerating gap from the hollow cathode glow discharge plasma through a flat or a spherical grid. The flat grid produces 16-cm-diameter beams with the density of transported per one pulse energy not exceeding 15 J·cm-2, which is not enough even for the surface hardening. The spherical grid enables compression of the beams and regulation of the energy density from 15 J·cm-2 up to 15 kJ·cm-2, thus allowing hardening, pulsed melting of the machine part surface with the further high-speed recrystallization as well as an explosive ablation of the surface layer.

Analysis of the SPS Long Term Orbit Drifts

Energy Technology Data Exchange (ETDEWEB)

Velotti, Francesco [CERN; Bracco, Chiara [CERN; Cornelis, Karel [CERN; Drøsdal, Lene [CERN; Fraser, Matthew [CERN; Gianfelice-Wendt, Eliana [Fermilab; Goddard, Brennan [CERN; Kain, Verena [CERN; Meddahi, Malika [CERN

2016-06-01

The Super Proton Synchrotron (SPS) is the last accelerator in the Large Hadron Collider (LHC) injector chain, and has to deliver the two high-intensity 450 GeV proton beams to the LHC. The transport from SPS to LHC is done through the two Transfer Lines (TL), TI2 and TI8, for Beam 1 (B1) and Beam 2 (B2) respectively. During the first LHC operation period Run 1, a long term drift of the SPS orbit was observed, causing changes in the LHC injection due to the resulting changes in the TL trajectories. This translated into longer LHC turnaround because of the necessity to periodically correct the TL trajectories in order to preserve the beam quality at injection into the LHC. Different sources for the SPS orbit drifts have been investigated: each of them can account only partially for the total orbit drift observed. In this paper, the possible sources of such drift are described, together with the simulated and measured effect they cause. Possible solutions and countermeasures are also discussed.

Characterization of compressive and short beam shear strength of bamboo opened cell foam core sandwich composites

Energy Technology Data Exchange (ETDEWEB)

Setyawan, Paryanto Dwi, E-mail: paryanto-ds@yahoo.com; Sugiman,; Saputra, Yudhi [Department of Mechanical Engineering, Faculty of Engineering, University of Mataram, Mataram, West Nusa Tenggara (Indonesia)

2016-03-29

The paper presents the compressive and the short beam shear strength of a sandwich composite with opened cell foam made of bamboo fiber as the core and plywood as the skins. The core thickness was varied from 10 mm to 40 mm keeping the volume fraction of fiber constant. Several test s were carried out including the core density, flatwise compressive and the short beam shear testing in three point bending. The results show that the density of bamboo opened cell foam is comparable with commercial plastic foam, such as polyurethane foam. The compressive strength tends to increase linearly with increasing the core thickness. The short beam shear failure load of the sandwich composite increases with the increase of core thickness, however on the contrary, the short beam shear strength which tends to sharply decrease from the thickness of 10 mm to 30 mm and then becomes flat.

First joint test beam of CMS Drift Tubes (DT) and Resistive Plate Chambers (RPC)

CERN Multimedia

Paolo Giacomelli

2001-01-01

The first full size muon drift tube chamber ever built for the CMS barrel with the final cell design (constructed at CIEMAT, Madrid) was succesfully tested with a muon beam in September 2001 at the Gamma Irradiation Facility (GIF) at CERN. For the first time also both muon detectors for the CMS barrel (DT + RPC) were coupled together. The results of this test were fully succesful and confirmed the excellent performance of both detectors together in a radiation environment.

Intense Ion Beams for Warm Dense Matter Physics

International Nuclear Information System (INIS)

Heimbucher, Lynn; Coleman, Joshua Eugene

2008-01-01

The Neutralized Drift Compression Experiment (NDCX) at Lawrence Berkeley National Laboratory is exploring the physical limits of compression and focusing of ion beams for heating material to warm dense matter (WDM) and fusion ignition conditions. The NDCX is a beam transport experiment with several components at a scale comparable to an inertial fusion energy driver. The NDCX is an accelerator which consists of a low-emittance ion source, high-current injector, solenoid matching section, induction bunching module, beam neutralization section, and final focusing system. The principal objectives of the experiment are to control the beam envelope, demonstrate effective neutralization of the beam space-charge, control the velocity tilt on the beam, and understand defocusing effects, field imperfections, and limitations on peak intensity such as emittance and aberrations. Target heating experiments with space-charge dominated ion beams require simultaneous longitudinal bunching and transverse focusing. A four-solenoid lattice is used to tune the beam envelope to the necessary focusing conditions before entering the induction bunching module. The induction bunching module provides a head-to-tail velocity ramp necessary to achieve peak axial compression at the desired focal plane. Downstream of the induction gap a plasma column neutralizes the beam space charge so only emittance limits the focused beam intensity. We present results of beam transport through a solenoid matching section and simultaneous focusing of a singly charged K + ion bunch at an ion energy of 0.3 MeV. The results include a qualitative comparison of experimental and calculated results after the solenoid matching section, which include time resolved current density, transverse distributions, and phase-space of the beam at different diagnostic planes. Electron cloud and gas measurements in the solenoid lattice and in the vicinity of intercepting diagnostics are also presented. Finally, comparisons of

The Electron Drift Instrument on Cluster: overview of first results

Directory of Open Access Journals (Sweden)

G. Paschmann

Full Text Available EDI measures the drift velocity of artificially injected electron beams. From this drift velocity, the perpendicular electric field and the local magnetic field gradients can be deduced when employing different electron energies. The technique requires the injection of two electron beams at right angles to the magnetic field and the search for those directions within the plane that return the beams to their associated detectors after one or more gyrations. The drift velocity is then derived from the directions of the two beams and/or from the difference in their times-of-flight, measured via amplitude-modulation and coding of the emitted electron beams and correlation with the signal from the returning electrons. After careful adjustment of the control parameters, the beam recognition algorithms, and the onboard magnetometer calibrations during the commissioning phase, EDI is providing excellent data over a wide range of conditions. In this paper, we present first results in a variety of regions ranging from the polar cap, across the magnetopause, and well into the magnetosheath.

Key words. Electron drift velocity (electric fields; plasma convection; instruments and techniques

Electrons in a positive-ion beam with solenoid or quadrupole magnetic transport

International Nuclear Information System (INIS)

Molvik, A.W.; Kireeff Covo, M.; Cohen, R.; Coleman, J.; Sharp, W.; Bieniosek, F.; Friedman, A.; Roy, P.K.; Seidl, P.; Lund, S.M.; Faltens, A.; Vay, J.L.; Prost, L.

2007-01-01

The High Current Experiment (HCX) is used to study beam transport and accumulation of electrons in quadrupole magnets and the Neutralized Drift-Compression Experiment (NDCX) to study beam transport through and accumulation of electrons in magnetic solenoids. We find that both clearing and suppressor electrodes perform as intended, enabling electron cloud densities to be minimized. Then, the measured beam envelopes in both quadrupoles and solenoids agree with simulations, indicating that theoretical beam current transport limits are reliable, in the absence of electrons. At the other extreme, reversing electrode biases with the solenoid transport effectively traps electrons; or, in quadrupole magnets, grounding the suppressor electrode allows electron emission from the end wall to flood the beam, in both cases producing significant degradation in the beam

Effect of ion and ion-beam mass ratio on the formation of ion-acoustic solitons in magnetized plasma in the presence of electron inertia

International Nuclear Information System (INIS)

Kalita, B. C.; Barman, S. N.

2009-01-01

The propagation of ion-acoustic solitary waves in magnetized plasma with cold ions and ion-beams together with electron inertia has been investigated theoretically through the Korteweg-de Vries equation. Subject to the drift velocity of the ion beam, the existence of compressive solitons is found to become extinct as α (=cold ion mass/ion-beam mass) tends to 0.01 when γ=0.985 (γ is the beam velocity/phase velocity). Interestingly, a transitional direction of propagation of solitary waves has been unearthed for change over, from compressive solitons to rarefactive solitons based on α and σ υ (=cosine of the angle θ made by the wave propagation direction ξ with the direction of the magnetic field) for fixed Q(=electron mass/ion mass). Further, the direction of propagation of ion-acoustic waves is found to be the deterministic factor to admit compressive or rarefactive solitons subject to beam outsource.

Study of the variation of maximum beam size with quadrupole gradient in the FMIT drift tube linac

International Nuclear Information System (INIS)

Boicourt, G.P.; Jameson, R.A.

1981-01-01

The sensitivity of maximum beam size to input mismatch is studied as a function of quadrupole gradient in a short, high-current, drift-tube linac (DTL), for two presriptions: constant phase advance with constant filling factor; and constant strength with constant-length quads. Numerical study using PARMILA shows that the choice of quadrupole strength that minimizes the maximum transverse size of the matched beam through subsequent cells of the linac tends to be most sensitive to input mismatch. However, gradients exist nearby that result in almost-as-small beams over a suitably broad range of mismatch. The study was used to choose the initial gradient for the DTL portion of the Fusion Material Irradiation Test (FMIT) linac. The matching required across quad groups is also discussed

Beam steering performance of compressed Luneburg lens based on transformation optics

Science.gov (United States)

Gao, Ju; Wang, Cong; Zhang, Kuang; Hao, Yang; Wu, Qun

2018-06-01

In this paper, two types of compressed Luneburg lenses based on transformation optics are investigated and simulated using two different sources, namely, waveguides and dipoles, which represent plane and spherical wave sources, respectively. We determined that the largest beam steering angle and the related feed point are intrinsic characteristics of a certain type of compressed Luneburg lens, and that the optimized distance between the feed and lens, gain enhancement, and side-lobe suppression are related to the type of source. Based on our results, we anticipate that these lenses will prove useful in various future antenna applications.

Spatiotemporal light-beam compression from nonlinear mode coupling

Science.gov (United States)

Krupa, Katarzyna; Tonello, Alessandro; Couderc, Vincent; Barthélémy, Alain; Millot, Guy; Modotto, Daniele; Wabnitz, Stefan

2018-04-01

We experimentally demonstrate simultaneous spatial and temporal compression in the propagation of light pulses in multimode nonlinear optical fibers. We reveal that the spatial beam self-cleaning recently discovered in graded-index multimode fibers is accompanied by significant temporal reshaping and up to fourfold shortening of the injected subnanosecond laser pulses. Since the nonlinear coupling among the modes strongly depends on the instantaneous power, we explore the entire range of the nonlinear dynamics with a single optical pulse, where the optical power is continuously varied across the pulse profile.

Highly Compressed Ion Beams for High Energy Density Science

CERN Document Server

Friedman, Alex; Briggs, Richard J; Callahan, Debra; Caporaso, George; Celata, C M; Davidson, Ronald C; Faltens, Andy; Grant-Logan, B; Grisham, Larry; Grote, D P; Henestroza, Enrique; Kaganovich, Igor D; Lee, Edward; Lee, Richard; Leitner, Matthaeus; Nelson, Scott D; Olson, Craig; Penn, Gregory; Reginato, Lou; Renk, Tim; Rose, David; Sessler, Andrew M; Staples, John W; Tabak, Max; Thoma, Carsten H; Waldron, William; Welch, Dale; Wurtele, Jonathan; Yu, Simon

2005-01-01

The Heavy Ion Fusion Virtual National Laboratory (HIF-VNL) is developing the intense ion beams needed to drive matter to the High Energy Density (HED) regimes required for Inertial Fusion Energy (IFE) and other applications. An interim goal is a facility for Warm Dense Matter (WDM) studies, wherein a target is heated volumetrically without being shocked, so that well-defined states of matter at 1 to 10 eV are generated within a diagnosable region. In the approach we are pursuing, low to medium mass ions with energies just above the Bragg peak are directed onto thin target "foils," which may in fact be foams or "steel wool" with mean densities 1% to 100% of solid. This approach complements that being pursued at GSI, wherein high-energy ion beams deposit a small fraction of their energy in a cylindrical target. We present the requirements for warm dense matter experiments, and describe suitable accelerator concepts, including novel broadband traveling wave pulse-line, drift-tube linac, RF, and single-gap approa...

Charge-exchange and fusion reaction measurements during compression experiments with neutral beam heating in the Tokamak Fusion Test Reactor

International Nuclear Information System (INIS)

Kaita, R.; Heidbrink, W.W.; Hammett, G.W.

1986-04-01

Adiabatic toroidal compression experiments were performed in conjunction with high power neutral beam injection in the Tokamak Fusion Test Reactor (TFTR). Acceleration of beam ions to energies nearly twice the injection energy was measured with a charge-exchange neutral particle analyzer. Measurements were also made of 2.5 MeV neutrons and 15 MeV protons produced in fusion reactions between the deuterium beam ions and the thermal deuterium and 3 He ions, respectively. When the plasma was compressed, the d(d,n) 3 He fusion reaction rate increased a factor of five, and the 3 He(d,p) 4 He rate by a factor of twenty. These data were simulated with a bounce-averaged Fokker-Planck program, which assumed conservation of angular momentum and magnetic moment during compression. The results indicate that the beam ion acceleration was consistent with adiabatic scaling

First test experiment to produce the slowed-down RI beam with the momentum-compression mode at RIBF

Energy Technology Data Exchange (ETDEWEB)

Sumikama, T., E-mail: sumikama@ribf.riken.jp [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Department of Physics, Tohoku University, Aoba, Sendai 980-8578 (Japan); Ahn, D.S.; Fukuda, N.; Inabe, N.; Kubo, T.; Shimizu, Y.; Suzuki, H.; Takeda, H. [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Aoi, N. [Research Center for Nuclear Physics, Osaka University, Ibaraki, Osaka 567-0047 (Japan); Beaumel, D. [Institut de Physique Nucléaire d’Orsay (IPNO), CNRS/IN2P3, 91405 Orsay (France); Hasegawa, K. [Department of Physics, Tohoku University, Aoba, Sendai 980-8578 (Japan); Ideguchi, E. [Research Center for Nuclear Physics, Osaka University, Ibaraki, Osaka 567-0047 (Japan); Imai, N. [Center for Nuclear Study, University of Tokyo, RIKEN Campus, 2-1 Hirosawa, Wako, Saitama 351-0298 (Japan); Kobayashi, T. [Department of Physics, Tohoku University, Aoba, Sendai 980-8578 (Japan); Matsushita, M.; Michimasa, S. [Center for Nuclear Study, University of Tokyo, RIKEN Campus, 2-1 Hirosawa, Wako, Saitama 351-0298 (Japan); Otsu, H. [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Shimoura, S. [Center for Nuclear Study, University of Tokyo, RIKEN Campus, 2-1 Hirosawa, Wako, Saitama 351-0298 (Japan); Teranishi, T. [Department of Physics, Kyushu University, 6-10-1 Hakozaki, Fukuoka 812-8581 (Japan)

2016-06-01

The {sup 82}Ge beam has been produced by the in-flight fission reaction of the {sup 238}U primary beam with 345 MeV/u at the RIKEN RI beam factory, and slowed down to about 15 MeV/u using the energy degraders. The momentum-compression mode was applied to the second stage of the BigRIPS separator to reduce the momentum spread. The energy was successfully reduced down to 13 ± 2.5 MeV/u as expected. The focus was not optimized at the end of the second stage, therefore the beam size was larger than the expectation. The transmission of the second stage was half of the simulated value mainly due to out of focus. The two-stage separation worked very well for the slowed-down beam with the momentum-compression mode.

Low Power Measurements on a Finger Drift Tube Linac

CERN Document Server

Schempp, A

2004-01-01

The efficiency of RFQs decreases at higher particle energies. The DTL structures used in this energy regions have a defocusing influence on the beam. To achieve a focusing effect, fingers with quadrupole symmetry were added to the drift tubes. Driven by the same power supply as the drift tubes, the fingers do not need an additional power source or feedthrough. Beam dynamics have been studied with PARMTEQ . Detailed analysis of the field distribution was done and the geometry of the finger array has been optimized with respect to beam dynamics. A spiral loaded cavity with finger drift tubes was built up and low power measurements were done. In this contribution, the results of the rf simulating with Microwave Studio are shown in comparison with bead pertubation measurement on a prototype cavity.

CROSS DRIFT ALCOVE/NICHE UTILITIES ANALYSIS

International Nuclear Information System (INIS)

S. Goodin

1999-01-01

The purpose of this analysis is to provide the design basis and general arrangement requirements of the non-potable water, waste water, compressed air and ventilation (post excavation) utilities required in support of the Cross Drift alcoves and niches

Intense Ion Beam for Warm Dense Matter Physics

Energy Technology Data Exchange (ETDEWEB)

Coleman, Joshua Eugene [Univ. of California, Berkeley, CA (United States)

2008-01-01

The Neutralized Drift Compression Experiment (NDCX) at Lawrence Berkeley National Laboratory is exploring the physical limits of compression and focusing of ion beams for heating material to warm dense matter (WDM) and fusion ignition conditions. The NDCX is a beam transport experiment with several components at a scale comparable to an inertial fusion energy driver. The NDCX is an accelerator which consists of a low-emittance ion source, high-current injector, solenoid matching section, induction bunching module, beam neutralization section, and final focusing system. The principal objectives of the experiment are to control the beam envelope, demonstrate effective neutralization of the beam space-charge, control the velocity tilt on the beam, and understand defocusing effects, field imperfections, and limitations on peak intensity such as emittance and aberrations. Target heating experiments with space-charge dominated ion beams require simultaneous longitudinal bunching and transverse focusing. A four-solenoid lattice is used to tune the beam envelope to the necessary focusing conditions before entering the induction bunching module. The induction bunching module provides a head-to-tail velocity ramp necessary to achieve peak axial compression at the desired focal plane. Downstream of the induction gap a plasma column neutralizes the beam space charge so only emittance limits the focused beam intensity. We present results of beam transport through a solenoid matching section and simultaneous focusing of a singly charged K⁺ ion bunch at an ion energy of 0.3 MeV. The results include a qualitative comparison of experimental and calculated results after the solenoid matching section, which include time resolved current density, transverse distributions, and phase-space of the beam at different diagnostic planes. Electron cloud and gas measurements in the solenoid lattice and in the vicinity of intercepting diagnostics are also presented. Finally

Small-scale lacustrine drifts in Lake Champlain, Vermont

Science.gov (United States)

Manley, Patricia L.; Manley, T.O.; Hayo, Kathryn; Cronin, Thomas

2012-01-01

High resolution CHIRP (Compressed High Intensity Radar Pulse) seismic profiles reveal the presence of two lacustrine sediment drifts located in Lake Champlain's Juniper Deep. Both drifts are positive features composed of highly laminated sediments. Drift B sits on a basement high while Drift A is built on a trough-filling acoustically-transparent sediment unit inferred to be a mass-transport event. These drifts are oriented approximately north–south and are parallel to a steep ridge along the eastern shore of the basin. Drift A, located at the bottom of a structural trough, is classified as a confined, elongate drift that transitions northward to become a system of upslope asymmetric mudwaves. Drift B is perched atop a structural high to the west of Drift A and is classified as a detached elongate drift. Bottom current depositional control was investigated using Acoustic Doppler Current Profilers (ADCPs) located across Drift A. Sediment cores were taken at the crest and at the edges of the Drift A and were dated. Drift source, deposition, and evolution show that these drifts are formed by a water column shear with the highest deposition occurring along its crest and western flank and began developing circa 8700–8800 year BP.

Method of controlling coherent synchroton radiation-driven degradation of beam quality during bunch length compression

Science.gov (United States)

Douglas, David R [Newport News, VA; Tennant, Christopher D [Williamsburg, VA

2012-07-10

A method of avoiding CSR induced beam quality defects in free electron laser operation by a) controlling the rate of compression and b) using a novel means of integrating the compression with the remainder of the transport system: both are accomplished by means of dispersion modulation. A large dispersion is created in the penultimate dipole magnet of the compression region leading to rapid compression; this large dispersion is demagnified and dispersion suppression performed in a final small dipole. As a result, the bunch is short for only a small angular extent of the transport, and the resulting CSR excitation is small.

Effect of drift-acoustic waves on magnetic island stability in slab geometry

International Nuclear Information System (INIS)

Fitzpatrick, R.; Waelbroeck, F.L.

2005-01-01

A mathematical formalism is developed for calculating the ion polarization term in the Rutherford island width evolution equation in the presence of drift-acoustic waves. The calculation is fully nonlinear, includes both ion and electron diamagnetic effects, as well as ion compressibility, but is performed in slab geometry. Magnetic islands propagating in a certain range of phase velocities are found to emit drift-acoustic waves. Wave emission gives rise to rapid oscillations in the ion polarization term as the island phase velocity varies, and also generates a net electromagnetic force acting on the island region. Increasing ion compressibility is found to extend the range of phase velocities over which drift-acoustic wave emission occurs in the electron diamagnetic direction

Multispecies Weibel Instability for Intense Ion Beam Propagation Through Background Plasma

CERN Document Server

Davidson, Ronald C; Kaganovich, Igor D; Qin, Hong; Startsev, Edward

2005-01-01

In application of heavy ion beams to high energy density physics and fusion, background plasma is utilized to neutralize the beam space charge during drift compression and/or final focus of the ion beam. It is important to minimize the deleterious effects of collective instabilities on beam quality associated with beam-plasma interactions. Plasma electrons tend to neutralize both the space charge and current of the beam ions. It is shown that the presence of the return current greatly modifies the electromagnetic Weibel instability (also called the filamentation instability), i.e., the growth rate of the filamentation instability greatly increases if the background ions are much lighter than the beam ions and the plasma density is comparable to the ion beam density. This may preclude using underdense plasma of light gases in heavy ion beam applications. It is also shown that the return current may be subject to the fast electrostatic two-stream instability.

Longitudinal compression of heavy-ion beams with minimum requirements on final focus

International Nuclear Information System (INIS)

Ho, D.D.M.; Bangerter, R.O.; Mark, J.W.K.; Brandon, S.T.; Lee, E.P.

1986-01-01

A method is developed to compress a heavy-ion beam longitudinally in such a way that the compressed pulse has a constant line-charge density profile and uniform longitudinal momentum. These conditions may be important from the standpoint of final focusing. By realizing the similarity of the equations that describe the 1-D charged-particle motion to the equations that describe 1-D ideal gas flow, the evolution of lambda and the velocity tilt can be calculated using the method of characteristics developed for unsteady supersonic gasdynamics. Particle simulations confirm the theory. Various schemes for pulse shaping have been investigated

Drift chamber

International Nuclear Information System (INIS)

Inagaki, Yosuke

1977-01-01

Drift chamber is becoming an important detector in high energy physics as a precision and fast position detector because of its high spatial resolution and count-rate. The basic principle is that it utilizes the drift at constant speed of electrons ionized along the tracks of charged particles towards the anode wire in the nearly uniform electric field. The method of measuring drift time includes the analog and digital ones. This report describes about the construction of and the application of electric field to the drift chamber, mathematical analysis on the electric field and equipotential curve, derivation of spatial resolution and the factor for its determination, and selection of gas to be used. The performance test of the chamber was carried out using a small test chamber, the collimated β source of Sr-90, and 500 MeV/C electron beam from the 1.3 GeV electron synchrotron in the Institute of Nuclear Study, University of Tokyo. Most chambers to date adopted one dimensional read-out, but it is very advantageous if the two dimensional read-out is feasible with one chamber when the resolution in that direction is low. The typical methods of delay line and charge division for two dimensional read-out are described. The development of digital read-out system is underway, which can process the signal of a large scale drift chamber at high speed. (Wakatsuki, Y.)

Velocity bunching of high-brightness electron beams

Directory of Open Access Journals (Sweden)

S. G. Anderson

2005-01-01

Full Text Available Velocity bunching has been recently proposed as a tool for compressing electron beam pulses in modern high brightness photoinjector sources. This tool is familiar from earlier schemes implemented for bunching dc electron sources, but presents peculiar challenges when applied to high current, low emittance beams from photoinjectors. The main difficulty foreseen is control of emittance oscillations in the beam in this scheme, which can be naturally considered as an extension of the emittance compensation process at moderate energies. This paper presents two scenarios in which velocity bunching, combined with emittance control, is to play a role in nascent projects. The first is termed ballistic bunching, where the changing of relative particle velocities and positions occur in distinct regions, a short high gradient linac, and a drift length. This scenario is discussed in the context of the proposed ORION photoinjector. Simulations are used to explore the relationship between the degree of bunching, and the emittance compensation process. Experimental measurements performed at the UCLA Neptune Laboratory of the surprisingly robust bunching process, as well as accompanying deleterious transverse effects, are presented. An unanticipated mechanism for emittance growth in bends for highly momentum chirped beam was identified and studied in these experiments. The second scenario may be designated as phase space rotation, and corresponds closely to the recent proposal of Ferrario and Serafini. Its implementation for the compression of the electron beam pulse length in the PLEIADES inverse Compton scattering (ICS experiment at LLNL is discussed. It is shown in simulations that optimum compression may be obtained by manipulation of the phases in low gradient traveling wave accelerator sections. Measurements of the bunching and emittance control achieved in such an implementation at PLEIADES, as well as aspects of the use of velocity-bunched beam directly

Pulsar bi-drifting: implications for polar cap geometry

Science.gov (United States)

Wright, Geoff; Weltevrede, Patrick

2017-01-01

For many years it has been considered puzzling how pulsar radio emission, supposedly created by a circulating carousel of sub-beams, can produce the drift bands demonstrated by PSR J0815+0939, and more recently PSR B1839-04, which simultaneously drifts in opposing directions. Here, we suggest that the carousels of these pulsars, and hence their beams, are not circular but elliptical with axes tilted with respect to the fiducial plane. We show that certain relatively unusual lines of sight can cause bi-drifting to be observed, and a simulation of the two known exemplars is presented. Although bi-drifting is rare, non-circular beams may be common among pulsars and reveal themselves by having profile centroids displaced from the fiducial plane identified by polarization position angle swings. They may also result in profiles with asymmetric- and frequency-dependent component evolution. It is further suggested that the carousels may change their tilt by specific amounts and later reverse them. This may occur suddenly, accompanying a mode change (e.g. PSR B0943+10), or more gradually and short lived as in `flare' pulsars (e.g. PSR B1859+07). A range of pulsar behaviour (e.g. the shifting drift patterns of PSRs B0818-41 and B0826-34) may also be the result of non-circular carousels with varying orientation. The underlying nature of these carousels - whether they are exclusively generated by polar cap physics or driven by magnetospheric effects - is briefly discussed.

Performance predictions of a focused ion beam from a laser cooled and compressed atomic beam

Energy Technology Data Exchange (ETDEWEB)

Haaf, G. ten; Wouters, S. H. W.; Vredenbregt, E. J. D.; Mutsaers, P. H. A. [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Geer, S. B. van der [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Pulsar Physics, Burghstraat 47, 5614 BC Eindhoven (Netherlands)

2014-12-28

Focused ion beams are indispensable tools in the semiconductor industry because of their ability to image and modify structures at the nanometer length scale. Here, we report on performance predictions of a new type of focused ion beam based on photo-ionization of a laser cooled and compressed atomic beam. Particle tracing simulations are performed to investigate the effects of disorder-induced heating after ionization in a large electric field. They lead to a constraint on this electric field strength which is used as input for an analytical model which predicts the minimum attainable spot size as a function of, amongst others, the flux density of the atomic beam, the temperature of this beam, and the total current. At low currents (I < 10 pA), the spot size will be limited by a combination of spherical aberration and brightness, while at higher currents, this is a combination of chromatic aberration and brightness. It is expected that a nanometer size spot is possible at a current of 1 pA. The analytical model was verified with particle tracing simulations of a complete focused ion beam setup. A genetic algorithm was used to find the optimum acceleration electric field as a function of the current. At low currents, the result agrees well with the analytical model, while at higher currents, the spot sizes found are even lower due to effects that are not taken into account in the analytical model.

Two-beam virtual cathode accelerator

International Nuclear Information System (INIS)

Peter, W.

1992-01-01

A proposed method to control the motion of a virtual cathode is investigated. Applications to collective ion acceleration and microwave generation are indicated. If two counterstreaming relativistic electron beams of current I are injected into a drift tube of space-charge-limiting current I L = 2I, it is shown that one beam can induce a moving virtual cathode in the other beam. By dynamically varying the current injected into the drift tube region, the virtual cathode can undergo controlled motion. For short drift tubes, the virtual cathodes on each end are strongly-coupled and undergo coherent large-amplitude spatial oscillations within the drift tube

Three dimensional simulations of space charge dominated heavy ion beams with applications to inertial fusion energy

International Nuclear Information System (INIS)

Grote, D.P.

1994-01-01

Heavy ion fusion requires injection, transport and acceleration of high current beams. Detailed simulation of such beams requires fully self-consistent space charge fields and three dimensions. WARP3D, developed for this purpose, is a particle-in-cell plasma simulation code optimized to work within the framework of an accelerator's lattice of accelerating, focusing, and bending elements. The code has been used to study several test problems and for simulations and design of experiments. Two applications are drift compression experiments on the MBE-4 facility at LBL and design of the electrostatic quadrupole injector for the proposed ILSE facility. With aggressive drift compression on MBE-4, anomalous emittance growth was observed. Simulations carried out to examine possible causes showed that essentially all the emittance growth is result of external forces on the beam and not of internal beam space-charge fields. Dominant external forces are the dodecapole component of focusing fields, the image forces on the surrounding pipe and conductors, and the octopole fields that result from the structure of the quadrupole focusing elements. Goal of the design of the electrostatic quadrupole injector is to produce a beam of as low emittance as possible. The simulations show that the dominant effects that increase the emittance are the nonlinear octopole fields and the energy effect (fields in the axial direction that are off-axis). Injectors were designed that minimized the beam envelope in order to reduce the effect of the nonlinear fields. Alterations to the quadrupole structure that reduce the nonlinear fields further were examined. Comparisons were done with a scaled experiment resulted in very good agreement

Electron beam instabilities in gyrotron beam tunnels

International Nuclear Information System (INIS)

Pedrozzi, M.; Alberti, S.; Hogge, J.P.; Tran, M.Q.; Tran, T.M.

1997-10-01

Electron beam instabilities occurring in a gyrotron electron beam can induce an energy spread which might significantly deteriorate the gyrotron efficiency. Three types of instabilities are considered to explain the important discrepancy found between the theoretical and experimental efficiency in the case of quasi-optical gyrotrons (QOG): the electron cyclotron maser instability, the Bernstein instability and the Langmuir instability. The low magnetic field gradient in drift tubes of QOG makes that the electron cyclotron maser instability can develop in the drift tube at very low electron beam currents. Experimental measurements show that with a proper choice of absorbing structures in the beam tunnel, this instability can be suppressed. At high beam currents, the electrostatic Bernstein instability can induce a significant energy spread at the entrance of the interaction region. The induced energy spread scales approximately linearly with the electron beam density and for QOG one observes that the beam density is significantly higher than the beam density of an equivalent cylindrical cavity gyrotron. (author) figs., tabs., refs

Beam-Plasma Interaction Experiments on the Princeton Advanced Test Stand

Science.gov (United States)

Stepanov, A.; Gilson, E. P.; Grisham, L.; Kaganovich, I. D.; Davidson, R. C.

2011-10-01

The Princeton Advanced Test Stand (PATS) is a compact experimental facility for studying the fundamental physics of intense beam-plasma interactions relevant to the Neutralized Drift Compression Experiment - II (NDCX-II). The PATS facility consists of a 100 keV ion beam source mounted on a six-foot-long vacuum chamber with numerous ports for diagnostic access. A 100 keV Ar+ beam is launched into a volumetric plasma, which is produced by a ferroelectric plasma source (FEPS). Beam diagnostics upstream and downstream of the FEPS allow for detailed studies of the effects that the plasma has on the beam. This setup is designed for studying the dependence of charge and current neutralization and beam emittance growth on the beam and plasma parameters. This work reports initial measurements of beam quality produced by the extraction electrodes that were recently installed on the PATS device. The transverse beam phase space is measured with double-slit emittance scanners, and the experimental results are compared to WARP simulations of the extraction system. This research is supported by the U.S. Department of Energy.

The drift chamber array at the external target facility in HIRFL-CSR

Science.gov (United States)

Sun, Y. Z.; Sun, Z. Y.; Wang, S. T.; Duan, L. M.; Sun, Y.; Yan, D.; Tang, S. W.; Yang, H. R.; Lu, C. G.; Ma, P.; Yu, Y. H.; Zhang, X. H.; Yue, K.; Fang, F.; Su, H.

2018-06-01

A drift chamber array at the External Target Facility in HIRFL-CSR has been constructed for three-dimensional particle tracking in high-energy radioactive ion beam experiments. The design, readout, track reconstruction program and calibration procedures for the detector are described. The drift chamber array was tested in a 311 AMeV 40Ar beam experiment. The detector performance based on the measurements of the beam test is presented. A spatial resolution of 230 μm is achieved.

Measurements of the toroidal plasma rotation velocity in TFTR major-radius compression experiments with auxiliary neutral beam heating

International Nuclear Information System (INIS)

Bitter, M.; Wong, K.L.; Scott, S.; Hsuan, H.; Grek, B.; Johnson, D.; Tait, G.

1990-01-01

The time history of the central toroidal plasma rotation velocity in Tokamak Fusion Test Reactor (TFTR) experiments [Phys. Rev. Lett. 55, 2587 (1985)] with auxiliary heating by neutral deuterium beam injection and major-radius compression has been measured from the Doppler shift of the emitted Ti XXI Kα line radiation. The experiments were conducted for neutral beam powers in the range 2.1--3.8 MW and line-averaged densities in the range 1.8--3.0x10 19 m -2 . The observed rotation velocity increase during compression is consistent with theoretical estimates

Short intense ion pulses for materials and warm dense matter research

Energy Technology Data Exchange (ETDEWEB)

Seidl, Peter A., E-mail: PASeidl@lbl.gov [Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Persaud, Arun; Waldron, William L. [Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Barnard, John J. [Lawrence Livermore National Laboratory, Livermore, CA (United States); Davidson, Ronald C. [Princeton Plasma Physics Laboratory, Princeton, NJ (United States); Friedman, Alex [Lawrence Livermore National Laboratory, Livermore, CA (United States); Gilson, Erik P. [Princeton Plasma Physics Laboratory, Princeton, NJ (United States); Greenway, Wayne G. [Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Grote, David P. [Lawrence Livermore National Laboratory, Livermore, CA (United States); Kaganovich, Igor D. [Princeton Plasma Physics Laboratory, Princeton, NJ (United States); Lidia, Steven M.; Stettler, Matthew; Takakuwa, Jeffrey H.; Schenkel, Thomas [Lawrence Berkeley National Laboratory, Berkeley, CA (United States)

2015-11-11

We have commenced experiments with intense short pulses of ion beams on the Neutralized Drift Compression Experiment-II at Lawrence Berkeley National Laboratory, by generating beam spots size with radius r<1 mm within 2 ns FWHM and approximately 10{sup 10} ions/pulse. To enable the short pulse durations and mm-scale focal spot radii, the 1.2 MeV Li{sup +} ion beam is neutralized in a 1.6-meter drift compression section located after the last accelerator magnet. An 8-Tesla short focal length solenoid compresses the beam in the presence of the large volume plasma near the end of this section before the target. The scientific topics to be explored are warm dense matter, the dynamics of radiation damage in materials, and intense beam and beam-plasma physics including selected topics of relevance to the development of heavy-ion drivers for inertial fusion energy. Here we describe the accelerator commissioning and time-resolved ionoluminescence measurements of yttrium aluminum perovskite using the fully integrated accelerator and neutralized drift compression components.

Short intense ion pulses for materials and warm dense matter research

International Nuclear Information System (INIS)

Seidl, Peter A.; Persaud, Arun; Waldron, William L.; Barnard, John J.; Davidson, Ronald C.; Friedman, Alex; Gilson, Erik P.; Greenway, Wayne G.; Grote, David P.; Kaganovich, Igor D.; Lidia, Steven M.; Stettler, Matthew; Takakuwa, Jeffrey H.; Schenkel, Thomas

2015-01-01

We have commenced experiments with intense short pulses of ion beams on the Neutralized Drift Compression Experiment-II at Lawrence Berkeley National Laboratory, by generating beam spots size with radius r<1 mm within 2 ns FWHM and approximately 10"1"0 ions/pulse. To enable the short pulse durations and mm-scale focal spot radii, the 1.2 MeV Li"+ ion beam is neutralized in a 1.6-meter drift compression section located after the last accelerator magnet. An 8-Tesla short focal length solenoid compresses the beam in the presence of the large volume plasma near the end of this section before the target. The scientific topics to be explored are warm dense matter, the dynamics of radiation damage in materials, and intense beam and beam-plasma physics including selected topics of relevance to the development of heavy-ion drivers for inertial fusion energy. Here we describe the accelerator commissioning and time-resolved ionoluminescence measurements of yttrium aluminum perovskite using the fully integrated accelerator and neutralized drift compression components.

Validation of the Read Out Electronics for the CMS Muon Drift Chambers at Tests Beam in CERN/GIF; Validacion en el Test Beam del CERN/GIF de la electronica de Lectura de las Camaras de Muones del Experimento CMS

Energy Technology Data Exchange (ETDEWEB)

Fernandez, C.; Fouz, M. c.; Marin, J.; Oller, J. C.; Willmott, C.; Amigo, L. J.

2002-07-01

Part of the readout system for the CMS muon drift chambers has been tested in test beams at CERN/GIF. Read Out Board (ROB) and HPTD have been validated with signals from a real muon beam, with an structure and flux similar to LHC operating conditions and using one of the chambers produced in CIEMAT already located in the test beam area under normal gas and voltage conditions. (Author) 5 refs.

Investigations in a drift chamber using 250 MHz analogue-digital-converters

International Nuclear Information System (INIS)

Scharf, F.A.

1993-06-01

The performance of a new 250 MHz FADC module was investigated in a small drift chamber system. Straight tracks were induced in the chamber volume by UV-LASER beams. The time resolution was determined from drift time measurements for four neighbouring signal wires. By use of a beam splitter a pair of parallel beams was produced. An appropriate rotation of this pair relative to the signal wire plane allowed the determination of the double hit resolution. A comparison of the obtained values with the results achieved with 100 MHz FADC modules showed that the new module is well suited for chamber read out. The attainable improvements however are small. (orig.) [de

SPS Beam Steering for LHC Extraction

Energy Technology Data Exchange (ETDEWEB)

Gianfelice-Wendt, Eliana [Fermilab; Bartosik, Hannes [CERN; Cornelis, Karel [CERN; Norderhaug Drøsdal, Lene [CERN; Goddard, Brennan [CERN; Kain, Verena [CERN; Meddahi, Malika [CERN; Papaphilippou, Yannis [CERN; Wenninger, Jorg [CERN

2014-07-01

The CERN Super Proton Synchrotron accelerates beams for the Large Hadron Collider to 450 GeV. In addition it produces beams for fixed target facilities which adds complexity to the SPS operation. During the run 2012-2013 drifts of the extracted beam trajectories have been observed and lengthy optimizations in the transfer lines were performed to reduce particle losses in the LHC. The observed trajectory drifts are consistent with the measured SPS orbit drifts at extraction. While extensive studies are going on to understand, and possibly suppress, the source of such SPS orbit drifts the feasibility of an automatic beam steering towards a “golden” orbit at the extraction septa, by means of the interlocked correctors, is also being investigated. The challenges and constraints related to the implementation of such a correction in the SPS are described. Simulation results are presented and a possible operational steering strategy is proposed.

Beam line design for a low energy electron beam

International Nuclear Information System (INIS)

Arvind Kumar; Mahadevan, S.

2002-01-01

The design of a beam line for transport of a 70 keV electron beam from a thermionic gun to the Plane Wave Transformer (PWT) linac incorporating two solenoid magnets, a beam profile monitor and drift sections is presented. We used beam dynamics codes EGUN, PARMELA and compare simulated results with analytical calculations. (author)

Measurements of the toroidal plasma rotation velocity in TFTR major-radius compression experiments with auxiliary neutral beam heating

International Nuclear Information System (INIS)

Bitter, M.; Scott, S.; Wong, K.L.

1986-07-01

The time history of the central toroidal plasma rotation velocity in Tokamak Fusion Test Reactor (TFTR) experiments with auxiliary heating by neutral deuterium beam injection and major-radius compression has been measured from the Doppler shift of the emitted TiXXI-Kα line radiation. The experiments were conducted for neutral beam powers in the range from 2.1 to 3.8 MW and line-averaged densities in the range from 1.8 to 3.0 x 10 19 m -2 . The observed rotation velocity increase during compression is in agreement with results from modeling calculations which assume classical slowing-down of the injected fast deuterium ions and momentum damping at the rate established in the precompression plasma

Intense ion beam neutralization using underdense background plasma

Energy Technology Data Exchange (ETDEWEB)

Berdanier, William [Department of Physics, The University of Texas at Austin, Austin, Texas 78712 (United States); Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States); Roy, Prabir K. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Kaganovich, Igor [Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States)

2015-01-15

Producing an overdense background plasma for neutralization purposes with a density that is high compared to the beam density is not always experimentally possible. We show that even an underdense background plasma with a small relative density can achieve high neutralization of intense ion beam pulses. Using particle-in-cell simulations, we show that if the total plasma electron charge is not sufficient to neutralize the beam charge, electron emitters are necessary for effective neutralization but are not needed if the plasma volume is so large that the total available charge in the electrons exceeds that of the ion beam. Several regimes of possible underdense/tenuous neutralization plasma densities are investigated with and without electron emitters or dense plasma at periphery regions, including the case of electron emitters without plasma, which does not effectively neutralize the beam. Over 95% neutralization is achieved for even very underdense background plasma with plasma density 1/15th the beam density. We compare results of particle-in-cell simulations with an analytic model of neutralization and find close agreement with the particle-in-cell simulations. Further, we show experimental data from the National Drift Compression experiment-II group that verifies the result that underdense plasma can neutralize intense heavy ion beams effectively.

Intense relativistic electron beam: generation and propagation

International Nuclear Information System (INIS)

Mittal, K.C.; Mondal, J.

2010-01-01

A general review of relativistic electron beam extracted from explosive field emission diode has been presented here. The beam current in the diode gap taking into account cathode and anode plasma expansion velocity and excluding the self magnetic field effect is directly proportional to gap voltage V 3/2 and inversely proportional to the square of the effective diode gap (d-vt). In the limit of high current, self magnetic field focusing effect comes into play and results in a critical current at which pinching will take place. When the diode current exceeds the critical current, the electron flow is in the para-potential regime. Different diode geometries such as planner, coaxial, rod-pinched, reflex triode are discussed qualitatively. When the beam is injected into a vacuum drift tube the propagation of the beam is only possible in presence of a strong axial magnetic field which prevents the beam expansion in the radial direction. If the beam is injected in the drift tube filled with dense plasma, then the redistribution of the plasma electrons effectively neutralizes the beam space charge, resulting subsequent propagation of the beam along the drift tube. The beam propagation through neutral gas is similar to the plasma filled drift tube. In this case both the neutral gas pressure and the beam current regulate the transmission of the REB. (author)

Single wire drift chamber design

International Nuclear Information System (INIS)

Krider, J.

1987-01-01

This report summarizes the design and prototype tests of single wire drift chambers to be used in Fermilab test beam lines. The goal is to build simple, reliable detectors which require a minimum of electronics. Spatial resolution should match the 300 μm rms resolution of the 1 mm proportional chambers that they will replace. The detectors will be used in beams with particle rates up to 20 KHz. Single track efficiency should be at least 99%. The first application will be in the MT beamline, which has been designed for calibration of CDF detectors. A set of four x-y modules will be used to track and measure the momentum of beam particles

Continuously live image processor for drift chamber track segment triggering

International Nuclear Information System (INIS)

Berenyi, A.; Chen, H.K.; Dao, K.

1999-01-01

The first portion of the BaBar experiment Level 1 Drift Chamber Trigger pipeline is the Track Segment Finder (TSF). Using a novel method incorporating both occupancy and drift-time information, the TSF system continually searches for segments in the supercells of the full 7104-wire Drift Chamber hit image at 3.7 MHz. The TSF was constructed to operate in a potentially high beam-background environment while achieving high segment-finding efficiency, deadtime-free operation, a spatial resolution of 5 simulated physics events

Modelling of the space-to-drift-time relationship of the ATLAS monitored drift-tube chambers in the presence of magnetic fields

International Nuclear Information System (INIS)

Dubbert, J.; Horvat, S.; Khartchenko, D.; Kortner, O.; Kotov, S.; Kroha, H.; Manz, A.; Nikolaev, K.; Rauscher, F.; Richter, R.; Staude, A.; Valderanis, Ch.

2007-01-01

The ATLAS muon spectrometer uses tracking chambers consisting of up to 5m long drift tubes filled with Ar:CO 2 (93:7) at 3bar. The chambers are run in a average toroidal magnetic field of 0.4T created by 8 air core coils. They provide a track-point accuracy of 40μm if the space-to-drift-time relationship r(t) is known with 20μm accuracy. The magnetic field B influences the electron drift inside the tubes: the maximum drift time t max =700ns increases by ∼70ns/T 2 B 2 . B varies by up to +/-0.4T along the tubes of the chambers mounted near the magnet coils which translates into a variation of t max of up to 45ns. The dependence of r(t) on B must be taken into account. Test-beam measurements show that the electron drift in case of B 0 can be modelled with the required accuracy by a Langevin equation with a friction term which is slightly non-linear in the drift velocity

Compression of Ultrafast Laser Beams

Science.gov (United States)

2016-03-01

Copyright 2003, AIP Publishing LLC. DOI: http://dx.doi.org/10.1063/1.1611998.) When designing the pulse shaper, the laser beam must completely fill the...for the design of future versions of this device. The easiest way to align the pulse shaper is to use the laser beam that will be shaped, without...Afterward, an ultrafast thin beam splitter is placed into the system after the diameter of the laser beam is reduced; this is done to monitor the beam

HIGH ENERGY DENSITY PHYSICS EXPERIMENTS WITH INTENSE HEAVY ION BEAMS

International Nuclear Information System (INIS)

Bieniosek, F.M.; Henestroza, E.; Leitner, M.; Logan, B.G.; More, R.M.; Roy, P.K.; Ni, P.; Seidl, P.A.; Waldron, W.L.; Barnard, J.J.

2008-01-01

The US heavy ion fusion science program has developed techniques for heating ion-beam-driven warm dense matter (WDM) targets. The WDM conditions are to be achieved by combined longitudinal and transverse space-charge neutralized drift compression of the ion beam to provide a hot spot on the target with a beam spot size of about 1 mm, and pulse length about 1-2 ns. As a technique for heating volumetric samples of matter to high energy density, intense beams of heavy ions are capable of delivering precise and uniform beam energy deposition dE/dx, in a relatively large sample size, and the ability to heat any solid-phase target material. Initial experiments use a 0.3 MeV K+ beam (below the Bragg peak) from the NDCX-I accelerator. Future plans include target experiments using the NDCX-II accelerator, which is designed to heat targets at the Bragg peak using a 3-6 MeV lithium ion beam. The range of the beams in solid matter targets is about 1 micron, which can be lengthened by using porous targets at reduced density. We have completed the fabrication of a new experimental target chamber facility for WDM experiments, and implemented initial target diagnostics to be used for the first target experiments in NDCX-1. The target chamber has been installed on the NDCX-I beamline. The target diagnostics include a fast multi-channel optical pyrometer, optical streak camera, VISAR, and high-speed gated cameras. Initial WDM experiments will heat targets by compressed NDCX-I beams and will explore measurement of temperature and other target parameters. Experiments are planned in areas such as dense electronegative targets, porous target homogenization and two-phase equation of state

Defocusing of an ion beam propagating in background plasma due to two-stream instability

Energy Technology Data Exchange (ETDEWEB)

Tokluoglu, Erinc; Kaganovich, Igor D. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

2015-04-15

The current and charge neutralization of charged particle beams by background plasma enable ballistic beam propagation and have a wide range of applications in inertial fusion and high energy density physics. However, the beam-plasma interaction can result in the development of collective instabilities that may have deleterious effects on ballistic propagation of an ion beam. In the case of fast, light-ion beams, non-linear fields created by instabilities can lead to significant defocusing of the beam. We study an ion beam pulse propagating in a background plasma, which is subjected to two-stream instability between the beam ions and plasma electrons, using PIC code LSP. The defocusing effects of the instability on the beam can be much more pronounced in small radius beams. We show through simulations that a beamlet produced from an ion beam passed through an aperture can be used as a diagnostic tool to identify the presence of the two-stream instability and quantify its defocusing effects. The effect can be observed on the Neutralized Drift Compression Experiment-II facility by measuring the spot size of the extracted beamlet propagating through several meters of plasma.

Fast non-explosive gases for drift chambers

International Nuclear Information System (INIS)

Green, D.; Haggerty, H.; Oshima, N.; Yamada, R.

1988-05-01

Typical gases which are stock at Fermilab are Ar:C 2 H 6 (50:50) and Ar:CO 2 (80:20). Argon:Ethane has the virtue of high gas gain and a saturated drift velocity. In fact, parametrizing the drift velocity as a function of electric field we find v/sub d/(E) = v/sub o/(1/minus/e/sup -E/E/o) with v/sub o/ ≅ 5.4 cm/μsec and E/sub o/ = 160 V/cm. However, safety considerations make this gas somewhat inconvenient. The addition of alcohol as quencher also raises the saturation field to, for example, E/sub o/ ≅ 500 V/cm for 1.5% added alcohol. This gas also tends to break up in a high-beam flux environment and leave carbon deposits. The addition of alcohol to avoid such aging often takes a unit cell out of saturation over its entire volume. Finally, for collider applications it is useful to exclude free protons from the gas in order to reduce the sensitivity to the sea of slow neutrons which are present in the collider environment. In contrast, Ar:CO 2 (80:20) is a gas with more moderate gas gain. The drift velocity at high field is v/sub d/(E > 1.5 kV/cm) ≅ 5.8 cm/μsec. For most field configurations this gas does not saturate, causing a long tail in the drift time distrubtion due to low field regions in the unit cell. The virtues of this gas mixture are that it is cheap, not flammable, and stable under high-beam flux. However as the Collider Upgrade progresses, we wish to find a gas which is faster than 5.0 cm/μsec since the time separation between collisions will at some point be less than drift time of 1μsec for drift distance of 5 cm. 3 refs., 5 figs

Measurement and simulation of the drift pulses and resolution in the micro-jet chamber

International Nuclear Information System (INIS)

Va'vra, J.

1983-01-01

We have tested a prototype of a micro-jet chamber, using both a nitrogen laser and a 10GeV electron beam. The achieved resolution in the particle beam was sigma = 18μm for a lmm impact parameter and 22μm when averaging over the entire beam profile. The experimental results were compared to a Monte Carlo program which simulates the pulse shapes and resolution in drift chambers of any geometry. The main emphasis in our simulation analysis was to study various strategies for drift chambers in order to achieve the best possible timing resolution

Trigger drift chamber for the upgraded mark II detector at PEP

Science.gov (United States)

Ford, W. T.; Smith, J. G.; Wagner, S. R.; Weber, P.; White, S. L.; Alvarez, M.; Calviño, F.; Fernandez, E.

1987-04-01

A small cylindrical track detector was built as an array of single-wire drift cells with aluminized mylar cathode tubes. Point measurement resolution of ˜ 90 μm was achieved with a drift gas of 50% argon-50% ethane at atmospheric pressure. The chamber construction, electronics, and calibration are discussed. Performance results from PEP colliding-beam data are presented.

Emittance Growth during Bunch Compression in the CTF-II

Energy Technology Data Exchange (ETDEWEB)

Raubenheimer, Tor O

1999-02-26

Measurements of the beam emittance during bunch compression in the CLIC Test Facility (CTF-II) are described. The measurements were made with different beam charges and different energy correlations versus the bunch compressor settings which were varied from no compression through the point of full compression and to over-compression. Significant increases in the beam emittance were observed with the maximum emittance occurring near the point of full (maximal) compression. Finally, evaluation of possible emittance dilution mechanisms indicate that coherent synchrotron radiation was the most likely cause.

Diogene pictorial drift chamber

International Nuclear Information System (INIS)

Gosset, J.

1984-01-01

A pictorial drift chamber, called DIOGENE, has been installed at Saturne in order to study central collisions of high energy heavy ions. It has been adapted from the JADE internal detector, with two major differences to be taken into account. First, the center-of-mass of these collisions is not identical to the laboratory reference frame. Second, the energy loss and the momentum ranges of the particles to be detected are different from the ones in JADE. It was also tried to keep the cost as small as possible, hence the choice of minimum size and minimum number of sensitive wires. Moreover the wire planes are shifted from the beam axis: this trick helps very much to quickly reject the bad tracks caused by the ambiguity of measuring drift distances (positive or negative) through times (always positive)

Fluffy dust forms icy planetesimals by static compression

Science.gov (United States)

Kataoka, Akimasa; Tanaka, Hidekazu; Okuzumi, Satoshi; Wada, Koji

2013-09-01

Context. Several barriers have been proposed in planetesimal formation theory: bouncing, fragmentation, and radial drift problems. Understanding the structure evolution of dust aggregates is a key in planetesimal formation. Dust grains become fluffy by coagulation in protoplanetary disks. However, once they are fluffy, they are not sufficiently compressed by collisional compression to form compact planetesimals. Aims: We aim to reveal the pathway of dust structure evolution from dust grains to compact planetesimals. Methods: Using the compressive strength formula, we analytically investigate how fluffy dust aggregates are compressed by static compression due to ram pressure of the disk gas and self-gravity of the aggregates in protoplanetary disks. Results: We reveal the pathway of the porosity evolution from dust grains via fluffy aggregates to form planetesimals, circumventing the barriers in planetesimal formation. The aggregates are compressed by the disk gas to a density of 10-3 g/cm3 in coagulation, which is more compact than is the case with collisional compression. Then, they are compressed more by self-gravity to 10-1 g/cm3 when the radius is 10 km. Although the gas compression decelerates the growth, the aggregates grow rapidly enough to avoid the radial drift barrier when the orbital radius is ≲6 AU in a typical disk. Conclusions: We propose a fluffy dust growth scenario from grains to planetesimals. It enables icy planetesimal formation in a wide range beyond the snowline in protoplanetary disks. This result proposes a concrete initial condition of planetesimals for the later stages of the planet formation.

Construction and test of a silicon drift chamber

International Nuclear Information System (INIS)

Holl, P.

1985-06-01

The present thesis presents the first fully applicable silicon detectors which work as drift chambers. Four different types of detectors were constructed. By a suitable geometry and electronic lay-out one- and two-dimensional position measurements were made possible. Chapter 2 describes function and construction of the detectors, chapter 3 their fabrication process. In chapter 4 construction and results of the test of a silicon drift chamber under laboratory conditions are described. By variation of the applied voltages the optimal operational conditions could be determined and material properties of the silicon, as for instance the electron mobility measured. A position resolution better than 5 μm at a drift length up to 4 mm was reached. Chapter 5 presents the results of the test of a silicon drift chamber under real experimental conditions in a particle beam of the super proton synchroton (SPS) of CERN. The best position resolution measured there is 10 μm. Chapter 6 summarizes the obtained results and discusses finally application possibilities and improvement proposals for silicon drift chambers. (orig./HSI) [de

Current neutralization of nanosecond risetime, high-current electron beam

International Nuclear Information System (INIS)

Lidestri, J.P.; Spence, P.W.; Bailey, V.L.; Putnam, S.D.; Fockler, J.; Eichenberger, C.; Champney, P.D.

1991-01-01

This paper reports that the authors have recently investigated methods to achieve current neutralization in fast risetime (<3 ns) electron beams propagating in low-pressure gas. For this investigation, they injected a 3-MV, 30-kA intense beam into a drift cell containing gas pressures from 0.10 to 20 torr. By using a fast net current monitor (100-ps risetime), it was possible to observe beam front gas breakdown phenomena and to optimize the drift cell gas pressure to achieve maximum current neutralization. Experimental observations have shown that by increasing the drift gas pressure (P ∼ 12.5 torr) to decrease the mean time between secondary electron/gas collisions, the beam can propagate with 90% current neutralization for the full beam pulsewidth (16 ns)

Trigger drift chamber for the upgraded Mark II detector at PEP

International Nuclear Information System (INIS)

Ford, W.T.; Smith, J.G.; Wagner, S.R.; Weber, P.; White, S.L.; Alvarez, M.; Calvino, F.; Fernandez, E.; Universidad Autonoma de Barcelona

1987-01-01

A small cylindrical track detector was built as an array of single-wire drift cells with aluminized mylar cathode tubes. Point measurement resolution of ∝90 μm was achieved with a drift gas of 50% argon-50% ethane at atmospheric pressure. The chamber construction, electronics, and calibration are discussed. Performance results from PEP colliding-beam data are presented. (orig.)

Dφ vertex drift chamber construction and test results

International Nuclear Information System (INIS)

Clark, A.R.; Goozen, F.; Grudberg, P.; Klopfenstein, C.; Kerth, L.T.; Loken, S.C.; Oltman, E.; Strovink, M.; Trippe, T.G.

1991-05-01

A jet-cell based vertex chamber has been built for the D OE experiment at Fermilab and operated in a test beam there. Low drift velocity and diffusion properties were achieved using CO 2 (95%)-ethane(5%) at atmospheric pressure. The drift velocity is found to be consistent with [9.74+8.68(|E|-1.25)] μm/nsec where E is the electric field strength in (kV/cm < |E| z 1.6 kV/cm.) An intrinsic spatial resolution of 60 μm or better for drift distances greater than 2 mm is measured. The track pair efficiency is estimated to be better than 90% for separations greater than 630 μm. 8 refs., 6 figs., 1 tab

The drift chamber system of the MEG experiment

Energy Technology Data Exchange (ETDEWEB)

Hildebrandt, Malte, E-mail: malte.hildebrandt@psi.c [Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland)

2010-11-01

The MEG experiment searches for the lepton flavour violating decay {mu}{yields}e{gamma} and is aiming for a sensitivity of 10{sup -13} in the branching ratio in order to probe new physics beyond the standard model. The experiment is located at the Paul Scherrer Institut (PSI) in Switzerland, where one of the world's most intensive surface muon beams is located. Physics data taking started in September 2008. The drift chamber system is part of the innovative positron spectrometer of the MEG experiment and consists of 16 drift chamber modules. The system is designed to ensure precision measurement of 52.8 MeV/c positrons. Design, construction, geometrical alignment and performance of the drift chamber system are presented.

Collective Focusing of Intense Ion Beam Pulses for High-energy Density Physics Applications

International Nuclear Information System (INIS)

Dorf, Mikhail A.; Kaganovich, Igor D.; Startsev, Edward A.; Davidson, Ronald C.

2011-01-01

The collective focusing concept in which a weak magnetic lens provides strong focusing of an intense ion beam pulse carrying a neutralizing electron background is investigated by making use of advanced particle-in-cell simulations and reduced analytical models. The original analysis by Robertson Phys. Rev. Lett. 48, 149 (1982) is extended to the parameter regimes of particular importance for several high-energy density physics applications. The present paper investigates (1) the effects of non-neutral collective focusing in a moderately strong magnetic field; (2) the diamagnetic effects leading to suppression of the applied magnetic field due to the presence of the beam pulse; and (3) the influence of a finite-radius conducting wall surrounding the beam cross-section on beam neutralization. In addition, it is demonstrated that the use of the collective focusing lens can significantly simplify the technical realization of the final focusing of ion beam pulses in the Neutralized Drift Compression Experiment-I (NDCX-I), and the conceptual designs of possible experiments on NDCX-I are investigated by making use of advanced numerical simulations.

Ultra-High Density Electron Beams for Beam Radiation and Beam Plasma Interaction

CERN Document Server

Anderson, Scott; Frigola, Pedro; Gibson, David J; Hartemann, Fred V; Jacob, Jeremy S; Lim, Jae; Musumeci, Pietro; Rosenzweig, James E; Travish, Gil; Tremaine, Aaron M

2005-01-01

Current and future applications of high brightness electron beams, which include advanced accelerators such as the plasma wake-field accelerator (PWFA) and beam-radiation interactions such as inverse-Compton scattering (ICS), require both transverse and longitudinal beam sizes on the order of tens of microns. Ultra-high density beams may be produced at moderate energy (50 MeV) by compression and subsequent strong focusing of low emittance, photoinjector sources. We describe the implementation of this method used at LLNL's PLEIADES ICS x-ray source in which the photoinjector-generated beam has been compressed to 300 fsec duration using the velocity bunching technique and focused to 20 μm rms size using an extremely high gradient, permanent magnet quadrupole (PMQ) focusing system.

Study and analysis of drift chamber parameters

International Nuclear Information System (INIS)

Martinez Laso, L.

1988-01-01

The present work deals mainly with drift chambers. In the first chapter a summary of drift chamber properties is presented. The information has been collected from the extensive bibliography available in this field. A very simple calculation procedure of drift chamber parameters has been developed and is presented in detail in the second chapter. Some prototypes have been made following two geometries (multidrift chamber and Z-chambers). Several installations have been used for test and calibration of these prototypes. A complete description of these installations is given in the third chapter. Cosmic rays, beta particles from a Ru106 radiactive source and a test beam in the WA (West Area) of SPS at CERN have been used for experimental purposes. The analysis and the results are described for the different setups. The experimental measurements have been used to produce a complete cell parametrization (position as function of drift time) and to obtain spatial resolution values (in the range of 200-250 um). Experimental results are in good agreement with numerical calculations. (Author)

Focused ion beam (FIB) milling of electrically insulating specimens using simultaneous primary electron and ion beam irradiation

International Nuclear Information System (INIS)

Stokes, D J; Vystavel, T; Morrissey, F

2007-01-01

There is currently great interest in combining focused ion beam (FIB) and scanning electron microscopy technologies for advanced studies of polymeric materials and biological microstructures, as well as for sophisticated nanoscale fabrication and prototyping. Irradiation of electrically insulating materials with a positive ion beam in high vacuum can lead to the accumulation of charge, causing deflection of the ion beam. The resultant image drift has significant consequences upon the accuracy and quality of FIB milling, imaging and chemical vapour deposition. A method is described for suppressing ion beam drift using a defocused, low-energy primary electron beam, leading to the derivation of a mathematical expression to correlate the ion and electron beam energies and currents with other parameters required for electrically stabilizing these challenging materials

Catching the Drift : Using Feature-Free Case-Based Reasoning for Spam Filtering.

OpenAIRE

Delany, Sarah Jane; Bridge, Derek

2007-01-01

n this paper, we compare case-based spam filters, focusing on their resilience to concept drift. In particular, we evaluate how to track concept drift using a case-based spam filter that uses a feature-free distance measure based on text compression. In our experiments, we compare two ways to normalise such a distance measure, finding that the one proposed in [1] performs better. We show that a policy as simple as retaining misclassified examples has a hugely beneficial effect on handling con...

A robust H.264/AVC video watermarking scheme with drift compensation.

Science.gov (United States)

Jiang, Xinghao; Sun, Tanfeng; Zhou, Yue; Wang, Wan; Shi, Yun-Qing

2014-01-01

A robust H.264/AVC video watermarking scheme for copyright protection with self-adaptive drift compensation is proposed. In our scheme, motion vector residuals of macroblocks with the smallest partition size are selected to hide copyright information in order to hold visual impact and distortion drift to a minimum. Drift compensation is also implemented to reduce the influence of watermark to the most extent. Besides, discrete cosine transform (DCT) with energy compact property is applied to the motion vector residual group, which can ensure robustness against intentional attacks. According to the experimental results, this scheme gains excellent imperceptibility and low bit-rate increase. Malicious attacks with different quantization parameters (QPs) or motion estimation algorithms can be resisted efficiently, with 80% accuracy on average after lossy compression.

The Roles of Fluid Compression and Shear in Electron Energization during Magnetic Reconnection

Science.gov (United States)

Li, Xiaocan; Guo, Fan; Li, Hui; Birn, Joachim

2018-03-01

Particle acceleration in space and astrophysical reconnection sites is an important unsolved problem in studies of magnetic reconnection. Earlier kinetic simulations have identified several acceleration mechanisms that are associated with particle drift motions. Here, we show that, for sufficiently large systems, the energization processes due to particle drift motions can be described as fluid compression and shear, and that the shear energization is proportional to the pressure anisotropy of energetic particles. By analyzing results from fully kinetic simulations, we show that the compression energization dominates the acceleration of high-energy particles in reconnection with a weak guide field, and the compression and shear effects are comparable when the guide field is 50% of the reconnecting component. Spatial distributions of those energization effects reveal that reconnection exhausts, contracting islands, and island-merging regions are the three most important regions for compression and shear acceleration. This study connects particle energization by particle guiding-center drift motions with that due to background fluid motions, as in the energetic particle transport theory. It provides foundations for building particle transport models for large-scale reconnection acceleration such as those in solar flares.

Drift-free MPEG-4 AVC semi-fragile watermarking

Science.gov (United States)

Hasnaoui, M.; Mitrea, M.

2014-02-01

While intra frame drifting is a concern for all types of MPEG-4 AVC compressed-domain video processing applications, it has a particular negative impact in watermarking. In order to avoid the drift drawbacks, two classes of solutions are currently considered in the literature. They try either to compensate the drift distortions at the expense of complex decoding/estimation algorithms or to restrict the insertion to the blocks which are not involved in the prediction, thus reducing the data payload. The present study follows a different approach. First, it algebraically models the drift distortion spread problem by considering the analytic expressions of the MPEG-4 AVC encoding operations. Secondly, it solves the underlying algebraic system under drift-free constraints. Finally, the advanced solution is adapted to take into account the watermarking peculiarities. The experiments consider an m-QIM semi-fragile watermarking method and a video surveillance corpus of 80 minutes. For prescribed data payload (100 bit/s), robustness (BER < 0.1 against transcoding at 50% in stream size), fragility (frame modification detection with accuracies of 1/81 from the frame size and 3s) and complexity constraints, the modified insertion results in gains in transparency of 2 dB in PSNR, of 0.4 in AAD, of 0.002 in IF, of 0.03 in SC, of 0.017 NCC and 22 in DVQ.

Plasma properties of a modified beam-plasma type ion source

International Nuclear Information System (INIS)

Ishikawa, Junzo; Sano, Fumimichi; Tsuji, Hiroshi; Ektessabi, A.M.; Takagi, Toshinori

1978-01-01

The properties of the plasma produced by beam-plasma discharge were experimentally investigated. The ion source used for this work consists of three parts, that is, the ion-extracting region with an electron gun, the drift space and the collector region. Primary and secondary electron beams are injected in to the drift tube. The interaction between plasma and these electron beams causes production of high density plasma by virtue of the beam-plasma discharge. The gas inlet is located in the middle of the drift tube, so that the gas conductance is high. The energy of the primary and secondary electron beams is transferred to that microwaves through beam-plasma interaction. The microwaves heat the plasma electrons by the cyclotron resonance or other mechanism. The amount of the energetic plasma electrons is much larger than that of the beam electrons, so that neutral gas is ionized. The density of the produced plasma is 10 2 or 10 3 times as large as the plasma produced by impact ionization. With a probe located in the middle of the drift tube, the plasma density and the electron temperature can be measured, and the power and spectra of the microwaves can be detected. The microwave oscillation, the primary electron beam characteristics, and the gas pressure characteristics were studied. Larger current of the high energy primary of secondary electron beam is required for the effective discharge. The ion source has to be operated at the minimum gas pressure. The length of beam-plasma interaction and the magnetic field intensity in the drift tube are also important parameters. (Kato, T.)

Fast electron microscopy via compressive sensing

Science.gov (United States)

Larson, Kurt W; Anderson, Hyrum S; Wheeler, Jason W

2014-12-09

Various technologies described herein pertain to compressive sensing electron microscopy. A compressive sensing electron microscope includes a multi-beam generator and a detector. The multi-beam generator emits a sequence of electron patterns over time. Each of the electron patterns can include a plurality of electron beams, where the plurality of electron beams is configured to impart a spatially varying electron density on a sample. Further, the spatially varying electron density varies between each of the electron patterns in the sequence. Moreover, the detector collects signals respectively corresponding to interactions between the sample and each of the electron patterns in the sequence.

Evaluation of Negative-Ion-Beam Driver Concepts for Heavy Ion Fusion

International Nuclear Information System (INIS)

Grisham, Larry R.

2002-01-01

We evaluate the feasibility of producing and using atomically neutral heavy ion beams produced from negative ions as drivers for an inertial confinement fusion reactor. Bromine and iodine appear to be the most attractive elements for the driver beams. Fluorine and chlorine appear to be the most appropriate feedstocks for initial tests of extractable negative ion current densities. With regards to ion sources, photodetachment neutralizers, and vacuum requirements for accelerators and beam transport, this approach appears feasible within existing technology, and the vacuum requirements are essentially identical to those for positive ion drivers except in the target chamber. The principal constraint is that this approach requires harder vacuums in the target chamber than do space-charge-neutralized positive ion drivers. With realistic (but perhaps pessimistic) estimates of the total ionization cross section, limiting the ionization of a neutral beam to less than 5% while traversing a four -meter path would require a chamber pressure of no more than 5 x 10 -5 torr. Alternatively, even at chamber pressures that are too high to allow propagation of atomically neutral beams, the negative ion approach may still have appeal, since it precludes the possibly serious problem of electron contamination of a positive ion beam during acceleration, drift compression, and focusing

A Robust H.264/AVC Video Watermarking Scheme with Drift Compensation

Directory of Open Access Journals (Sweden)

Xinghao Jiang

2014-01-01

Full Text Available A robust H.264/AVC video watermarking scheme for copyright protection with self-adaptive drift compensation is proposed. In our scheme, motion vector residuals of macroblocks with the smallest partition size are selected to hide copyright information in order to hold visual impact and distortion drift to a minimum. Drift compensation is also implemented to reduce the influence of watermark to the most extent. Besides, discrete cosine transform (DCT with energy compact property is applied to the motion vector residual group, which can ensure robustness against intentional attacks. According to the experimental results, this scheme gains excellent imperceptibility and low bit-rate increase. Malicious attacks with different quantization parameters (QPs or motion estimation algorithms can be resisted efficiently, with 80% accuracy on average after lossy compression.

Simulations in the Analysis of Experimental Data Measured by BM@N Drift Chambers

Science.gov (United States)

Fedorišin, Ján

2018-02-01

The drift chambers (DCH's) are an important part of the tracking system of the BM@N experiment designed to study the production of baryonic matter at the Nuclotron energies. The method of particle hit and track reconstruction in the drift chambers has been already proposed and tested on the BM@N deuteron beam data. In this study the DCH's are first locally and globally aligned, and subsequently the consistency of the track reconstruction chain is tested by two methods. The first one is based on the backward extrapolation of the DCH reconstructed deuteron beam to a position where its deflection in the BM@N magnetic field begins. The second method reconstructs the deuteron beam momentum through its deflection angle. Both methods confirm correctness of the track reconstruction algorithm.

Ultra-Short Electron Beam Compression and Phase Locking Using an Inverse Free Electron Laser Interaction in the THz Regime

International Nuclear Information System (INIS)

Moody, J. T.; Musumeci, P.; Scoby, C. M.; To, H.; Marcoux, C.

2010-01-01

The concept of a THz-based IFEL compressor at the UCLA Pegasus photoinjector laboratory is explored. A 3.5 MeV sub-picosecond electron beam generated in the photoinjector blowout regime can be compressed to femtosecond timescales by a THz IFEL interaction.

Space-charge effects on the propagation of hollow electron beams

International Nuclear Information System (INIS)

Barroso, J.J.; Stellati, C.

1994-01-01

The dynamics of hollow electron beams with gyro motion propagating down a cylindrical drift tube is analysed on the basis of a non-adiabatic-gun-generated laminar beam. Due to the action of beam's self-space charge field, the transverse velocity spread has an oscillatory behavior along the drift tube wherein the spatial auto modulation period shortens with increasing current. Numerical simulation results indicate that even at a 10 A beam current, the resulting transverse velocity spread is still less than the spread for a zero beam current. (author). 5 refs, 3 figs

Effects of magnetic drift tangential to magnetic surfaces on neoclassical transport in non-axisymmetric plasmas

International Nuclear Information System (INIS)

Matsuoka, Seikichi; Satake, Shinsuke; Kanno, Ryutaro; Sugama, Hideo

2015-01-01

In evaluating neoclassical transport by radially local simulations, the magnetic drift tangential to a flux surface is usually ignored in order to keep the phase-space volume conservation. In this paper, effect of the tangential magnetic drift on the local neoclassical transport is investigated. To retain the effect of the tangential magnetic drift in the local treatment of neoclassical transport, a new local formulation for the drift kinetic simulation is developed. The compressibility of the phase-space volume caused by the tangential magnetic drift is regarded as a source term for the drift kinetic equation, which is solved by using a two-weight δf Monte Carlo method for non-Hamiltonian system [G. Hu and J. A. Krommes, Phys. Plasmas 1, 863 (1994)]. It is demonstrated that the effect of the drift is negligible for the neoclassical transport in tokamaks. In non-axisymmetric systems, however, the tangential magnetic drift substantially changes the dependence of the neoclassical transport on the radial electric field E r . The peaked behavior of the neoclassical radial fluxes around E r  =   0 observed in conventional local neoclassical transport simulations is removed by taking the tangential magnetic drift into account

Effects of magnetic drift tangential to magnetic surfaces on neoclassical transport in non-axisymmetric plasmas

Energy Technology Data Exchange (ETDEWEB)

Matsuoka, Seikichi, E-mail: matsuoka@rist.or.jp [Research Organization for Information Science and Technology, 6F Kimec-Center Build., 1-5-2 Minatojima-minamimachi, Chuo-ku, Kobe 650-0047 (Japan); Satake, Shinsuke; Kanno, Ryutaro [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan); Department of Fusion Science, SOKENDAI (The Graduate University for Advanced Studies), 322-6 Oroshi-cho, Toki 509-5292 (Japan); Sugama, Hideo [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan)

2015-07-15

In evaluating neoclassical transport by radially local simulations, the magnetic drift tangential to a flux surface is usually ignored in order to keep the phase-space volume conservation. In this paper, effect of the tangential magnetic drift on the local neoclassical transport is investigated. To retain the effect of the tangential magnetic drift in the local treatment of neoclassical transport, a new local formulation for the drift kinetic simulation is developed. The compressibility of the phase-space volume caused by the tangential magnetic drift is regarded as a source term for the drift kinetic equation, which is solved by using a two-weight δf Monte Carlo method for non-Hamiltonian system [G. Hu and J. A. Krommes, Phys. Plasmas 1, 863 (1994)]. It is demonstrated that the effect of the drift is negligible for the neoclassical transport in tokamaks. In non-axisymmetric systems, however, the tangential magnetic drift substantially changes the dependence of the neoclassical transport on the radial electric field E{sub r}. The peaked behavior of the neoclassical radial fluxes around E{sub r }={sub  }0 observed in conventional local neoclassical transport simulations is removed by taking the tangential magnetic drift into account.

Resolution and Efficiency of the ATLAS Muon Drift-Tube Chambers at High Background Rates

CERN Document Server

Deile, M.; Horvat, S.; Kortner, O.; Kroha, H.; Manz, A.; Mohrdieck-Mock, S.; Rauscher, F.; Richter, Robert; Staude, A.; Stiller, W.

2016-01-01

The resolution and efficiency of a precision drift-tube chamber for the ATLAS muon spectrometer with final read-out electronics was tested at the Gamma Irradiation Facility at CERN in a 100 GeV muon beam and at photon irradiation rates of up to 990 Hz/square cm which corresponds to twice the highest background rate expected in ATLAS. A silicon strip detector telescope was used as external reference in the beam. The pulse-height measurement of the read-out electronics was used to perform time-slewing corrections which lead to an improvement of the average drift-tube resolution from 104 microns to 82 microns without irradiation and from 128 microns to 108 microns at the maximum expected rate. The measured drift-tube efficiency agrees with the expectation from the dead time of the read-out electronics up to the maximum expected rate.

Neutral beam monitoring

International Nuclear Information System (INIS)

Fink, J.H.

1979-01-01

A neutral beam generated by passing accelerated ions through a walled cell containing a low energy neutral gas, such that charge exchange partially neutralizes the high energy beam, is monitored by detecting the current flowing through the cell wall produced by low energy ions which drift to the wall after the charge exchange. By segmenting the wall into radial and longitudinal segments various beam conditions are identified. (U.K.)

Studies of beam position monitor stability

International Nuclear Information System (INIS)

Tenenbaum, P.

1998-05-01

The authors present the result s from two studies of the time stability between the mechanical center of a beam position monitor and its electrical/electronic center. In the first study, a group of 93 BPM processors was calibrated via Test Pulse Generator once per hour in order to measure the contribution of the readout electronics to offset drifts. In the second study, a triplet of stripline BPMs in the Final Focus Test Beam, separated only by drift spaces, was read out every 6 minutes during 1 week of beam operation. In both cases offset stability was observed to be on the order of microns over time spans ranging from hours to days, although during the beam study much worse performance was also observed. Implications for the beam position monitor system of future linear collider systems are discussed

Assembly of Drift Tubes (DT) Chambers at CIEMAT (Madrid)

CERN Multimedia

Jesus Puerta-Pelayo

2003-01-01

The construction of muon drift tube chambers (DT) has been carried out in four different european institutes: Aachen (Germany), CIEMAT-Madrid (Spain), Legnaro and Turin (Italy), all of them following similar procedures and quality tests. Each chamber is composed by three or two independent units called superlayers, with four layers of staggered drift cells each. The assembly of a superlayer is a succesive glueing of aluminium plates and I-beams with electrodes previously attached, forming a rectangular and gas-tight volume. These pictures illustrate the various processes of material preparation, construction, equipment and assembly of full chambers at CIEMAT (Madrid).

Automated cyclotron tuning using beam phase measurements

International Nuclear Information System (INIS)

Timmer, J.H.; Roecken, H.; Stephani, T.; Baumgarten, C.; Geisler, A.

2006-01-01

The ACCEL K250 superconducting cyclotron is specifically designed for the use in proton therapy systems. The compact medical 250 MeV proton accelerator fulfils all present and future beam requirements for fast scanning treatment systems and is delivered as a turn key system; no operator is routinely required. During operation of the cyclotron heat dissipation of the RF system induces a small drift in iron temperature. This temperature drift slightly detunes the magnetic field and small corrections must be made. A non-destructive beam phase detector has been developed to measure and quantify the effect of a magnetic field drift. Signal calculations were made and the design of the capacitive pickup probe was optimised to cover the desired beam current range. Measurements showed a very good agreement with the calculated signals and beam phase can be measured with currents down to 3 nA. The measured phase values are used as input for a feedback loop controlling the current in the superconducting coil. The magnetic field of the cyclotron is tuned automatically and online to maintain a fixed beam phase. Extraction efficiency is thereby optimised continuously and activation of the cyclotron is minimised. The energy and position stability of the extracted beam are well within specification

A straw drift chamber spectrometer for studies of rare kaon decays

International Nuclear Information System (INIS)

Lang, K.; Ambrose, D.; Arroyo, C.; Bachman, M.; Connor, D.; Eckhause, M.; Ecklund, K.M.; Graessle, S.; Hamela, M.; Hamilton, S.; Hancock, A.D.; Hartman, K.; Hebert, M.; Hoff, C.H.; Hoffmann, G.W.; Irwin, G.M.; Kane, J.R.; Kanematsu, N.; Kuang, Y.; Lee, R.; Marcin, M.; Martin, R.D.; McDonough, J.; Milder, A.; Molzon, W.R.; Ouimette, D.; Pommot-Maia, M.; Proga, M.; Riley, P.J.; Ritchie, J.L.; Rubin, P.D.; Vassilakopoulos, V.I.; Ware, B.; Welsh, R.E.; Wojcicki, S.G.; Worm, S.

2004-01-01

We describe the design, construction, readout, tests, and performance of planar drift chambers, based on 5-mm-diameter copperized Mylar and Kapton straws, used in an experimental search for rare kaon decays. The experiment took place in the high-intensity neutral beam at the Alternating Gradient Synchrotron of Brookhaven National Laboratory, using a neutral beam stop, two analyzing dipoles, and redundant particle identification to remove backgrounds

Drift chamber and pulse height readout systems using analog multiplexing

International Nuclear Information System (INIS)

Cisneros, E.L; Kang, H.K.; Hall, J.N.; Larsen, R.S.

1976-11-01

Drift chamber and pulse-height readout systems are being developed for use in a new large scale detector at the SPEAR colliding beam facility. The systems are based upon 32 channels of sample-and-hold together with an analog multiplexer in a single-width CAMAC module. The modules within each crate are scanned by an autonomous controller containing a single ADC and memory plus arithmetic capability for offset, gain and linearity corrections. The drift chamber module has a facility for extracting hit wire information for use in trigger decision circuitry

SU-F-T-121: Abdominal Compression Effectively Reduces the Interplay Effect and Enables Pencil Beam Scanning Proton Therapy of Liver Tumors

International Nuclear Information System (INIS)

Souris, K; Glick, A; Kang, M; Lin, H; McDonough, J; Simone, C; Solberg, T; Ben-Josef, E; Lin, L; Janssens, G; Sterpin, E; Lee, J

2016-01-01

Purpose: To study if abdominal compression can reduce breathing motion and mitigate interplay effect in pencil beam scanning proton therapy (PBSPT) treatment of liver tumors in order to better spare healthy liver volumes compared with photon therapy. Methods: Ten patients, six having large tumors initially treated with IMRT and four having small tumors treated with SBRT, were replanned for PBSPT. ITV and beam-specific PTVs based on 4D-CT were used to ensure target coverage in PBSPT. The use of an abdominal compression belt and volumetric repainting was investigated to mitigate the interplay effect between breathing motion and PBSPT dynamic delivery. An in-house Matlab script has been developed to simulate this interplay effect. The dose is computed on each phase individually by sorting all spots according to their simulated delivery timing. The final dose distribution is then obtained by accumulating all dose maps to a reference phase. Results: For equivalent target coverage PBSPT reduced average healthy liver dose by 9.5% of the prescription dose compared with IMRT/SBRT. Abdominal compression of 113.2±42.2 mmHg was effective for all 10 patients and reduced average motion by 2.25 mm. As a result, the average ITV volume decreased from 128.2% to 123.1% of CTV volume. Similarly, the average beam-specific PTV volume decreased from 193.2% to 183.3%. For 8 of the 10 patients, the average motion was reduced below 5 mm, and up to 3 repainting were sufficient to mitigate interplay. For the other two patients with larger residual motion, 4–5 repainting were needed. Conclusion: We recommend evaluation of the 4DCT motion histogram following simulation and the interplay effect following treatment planning in order to personalize the use of compression and volumetric repainting for each patient. Abdominal compression enables safe and more effective PBS treatment of liver tumors by reduction of motion and interplay effect. Kevin Souris is supported by IBA and Televie Grant

SU-F-T-121: Abdominal Compression Effectively Reduces the Interplay Effect and Enables Pencil Beam Scanning Proton Therapy of Liver Tumors

Energy Technology Data Exchange (ETDEWEB)

Souris, K [Universite catholique de Louvain, Brussels (Belgium); University of Pennsylvania, Philadelphia, PA (United States); Glick, A; Kang, M; Lin, H; McDonough, J; Simone, C; Solberg, T; Ben-Josef, E; Lin, L [University of Pennsylvania, Philadelphia, PA (United States); Janssens, G [IBA, Louvain-la-neuve (Belgium); Sterpin, E [Universite catholique de Louvain, Brussels (Belgium); KU Leuven, Leuven (Belgium); Lee, J [Universite catholique de Louvain, Brussels (Belgium)

2016-06-15

Purpose: To study if abdominal compression can reduce breathing motion and mitigate interplay effect in pencil beam scanning proton therapy (PBSPT) treatment of liver tumors in order to better spare healthy liver volumes compared with photon therapy. Methods: Ten patients, six having large tumors initially treated with IMRT and four having small tumors treated with SBRT, were replanned for PBSPT. ITV and beam-specific PTVs based on 4D-CT were used to ensure target coverage in PBSPT. The use of an abdominal compression belt and volumetric repainting was investigated to mitigate the interplay effect between breathing motion and PBSPT dynamic delivery. An in-house Matlab script has been developed to simulate this interplay effect. The dose is computed on each phase individually by sorting all spots according to their simulated delivery timing. The final dose distribution is then obtained by accumulating all dose maps to a reference phase. Results: For equivalent target coverage PBSPT reduced average healthy liver dose by 9.5% of the prescription dose compared with IMRT/SBRT. Abdominal compression of 113.2±42.2 mmHg was effective for all 10 patients and reduced average motion by 2.25 mm. As a result, the average ITV volume decreased from 128.2% to 123.1% of CTV volume. Similarly, the average beam-specific PTV volume decreased from 193.2% to 183.3%. For 8 of the 10 patients, the average motion was reduced below 5 mm, and up to 3 repainting were sufficient to mitigate interplay. For the other two patients with larger residual motion, 4–5 repainting were needed. Conclusion: We recommend evaluation of the 4DCT motion histogram following simulation and the interplay effect following treatment planning in order to personalize the use of compression and volumetric repainting for each patient. Abdominal compression enables safe and more effective PBS treatment of liver tumors by reduction of motion and interplay effect. Kevin Souris is supported by IBA and Televie Grant

Rf quadrupole beam dynamics

International Nuclear Information System (INIS)

Stokes, R.H.; Crandall, K.R.; Stovall, J.E.; Swenson, D.A.

1979-01-01

A method has been developed to analyze the beam dynamics of the radiofrequency quadrupole accelerating structure. Calculations show that this structure can accept a dc beam at low velocity, bunch it with high capture efficiency, and accelerate it to a velocity suitable for injection into a drift tube linac

A New Approach in the Simplification of a Multiple-Beam Forming Network Based on CORPS Using Compressive Arrays

Directory of Open Access Journals (Sweden)

Armando Arce

2012-01-01

Full Text Available This research paper deals with a innovative way to simplify the design of beam-forming networks (BFNs for multibeam steerable antenna arrays based on coherently radiating periodic structures (CORPS technology using the noniterative matrix pencil method (MPM. This design approach is based on the application of the MPM to linear arrays fed by CORPS-BFN configurations to further reduce the complexity of the beam-forming network. Two 2-beam design configurations of CORPS-BFN for a steerable linear array are analyzed and compared using this compressive method. Simulation results show the effectiveness and advantages of applying the MPM on BFNs based on CORPS exploiting the nonuniformity of the antenna elements. Furthermore, final results show that the integration of CORPS-BFN and MPM reduces the entire antenna system including the antenna array and the beam-forming network subsystem resulting in a substantial simplification in such systems.

Design and Fabrication of the Lithium Beam Ion Injector for NDCX-II

International Nuclear Information System (INIS)

Takakuwa, J.

2011-01-01

A 130 keV injector is developed for the NDCX-II facility. It consists of a 10.9 cm diameter lithium doped alumina-silicate ion source heated to ∼1300 C and 3 electrodes. Other components include a segmented Rogowski coil for current and beam position monitoring, a gate valve, pumping ports, a focusing solenoid, a steering coil and space for inspection and maintenance access. Significant design challenges including managing the 3-4 kW of power dissipation from the source heater, temperature uniformity across the emitter surface, quick access for frequent ion source replacement, mechanical alignment with tight tolerance, and structural stabilization of the cantilevered 27-inch OD graded HV ceramic column. The injector fabrication is scheduled to complete by May 2011, and assembly and installation is scheduled to complete by the beginning of July. The Neutralized Drift Compression eXperiment (NDCX-II) is for the study of high energy density physics and inertial fusion energy research utilizing a lithium ion (Li+) beam with a current of 93 mA and a pulse length of 500 ns (compressed to 1 ns at the target). The injector is one of the most complicated sections of the NDCX-II accelerator demanding significant design and fabrication resources. It needs to accommodate a relatively large ion source (10.9 cm), a high heat load (3-4 kW) and specific beam optics developed from the physics model. Some specific design challenges are noted in this paper.

Experimental work on drift chambers

International Nuclear Information System (INIS)

Alcaraz, J.; Duran, I.; Gonzalez, E.; Martinez-Laso, L.; Olmos, P.

1989-01-01

An experimental work made on drift chambers is described in two chapters. In the firt chapter we present the description of the experimental installation used, as well as some details on the data adquisition systems and the characteristics on three ways used for calibration proposes (cosmic muons, β radiation and test beam using SPS at CERN facilities). The second chapter describes the defferent prototypes studied. The experimental set up and the analysis are given. Some results are discussed. The magnetic field effect is also studied. (Author)

Electroluminescent drift chamber with 16 μm spatial resolution

International Nuclear Information System (INIS)

Baskakov, V.I.; Dolgoshein, V.A.; Lebedenko, V.N.

1978-01-01

Studied are the characteristics of the dft electroluminscent chamber of an original design. For insuring high spatial resolution, the chamber has been filled with xenon to a pressure of 20 atm, which substantially decreases the electron diffusion during drift. Located at the end of the drift gap is an anode wire, 50 μm in dia. A strong electric field available near the thin wire causes electroluminescence of the electrons. The signal is localized within a small volume and contribution of the luminescence time in the total duration of a signal is small. In this case no electron multiplication occurs at all and, consequently, no space charge of positive ions takes place, which makes it possible to operate at very high loadings (2x10 6 particle/s). The characteristics of the chamber are measured in a beam of the Serpukhov accelerator. Use has been made of a model comprising two chambers, 5 mm thick, located successively along the beam with the effective area being 40x40 mm. The studies and analysis performed reveal that the drift electroluminescent chamber operates reliably in the wide range of the working gas pressure at an intensity of the incident particles up to 10 5 particle/s. The best resolution is obtained at a pressure of 20 atm and it equals 16 μm

Numerical investigation of a plasma beam entering transverse magnetic fields

International Nuclear Information System (INIS)

Koga, J.; Geary, J.L.; Tajima, T.; Rostoker, N.

1988-11-01

We study plasma beam injection into transverse magnetic fields using both electrostatic and electromagnetic particle-in-cell (PIC) codes. In the case of small beam momentum or energy (low drift kinetic /beta/) we study both large and small ion gyroradius beams. Large ion gyroradius beams with a large dielectric constant /epsilon/ /muchreverse arrowgt/ (M/m)/sup /1/2// are found to propagate across the magnetic field via E /times/ B drifts at nearly the initial injection velocity, where /epsilon/ = 1 + (/omega//sup pi//sup 2/)/(/Omega//sub i//sup 2/) and (M/m) is the ion to electron mass ratio. Beam degradation and undulations are observed in agreement with previous experimental and analytical results. When /epsilon/ is on the order of (M/m)/sup /1/2//, the plasma beam propagates across field lines at only half its initial velocity and loses its coherent structure. When /epsilon/ is much less than (M/m)/sup /1/2//, the beam particles decouple at the magnetic field boundary, scattering the electrons and slightly deflecting the ions. For small ion gyroradius beam injection a flute type instability is observed at the beam magnetic fields interface. In the case of large beam momentum or energy (high drift kinetic /beta/) we observe good penetration of a plasma beam which shields the magnetic field from the interior of the beam (diagmagnetism). 25 refs., 13 figs., 1 tab

Quasi-static drift-tube accelerating structures for low-speed heavy ions

International Nuclear Information System (INIS)

Faltens, A.; Keefe, D.

1978-01-01

A pulsed drift-tube accelerating structure for use in Heavy Ion Fusion applications is described. Possible arrangements of components in such a structure, the injector design needs, and the influence of the existing state of component technology on drift-tube structure design are considered. It is concluded that the major attractions of the pulsed drift tubes are that they are nonresonant structures and that they appear suitable for accelerating a very high current bunch at low energies. The mechanical tolerances of the nonresonant structure are very loose and the cost per meter should be low; the cost of the transport system is expected to be the major cost. The pulse-power modulators used to drive the drift tubes are inexpensive compared with rf sources of equivalent peak power. The longitudinal emittance of the beam emerging from the structure could be extremely low. (U.K.)

Neutral beam program

International Nuclear Information System (INIS)

Anon.

1979-01-01

The structure of the beam injection program for the Doublet-3 device is discussed. The design considerations for the beam line and design parameters for the Doublet-3 ion souce are given. Major components of the neutral beam injector system are discussed in detail. These include the neutralizer, magnetic shielding, reflecting magnets, vacuum system, calorimeter and beam dumps, and drift duct. The planned location of the two-injector system for Doublet-3 is illustrated and site preparation is considered. The status of beamline units 1 and 2 and the future program schedule are discussed

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

Absolute beam current monitoring in endstation c

International Nuclear Information System (INIS)

Bochna, C.

1995-01-01

The first few experiments at CEBAF require approximately 1% absolute measurements of beam currents expected to range from 10-25μA. This represents errors of 100-250 nA. The initial complement of beam current monitors are of the non intercepting type. CEBAF accelerator division has provided a stripline monitor and a cavity monitor, and the authors have installed an Unser monitor (parametric current transformer or PCT). After calibrating the Unser monitor with a precision current reference, the authors plan to transfer this calibration using CW beam to the stripline monitors and cavity monitors. It is important that this be done fairly rapidly because while the gain of the Unser monitor is quite stable, the offset may drift on the order of .5μA per hour. A summary of what the authors have learned about the linearity, zero drift, and gain drift of each type of current monitor will be presented

Theory of semicollisional drift-interchange modes in cylindrical plasmas

International Nuclear Information System (INIS)

Hahm, T.S.; Chen, L.

1985-01-01

Resistive interchange instabilities in cylindrical plasmas are studied, including the effects of electron diamagnetic drift, perpendicular resistivity, and plasma compression. The analyses are pertinent to the semicollisional regime where the effective ion gyro-radius is larger than the resistive layer width. Both analytical and numerical results show that the modes can be completely stabilized by the perpendicular plasma transport. Ion sound effects, meanwhile, are found to be negligible in the semicollisional regime

Reducing Pesticide Drift

Science.gov (United States)

Provides information about pesticide spray drift, including problems associated with drift, managing risks from drift and the voluntary Drift Reduction Technology program that seeks to reduce spray drift through improved spray equipment design.

Beam dynamics and commissioning of low and medium energy H- beam at Linac4

CERN Document Server

Satri, Masoomeh Yarmohammadi; Lombardi, Alessandra; Lamehi-Rachti , Mohammad

The First step of the CERN Large Hadron Collider injectors upgrade (LIU) project is Linac4. It accelerates H- ions to 160 MeV in an 80 m long accelerator housed in a tunnel 12 m underground, presently under construction. It will replace the present 50 MeV proton Linac2 as injector of the proton accelerator complex to increase the LHC luminosity. It consists of a 45 keV RF volume source, a twosolenoid Low Energy Beam Transport (LEBT), a 352.2 MHz Radio Frequency Quadrupole (RFQ) accelerating the beam to 3 MeV, a Medium Energy Beam Transport (MEBT) line. The MEBT houses a fast chopper to selectively remove unwanted micro-bunches in the 352 MHz sequence and avoid losses at capture in the CERN PSB (1 MHz). After chopping, the beam acceleration continues by a 50 MeV Drift Tube Linac (DTL), a 100 MeV Cell-Coupled Drift Tube Linac and a Pi-Mode Structure bringing the beam to the final energy of 160 MeV. Linac4 has been commissioned with a temporary source up to 12 MeV. The beam commissioning stages of Linac4 in LEBT...

Analysis of particle species evolution in neutral beam injection lines

International Nuclear Information System (INIS)

Kim, J.; Haselton, H.H.

1978-07-01

Analytic solutions to the rate equations describing the species evolution of a multispecies positive ion beam of hydrogen due to charge exchange and molecular dissociation are derived as a function of the background gas (H 2 ) line density in the neutralizing gas cell and in the drift tube. Using the solutions, calculations are presented for the relative abundance of each species as a function of the gas cell thickness, the reionization loss rates in the drift tube, and the neutral beam power as a function of the beam energy and the species composition of the original ion beam

Drift chamber system for use in a high rate environment

International Nuclear Information System (INIS)

Etkin, A.

1978-01-01

A system of short drift distance (0.125'') drift chambers is described. This system is being built for use in the Brookhaven National Laboratory Multiparticle Spectrometer. These chambers will be able to handle beam rates of several million/pulse and give a spatial resolution of the order of 150 μm. Cathode readout will provide unique 3-dimensional points for each crack. The readout will utilize three custom built integrated circuits, a four channel amplifier-shaper, a four channel discriminator and a four channel shift register delay and time digitizer. A summary of test results on a prototype is also given

SPECIFIC FEATURES OF DEFORMATION OF THE CONTINENTAL AND OCEANIC LITHOSPHERE AS A RESULT OF THE EARTH CORE NORTHERN DRIFT

Directory of Open Access Journals (Sweden)

Mikhail A. Goncharov

2012-01-01

Full Text Available Drifting and submeridional compression of the continental and oceanic lithosphere, both with the northward vector (Figure 1 are revealed at the background of various directions of horizontal displacement combined with deformations of horizontal extension, compression and shear of the lithosphere (Figures 7–14. Among various structural forms and their paragenezises, indicators of such compression, the north vergence thrusts play the leading role (Figures 15–17, 19, and 22–24. This process was discontinuous, manifested discretely in time, and superimposed on processes of collisional orogenesis and platform deformations of the continental lithosphere and accretion of the oceanic lithosphere in spreading zones. Three main stages of submeridional compression of the oceanic lithosphere are distinguished as follows: Late Jurassic-Late Cretaceous, Late Miocene, and the contemporary stages.Based on the concept of balanced tectonic flow in the Earth’s body, a model of meridional convection (Figure 25 is proposed. In this case, meridional convection is considered as an integral element of the overglobal convective geodynamic system of the largest-scale rank, which also includes the western component of the lithosphere drift (Figure 6 and the Earth’s ‘wrenching’. At the background of this system, geodynamic systems of smaller scale ranks are functioning (Table 1; Figures 2, and 3. The latters are responsible for the periodic creation and break-up of supercontinents, plate tectonics and regional geodynamical processes; they also produce the ‘structural background’, in the presence of which it is challenging to reveal the above mentioned submeridional compression structures. Formation of such structures is caused by the upper horizontal flow of meridional convection.Meridional convection occurs due to drifting of the Earth core towards the North Pole (which is detected by a number of independent methods and resistance of the mantle to

A drift-pump coil design for a Tandem Mirror Reactor

International Nuclear Information System (INIS)

Neef, W.S.; Logan, B.

1983-01-01

This paper describes both the theory and mechanical design behind a new concept for trapped ion removal from tandem mirror end plugs. The design has been developed for the Mirror Advanced Reactor Study (MARS). The new drift-pump coils replace charge exchange pump beams. Pump beams consume large amounts of power and seriously reduce reactor performance. Drift-pump coils consume only a few megawatts of power and introduce no added burden to the reactor vacuum pumps. In addition, they are easy to replace. The coils are similar in shape to a paper clip and are located at two positions in each end plug. The coils between the transition coil and the first anchor yinyang serve to remove ions trapped in the magnetic well just outboard of the high field choke coil. The coils located between the anchor coil set and the plug coil set remove sloshing ions and trapped cold ions from the plug region

Pressure correction schemes for compressible flows: application to baro-tropic Navier-Stokes equations and to drift-flux model

International Nuclear Information System (INIS)

Gastaldo, L.

2007-11-01

We develop in this PhD thesis a simulation tool for bubbly flows encountered in some late phases of a core-melt accident in pressurized water reactors, when the flow of molten core and vessel structures comes to chemically interact with the concrete of the containment floor. The physical modelling is based on the so-called drift-flux model, consisting of mass balance and momentum balance equations for the mixture (Navier-Stokes equations) and a mass balance equation for the gaseous phase. First, we propose a pressure correction scheme for the compressible Navier-Stokes equations based on mixed non-conforming finite elements. An ad hoc discretization of the advection operator, by a finite volume technique based on a dual mesh, ensures the stability of the velocity prediction step. A priori estimates for the velocity and the pressure yields the existence of the solution. We prove that this scheme is stable, in the sense that the discrete entropy is decreasing. For the conservation equation of the gaseous phase, we build a finite volume discretization which satisfies a discrete maximum principle. From this last property, we deduce the existence and the uniqueness of the discrete solution. Finally, on the basis of these works, a conservative and monotone scheme which is stable in the low Mach number limit, is build for the drift-flux model. This scheme enjoys, moreover, the following property: the algorithm preserves a constant pressure and velocity through moving interfaces between phases (i.e. contact discontinuities of the underlying hyperbolic system). In order to satisfy this property at the discrete level, we build an original pressure correction step which couples the mass balance equation with the transport terms of the gas mass balance equation, the remaining terms of the gas mass balance being taken into account with a splitting method. We prove the existence of a discrete solution for the pressure correction step. Numerical results are presented; they

Performance of the ATLAS Muon Drift-Tube Chambers at High Background Rates and in Magnetic Fields

CERN Document Server

INSPIRE-00213689; Horvat, S.; Legger, F.; Kortner, O.; Kroha, H.; Richter, R.; Valderanis, Ch.; Rauscher, F.; Staude, A.

2016-01-01

The ATLAS muon spectrometer uses drift-tube chambers for precision tracking. The performance of these chambers in the presence of magnetic field and high radiation fluxes is studied in this article using test-beam data recorded in the Gamma Irradiation Facility at CERN. The measurements are compared to detailed predictions provided by the Garfield drift-chamber simulation programme.

Configuring and Characterizing X-Rays for Laser-Driven Compression Experiments at the Dynamic Compression Sector

Science.gov (United States)

Li, Y.; Capatina, D.; D'Amico, K.; Eng, P.; Hawreliak, J.; Graber, T.; Rickerson, D.; Klug, J.; Rigg, P. A.; Gupta, Y. M.

2017-06-01

Coupling laser-driven compression experiments to the x-ray beam at the Dynamic Compression Sector (DCS) at the Advanced Photon Source (APS) of Argonne National Laboratory requires state-of-the-art x-ray focusing, pulse isolation, and diagnostics capabilities. The 100J UV pulsed laser system can be fired once every 20 minutes so precise alignment and focusing of the x-rays on each new sample must be fast and reproducible. Multiple Kirkpatrick-Baez (KB) mirrors are used to achieve a focal spot size as small as 50 μm at the target, while the strategic placement of scintillating screens, cameras, and detectors allows for fast diagnosis of the beam shape, intensity, and alignment of the sample to the x-ray beam. In addition, a series of x-ray choppers and shutters are used to ensure that the sample is exposed to only a single x-ray pulse ( 80ps) during the dynamic compression event and require highly precise synchronization. Details of the technical requirements, layout, and performance of these instruments will be presented. Work supported by DOE/NNSA.

Advances in orbit drift correction in the advanced photon source storage ring

International Nuclear Information System (INIS)

Emery, L.; Borland, M.

1997-01-01

The Advanced Photon Source storage ring is required to provide X-ray beams of high positional stability, specified as 17 μm rms in the horizontal plane and 4.4 μm rms in the vertical plane. The author reports on the difficult task of stabilizing the slow drift component of the orbit motion down to a few microns rms using workstation-based orbit correction. There are two aspects to consider separately the correction algorithm and the configuration of the beam position monitors (BPMs) and correctors. Three notable features of the correction algorithm are: low-pass digital filtering of BPM readbacks; open-quotes despikingclose quotes of the filtered orbit to desensitize the orbit correction to spurious BPM readbacks without having to change the correction matrix; and BPM intensity-dependent offset compensation. The BPM/corrector configuration includes all of the working BPMs but only a small set of correctors distributed around the ring. Thus only those orbit modes that are most likely to be representative of real beam drift are handled by the correction algorithm

Generation of an intense ion beam by a pinched relativistic electron beam

International Nuclear Information System (INIS)

Gilad, P.; Zinamon, Z.

1976-01-01

The pinched electron beam of a pulsed electron accelerator is used to generate an intense beam of ions. A foil anode and vacuum drift tube are used. The space charge field of the pinched beam in the tube accelerates ions from the foil anode. Ion currents of 10 kA at a density of 5kA/cm 2 with pulse length of 50 ns are obtained using a 5 kJ, 450 kV, 3 Ω diode. (author)

Coherent optical transition radiation and self-amplified spontaneous emission generated by chicane-compressed electron beams

Directory of Open Access Journals (Sweden)

A. H. Lumpkin

2009-04-01

Full Text Available Observations of strongly enhanced optical transition radiation (OTR following significant bunch compression of photoinjector beams by a chicane have been reported during the commissioning of the Linac Coherent Light Source accelerator and recently at the Advanced Photon Source (APS linac. These localized transverse spatial features involve signal enhancements of nearly a factor of 10 and 100 in the APS case at the 150-MeV and 375-MeV OTR stations, respectively. They are consistent with a coherent process seeded by noise and may be evidence of a longitudinal space charge microbunching instability which leads to coherent OTR emissions. Additionally, we suggest that localized transverse structure in the previous self-amplified spontaneous emission (SASE free-electron laser (FEL data at APS in the visible regime as reported at FEL02 may be attributed to such beam structure entering the FEL undulators and inducing the SASE startup at those “prebunched” structures. Separate beam structures 120 microns apart in x and 2.9 nm apart in wavelength were reported. The details of these observations and operational parameters will be presented.

Cylindrical geometry for proportional and drift chambers

International Nuclear Information System (INIS)

Sadoulet, B.

1975-06-01

For experiments performed around storage rings such as e + e - rings or the ISR pp rings, cylindrical wire chambers are very attractive. They surround the beam pipe completely without any dead region in the azimuth, and fit well with the geometry of events where particles are more or less spherically produced. Unfortunately, cylindrical proportional or drift chambers are difficult to make. Problems are discussed and two approaches to fabricating the cathodes are discussed. (WHK)

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

Ion acceleration in non-equilibrium plasmas driven by fast drifting electron

Energy Technology Data Exchange (ETDEWEB)

Castro, G. [INFN- Laboratori Nazionali del Sud, via S.Sofia 62, 95123 Catania (Italy); Università degli Studi di Catania, Dipartimento di Fisica e Astronomia, V. S.Sofia 64, 95123 Catania (Italy); Di Bartolo, F., E-mail: fdibartolo@unime.it [Università di Messina, V.le F. Stagno D’Alcontres 31, 98166, Messina (Italy); Gambino, N. [INFN- Laboratori Nazionali del Sud, via S.Sofia 62, 95123 Catania (Italy); Università degli Studi di Catania, Dipartimento di Metodologie Fisiche e Chimiche per L’ingegneria, Viale A.Doria 6, 95125 Catania (Italy); Mascali, D. [INFN- Laboratori Nazionali del Sud, via S.Sofia 62, 95123 Catania (Italy); CSFNSM, Viale A. Doria 6, 95125 Catania (Italy); Romano, F.P. [INFN- Laboratori Nazionali del Sud, via S.Sofia 62, 95123 Catania (Italy); CNR-IBAM Via Biblioteca 4, 95124 Catania (Italy); Anzalone, A.; Celona, L.; Gammino, S. [INFN- Laboratori Nazionali del Sud, via S.Sofia 62, 95123 Catania (Italy); Di Giugno, R. [INFN- Laboratori Nazionali del Sud, via S.Sofia 62, 95123 Catania (Italy); Università degli Studi di Catania, Dipartimento di Fisica e Astronomia, V. S.Sofia 64, 95123 Catania (Italy); Lanaia, D. [INFN- Laboratori Nazionali del Sud, via S.Sofia 62, 95123 Catania (Italy); Miracoli, R. [INFN- Laboratori Nazionali del Sud, via S.Sofia 62, 95123 Catania (Italy); Università degli Studi di Catania, Dipartimento di Fisica e Astronomia, V. S.Sofia 64, 95123 Catania (Italy); Serafino, T. [CSFNSM, Viale A. Doria 6, 95125 Catania (Italy); Tudisco, S. [INFN- Laboratori Nazionali del Sud, via S.Sofia 62, 95123 Catania (Italy); CSFNSM, Viale A. Doria 6, 95125 Catania (Italy)

2013-05-01

We hereby present results on ion acceleration mechanisms in non equilibrium plasmas generated by microwaves or high intensity laser pulses. Experiments point out that in magnetized plasmas X–B conversion takes place for under resonance values of the magnetic field, i.e. an electromagnetic mode is converted into an electrostatic wave. The strong self-generated electric field, of the order of 10{sup 7} V/m, causes a E × B drift which accelerates both ions and electrons, as it is evident by localized sputtering in the plasma chamber. These fields are similar (in magnitude) to the ones obtainable in laser generated plasmas at intensity of 10{sup 12} W/cm{sup 2}. In this latter case, we observe that the acceleration mechanism is driven by electrons drifting much faster than plasma bulk, thus generating an extremely strong electric field ∼10{sup 7} V/m. The two experiments confirm that ions acceleration at low energy is possible with table-top devices and following complementary techniques: i.e. by using microwave-driven (producing CW beams) plasmas, or non-equilibrium laser-driven plasmas (producing pulsed beams). Possible applications involve ion implantation, materials surface modifications, ion beam assisted lithography, etc.

Method for controlling low-energy high current density electron beams

International Nuclear Information System (INIS)

Lee, J.N.; Oswald, R.B. Jr.

1977-01-01

A method and an apparatus for controlling the angle of incidence of low-energy, high current density electron beams are disclosed. The apparatus includes a current generating diode arrangement with a mesh anode for producing a drifting electron beam. An auxiliary grounded screen electrode is placed between the anode and a target for controlling the average angle of incidence of electrons in the drifting electron beam. According to the method of the present invention, movement of the auxiliary screen electrode relative to the target and the anode permits reliable and reproducible adjustment of the average angle of incidence of the electrons in low energy, high current density relativistic electron beams

High time resolution beam-based measurement of the rf-to-laser jitter in a photocathode rf gun

Directory of Open Access Journals (Sweden)

Zhen Zhang

2014-03-01

Full Text Available Characterizing the rf-to-laser jitter in the photocathode rf gun and its possible origins is important for improving the synchronization and beam quality of the linac based on the photocathode rf gun. A new method based on the rf compression effect in the photocathode rf gun is proposed to measure the rf-to-laser jitter in the gun. By taking advantage of the correlation between the rf compression and the laser injection phase, the error caused by the jitter of the accelerating field in the gun is minimized and thus 10 fs time resolution is expected. Experimental demonstration at the Tsinghua Thomson scattering x-ray source with a time resolution better than 35 fs is reported in this paper. The experimental results are successfully used to obtain information on the possible cause of the jitter and the accompanying drifts.

Beam Techniques - Beam Control and Manipulation

International Nuclear Information System (INIS)

Minty, Michiko G

2003-01-01

We describe commonly used strategies for the control of charged particle beams and the manipulation of their properties. Emphasis is placed on relativistic beams in linear accelerators and storage rings. After a brief review of linear optics, we discuss basic and advanced beam control techniques, such as transverse and longitudinal lattice diagnostics, matching, orbit correction and steering, beam-based alignment, and linac emittance preservation. A variety of methods for the manipulation of particle beam properties are also presented, for instance, bunch length and energy compression, bunch rotation, changes to the damping partition number, and beam collimation. The different procedures are illustrated by examples from various accelerators. Special topics include injection and extraction methods, beam cooling, spin transport and polarization

Beam Techniques - Beam Control and Manipulation

Energy Technology Data Exchange (ETDEWEB)

Minty, Michiko G

2003-04-24

We describe commonly used strategies for the control of charged particle beams and the manipulation of their properties. Emphasis is placed on relativistic beams in linear accelerators and storage rings. After a brief review of linear optics, we discuss basic and advanced beam control techniques, such as transverse and longitudinal lattice diagnostics, matching, orbit correction and steering, beam-based alignment, and linac emittance preservation. A variety of methods for the manipulation of particle beam properties are also presented, for instance, bunch length and energy compression, bunch rotation, changes to the damping partition number, and beam collimation. The different procedures are illustrated by examples from various accelerators. Special topics include injection and extraction methods, beam cooling, spin transport and polarization.

Autocalibration of high precision drift tubes

International Nuclear Information System (INIS)

Bacci, C.; Bini, C.; Ciapetti, G.; De Zorzi, G.; Gauzzi, P.; Lacava, F.; Nisati, A.; Pontecorvo, L.; Rosati, S.; Veneziano, S.; Cambiaghi, M.; Casellotti, G.; Conta, C.; Fraternali, M.; Lanza, A.; Livan, M.; Polesello, G.; Rimoldi, A.; Vercesi, V.

1997-01-01

We present the results on MDT (monitored drift tubes) autocalibration studies obtained from the analysis of the data collected in Summer 1995 on the H8B Muon Test Beam. In particular we studied the possibility of autocalibration of the MDT using four or three layers of tubes, and we compared the calibration obtained using a precise external tracker with the output of the autocalibration procedure. Results show the feasibility of autocalibration with four and three tubes and the good accuracy of the autocalibration procedure. (orig.)

Quasi-static drift-tube accelerating structures for low-speed heavy ions

International Nuclear Information System (INIS)

Faltens, A.; Keefe, D.

1977-01-01

The major attractions of the pulsed drift-tubes are that they are non-resonant structures and that they appear suitable for accelerating a very high current bunch at low energies. The mechanical tolerances of the non-resonant structure are very loose and the cost per meter should be low; the cost of the transport system is expected to be the major cost. The pulse power modulators used to drive the drift-tubes are inexpensive compared to r.f. sources with equivalent peak-power. The longitudinal emittance of the beam emerging from the structure could be extremely low

Consideration of beam plasma ion-source

International Nuclear Information System (INIS)

Sano, Fumimichi; Kusano, Norimasa; Ishida, Yoshihiro; Ishikawa, Junzo; Takagi, Toshinori

1976-01-01

Theoretical and experimental analyses and their comparison were made on the plasma generation and on the beam extraction for the beam plasma ion-source. The operational principle and the structure of the ion-source are explained in the first part. Considerations are given on the electron beam-plasma interaction and the resulting generation of high frequency or microwaves which in turn increases the plasma density. The flow of energy in this system is also explained in the second part. The relation between plasma density and the imaginary part of frequency is given by taking the magnetic flux density, the electron beam energy, and the electron beam current as parameters. The relations between the potential difference between collector and drift tube and the plasma density or the ion-current are also given. Considerations are also given to the change of the plasma density due to the change of the magnetic flux density at drift tube, the change of the electron beam energy, and the change of the electron beam current. The third part deals with the extraction characteristics of the ion beam. The structure of the multiple-aperture electrode and the relation between plasma density and the extracted ion current are explained. (Aoki, K.)

Electromagnetic computer simulations of collective ion acceleration by a relativistic electron beam

International Nuclear Information System (INIS)

Galvez, M.; Gisler, G.R.

1988-01-01

A 2.5 electromagnetic particle-in-cell computer code is used to study the collective ion acceleration when a relativistic electron beam is injected into a drift tube partially filled with cold neutral plasma. The simulations of this system reveals that the ions are subject to electrostatic acceleration by an electrostatic potential that forms behind the head of the beam. This electrostatic potential develops soon after the beam is injected into the drift tube, drifts with the beam, and eventually settles to a fixed position. At later times, this electrostatic potential becomes a virtual cathode. When the permanent position of the electrostatic potential is at the edge of the plasma or further up, then ions are accelerated forward and a unidirectional ion flow is obtained otherwise a bidirectional ion flow occurs. The ions that achieve higher energy are those which drift with the negative potential. When the plasma density is varied, the simulations show that optimum acceleration occurs when the density ratio between the beam (n b ) and the plasma (n o ) is unity. Simulations were carried out by changing the ion mass. The results of these simulations corroborate the hypothesis that the ion acceleration mechanism is purely electrostatic, so that the ion acceleration depends inversely on the charge particle mass. The simulations also show that the ion maximum energy increased logarithmically with the electron beam energy and proportional with the beam current

The Absence of Stokes Drift in Waves

OpenAIRE

Chafin, Clifford

2015-01-01

Stokes drift has been as central to the history of wave theory as it has been distressingly absent from experiment. Neither wave tanks nor experiments in open bodies detect this without nearly canceling "eulerian flows." Acoustic waves have an analogous problem that is particularly problematic in the vorticity production at the edges of beams. Here we demonstrate that the explanation for this arises from subtle end-of-packet and wavetrain gradient effects such as microbreaking events and wave...

Electron drift time in silicon drift detectors: A technique for high precision measurement of electron drift mobility

International Nuclear Information System (INIS)

Castoldi, A.; Rehak, P.

1995-01-01

This paper presents a precise absolute measurement of the drift velocity and mobility of electrons in high resistivity silicon at room temperature. The electron velocity is obtained from the differential measurement of the drift time of an electron cloud in a silicon drift detector. The main features of the transport scheme of this class of detectors are: the high uniformity of the electron motion, the transport of the signal electrons entirely contained in the high-purity bulk, the low noise timing due to the very small anode capacitance (typical value 100 fF), and the possibility to measure different drift distances, up to the wafer diameter, in the same semiconductor sample. These features make the silicon drift detector an optimal device for high precision measurements of carrier drift properties. The electron drift velocity and mobility in a 10 kΩ cm NTD n-type silicon wafer have been measured as a function of the electric field in the range of possible operation of a typical drift detector (167--633 V/cm). The electron ohmic mobility is found to be 1394 cm 2 /V s. The measurement precision is better than 1%. copyright 1995 American Institute of Physics

Drift Degradation Analysis

Energy Technology Data Exchange (ETDEWEB)

Dwayne C. Kicker

2001-09-28

A statistical description of the probable block sizes formed by fractures around the emplacement drifts has been developed for each of the lithologic units of the repository host horizon. A range of drift orientations with the drift azimuth varied in 15{sup o} increments has been considered in the static analysis. For the quasi-static seismic analysis, and the time-dependent and thermal effects analysis, two drift orientations have been considered: a drift azimuth of 105{sup o} and the current emplacement drift azimuth of 75{sup o}. The change in drift profile resulting from progressive deterioration of the emplacement drifts has been assessed both with and without backfill. Drift profiles have been determined for four different time increments, including static (i.e., upon excavation), 200 years, 2,000 years, and 10,000 years. The effect of seismic events on rock fall has been analyzed. Block size distributions and drift profiles have been determined for three seismic levels, including a 1,000-year event, a 5,000-year event, and a 10,000-year event. Data developed in this modeling and analysis activity have been entered into the TDMS (DTN: MO0109RDDAAMRR.003). The following conclusions have resulted from this drift degradation analysis: (1) The available fracture data are suitable for supporting a detailed key block analysis of the repository host horizon rock mass. The available data from the north-south Main Drift and the east-west Cross Drift provide a sufficient representative fracture sample of the repository emplacement drift horizon. However, the Tptpln fracture data are only available from a relatively small section of the Cross Drift, resulting in a smaller fracture sample size compared to the other lithologic units. This results in a lower degree of confidence that the key block data based on the Tptpln data set is actually representative of the overall Tptpln key block population. (2) The seismic effect on the rock fall size distribution for all events

A beam position feedback system for beam lines at the photon factory

International Nuclear Information System (INIS)

Katsura, T.; Kamiya, Y.; Haga, K.; Mitsuhashi, T.

1987-01-01

The beam position of the synchrotron radiation produced from the Storage Ring was stabilized by a twofold position feedback system. A digital feedback system was developed to suppress the diurnal beam movement (one cycle of sin-like drifting motion per day) which became a serious problem in low-emittance operation. The feedback was applied to the closed-orbit-distortion (COD) correction system in order to cancel the position variation at all the beam lines proportionately to the variation monitored at one beam line. An analog feedback system is also used to suppress frequency components faster than the slow diurnal movement

Compression of laminated composite beams with initial damage

Science.gov (United States)

Breivik, Nicole L.; Gurdal, Zafer; Griffin, O. H., Jr.

1993-01-01

The effect of isolated damage modes on the compressive strength and failure characteristics of laminated composite test specimens were evaluated experimentally and numerically. In addition to specimens without initial damage, specimens with three types of initial damage were considered: (1) specimens with short delaminations distributed evenly through the specimen thickness, (2) specimens with few long delaminations, and (3) specimens with local fiber damage in the surface plies under the three-point bend contact point. It was found that specimens with short multiple delamination experienced the greatest reduction in compression strength compared to the undamaged specimens. Single delaminations far from the specimen surface had little effect on the final compression strength, and moderate strength reduction was observed for specimens with localized surface ply damage.

Neutralization of positive particle beams by electron trapping

International Nuclear Information System (INIS)

Mobley, R.M.; Irani, A.A.; LeMaire, J.L.; Maschke, A.W.

1977-01-01

Initial results are presented of a planned series of experimental tests of positive ion beam neutralization, involving transverse space charge studies of a 720 keV 60mA H + beam in a drift region of 4.6 meters. Two conclusions drawn from the data are: (1) the change in transmission observed is consistent with complete neutralization in the drift pipe for grounded or negative electrodes, and with complete de-neutralization in the case of greater than +240 V electrodes; and (2) background gas ionization cannot be the main source of electrons

Hydrogen high pressure proportional drift detector

International Nuclear Information System (INIS)

Arefiev, A.; Balaev, A.

1983-01-01

The design and operation performances of a proportional drift detector PDD are described. High sensitivity of the applied PAD makes it possible to detect the neutron-proton elastic scattering in the energy range of recoil protons as low as 1 keV. The PDD is filled with hydrogen up to the pressure at 40 bars. High purity of the gas is maintained by a continuously operating purification system. The detector has been operating for several years in a neutron beam at the North Area of the CERN SPS

Dike/Drift Interactions

Energy Technology Data Exchange (ETDEWEB)

E.S. Gaffney

2003-10-08

This report documents the model of events associated with a potential intrusion of magma from a volcanic dike into a drift or drifts in the Yucca Mountain Nuclear Waste Repository. The following topics are included in this report: (1) A discussion of dike propagation, which provides the basis for describing the path that a representative dike, or swarm of dikes, would follow during an event. (2) A discussion of magma flow, which evaluates the interaction at the junction of the propagating dike with the drift and the movement of magmatic products into and down drifts and, potentially, through a drift to the surface by way of access drift or a secondary dike opened up along the drift. (3) A discussion of gas flow and conductive cooling of a magma-filled drift, describing how an adjacent drift that has not been intersected by a dike could be affected by post-intrusion phenomena. Note that a gas flow analysis is also addressed in ''Igneous Intrusion Impacts on Waste Form and Waste Packages'' (BSC 2003 [DIRS 161810]), and those results are consistent with the results presented in this report.

Dike/Drift Interactions

International Nuclear Information System (INIS)

E.S. Gaffney

2003-01-01

This report documents the model of events associated with a potential intrusion of magma from a volcanic dike into a drift or drifts in the Yucca Mountain Nuclear Waste Repository. The following topics are included in this report: (1) A discussion of dike propagation, which provides the basis for describing the path that a representative dike, or swarm of dikes, would follow during an event. (2) A discussion of magma flow, which evaluates the interaction at the junction of the propagating dike with the drift and the movement of magmatic products into and down drifts and, potentially, through a drift to the surface by way of access drift or a secondary dike opened up along the drift. (3) A discussion of gas flow and conductive cooling of a magma-filled drift, describing how an adjacent drift that has not been intersected by a dike could be affected by post-intrusion phenomena. Note that a gas flow analysis is also addressed in ''Igneous Intrusion Impacts on Waste Form and Waste Packages'' (BSC 2003 [DIRS 161810]), and those results are consistent with the results presented in this report

Dynamics of ion beam charge neutralization by ferroelectric plasma sources

Energy Technology Data Exchange (ETDEWEB)

Stepanov, Anton D.; Gilson, Erik P.; Grisham, Larry R.; Kaganovich, Igor D.; Davidson, Ronald C. [Princeton Plasma Physics Laboratory, Princeton University, P.O. Box 451, Princeton, New Jersey 08543 (United States)

2016-04-15

Ferroelectric Plasma Sources (FEPSs) can generate plasma that provides effective space-charge neutralization of intense high-perveance ion beams, as has been demonstrated on the Neutralized Drift Compression Experiment NDCX-I and NDCX-II. This article presents experimental results on charge neutralization of a high-perveance 38 keV Ar{sup +} beam by a plasma produced in a FEPS discharge. By comparing the measured beam radius with the envelope model for space-charge expansion, it is shown that a charge neutralization fraction of 98% is attainable with sufficiently dense FEPS plasma. The transverse electrostatic potential of the ion beam is reduced from 15 V before neutralization to 0.3 V, implying that the energy of the neutralizing electrons is below 0.3 eV. Measurements of the time-evolution of beam radius show that near-complete charge neutralization is established ∼5 μs after the driving pulse is applied to the FEPS and can last for 35 μs. It is argued that the duration of neutralization is much longer than a reasonable lifetime of the plasma produced in the sub-μs surface discharge. Measurements of current flow in the driving circuit of the FEPS show the existence of electron emission into vacuum, which lasts for tens of μs after the high voltage pulse is applied. It is argued that the beam is neutralized by the plasma produced by this process and not by a surface discharge plasma that is produced at the instant the high-voltage pulse is applied.

Drift velocity monitoring of the CMS muon drift chambers

CERN Document Server

Sonnenschein, Lars

2010-01-01

The drift velocity in drift tubes of the CMS muon chambers is a key parameter for the muon track reconstruction and trigger. It needs to be monitored precisely in order to detect any deviation from its nominal value. A change in absolute pressure, a variation of the gas admixture or a contamination of the chamber gas by air affect the drift velocity. Furthermore the temperature and magnetic field influence its value. First data, taken with a dedicated Velocity Drift Chamber (VDC) built by RWTH Aachen IIIA are presented.

Electron bunch compression and coherent effects at the SDL

International Nuclear Information System (INIS)

Loos, Henrik; Carr, G. Lawrence; Doyuran, Adnan; Graves, William S.; Johnson, Eric D.; Krinsky, Samuel; Rose, James; Sheehy, Brian; Shaftan, Timur V.; Skaritka, John; Yu Lihua

2002-01-01

The DUVFEL accelerator in the Source Development Lab of NSLS/BNL generates a high brightness electron beam from a laser driven electron source and a magnetic bunch compressor. This beam is used for different FEL experiments in SASE and future HGHG configurations. The compression of the electron beam to high peak current while preserving the transverse properties is of great importance to the performance goals of these FELs. In this paper we report on the experimental methods to characterize the longitudinal properties of the electron beam and the measured results for various settings of the DUVFEL accelerator. The observed effects on the electron beam spectra and time profiles during compression are most likely due to coherent effects while their exact origin is still subject of ongoing investigation

Design and tests of the z-coordinate drift chamber system for the OPAL central detector at LEP

International Nuclear Information System (INIS)

Mes, H.; Dixit, M.S.; Godfrey, L.; Hanna, D.; Hargrove, C.K.; Losty, M.J.; Oakham, F.G.; Bavaria, G.; Jeremie, H.; Lessard, L.; Lorazo, B.; Martin, J.P.

1988-01-01

A system of drift chambers has been designed to make high resolution measurements of the z-coordinates of charged tracks at the outer radius of the OPAL central detector at LEP. The unit module of this detector is a 25 cm drift length bidirectional cell with six sense wires in a thin 50 cm wide by 29 mm high drift slot. Tests indicate that the chamber has a wide and stable electric field operating range and its performance is unaffected by small misalignments between the drift electric field and an external magnetic field. The drift cell was found to have uniform acceptance up to its geometrical boundaries, and the z-resolution for beam tracks normal to the chamber was measured to be in the range of 40-175 μm. (orig.)

Measurement of the positron-drift time relation of a high-pressure drift chamber

International Nuclear Information System (INIS)

Pruefert, W.

1989-04-01

As a test of its performance, the measurement of the drift time versus drift distance relation of a high pressure drift chamber using cosmic rays is described. Two multiwire proportional chambers, mounted above and below the detector, are used to define the track of the cosmic particle in the drift chamber. The drift chamber is read out by FADCs (Flash Analog to Digital Converter), and the drift time is determined from the FADC signals by the DOS- (Difference Of Samples) method. The measured drift time versus drift distance relation showed good agreement with the relation, which is expected from the spatial dependence of the electric field and the dependence of the drift velocity on this field. (orig.) [de

Buildup of electrons with hot electron beam injection into a homogeneous magnetic field

International Nuclear Information System (INIS)

Bashko, V.A.; Krivoruchko, A.M.; Tarasov, I.K.

1989-01-01

The injection of the monoenergetic beam of electrons into the vacuum drift channel under the conditions when the beam current exceeds a certain threshold value involves a virtual cathode creation. The process of virtual cathode creation leads to an exchange of one-fluid movement of beam particles to three-fluid one corresponding to incident, reflected and passed through anticathode beam particles. For the monoenergetic beam case when the velocity spread Δv dr (v dr is the beam drift velocity), the beam instability was predicted in theory and was observed in experiment. Meanwhile, the injection in the drift space of the 'hot' beam having finite spread in velocities may be accompanied not only by the reflection of particles if their velocity v 1/2 (where φ is the electrostatic potential dip value, e and m are the electron charge and mass, respectively), but also the mutual Coulomb scattering of incident and reflected electrons. The scattering process leads in its turn to appearance of viscosity forces and to trapping of a part of beam electrons into the effective potential well formed by electrostatic potential dip and the viscous force potential. The interaction of travelling and trapped particles may occur even at the stage preceding the virtual electrode formation and it may influence the process of its appearance and also the current flow through the drift space. In this report there are described the experimental results on accumulation of electrons when electron beam propagates in vacuum and has a large spread in particle velocities Δv dr in the homogeneous longitudinal magnetic field when ω pe He where ω pe is the electron Langmuir frequency of beam electrons, ω He is the electron cyclotron frequency. (author) 6 refs., 2 figs

Drift Degradation Analysis

International Nuclear Information System (INIS)

G.H. Nieder-Westermann

2005-01-01

The outputs from the drift degradation analysis support scientific analyses, models, and design calculations, including the following: (1) Abstraction of Drift Seepage; (2) Seismic Consequence Abstraction; (3) Structural Stability of a Drip Shield Under Quasi-Static Pressure; and (4) Drip Shield Structural Response to Rock Fall. This report has been developed in accordance with ''Technical Work Plan for: Regulatory Integration Modeling of Drift Degradation, Waste Package and Drip Shield Vibratory Motion and Seismic Consequences'' (BSC 2004 [DIRS 171520]). The drift degradation analysis includes the development and validation of rockfall models that approximate phenomenon associated with various components of rock mass behavior anticipated within the repository horizon. Two drift degradation rockfall models have been developed: the rockfall model for nonlithophysal rock and the rockfall model for lithophysal rock. These models reflect the two distinct types of tuffaceous rock at Yucca Mountain. The output of this modeling and analysis activity documents the expected drift deterioration for drifts constructed in accordance with the repository layout configuration (BSC 2004 [DIRS 172801])

Drift velocity and pressure monitoring of the CMS muon drift chambers

CERN Document Server

Sonnenschein, Lars

2011-01-01

The drift velocity in drift tubes of the CMS muon chambers is a key parameter for the muon track reconstruction and trigger. It needs to be monitored precisely in order to detect any deviation from its nominal value. A change in absolute pressure, a variation of the gas admixture or a contamination of the chamber gas by air affect the drift velocity. Furthermore, the temperature and magnetic field influence its value. First data, taken with a dedicated Velocity Drift Chamber (VDC) built by RWTH Aachen IIIA are presented. Another important parameter to be monitored is the pressure inside the muon drift tube chambers. The differential pressure must not exceed a certain value and the absolute pressure has to be kept slightly above ambient pressure to prevent air from entering into the muon drift tube chambers in case of a leak. Latest drift velocity monitoring results are discussed.

Negative compressibility observed in graphene containing resonant impurities

International Nuclear Information System (INIS)

Chen, X. L.; Wang, L.; Li, W.; Wang, Y.; He, Y. H.; Wu, Z. F.; Han, Y.; Zhang, M. W.; Xiong, W.; Wang, N.

2013-01-01

We observed negative compressibility in monolayer graphene containing resonant impurities under different magnetic fields. Hydrogenous impurities were introduced into graphene by electron beam (e-beam) irradiation. Resonant states located in the energy region of ±0.04 eV around the charge neutrality point were probed in e-beam-irradiated graphene capacitors. Theoretical results based on tight-binding and Lifshitz models agreed well with experimental observations of graphene containing a low concentration of resonant impurities. The interaction between resonant states and Landau levels was detected by varying the applied magnetic field. The interaction mechanisms and enhancement of the negative compressibility in disordered graphene are discussed.

Steady state distribution for unbunched beams colliding in a drift space

International Nuclear Information System (INIS)

Kheifets, S.; Chao, A.W.

1979-12-01

A self-consistent time-independent solution of the system of coupled equations for the distribution of two colliding unbunched beams of opposite charges is found. The solution for each beam contains an arbitrary constant which characterizes the lateral size of the beam. On the other hand, the angular divergence is uniquely determined by the line charge density of the opposite beam in case the beams have cylindrical symmetry. The possible implications of this solution for a linac collider are discussed. Further work on the stability of this solution is needed. 6 refs., 9 figs., 2 tabs

Radial focusing and energy compression of a laser-produced proton beam by a synchronous rf field

Directory of Open Access Journals (Sweden)

Masahiro Ikegami

2009-06-01

Full Text Available The dynamics of a MeV laser-produced proton beam affected by a radio frequency (rf electric field has been studied. The proton beam was emitted normal to the rear surface of a thin polyimide target irradiated with an ultrashort pulsed laser with a power density of 4×10^{18}  W/cm^{2}. The energy spread was compressed to less than 11% at the full width at half maximum (FWHM by an rf field. Focusing and defocusing effects of the transverse direction were also observed. These effects were analyzed and reproduced by Monte Carlo simulations. The simulation results show that the transversely focused protons had a broad continuous spectrum, while the peaks in the proton spectrum were defocused. Based on this new information, we propose that elimination of the continuous energy component of laser-produced protons is possible by utilizing a focal length difference between the continuous spectral protons and the protons included in the spectral peak.

Stokes drift

Science.gov (United States)

van den Bremer, T. S.; Breivik, Ø.

2017-12-01

During its periodic motion, a particle floating at the free surface of a water wave experiences a net drift velocity in the direction of wave propagation, known as the Stokes drift (Stokes 1847 Trans. Camb. Philos. Soc. 8, 441-455). More generally, the Stokes drift velocity is the difference between the average Lagrangian flow velocity of a fluid parcel and the average Eulerian flow velocity of the fluid. This paper reviews progress in fundamental and applied research on the induced mean flow associated with surface gravity waves since the first description of the Stokes drift, now 170 years ago. After briefly reviewing the fundamental physical processes, most of which have been established for decades, the review addresses progress in laboratory and field observations of the Stokes drift. Despite more than a century of experimental studies, laboratory studies of the mean circulation set up by waves in a laboratory flume remain somewhat contentious. In the field, rapid advances are expected due to increasingly small and cheap sensors and transmitters, making widespread use of small surface-following drifters possible. We also discuss remote sensing of the Stokes drift from high-frequency radar. Finally, the paper discusses the three main areas of application of the Stokes drift: in the coastal zone, in Eulerian models of the upper ocean layer and in the modelling of tracer transport, such as oil and plastic pollution. Future climate models will probably involve full coupling of ocean and atmosphere systems, in which the wave model provides consistent forcing on the ocean surface boundary layer. Together with the advent of new space-borne instruments that can measure surface Stokes drift, such models hold the promise of quantifying the impact of wave effects on the global atmosphere-ocean system and hopefully contribute to improved climate projections. This article is part of the theme issue 'Nonlinear water waves'.

Drift velocity and pressure monitoring of the CMS muon drift chambers

CERN Document Server

Sonnenschein, Lars

2010-01-01

The drift velocity in drift tubes of the CMS muon chambers is a key parameter for the muon track reconstruction and trigger. It needs to be monitored precisely in order to detect any deviation from its nominal value. A change in absolute pressure, a variation of the gas admixture or a contamination of the chamber gas by air affect the drift velocity. Furthermore, the temperature and magnetic field influence its value. First data, taken with a dedicated Velocity Drift Chamber (VDC) built by RWTH Aachen IIIA are presented. Another important parameter to be monitored is the pressure inside the muon drift tube chambers because the drift velocity depends on it. Furthermore the differential pressure must not exceed a certain value and the absolute pressure has to be kept slightly above ambient pressure to prevent air from entering into the muon drift tube chambers in case of a leak. Latest pressure monitoring results are discussed.

Computer simulations of electromagnetic cool ion beam instabilities. [in near earth space

Science.gov (United States)

Gary, S. P.; Madland, C. D.; Schriver, D.; Winske, D.

1986-01-01

Electromagnetic ion beam instabilities driven by cool ion beams at propagation parallel or antiparallel to a uniform magnetic field are studied using computer simulations. The elements of linear theory applicable to electromagnetic ion beam instabilities and the simulations derived from a one-dimensional hybrid computer code are described. The quasi-linear regime of the right-hand resonant ion beam instability, and the gyrophase bunching of the nonlinear regime of the right-hand resonant and nonresonant instabilities are examined. It is detected that in the quasi-linear regime the instability saturation is due to a reduction in the beam core relative drift speed and an increase in the perpendicular-to-parallel beam temperature; in the nonlinear regime the instabilities saturate when half the initial beam drift kinetic energy density is converted to fluctuating magnetic field energy density.

Optimization of a transition radiation detector for the compressed baryonic matter experiment

Energy Technology Data Exchange (ETDEWEB)

Arend, Andreas

2014-07-01

The Transition Radiation Detector (TRD) of the compressed baryonic matter (CBM) experiment at FAIR has to provide electron-pion separation as well as charged-particle tracking. Within this work, thin and symmetric Multi-Wire Proportional Chambers (MWPCs) without additional drift region were proposed. the proposed prototypes feature a foil-based entrance window to minimize the material budget and to reduce the absorption probability of the generated TR photon. Based on the conceptual design of thin and symmetric MWPCs without drift region, multiple prototypes were constructed and their performance presented within this thesis. With the constructed prototypes of generations II and III the geometries of the wire and cathode planes were determined to be 4+4 mm and 5+5 mm. Based on the results of a performed test beam campaign in 2011 with this prototypes new prototypes of generation IV were manufactured and tested in a subsequent test beam campaign in 2012. Prototypes of different radiators were developed together with the MWPC prototypes. Along with regular foil radiators, foam-based radiator types made of polyethylene foam were utilized. Also radiators constructed in a sandwich design, which used different fiber materials confined with solid foam sheets, were used. For the prototypes without drift region, simulations of the electrostatic and mechanical properties were performed. The GARFIELD software package was used to simulate the electric field and to determine the resulting drift lines of the generated electrons. The mean gas amplification depending on the utilized gas and the applied anode voltage was simulated and the gas-gain homogeneity was verified. Since the thin foil-based entrance window experiences a deformation due to pressure differences inside and outside the MWPC, the variation on the gas gain depending on the deformation was simulated. The mechanical properties focusing on the stability of the entrance window was determined with a finiteelement

Optimization of a transition radiation detector for the compressed baryonic matter experiment

International Nuclear Information System (INIS)

Arend, Andreas

2014-01-01

The Transition Radiation Detector (TRD) of the compressed baryonic matter (CBM) experiment at FAIR has to provide electron-pion separation as well as charged-particle tracking. Within this work, thin and symmetric Multi-Wire Proportional Chambers (MWPCs) without additional drift region were proposed. the proposed prototypes feature a foil-based entrance window to minimize the material budget and to reduce the absorption probability of the generated TR photon. Based on the conceptual design of thin and symmetric MWPCs without drift region, multiple prototypes were constructed and their performance presented within this thesis. With the constructed prototypes of generations II and III the geometries of the wire and cathode planes were determined to be 4+4 mm and 5+5 mm. Based on the results of a performed test beam campaign in 2011 with this prototypes new prototypes of generation IV were manufactured and tested in a subsequent test beam campaign in 2012. Prototypes of different radiators were developed together with the MWPC prototypes. Along with regular foil radiators, foam-based radiator types made of polyethylene foam were utilized. Also radiators constructed in a sandwich design, which used different fiber materials confined with solid foam sheets, were used. For the prototypes without drift region, simulations of the electrostatic and mechanical properties were performed. The GARFIELD software package was used to simulate the electric field and to determine the resulting drift lines of the generated electrons. The mean gas amplification depending on the utilized gas and the applied anode voltage was simulated and the gas-gain homogeneity was verified. Since the thin foil-based entrance window experiences a deformation due to pressure differences inside and outside the MWPC, the variation on the gas gain depending on the deformation was simulated. The mechanical properties focusing on the stability of the entrance window was determined with a finiteelement

Simulations in the Analysis of Experimental Data Measured by BM@N Drift Chambers

Directory of Open Access Journals (Sweden)

Fedorišin Ján

2018-01-01

The method of particle hit and track reconstruction in the drift chambers has been already proposed and tested on the BM@N deuteron beam data. In this study the DCH’s are first locally and globally aligned, and subsequently the consistency of the track reconstruction chain is tested by two methods. The first one is based on the backward extrapolation of the DCH reconstructed deuteron beam to a position where its deflection in the BM@N magnetic field begins. The second method reconstructs the deuteron beam momentum through its deflection angle. Both methods confirm correctness of the track reconstruction algorithm.

Dike/Drift Interactions

Energy Technology Data Exchange (ETDEWEB)

E. Gaffiney

2004-11-23

This report presents and documents the model components and analyses that represent potential processes associated with propagation of a magma-filled crack (dike) migrating upward toward the surface, intersection of the dike with repository drifts, flow of magma in the drifts, and post-magma emplacement effects on repository performance. The processes that describe upward migration of a dike and magma flow down the drift are referred to as the dike intrusion submodel. The post-magma emplacement processes are referred to as the post-intrusion submodel. Collectively, these submodels are referred to as a conceptual model for dike/drift interaction. The model components and analyses of the dike/drift interaction conceptual model provide the technical basis for assessing the potential impacts of an igneous intrusion on repository performance, including those features, events, and processes (FEPs) related to dike/drift interaction (Section 6.1).

Dike/Drift Interactions

International Nuclear Information System (INIS)

Gaffiney, E.

2004-01-01

This report presents and documents the model components and analyses that represent potential processes associated with propagation of a magma-filled crack (dike) migrating upward toward the surface, intersection of the dike with repository drifts, flow of magma in the drifts, and post-magma emplacement effects on repository performance. The processes that describe upward migration of a dike and magma flow down the drift are referred to as the dike intrusion submodel. The post-magma emplacement processes are referred to as the post-intrusion submodel. Collectively, these submodels are referred to as a conceptual model for dike/drift interaction. The model components and analyses of the dike/drift interaction conceptual model provide the technical basis for assessing the potential impacts of an igneous intrusion on repository performance, including those features, events, and processes (FEPs) related to dike/drift interaction (Section 6.1)

Studies of electron drift velocity in nitrogen and isobutane

Energy Technology Data Exchange (ETDEWEB)

Goncalves, Josemary A.C.; Botelho, Suzana; Tobias, Carmen C.B. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Pontificia Univ. Catolica de Sao Paulo (PUC/SP), SP (Brazil); Vivaldini, Tulio C.; Lima, Iara B. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Ridenti, Marco A.; Pascholati, Paulo R. [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Fisica. Lab. do Acelerador Linear; Fonte, Paulo; Mangiarotti, Alessio [Universidade de Coimbra (Portugal). Dept. de fisica. Lab. de Instrumentacao e Fisica Experimental de Particulas

2009-07-01

Full text: The electron drift velocity is one of the most important transport parameters used to describe the physical behaviour of gas discharges and the development of avalanches in gaseous detectors, mainly when temporal information is significant, as in drift chambers and in the recent Resistive Plate Chambers (RPCs). Although many filling gases, isobutane is frequently used in RPCs, due to its excellent timing properties, but at high electric fields conditions there are insufficient data available in literature. In the present work we report the preliminary results related to the dependence of the electron drift velocity for isobutane as function of the reduced electric field E/N, in the range of 100 Td up to 216 Td. There are different methods to determine electron drift velocity in a gas, and our measurements were based on the Pulsed Townsend technique, which consists of extracting electrons from a metallic cathode and accelerates them toward the anode by a uniform electric field. Once the drift distance and the transit time are known, the drift velocities can be determined. In our system, the incidence of a nitrogen laser beam (LTB MNL200-LD) liberates electron from the cathode made of aluminium (40mm diameter). By means of a high voltage supply (Bertan, 225-30), these electrons are accelerated toward the anode (made of a high resistivity glass - 2:10{sup 12}{omega} cm) and this movement produces a fast electric signal in the anode, which is digitalized in an oscilloscope (LeCroy WavePro 7000) with 1 GHz bandwidth and 10 GS/s. The values obtained were compared to that ones of a Bolsig+ simulation code. In order to validate the technique and to analyze non-uniformity effects, results for nitrogen are also presented. (author)

Studies of electron drift velocity in nitrogen and isobutane

International Nuclear Information System (INIS)

Goncalves, Josemary A.C.; Botelho, Suzana; Tobias, Carmen C.B.; Vivaldini, Tulio C.; Lima, Iara B.; Ridenti, Marco A.; Pascholati, Paulo R.; Fonte, Paulo; Mangiarotti, Alessio

2009-01-01

Full text: The electron drift velocity is one of the most important transport parameters used to describe the physical behaviour of gas discharges and the development of avalanches in gaseous detectors, mainly when temporal information is significant, as in drift chambers and in the recent Resistive Plate Chambers (RPCs). Although many filling gases, isobutane is frequently used in RPCs, due to its excellent timing properties, but at high electric fields conditions there are insufficient data available in literature. In the present work we report the preliminary results related to the dependence of the electron drift velocity for isobutane as function of the reduced electric field E/N, in the range of 100 Td up to 216 Td. There are different methods to determine electron drift velocity in a gas, and our measurements were based on the Pulsed Townsend technique, which consists of extracting electrons from a metallic cathode and accelerates them toward the anode by a uniform electric field. Once the drift distance and the transit time are known, the drift velocities can be determined. In our system, the incidence of a nitrogen laser beam (LTB MNL200-LD) liberates electron from the cathode made of aluminium (40mm diameter). By means of a high voltage supply (Bertan, 225-30), these electrons are accelerated toward the anode (made of a high resistivity glass - 2:10 12 Ω cm) and this movement produces a fast electric signal in the anode, which is digitalized in an oscilloscope (LeCroy WavePro 7000) with 1 GHz bandwidth and 10 GS/s. The values obtained were compared to that ones of a Bolsig+ simulation code. In order to validate the technique and to analyze non-uniformity effects, results for nitrogen are also presented. (author)

Drift chambers in BM@N Experiment

Directory of Open Access Journals (Sweden)

Fedorišin Ján

2017-01-01

In first step, the radius vs drift time calibration curve is estimated and applied to calculate DCH hit closest approach coordinates. These coordinates are used to construct hits in each DCH under the assumption of track linearity. Hits in both the DCHs are subsequently aligned and fitted to produce global linear track candidates. Eventually the hit and track reconstruction is optimized by the autocalibration method. The coordinate resolutions are estimated from Gaussian fits of the DCH hit residual spectra for different DCH planes. Furthermore, the deuteron beam momentum value is reconstructed in order to check reliability of the employed track reconstruction algorithm.

Behavior of corroded bonded partially prestressed concrete beams

Directory of Open Access Journals (Sweden)

Mohamed Moawad

2018-04-01

Full Text Available Prestressed concrete is widely used in the construction industry in buildings. And corrosion of reinforcing steel is one of the most important and prevalent mechanisms of deterioration for concrete structures. Consequently the capacity of post-tension elements decreased after exposure to corrosion. This study presents results of the experimental investigation of the performance and the behavior of partially prestressed beams, with 40 and 80 MPa compressive strength exposed to corrosion. The experimental program of this study consisted of six partially prestressed beams with overall dimensions equal to 150 × 400 × 4500 mm. The variables were considered in terms of concrete compressive strength, and corrosion location effect. The mode of failure, and strain of steel reinforcement, cracking, yield, ultimate load and the corresponding deflection of each beam, and crack width and distribution were recorded. The results showed that the partially prestressed beam with 80 MPa compressive strength has higher resistance to corrosion exposure than that of partially prestressed concrete beam with 40 MPa compressive strength. Not big difference in deterioration against fully/partially corrosion exposure found between partially prestressed beams at the same compressive strength. The most of deterioration incident in partially prestressed beam acts on non prestressed steel reinforcement. Because the bonded tendons are less likely to corrode, cement grout and duct act as a barrier to moisture and chloride penetration, especially plastic duct without splices and connections. The theoretical analysis based on strain compatibility and force equilibrium gave a good prediction of the deformational behavior for high/normal partially prestressed beams. Keywords: Beam, Corrosion, Deterioration, Partially prestressed, High strength concrete

Silicon drift detectors in alice experiment at lhc, performance tests and simulations

International Nuclear Information System (INIS)

ALICE collaboration

2001-01-01

A brief introduction to the silicon drift detector (SDD) in ALICE experiment at LHC CERN. Excellent agreement are found between the results from the simulation code (Ali Root) and the results of the test beam data for SDD s. A study of SDD performance and double track separation capability are shown

Behavior of reinforcement SCC beams under elevated temperatures

Science.gov (United States)

Fathi, Hamoon; Farhang, Kianoosh

2015-09-01

This experimental study focuses on the behavior of heated reinforced concrete beams. Four types of concrete mixtures were used for the tested self-compacting concrete beams. A total of 72 reinforced concrete beams and 72 standard cylindrical specimens were tested. The compressive strength under uniaxial loading at 23 °C ranged from 30 to 45 MPa. The specimens were exposed to different temperatures. The test parameters of interest were the compressive strength and the temperature of the specimens. The effect of changes in the parameters was examined so as to control the behavior of the tested concrete and that of the reinforced concrete beam. The results indicated that flexibility and compressive strength of the reinforced concrete beams decreased at higher temperatures. Furthermore, heating beyond 400 °C produced greater variations in the structural behavior of the materials in both the cylindrical samples and the reinforced concrete beams.

Brookhaven National Laboratory's multiparticle spectrometer drift chamber system

International Nuclear Information System (INIS)

Etkin, A.; Kramer, M.A.

1979-01-01

A system of drift chambers is being built to replace the present spark chambers in the Brookhaven National Laboratory's Multiparticle Spectrometer. This system will handle a beam of approx. 3 million particles per second and have a resolution of 200 μm. A summary of the status of the chambers and the custom integrated circuits is presented. The data acquisition system is described. Prototype chambers have been built and tested with results that are consistent with the expected chamber properties

Cost effective electronics for proportional and drift chambers of 'EPECUR' experiment

International Nuclear Information System (INIS)

Alekseev, I.G.; Andreev, V.A.; Budkovsky, P.E.; Filimonov, E.A.; Golubev, V.V.; Kanavets, V.P.; Kats, M.M.; Koroleva, L.I.; Kovalev, A.I.; Kozlenko, N.G.; Kozlov, V.S.; Krivshich, A.G.; Kulikov, V.V.; Morozov, B.V.; Nesterov, V.M.; Novinsky, D.V.; Ryltsov, V.V.; Sadler, M.E.; Sakharov, V.A.; Soboyede, D.; Sulimov, A.D.; Sumachev, V.V.; Svirida, D.N.; Trautman, V.Yu.; Walker, E.; Watson, S.

2007-01-01

The 'EPECUR' experimental setup is under construction at beam line 322 of the ITEP proton synchrotron. The experiment requires several large area drift chambers to provide reasonable acceptance and fine-pitch proportional chambers for beam particle tracking. The total number of electronic channels is about 7000. A new compact and cost effective readout system for these gaseous detectors was designed, prototyped and tested in the last two years. It is based on modern technologies in analog and digital electronics and data transfer protocols. This paper presents the functional description of the whole DAQ system, including test results as an illustration of its performance

Reaching for highest ion beam intensities through laser ion acceleration and beam compression

Energy Technology Data Exchange (ETDEWEB)

Schumacher, Dennis; Brabetz, Christian; Blazevic, Abel; Bagnoud, Vincent; Weih, Simon [GSI Helmholtzzentrum fuer Schwerionenforschung (Germany); Jahn, Diana; Ding, Johannes; Roth, Markus [TU Darmstadt (Germany); Kroll, Florian; Schramm, Ulrich; Cowan, Tom [Helmholtzzentrum Dresden Rossendorf (Germany); Collaboration: LIGHT-Collaboration

2016-07-01

Laser ion acceleration provides access to ion sources with unique properties. To use these capabilities the LIGHT collaboration (Laser Ion Generation Handling and Transport) was founded. The aim of this collaboration is the beam transport and manipulation of laser accelerated ions with conventional accelerator structures. Therefor a dedicated beam line has been build up at GSI Helmholtzzentrum fuer Schwerionenforschung. With this beam line the manipulation of the transversal and also the longitudinal beam parameters has been achieved. It has been shown that laser generated ion beams can be transported over more than 6 meters and pulses shorter than 300 ps can be generated at this distance. This Talk will give an overview over the recent developments and plans of the LIGHT collaboration.

Drift-Scale Radionuclide Transport

International Nuclear Information System (INIS)

Houseworth, J.

2004-01-01

The purpose of this model report is to document the drift scale radionuclide transport model, taking into account the effects of emplacement drifts on flow and transport in the vicinity of the drift, which are not captured in the mountain-scale unsaturated zone (UZ) flow and transport models ''UZ Flow Models and Submodels'' (BSC 2004 [DIRS 169861]), ''Radionuclide Transport Models Under Ambient Conditions'' (BSC 2004 [DIRS 164500]), and ''Particle Tracking Model and Abstraction of Transport Process'' (BSC 2004 [DIRS 170041]). The drift scale radionuclide transport model is intended to be used as an alternative model for comparison with the engineered barrier system (EBS) radionuclide transport model ''EBS Radionuclide Transport Abstraction'' (BSC 2004 [DIRS 169868]). For that purpose, two alternative models have been developed for drift-scale radionuclide transport. One of the alternative models is a dual continuum flow and transport model called the drift shadow model. The effects of variations in the flow field and fracture-matrix interaction in the vicinity of a waste emplacement drift are investigated through sensitivity studies using the drift shadow model (Houseworth et al. 2003 [DIRS 164394]). In this model, the flow is significantly perturbed (reduced) beneath the waste emplacement drifts. However, comparisons of transport in this perturbed flow field with transport in an unperturbed flow field show similar results if the transport is initiated in the rock matrix. This has led to a second alternative model, called the fracture-matrix partitioning model, that focuses on the partitioning of radionuclide transport between the fractures and matrix upon exiting the waste emplacement drift. The fracture-matrix partitioning model computes the partitioning, between fractures and matrix, of diffusive radionuclide transport from the invert (for drifts without seepage) into the rock water. The invert is the structure constructed in a drift to provide the floor of the

The creation of strongly coupled plasmas using an intense heavy ion beam: low-entropy compression of hydrogen and the problem of hydrogen metallization

CERN Document Server

Tahir, N A; Shutov, A; Varentsov, D; Udrea, S; Hoffmann, Dieter H H; Juranek, H; Redmer, R; Portugues, R F; Lomonosov, I V; Fortov, V E

2003-01-01

Intense heavy ion beams deposit energy very efficiently over extended volumes of solid density targets, thereby creating large samples of strongly coupled plasmas. Intense beams of energetic heavy ions are therefore an ideal tool to research this interesting field. It is also possible to design experiments using special beam-target geometries to achieve low-entropy compression of samples of matter. This type of experiments is of particular interest for studying the problem of hydrogen metallization. In this paper we present a design study of such a proposed experiment that will be carried out at the future heavy ion synchrotron facility SIS100, at the Gesellschaft fuer Schwerionenforschung, Darmstadt. This study has been done using a two-dimensional hydrodynamic computer code. The target consists of a solid hydrogen cylinder that is enclosed in a thick shell of lead whose one face is irradiated with an ion beam which has an annular (ring shaped) focal spot. The beam intensity and other parameters are consider...

High-Voltage, High-Impedance Ion Beam Production

Science.gov (United States)

2009-06-01

the anode tube with a loosely-crumpled, thin aluminized- mylar foil. This spoils the virtual cathode and greatly reduces the neutron signal, as seen...ions follow ballistic (straight-line) trajectories in the drift tube (see Sec. VIII), then (except for the small displacement associated with bending...mTorr) ambient in the drift tube . Based on our previous experience, we would expect charge, but not necessarily current, neutralization of the beam

Kinetic theory of plasma adiabatic major radius compression in tokamaks

International Nuclear Information System (INIS)

Gorelenkova, M.V.; Gorelenkov, N.N.; Azizov, E.A.; Romannikov, A.N.; Herrmann, H.W.

1998-01-01

In order to understand the individual charged particle behavior as well as plasma macroparameters (temperature, density, etc.) during the adiabatic major radius compression (R-compression) in a tokamak, a kinetic approach is used. The perpendicular electric field from the Ohm close-quote s law at zero resistivity is made use of in order to describe particle motion during the R-compression. Expressions for both passing and trapped particle energy and pitch angle change are derived for a plasma with high aspect ratio and circular magnetic surfaces. The particle behavior near the passing trapped boundary during the compression is studied to simulate the compression-induced collisional losses of alpha particles. Qualitative agreement is obtained with the alphas loss measurements in deuterium-tritium (D-T) experiments in the Tokamak Fusion Test Reactor (TFTR) [World Survey of Activities in Controlled Fusion Research [Nucl. Fusion special supplement (1991)] (International Atomic Energy Agency, Vienna, 1991)]. The plasma macroparameters evolution at the R-compression is calculated by solving the gyroaveraged drift kinetic equation. copyright 1998 American Institute of Physics

Generation of helical electron beams by a nonadiabatic gun

International Nuclear Information System (INIS)

Barroso, J.J.; Stellati, C.

1996-01-01

The design of a non-adiabatic gun to produce a 10A, 50kV hollow laminar electron beam for gyrotron applications is reported. The beam is extracted from the emitting ring in a direction parallel to the axial guide magnetic field and then propagates across the radial electric field in the anode gap. The electrons are thereby given a transverse velocity upon passing through the modulation anode region where an electrostatic pumping mechanism takes place, so that a considerable amount of the electron energy is converted to transverse kinetic energy. Such a beam extraction method gives rise to favourable features that are examined throughout the work. The dynamics of hollow electron beams with gyromotion propagating down a cylindrical drift tube are also analysed. Due to the action of the beam's self-space charge field, the transverse velocity spread has an oscillatory behaviour along the drift tube wherein the spatial automodulation period shortens with increasing current. Numerical simulation results indicate that even at a 10A beam current, the resulting transverse velocity spread is still less than the spread for a zero beam current. (UK)

Bunch compression efficiency of the femtosecond electron source at Chiang Mai University

International Nuclear Information System (INIS)

Thongbai, C.; Kusoljariyakul, K.; Saisut, J.

2011-01-01

A femtosecond electron source has been developed at the Plasma and Beam Physics Research Facility (PBP), Chiang Mai University (CMU), Thailand. Ultra-short electron bunches can be produced with a bunch compression system consisting of a thermionic cathode RF-gun, an alpha-magnet as a magnetic bunch compressor, and a linear accelerator as a post acceleration section. To obtain effective bunch compression, it is crucial to provide a proper longitudinal phase-space distribution at the gun exit matched to the subsequent beam transport system. Via beam dynamics calculations and experiments, we investigate the bunch compression efficiency for various RF-gun fields. The particle distribution at the RF-gun exit will be tracked numerically through the alpha-magnet and beam transport. Details of the study and results leading to an optimum condition for our system will be presented.

Bunch compression efficiency of the femtosecond electron source at Chiang Mai University

Science.gov (United States)

Thongbai, C.; Kusoljariyakul, K.; Saisut, J.

2011-07-01

A femtosecond electron source has been developed at the Plasma and Beam Physics Research Facility (PBP), Chiang Mai University (CMU), Thailand. Ultra-short electron bunches can be produced with a bunch compression system consisting of a thermionic cathode RF-gun, an alpha-magnet as a magnetic bunch compressor, and a linear accelerator as a post acceleration section. To obtain effective bunch compression, it is crucial to provide a proper longitudinal phase-space distribution at the gun exit matched to the subsequent beam transport system. Via beam dynamics calculations and experiments, we investigate the bunch compression efficiency for various RF-gun fields. The particle distribution at the RF-gun exit will be tracked numerically through the alpha-magnet and beam transport. Details of the study and results leading to an optimum condition for our system will be presented.

Assembly techniques for ultra-low mass drift chambers

International Nuclear Information System (INIS)

Assiro, R.; Cascella, M.; Grancagnolo, F.; L'Erario, A.; Miccoli, A.; Rella, S.; Spedicato, M.; Tassielli, G.

2014-01-01

We presents a novel technique for the fast assembly of next generation ultra low mass drift chambers offering space point resolution of the order of 100 μm and high tolerance to pile-up. The chamber design has been developed keeping in mind the requirements for the search of rare processes: high resolutions (order of 100–200 KeV/c) for particles momenta in a range (50–100 MeV/c) totally dominated by the multiple scattering contribution (e.g., muon and kaon decay experiment such as MEG at PSI and Mu2e and ORKA at Fermilab). We describe a novel wiring strategy enabling the semiautomatic wiring of a complete layer with a high degree of control over wire tension and position. We also present feed-through-less wire anchoring system. These techniques have been already implemented at INFN-Lecce in the construction of a prototype drift chamber to be soon tested with cosmic rays and particle beams

Assembly techniques for ultra-low mass drift chambers

Science.gov (United States)

Assiro, R.; Cascella, M.; Grancagnolo, F.; L'Erario, A.; Miccoli, A.; Rella, S.; Spedicato, M.; Tassielli, G.

2014-03-01

We presents a novel technique for the fast assembly of next generation ultra low mass drift chambers offering space point resolution of the order of 100 μm and high tolerance to pile-up. The chamber design has been developed keeping in mind the requirements for the search of rare processes: high resolutions (order of 100-200 KeV/c) for particles momenta in a range (50-100 MeV/c) totally dominated by the multiple scattering contribution (e.g., muon and kaon decay experiment such as MEG at PSI and Mu2e and ORKA at Fermilab). We describe a novel wiring strategy enabling the semiautomatic wiring of a complete layer with a high degree of control over wire tension and position. We also present feed-through-less wire anchoring system. These techniques have been already implemented at INFN-Lecce in the construction of a prototype drift chamber to be soon tested with cosmic rays and particle beams.

Estimation of fracture conditions of ceramics by thermal shock with laser beams based on the maximum compressive stress criterion

International Nuclear Information System (INIS)

Akiyama, Shigeru; Amada, Shigeyasu.

1992-01-01

Structural ceramics are attracting attention in the development of space planes, aircraft and nuclear fusion reactors because they have excellent wear-resistant and heat-resistant characteristics. However, in some applications it is anticipated that they will be exposed to very-high-temperature environments of the order of thousands of degrees. Therefore, it is very important to investigate their thermal shock characteristics. In this report, the distributions of temperatures and thermal stresses of cylindrically shaped ceramics under irradiation by laser beams are discussed using the finite-element computer code (MARC) with arbitrary quadrilateral axisymmetric ring elements. The relationships between spot diameters of laser beams and maximum values of compressive thermal stresses are derived for various power densities. From these relationships, a critical fracture curve is obtained, and it is compared with the experimental results. (author)

Self-shielding flex-circuit drift tube, drift tube assembly and method of making

Science.gov (United States)

Jones, David Alexander

2016-04-26

The present disclosure is directed to an ion mobility drift tube fabricated using flex-circuit technology in which every other drift electrode is on a different layer of the flex-circuit and each drift electrode partially overlaps the adjacent electrodes on the other layer. This results in a self-shielding effect where the drift electrodes themselves shield the interior of the drift tube from unwanted electro-magnetic noise. In addition, this drift tube can be manufactured with an integral flex-heater for temperature control. This design will significantly improve the noise immunity, size, weight, and power requirements of hand-held ion mobility systems such as those used for explosive detection.

Drift chamber detectors

International Nuclear Information System (INIS)

Duran, I.; Martinez Laso, L.

1989-01-01

A review of High Energy Physics detectors based on drift chambers is presented. The ionization, drift diffusion, multiplication and detection principles are described. Most common drift media are analysied, and a classification of the detectors according to its geometry is done. Finally the standard read-out methods are displayed and the limits of the spatial resolution are discussed. (Author)

Design of bunch compressing system with suppression of coherent synchrotron radiation for ATF upgrade

International Nuclear Information System (INIS)

Jing, Yichao; Fedurin, Mikhail; Stratakis, Diktys

2015-01-01

One of the operation modes for Accelerator Test Facility (ATF) upgrade is to provide high peak current, high quality electron beam for users. Such operation requires a bunch compressing system with a very large compression ratio. The CSR originating from the strong compressors generally could greatly degrade the quality of the electron beam. In this paper, we present our design for the entire bunch compressing system that will limit the effect of CSR on the e-beam@s quality. We discuss and detail the performance from the start to end simulation of such a compressor for ATF.

Construction update and drift velocity calibration for the CLAS drift chamber system

International Nuclear Information System (INIS)

Mestayer, M.D.; Barbosa, F.J.; Bonneau, P.; Burtin, E.; Christo, S.; Doolittle, G.; Dytman, S.A.; Gilfoyle, G.P.; Hyde-Wright, C.E.; Klein, A.; Kossov, M.V.; Kuhn, S.E.; Magahiz, R.; Miskimen, R.A.; Murphy, L.Y.; O'Meara, J.E.; Pyron, T.D.; Qin, L.; Raue, B.A.; Schumacher, R.A.; Tuzel, W.; Weinstein, L.B.; Yegneswaran, A.

1995-01-01

We briefly describe the drift chamber system for the CLAS detector at CEBAF, concentrating on the method which will be used to calibrate the drift velocity function. We identify key features of the function which should apply to any small-cell drift chamber geometry in which the cathode and anode surfaces are wires. Using these ideas, we describe a simple method to compensate for variations in the drift velocity function due to environmental changes. (orig.)

Construction update and drift velocity calibration for the CLAS drift chamber system

Energy Technology Data Exchange (ETDEWEB)

Mestayer, M.D. [Continuous Electron Beam Accelerator Facility, Newport News, VA (United States); Barbosa, F.J. [Continuous Electron Beam Accelerator Facility, Newport News, VA (United States); Bonneau, P. [Continuous Electron Beam Accelerator Facility, Newport News, VA (United States); Burtin, E. [University of South Carolina, Columbia, SC (United States); Christo, S. [Continuous Electron Beam Accelerator Facility, Newport News, VA (United States); Doolittle, G. [Continuous Electron Beam Accelerator Facility, Newport News, VA (United States); Dytman, S.A. [University of Pittsburg, Pittsburg, PA (United States); Gilfoyle, G.P. [University of Richmond, Richmond, VA (United States); Hyde-Wright, C.E. [Old Dominion University, Norfolk, VA (United States); Klein, A. [Old Dominion University, Norfolk, VA (United States); Kossov, M.V. [Christopher Newport University, Newport News, VA (United States); Kuhn, S.E. [Old Dominion University, Norfolk, VA (United States); Magahiz, R. [Carnegie-Mellon Univ., Pittsburgh, PA (United States); Miskimen, R.A. [University of Massachussetts, Amherst, MA (United States); Murphy, L.Y. [CE Saclay, Gif sur Yvette (France); O`Meara, J.E. [Continuous Electron Beam Accelerator Facility, Newport News, VA (United States); Pyron, T.D. [Old Dominion University, Norfolk, VA (United States); Qin, L. [Old Dominion University, Norfolk, VA (United States); Raue, B.A. [Old Dominion University, Norfolk, VA (United States); Schumacher, R.A. [Carnegie-Mellon Univ., Pittsburgh, PA (United States); Tuzel, W. [Continuous Electron Beam Accelerator Facility, Newport News, VA (United States); Weinstein, L.B. [Continuous Electron Beam Accelerator Facility, Newport News, VA (United States); Yegneswaran, A. [Continuous Electron Beam Accelerator Facility, Newport News, VA (United States)

1995-12-11

We briefly describe the drift chamber system for the CLAS detector at CEBAF, concentrating on the method which will be used to calibrate the drift velocity function. We identify key features of the function which should apply to any small-cell drift chamber geometry in which the cathode and anode surfaces are wires. Using these ideas, we describe a simple method to compensate for variations in the drift velocity function due to environmental changes. (orig.).

Drift Chambers detectors

International Nuclear Information System (INIS)

Duran, I.; Martinez laso, L.

1989-01-01

We present here a review of High Energy Physics detectors based on drift chambers. The ionization, drift diffusion, multiplication and detection principles are described. Most common drift media are analysed, and a classification of the detectors according to its geometry is done. Finally the standard read-out methods are displayed and the limits of the spatial resolution are discussed. (Author) 115 refs

W-Band Sheet Beam Klystron Design

International Nuclear Information System (INIS)

Scheitrum, G.; Caryotakis, G.; Burke, A.; Jensen, A.; Jongewaard, E.; Krasnykh, A.; Neubauer, M.; Phillips, R.; Rauenbuehler, K.

2011-01-01

Sheet beam devices provide important advantages for very high power, narrow bandwidth RF sources like accelerator klystrons (1). Reduced current density and increased surface area result in increased power capabi1ity, reduced magnetic fields for focusing and reduced cathode loading. These advantages are offset by increased complexity, beam formation and transport issues and potential for mode competition in the ovennoded cavities and drift tube. This paper will describe the design issues encountered in developing a 100 kW peak and 2 kW average power sheet beam k1ystron at W-band including beam formation, beam transport, circuit design, circuit fabrication and mode competition.

Simulations of ion beams for NDCX-II

Energy Technology Data Exchange (ETDEWEB)

Grote, D.P., E-mail: dpgrote@lbl.gov [LBNL MS47-112, 1 Cyclotron Rd, Bekerley, CA 94720 (United States); Lawrence Livermore National Lab, Livermore, CA 94550 (United States); Friedman, A., E-mail: afriedman@lbl.gov [Lawrence Livermore National Lab, Livermore, CA 94550 (United States); Sharp, W.M. [Lawrence Livermore National Lab, Livermore, CA 94550 (United States)

2014-01-01

NDCX-II, the second neutralized drift compression experiment, is a moderate energy, high current accelerator designed to drive targets for warm dense matter and IFE-relevant energy coupling studies, and to serve as a testbed for high current accelerator physics. As part of the design process, studies were carried out to assess the sensitivities of the accelerator to errors, and to further optimize the design in concert with the evolving pulsed power engineering. The Warp code was used to carry out detailed simulations in both axisymmetric and full 3-D geometry. Ensembles of simulations were carried out to characterize the effects of errors, such as timing jitter and noise on the accelerator waveforms, noise on the source waveform, and solenoid and source offsets. In some cases, the ensemble studies resulted in better designs, revealing operating points with improved performance and showing possible means for further improvement. These studies also revealed a new non-paraxial effect of the final focus solenoid on the beam, which must be taken into account in designing an optimal final focusing system.

Popular heavy particle beam cancer therapeutic system (3). Development of high efficiency compact incident system-2. Great success of beam test of new APF-IH type DTL

International Nuclear Information System (INIS)

Yamamoto, Kazuo; Iwata, Yoshiyuki

2006-01-01

High efficiency compact incident system consists of an electron cyclotron resonance (ECR) ion source, a radio frequency quadrupole (RFQ) linear accelerator and an interdigital H-mode (IH) drift tube linear accelerator (DTL). IH type DTL and alternating phase focusing (APF) method is explained. Its special features, production, and beam test are reported. The electric field generation method, outline of the APF method, drift tube, IH type DTL, distribution of electric field and voltage, set up of beam test, ECR ion source and incident line, the inside structure of the RFQ type linear accelerator and the APF-IH type DTL, matching Q lens section, beam, emittance, measurement results of momentum dispersion are illustrated. (S.Y.)

BATMAN beam properties characterization by the beam emission spectroscopy diagnostic

Science.gov (United States)

Bonomo, F.; Ruf, B.; Barbisan, M.; Cristofaro, S.; Schiesko, L.; Fantz, U.; Franzen, P.; Pasqualotto, R.; Riedl, R.; Serianni, G.; Wünderlich, D.

2015-04-01

The ITER neutral beam heating systems are based on the production and acceleration of negative ions (H/D) up to 1 MV. The requirements for the beam properties are strict: a low core beam divergence (BATMAN (BAvarian Test MAchine for Negative ions) allows for deepening the knowledge of the determination of the beam properties. One of the diagnostics routinely used to this purpose is the Beam Emission Spectroscopy (BES): the Hα light emitted in the beam is detected and the corresponding spectra are evaluated to estimate the beam divergence and the stripping losses. The BES number of lines of sight in BATMAN has been recently increased: five horizontal lines of sight providing a vertical profile of the beam permit to characterize the negative ion beam properties in relation to the source parameters. Different methods of Hα spectra analysis are here taken into account and compared for the estimation of the beam divergence and the amount of stripping. In particular, to thoroughly study the effect of the space charge compensation on the beam divergence, an additional hydrogen injection line has been added in the tank, which allows for setting different background pressure values (one order of magnitude, from about 0.04 Pa up to the source pressure) in the beam drift region.

Beam brilliance investigation of high current ion beams at GSI heavy ion accelerator facility.

Science.gov (United States)

Adonin, A A; Hollinger, R

2014-02-01

In this work the emittance measurements of high current Ta-beam provided by VARIS (Vacuum Arc Ion Source) ion source are presented. Beam brilliance as a function of beam aperture at various extraction conditions is investigated. Influence of electrostatic ion beam compression in post acceleration gap on the beam quality is discussed. Use of different extraction systems (single aperture, 7 holes, and 13 holes) in order to achieve more peaked beam core is considered. The possible ways to increase the beam brilliance are discussed.

Quasistationary model of high-current relativistic electron beam. 1. Exact solution of Poisson equations

International Nuclear Information System (INIS)

Brenner, S.E.; Gandyl', E.M.; Podkopaev, A.P.

1995-01-01

The dynamics of high-current relativistic electron beam moving trough the cylindrical drift space has been modelled by the large particles, the shape of which allows to solve the Poisson equations exactly, and in such a way to avoid the linearization being usually used in those problems. The expressions for the components of own electric field of electron beam passing through the cylindrical drift space have been obtained. (author). 11 refs., 1 fig

Effect of different parameters governing the stability of drift wave in a magnetised plasma

International Nuclear Information System (INIS)

Elashkar, F.F.

1990-01-01

Influence of the governing parameters, such as electron drift parallel speed, parallel wave length, electron-neutral and ion-neutral collision frequencies, electron temperature and magnetic field, on the stability of drift wave in a magnetized plasma has been studied experimentally and theoretically using a full numerical solution of the exact equation. Drift wave has been excited by a positively biased grid; at a threshold grid potential secondary excitation and ionisation processes take place in the ejected beam of plasma. Effect of the applied magnetic field on the probability of these processes is discussed. Grid positive potential, electron-neutral collision, parallel wave length, electron temperature and speed are found to be destabilizing, While ion neutral collision is stabilizing. Using a new parameter β, the effect of magnetic field is investigated and it is destabilizing only upto a certain limit. (author). 11 figs., 21 refs

Low frequency fluid drift turbulence in magnetised plasmas

International Nuclear Information System (INIS)

Scott, B.

2001-03-01

We start with the first principles of fluid dynamics and classical electrodynamics and then find the regime in which we can reduce to quasineutral dynamics, which also implicitly underlies MHD. Then, we find the limits under which we can specialise to the MHD model as a subset, first of two fluid dynamics, then of the fluid drift dynamics that results when the motions are not vigorous enough to compress the magnetic field. In Chapters 4 and 5 we find the basic character of small disturbances in this system. Chapters 6 through 9 treat various aspects of fluid drift turbulence, also called drift wave turbulence, moving from a simple consideration of the underlying nonlinear dynamics, to some methods by which one can diagnose computations to find out what is going on, and then to the nonlinear instability which is the hallmark of this physics, and then to the interactions with large scale sheared flows. Chapter 10 introduces interchange turbulence, which is the plasma analog of the buoyant convection well known from fluid dynamics. Chapters 11 through 13 treat electromagnetic drift wave turbulence in closed magnetic field geometry, starting with a simplified model treating only the electron pressure and then introducing the electron and ion temperatures. Chapter 14 treats the basic characteristics of the transport that results from fluid drift turbulence, as this is quite different from the kinetic diffusion, such as heat conduction, that is more familiar. Appendices A and B treat the details of the numerical methods and models of magnetic field geometry necessary to treat all but the simplest cases. For this subject is dominated by nonlinear physics and therefore numerical computation. Computations therefore form an integral part of its study right from the beginning. Citations to the literature are not intended to be comprehensive but to serve as starting points for further reading, a section for which is included in every chapter. Much of this work is very new, and

Present status of beam position stabilization at photon factory storage ring

International Nuclear Information System (INIS)

Nakamura, Norio

1990-01-01

Stabilization of photon beam position became a major issue in the operation of the storage rings dedicated as synchrotron radiation source. At the Photon Factory storage ring (PF ring), the orbit movement appeared remarkably when the low-emittance operation started. This orbit movement became a serious problem to synchrotron radiation users because the photon beam to drift with a large amplitude. The horizontal and vertical orbit feedback systems were constructed and developed in order to suppress the orbit movement globally. As a result, the horizontal and vertical orbit movements were reduced by a factor of five and ten, respectively. In addition, another type of feedback system using a local bump was constructed. In the test operation, this system could remove the fast photon beam motion as well as the slow photon beam drift for a beamline. (author)

Effect of tension and compression reinforcements on the serviceability of HSC beams with relatively small shear span to depth ratio

International Nuclear Information System (INIS)

Maghsoudi, A.A.; Akbarzadeh, B.H.

2007-01-01

To investigate the serviceability performance of High-Strength Concrete (HSC) beams, 12 beams (L=2m, b=0.2m, h=0.3m and shear span to depth ratio of 1.8) with different ratios of p and p' (percentage of tensile and compressive steel) were cast and tested under bending. During the test, concrete and steel strains, deflections and crack widths were measured at different locations along each beam. Based on experimental readings and observations, the cracked moment of inertia (Icr) of HSC beams was determined and the results were compared with some selective theoretical methods. Also, the flexural crack widths of the beams were measured and the applicability of ACI, BS and CSA code for normal strength concrete (NSC) was verified for HSC beams tested. The experimental (Icr) exp values of HSC beams were lower than the theoretical (Icr) th values from different codes. It was concluded that the serviceability and post serviceability performance of reinforced concrete structures can be improved using high strength concrete. In general, for almost all HSC tested beams at three crack width (0.1, 0.2, 0.3 mm); the use of ACI equation led to predict 50% of the crack width conservatively (the ratio of ((wcr) th / (wcr) exp) is greater than unity) but the results of the BS equation are conservative while compare to the ACI equation. The use of the CSA equation for the beams of higher and lower reinforcement ratio caused a more conservative and a closer value respectively, to limiting values of CSA. The deflection at initial steel horizontal yield plateau is less than 9 mm which is a sign of excellent deflection performance of HSC beams. (author)

High current beam transport with multiple beam arrays

International Nuclear Information System (INIS)

Kim, C.H.

1985-05-01

Highlights of recent experimental and theoretical research progress on the high current beam transport of single and multiple beams by the Heavy Ion Fusion Accelerator Research (HIFAR) group at the Lawrence Berkeley Laboratory (LBL) are presented. In the single beam transport experiment (SBTE), stability boundaries and the emittance growth of a space charge dominated beam in a long quadrupole transport channel were measured and compared with theory and computer simulations. Also, a multiple beam ion induction linac (MBE-4) is being constructed at LBL which will permit study of multiple beam transport arrays, and acceleration and bunch length compression of individually focused beamlets. Various design considerations of MBE-4 regarding scaling laws, nonlinear effects, misalignments, and transverse and longitudinal space charge effects are summarized. Some aspects of longitudinal beam dynamics including schemes to generate the accelerating voltage waveforms and to amplify beam current are also discussed

Beam instability during high-current heavy-ion beam transport

International Nuclear Information System (INIS)

Kikuchi, T.; Someya, T.; Kawata, S.; Nakajima, M.; Horioka, K.

2005-01-01

In driver system for heavy ion inertial fusion, beam dynamics is investigated by particle-in-cell simulations during final beam bunching. The particle simulations predict that the beam is transported with the localized transverse charge distribution induced by the strong space charge effect. The calculation results also show that the emittance growth during the longitudinal bunch compression for various particle distributions at the initial conditions and with two types of transverse focusing model, which are a continuous focusing and an alternating gradient focusing lattice configurations. (author)

LONGITUDINAL MISMATCH IN SCL AS A SOURCE OF BEAM HALO.

Energy Technology Data Exchange (ETDEWEB)

RUGGIERO,A.G.

2003-06-19

An advantage of a proton Super-conducting Linac (SCL) is that RF cavities can be operated independently, allowing easier beam transport: and acceleration. But cavities are to be separated by drifts long enough to avoid they couple to each other. Moreover, cavities are placed in cryostats that include inactive insertions for cold-warm transitions; and interspersed are warm insertions for magnets and other devices. The SCL is then an alternating sequence of accelerating elements and drifts. No periodicity is present, and the longitudinal motion is not adiabatic. This has the consequence that the beam bunch ellipse will tumble, dilute and create a halo in the momentum plane because of inherent nonlinearities. When this is coupled to longitudinal space-charge forces, it may cause beam loss with latent activation of the accelerator components.

Compression of thick laminated composite beams with initial impact-like damage

Science.gov (United States)

Breivik, N. L.; Guerdal, Z.; Griffin, O. H., Jr.

1992-01-01

While the study of compression after impact of laminated composites has been under consideration for many years, the complexity of the damage initiated by low velocity impact has not lent itself to simple predictive models for compression strength. The damage modes due to non-penetrating, low velocity impact by large diameter objects can be simulated using quasi-static three-point bending. The resulting damage modes are less coupled and more easily characterized than actual impact damage modes. This study includes the compression testing of specimens with well documented initial damage states obtained from three-point bend testing. Compression strengths and failure modes were obtained for quasi-isotropic stacking sequences from 0.24 to 1.1 inches thick with both grouped and interspersed ply stacking. Initial damage prior to compression testing was divided into four classifications based on the type, extent, and location of the damage. These classifications are multiple through-thickness delaminations, isolated delamination, damage near the surface, and matrix cracks. Specimens from each classification were compared to specimens tested without initial damage in order to determine the effects of the initial damage on the final compression strength and failure modes. A finite element analysis was used to aid in the understanding and explanation of the experimental results.

Electromagnetic pulse compression and energy localization in quantum plasmas

International Nuclear Information System (INIS)

Hefferon, Gareth; Sharma, Ashutosh; Kourakis, Ioannis

2010-01-01

The evolution of the intensity of a relativistic laser beam propagating through a dense quantum plasma is investigated, by considering different plasma regimes. A cold quantum fluid plasma and then a thermal quantum description(s) is (are) adopted, in comparison with the classical case of reference. Considering a Gaussian beam cross-section, we investigate both the longitudinal compression and lateral/longitudinal localization of the intensity of a finite-radius electromagnetic pulse. By employing a quantum plasma fluid model in combination with Maxwell's equations, we rely on earlier results on the quantum dielectric response, to model beam-plasma interaction. We present an extensive parametric investigation of the dependence of the longitudinal pulse compression mechanism on the electron density in cold quantum plasmas, and also study the role of the Fermi temperature in thermal quantum plasmas. Our numerical results show pulse localization through a series of successive compression cycles, as the pulse propagates through the plasma. A pulse of 100 fs propagating through cold quantum plasma is compressed to a temporal size of ∼1.35 attosecond and a spatial size of ∼1.08.10 -3 cm. Incorporating Fermi pressure via a thermal quantum plasma model is shown to enhance localization effects. A 100 fs pulse propagating through quantum plasma with a Fermi temperature of 350 K is compressed to a temporal size of ∼0.6 attosecond and a spatial size of ∼2.4.10 -3 cm.

The Design of Compressed air system in the Conventional Facility of Proton Accelerator Research Center

International Nuclear Information System (INIS)

Jeon, G. P.; Kim, J. Y.; Cho, S. W.; Min, Y. S.; Mun, K. J.; Cho, J. S.; Nam, J. M.; Park, S. S.; Jo, J. H.

2012-01-01

The Compressed Air System (CA) supplies compressed air for all air operated devices and instruments, pneumatic equipment and other miscellaneous air user points in the Conventional Facilities of Proton Engineering Frontier Project. CA System consist of the Instrument Air System and the Service air System. The Instrument Air System supplies oil-free, dried, filtered, and compressed instrument air for the air operated control devices and instruments in the Accelerator and Beam Application Building, Ion Beam Application Building, Utility Building and etc.. The Service air System supplies compressed air for pneumatic equipment and other services

Abstraction of Drift Seepage

International Nuclear Information System (INIS)

J.T. Birkholzer

2004-01-01

This model report documents the abstraction of drift seepage, conducted to provide seepage-relevant parameters and their probability distributions for use in Total System Performance Assessment for License Application (TSPA-LA). Drift seepage refers to the flow of liquid water into waste emplacement drifts. Water that seeps into drifts may contact waste packages and potentially mobilize radionuclides, and may result in advective transport of radionuclides through breached waste packages [''Risk Information to Support Prioritization of Performance Assessment Models'' (BSC 2003 [DIRS 168796], Section 3.3.2)]. The unsaturated rock layers overlying and hosting the repository form a natural barrier that reduces the amount of water entering emplacement drifts by natural subsurface processes. For example, drift seepage is limited by the capillary barrier forming at the drift crown, which decreases or even eliminates water flow from the unsaturated fractured rock into the drift. During the first few hundred years after waste emplacement, when above-boiling rock temperatures will develop as a result of heat generated by the decay of the radioactive waste, vaporization of percolation water is an additional factor limiting seepage. Estimating the effectiveness of these natural barrier capabilities and predicting the amount of seepage into drifts is an important aspect of assessing the performance of the repository. The TSPA-LA therefore includes a seepage component that calculates the amount of seepage into drifts [''Total System Performance Assessment (TSPA) Model/Analysis for the License Application'' (BSC 2004 [DIRS 168504], Section 6.3.3.1)]. The TSPA-LA calculation is performed with a probabilistic approach that accounts for the spatial and temporal variability and inherent uncertainty of seepage-relevant properties and processes. Results are used for subsequent TSPA-LA components that may handle, for example, waste package corrosion or radionuclide transport

RADLAC II high current electron beam propagation experiment

International Nuclear Information System (INIS)

Frost, C.A.; Shope, S.L.; Mazarakis, M.G.; Poukey, J.W.; Wagner, J.S.; Turman, B.N.; Crist, C.E.; Welch, D.R.; Struve, K.W.

1993-01-01

The resistive hose instability of an electron beam was observed to be convective in recent RADLAC II experiments for higher current shots. The effects of air scattering for these shots were minimal. These experiments and theory suggest low-frequency hose motion which does not appear convective may be due to rapid expansion and subsequent drifting of the beam nose

Time dependent drift Hamiltonian

International Nuclear Information System (INIS)

Boozer, A.H.

1982-04-01

The motion of individual charged particles in a given magnetic and an electric fields is discussed. An idea of a guiding center distribution function f is introduced. The guiding center distribution function is connected to the asymptotic Hamiltonian through the drift kinetic equation. The general non-stochastic magnetic field can be written in a contravariant and a covariant forms. The drift Hamiltonian is proposed, and the canonical gyroradius is presented. The proposed drift Hamiltonian agrees with Alfven's drift velocity to lowest non-vanishing order in the gyroradius. The relation between the exact, time dependent equations of motion and the guiding center equation is clarified by a Lagrangian analysis. The deduced Lagrangian represents the drift motion. (Kato, T.)

Drift Degradation Analysis

International Nuclear Information System (INIS)

D. Kicker

2004-01-01

Degradation of underground openings as a function of time is a natural and expected occurrence for any subsurface excavation. Over time, changes occur to both the stress condition and the strength of the rock mass due to several interacting factors. Once the factors contributing to degradation are characterized, the effects of drift degradation can typically be mitigated through appropriate design and maintenance of the ground support system. However, for the emplacement drifts of the geologic repository at Yucca Mountain, it is necessary to characterize drift degradation over a 10,000-year period, which is well beyond the functional period of the ground support system. This document provides an analysis of the amount of drift degradation anticipated in repository emplacement drifts for discrete events and time increments extending throughout the 10,000-year regulatory period for postclosure performance. This revision of the drift degradation analysis was developed to support the license application and fulfill specific agreement items between the U.S. Nuclear Regulatory Commission (NRC) and the U.S. Department of Energy (DOE). The earlier versions of ''Drift Degradation Analysis'' (BSC 2001 [DIRS 156304]) relied primarily on the DRKBA numerical code, which provides for a probabilistic key-block assessment based on realistic fracture patterns determined from field mapping in the Exploratory Studies Facility (ESF) at Yucca Mountain. A key block is defined as a critical block in the surrounding rock mass of an excavation, which is removable and oriented in an unsafe manner such that it is likely to move into an opening unless support is provided. However, the use of the DRKBA code to determine potential rockfall data at the repository horizon during the postclosure period has several limitations: (1) The DRKBA code cannot explicitly apply dynamic loads due to seismic ground motion. (2) The DRKBA code cannot explicitly apply loads due to thermal stress. (3) The DRKBA

Drift Degradation Analysis

Energy Technology Data Exchange (ETDEWEB)

D. Kicker

2004-09-16

Degradation of underground openings as a function of time is a natural and expected occurrence for any subsurface excavation. Over time, changes occur to both the stress condition and the strength of the rock mass due to several interacting factors. Once the factors contributing to degradation are characterized, the effects of drift degradation can typically be mitigated through appropriate design and maintenance of the ground support system. However, for the emplacement drifts of the geologic repository at Yucca Mountain, it is necessary to characterize drift degradation over a 10,000-year period, which is well beyond the functional period of the ground support system. This document provides an analysis of the amount of drift degradation anticipated in repository emplacement drifts for discrete events and time increments extending throughout the 10,000-year regulatory period for postclosure performance. This revision of the drift degradation analysis was developed to support the license application and fulfill specific agreement items between the U.S. Nuclear Regulatory Commission (NRC) and the U.S. Department of Energy (DOE). The earlier versions of ''Drift Degradation Analysis'' (BSC 2001 [DIRS 156304]) relied primarily on the DRKBA numerical code, which provides for a probabilistic key-block assessment based on realistic fracture patterns determined from field mapping in the Exploratory Studies Facility (ESF) at Yucca Mountain. A key block is defined as a critical block in the surrounding rock mass of an excavation, which is removable and oriented in an unsafe manner such that it is likely to move into an opening unless support is provided. However, the use of the DRKBA code to determine potential rockfall data at the repository horizon during the postclosure period has several limitations: (1) The DRKBA code cannot explicitly apply dynamic loads due to seismic ground motion. (2) The DRKBA code cannot explicitly apply loads due to thermal

Emittance preservation during bunch compression with a magnetized beam

Energy Technology Data Exchange (ETDEWEB)

Stratakis, Diktys [Brookhaven National Lab. (BNL), Upton, NY (United States)

2015-09-02

The deleterious effects of coherent synchrotron radiation (CSR) on the phase-space and energy spread of high-energy beams in accelerator light sources can significantly constrain the machine design and performance. In this paper, we present a simple method to preserve the beam emittance by means of using magnetized beams that exhibit a large aspect ratio on their transverse dimensions. The concept is based on combining a finite solenoid field where the beam is generated together with a special optics adapter. Numerical simulations of this new type of beam source show that the induced phase-space density growth can be notably suppressed to less than 1% for any bunch charge. This work elucidates the key parameters that are needed for emittance preservation, such as the required field and aspect ratio for a given bunch charge.

MUON DETECTOR: BARREL DRIFT TUBES (DT) AND ALIGNMENT

CERN Multimedia

Marco Dallavalle

After months of cosmics data taking the drift tube (DT) detector is in good shape, ready for LHC beams. Several hundreds of millions of cosmics events have been recorded; out of those, more than 90% were triggered by the DT system. Data integrity analyses have shown a very reliable read-out system, also during high rate tests. With a 98% of the detector operational, only awaiting the arrival of some low voltage modules and for the completion of the DT Track Finder system, data taking is starting to become routine job. These continuous running exercises have been very useful to study performance and reliability of the detector in a medium term period, allowing understanding and fixing failures that have occurred with low frequency. Drift tubes have become a very stable system, becoming a service of muon triggering for the tracker after its final installation. During the last months, major efforts have taken place in synchronization tasks, within the DT system (250 chambers) and also with the rest of the CMS su...

Low complexity lossless compression of underwater sound recordings.

Science.gov (United States)

Johnson, Mark; Partan, Jim; Hurst, Tom

2013-03-01

Autonomous listening devices are increasingly used to study vocal aquatic animals, and there is a constant need to record longer or with greater bandwidth, requiring efficient use of memory and battery power. Real-time compression of sound has the potential to extend recording durations and bandwidths at the expense of increased processing operations and therefore power consumption. Whereas lossy methods such as MP3 introduce undesirable artifacts, lossless compression algorithms (e.g., flac) guarantee exact data recovery. But these algorithms are relatively complex due to the wide variety of signals they are designed to compress. A simpler lossless algorithm is shown here to provide compression factors of three or more for underwater sound recordings over a range of noise environments. The compressor was evaluated using samples from drifting and animal-borne sound recorders with sampling rates of 16-240 kHz. It achieves >87% of the compression of more-complex methods but requires about 1/10 of the processing operations resulting in less than 1 mW power consumption at a sampling rate of 192 kHz on a low-power microprocessor. The potential to triple recording duration with a minor increase in power consumption and no loss in sound quality may be especially valuable for battery-limited tags and robotic vehicles.

Study of CSR longitudinal bunch compression cavity

International Nuclear Information System (INIS)

Yin Dayu; Li Peng; Liu Yong; Xie Qingchun

2009-01-01

The scheme of longitudinal bunch compression cavity for the Cooling Storage Ring (CSR)is an important issue. Plasma physics experiments require high density heavy ion beam and short pulsed bunch,which can be produced by non-adiabatic compression of bunch implemented by a fast compression with 90 degree rotation in the longitudinal phase space. The phase space rotation in fast compression is initiated by a fast jump of the RF-voltage amplitude. For this purpose, the CSR longitudinal bunch compression cavity, loaded with FINEMET-FT-1M is studied and simulated with MAFIA code. In this paper, the CSR longitudinal bunch compression cavity is simulated and the initial bunch length of 238 U 72+ with 250 MeV/u will be compressed from 200 ns to 50 ns.The construction and RF properties of the CSR longitudinal bunch compression cavity are simulated and calculated also with MAFIA code. The operation frequency of the cavity is 1.15 MHz with peak voltage of 80 kV, and the cavity can be used to compress heavy ions in the CSR. (authors)

The optimization of the electrostatic field inside the ZEUS forward drift chambers: Calculations and measurements

International Nuclear Information System (INIS)

Dobberstein, M.P.; Krawczyk, F.; Schaefer-Jotter, M.

1990-11-01

The electrostatic field inside small drift cells shows in general edge effects which are not negligible. These are usually corrected by field shaping wires or strips. The operating voltages of the field shaping electrodes have to be adjusted to maximize the field homogeneity. We present the underlying ideas of such an optimization procedure for the cells of the ZEUS forward drift chambers. Using the finite difference code PROFI, the optimization can be performed automatically by a multiple solution of the Poisson equation. An experimental verification of the optimal voltages was carried out measuring the gas amplifications at the six sense wires. Modifications of the drift cell geometry were necessary for calibration measurements with a laser beam. This caused additional distortions of the electrostatic field. Their influence was calculated using the MAFIA code, which allows to include open boundary conditions. (orig.)

Three-dimensional simulation studies of 10 MeV, 352.2 MHz drift ...

Indian Academy of Sciences (India)

It is proposed to build a drift tube Linac (DTL) at Raja Ramanna Centre for Advanced Technology, Indore, India, that will form a part of the future Spallation Neutron Source. This DTL will accelerate 30 mA H-ion beam from 3 MeV to 10 MeV. The DTL is designed to operate at 352.2 MHz with a maximum duty cycle of 3%.

Emittance preservation during bunch compression with a magnetized beam

Energy Technology Data Exchange (ETDEWEB)

Stratakis, Diktys

2016-03-01

The deleterious effects of coherent synchrotron radiation (CSR) on the phase-space and energy spread of high-energy beams in accelerator light sources can significantly constrain the machine design and performance. In this paper, we present a simple method to preserve the beam emittance by means of using magnetized beams that exhibit a large aspect ratio on their transverse dimensions. The concept is based in combining a finite solenoid field where the beam is generated with a special optics adapter. Numerical simulations of this new type of beam source show that the induced phase-space density growth from CSR can be notably suppressed to less than 1% for any bunch charge. This work elucidates the key parameters that are needed for emittance preservation, such as the required field and aspect ratio for a given bunch charge.

Consistent guiding center drift theories

International Nuclear Information System (INIS)

Wimmel, H.K.

1982-04-01

Various guiding-center drift theories are presented that are optimized in respect of consistency. They satisfy exact energy conservation theorems (in time-independent fields), Liouville's theorems, and appropriate power balance equations. A theoretical framework is given that allows direct and exact derivation of associated drift-kinetic equations from the respective guiding-center drift-orbit theories. These drift-kinetic equations are listed. Northrop's non-optimized theory is discussed for reference, and internal consistency relations of G.C. drift theories are presented. (orig.)

Studies on the beam system for the calibration of the OPAL jet chamber with laser beams

International Nuclear Information System (INIS)

Maringer, G.

1988-07-01

UV laser beams are an important tool for the calibration of the OPAL jet chamber. A beam transport system containing about 350 mirrors in total guides the beams from the laser outside the detector into the chamber. Four of the mirrors are moveable under remote control allowing to guide the beams into each of the 24 sectors and to correct the beam path in case of deviations. A program to control these moveable mirrors has been developed. Drift velocity measurements will be performed by means of double beams which are generated by appropriate beamsplitters. Accurate knowledge of the double beam distances is essential to obtain the desired accuracy of better than 0.1% or 10 μm. Using a CCD device with a pixel size of 23x23 μm 2 the beam distance could be measured with errors below the required limit. (orig.)

New concepts for drift pumping a thermal barrier with rf

International Nuclear Information System (INIS)

Barter, J.D.; Baldwin, D.; Chen, Y.; Poulsen, P.

1985-01-01

Pump neutral beams, which are directed into the loss cone of the TMX-U plugs, are normally used to pump ions from the thermal barriers. Because these neutral beams introduce cold gas that reduces pumping efficiency, and require a straight line entrance and exit from the plug, alternate methods are being investigated to provide barrier pumping. To maintain the thermal barrier, either of two classes of particles can be pumped. First, the collisionally trapped ions can be pumped directly. In this case, the most promising selection criterion is the azimuthal drift frequency. Second, the excess sloshing-ion density can be removed, allowing the use of increased sloshing-beam density to pump the trapped ions. The selection mechanism in this case is the Doppler-shifted ion-cyclotron resonance of the high-energy sloshing-ions (3 keV less than or equal to U/sub parallel/ less than or equal to 10 keV)

SU-G-BRA-16: Target Dose Comparison for Dynamic MLC Tracking and Mid- Ventilation Planning in Lung Radiotherapy Subject to Intrafractional Baseline Drifts

Energy Technology Data Exchange (ETDEWEB)

Menten, MJ; Fast, MF; Nill, S; Oelfke, U [Joint Department of Physics at The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London (United Kingdom)

2016-06-15

Purpose: Lung tumor motion during radiotherapy can be accounted for by expanded treatment margins, for example using a mid-ventilation planning approach, or by localizing the tumor in real-time and adapting the treatment beam with multileaf collimator (MLC) tracking. This study evaluates the effect of intrafractional changes in the average tumor position (baseline drifts) on these two treatment techniques. Methods: Lung stereotactic treatment plans (9-beam IMRT, 54Gy/3 fractions, mean treatment time: 9.63min) were generated for three patients: either for delivery with MLC tracking (isotropic GTV-to-PTV margin: 2.6mm) or planned with a mid-ventilation approach and delivered without online motion compensation (GTV-to-PTV margin: 4.4-6.3mm). Delivery to a breathing patient was simulated using DynaTrack, our in-house tracking and delivery software. Baseline drifts in cranial and posterior direction were simulated at a rate of 0.5, 1.0 or 1.5mm/min. For dose reconstruction, the corresponding 4DCT phase was selected for each time point of the delivery. Baseline drifts were accounted for by rigidly shifting the CT to ensure correct relative beam-to-target positioning. Afterwards, the doses delivered to each 4DCT phase were accumulated deformably on the mid-ventilation phase using research RayStation v4.6 and dose coverage of the GTV was evaluated. Results: When using the mid-ventilation planning approach, dose coverage of the tumor deteriorated substantially in the presence of baseline drifts. The reduction in D98% coverage of the GTV in a single fraction ranged from 0.4-1.2, 0.6-3.3 and 4.5-6.2Gy, respectively, for the different drift rates. With MLC tracking the GTV D98% coverage remained unchanged (+/− 0.1Gy) regardless of drift. Conclusion: Intrafractional baseline drifts reduce the tumor dose in treatments based on mid-ventilation planning. In rare, large target baseline drifts tumor dose coverage may drop below the prescription, potentially affecting clinical

Application of a transverse phase-space measurement technique for high-brightness, H- beams to the GTA H- beam

International Nuclear Information System (INIS)

Johnson, K.F.; Garcia, R.C.; Rusthoi, D.P.; Sander, O.R.; Sandoval, D.P.; Shinas, M.A.; Smith, M.; Yuan, V.W.; Connolly, R.C.

1995-01-01

The Ground Test Accelerator (GTA) had the objective Of Producing a high-brightness, high-current H-beam. The major components were a 35 keV injector, a Radio Frequency Quadrupole (RFQ), an intertank matching section (IMS), and a drift tube linac (DTL), consisting of 10 modules. A technique for measuring the transverse phase-space of high-power density beams has been developed and tested. This diagnostic has been applied to the GTA H-beam. Experimental results are compared to the slit and collector technique for transverse phase-space measurements and to simulations

Precise muon drift tube detectors for high background rate conditions

Energy Technology Data Exchange (ETDEWEB)

Engl, Albert

2011-08-04

with halved radius, which also provide better high rate capability. The single tube resolution of these 15 mm drift tubes was determined to be 95 {mu}m at the H8 test facility at CERN using a muon beam with an energy of 140 GeV. (orig.)

Spray particle drift mitigation using field corn (Zea mays L.) as a drift barrier.

Science.gov (United States)

Vieira, Bruno C; Butts, Thomas R; Rodrigues, Andre O; Golus, Jeffrey A; Schroeder, Kasey; Kruger, Greg R

2018-04-24

Herbicide particle drift reduces application efficacy and can cause severe impacts on nearby vegetation depending on the herbicide mode-of-action, exposure level, and tolerance to the herbicide. A particle drift mitigation effort placing windbreaks or barriers on the field boundaries to reduce off-target movement of spray particles has been utilized in the past. The objective of this research was to evaluate the effectiveness of field corn (Zea mays L.) at different heights as a particle drift barrier. Applications with a non-air inclusion flat fan nozzle (ER11004) resulted in greater particle drift when compared to an air inclusion nozzle (TTI11004). Eight rows of corn were used as barriers (0.91, 1.22, and 1.98 m height) which reduced the particle drift for both nozzles, especially at shorter downwind distances. Applications with the ER11004 nozzle without corn barriers had 1% of the applied rate (D 99 ) predicted to deposit at 14.8 m downwind, whereas this distance was reduced (up to 7-fold) when applications were performed with corn barriers. The combination of corn drift barriers and nozzle selection (TTI11004) provided satisfactory particle drift reduction when the D 99 estimates were compared to applications with the ER11004 nozzle without corn barriers (up to 10-fold difference). The corn drift barriers were effective in reducing particle drift from applications with the ER11004 and the TTI11004 nozzles (Fine and Ultra Coarse spray classifications, respectively). The corn drift barrier had appropriate porosity and width as the airborne spray was captured within its canopy instead of deflecting up and over it. This article is protected by copyright. All rights reserved.

Beam position monitor sensitivity for low-β beams

International Nuclear Information System (INIS)

Shafer, R.E.

1993-01-01

At low velocities, the EM field of a particle in a conducting beam tube is no longer a TEM wave, but has a finite longitudinal extent. The net effect of this is to reduce the coupling of the high-frequency Fourier components of the beam current to BPM (beam position monitor) electrodes, which modifies the BPM sensitivity to beam displacement. This effect is especially pronounced for high-frequency, large-aperture pickups used for low-β beams. Non-interceptive beam position monitors used in conjunction with high frequency RFQ (radio-frequency-quadrupole) and DTL (drift-tube-linac) accelerators fall into this category. When testing a BPM with a thin wire excited with either pulses or high-frequency sinusoidal currents, the EM wave represents the principal (TEM) mode in a coaxial transmission line, which is equivalent to a highly relativistic (β = 1) beam. Thus wire measurements are not suitable for simulating slow particle beams in high bandwidth diagnostic devices that couple to the image currents in the beam tube wall. Attempts to load the tin wire either capacitively or inductively to slow the EM wave down have met with limited success. In general, the equations used to represent the 2-D response of cylindrical-geometry BPMs to charged-particle beams make several assumptions: (1) the BPM electrodes are flush with and grounded to the surface of the conducting beam tube; (2) the beam is a line source (pencil beam); (3) the longitudinal extent of the EM field of a beam particle at the beam tube wall is zero, corresponding to a highly relativistic beam. The purpose of this paper is to make some quantitative estimates of the corrections to the conventional approximations when a BPM is used to measure the position of low velocity (low-β) beams

Collisional drift fluids and drift waves

International Nuclear Information System (INIS)

Pfirsch, D.; Correa-Restrepo, D.

1995-05-01

The usual theoretical description of drift-wave turbulence (considered to be one possible cause of anomalous transport in a plasma), e.g. the Hasegawa-Wakatani theory, makes use of various approximations, the effect of which is extremely difficult to assess. This concerns in particular the conservation laws for energy and momentum. The latter is important as concerns charge separation and resulting electric fields which are possibly related to the L-H transition. Energy conservation is crucial for the stability behaviour; it will be discussed via an example. New collisional multispecies drift-fluid equations were derived by a new method which yields in a transparent way conservation of energy and total angular momentum, and the law for energy dissipation. Both electrostatic and electromagnetic field variations are considered. The method is based primarily on a Lagrangian for dissipationless fluids in drift approximation with isotropic pressures. The dissipative terms are introduced by adding corresponding terms to the ideal equations of motion and of the pressures. The equations of motion, of course, no longer result from a Lagrangian via Hamilton's principle. Their relation to the ideal equations imply, however, also a relation to the ideal Lagrangian of which one can take advantage. Instead of introducing heat conduction one can also assume isothermal behaviour, e.g. T ν (x)=const. Assumptions of this kind are often made in the literature. The new method of introducing dissipation is not restricted to the present kind of theories; it can equally well be applied to theories such as multi-fluid theories without using the drift approximation of the present paper. Linear instability is investigated via energy considerations and the implications of taking ohmic resistivity into account are discussed. (orig./WL)

Beam-plasma discharge in a Kyoto beam-plasma-ion source

International Nuclear Information System (INIS)

Ishikawa, J.; Takagi, T.

1983-01-01

A beam-plasma type ion source employing an original operating principle has been developed by the present authors. The ion source consists of an ion extraction region with an electron gun, a thin long drift tube as the plasma production chamber, and a primary electron beam collector. An electron beam is effectively utilized for the dual purpose of high density plasma production as a result of beam-plasma discharge, and high current ion beam extraction with ion space-charge compensation. A high density plasma of the order of 10 11 --10 13 cm -3 was produced by virtue of the beam-plasma discharge which was caused by the interaction between a space-charge wave on the electron beam and a high frequency plasma wave. The plasma density then produced was 10 2 --10 3 times the density produced only by collisional ionization by the electron beam. In order to obtain a stable beam-plasma discharge, a secondary electron beam emitted from the electron collector should be utilized. The mechanism of the beam-plasma discharge was analyzed by use of a linear theory in the case of the small thermal energy of the electron beam, and by use of a quasilinear theory in the case of the large thermal energy. High current ion beams of more than 0.1 A were extracted even at a low extraction voltage of 1--5 kV

Beam dynamics in linear colliders

International Nuclear Information System (INIS)

Ruth, R.D.

1990-09-01

In this paper, we discuss some basic beam dynamics issues related to obtaining and preserving the luminosity of a next generation linear collider. The beams are extracted from a damping ring and compressed in length by the first bunch compressor. They are then accelerated in a preaccelerator linac up to an energy appropriate for injection into a high gradient linac. In many designs this pre-acceleration is followed by another bunch compression to reach a short bunch. After acceleration in the linac, the bunches are finally focused transversely to a small spot. 27 refs., 1 fig

A multi-centre analysis of radiotherapy beam output measurement

Directory of Open Access Journals (Sweden)

Matthew A. Bolt

2017-10-01

Conclusions: Machine beam output measurements were largely within ±2% of 1.00 cGy/MU. Clear trends in measured output over time were seen, with some machines having large drifts which would result in additional burden to maintain within acceptable tolerances. This work may act as a baseline for future comparison of beam output measurements.

Calculation of ballistic focusing of ion beams

International Nuclear Information System (INIS)

Astrelin, V.T.; Syresin, E.M.

1984-01-01

The motion of ions passing from the homogeneous magnetic field into a conical one is treated analytically in paraxial approximation. Further ions transform into neutral particles at the recharging target which is placed in the conical area of field. The optimal conditions for maximum compression of the beams of neutral particles are investigated. An influence of the initial angular spread on the beam compression is analysed. The computation results together with the those of analytical treatment are presented

A novel silicon drift detector with two dimensional drift time measurement

International Nuclear Information System (INIS)

Hijzen, E.A.; Schooneveld, E.M.; Van Eijk, C.W.E.; Hollander, R.W.; Sarro, P.M.; Van den Bogaard, A.

1994-01-01

Until now silicon drift detectors with two dimensional position resolution made use of drift time measurement in one dimension only. The resolution in the other dimension was obtained by dividing the collecting anode into small pixels. In this paper we present a new type of drift detector that uses drift time measurements for both dimensions. The design consists of concentric quadrilateral closed strips with a small collecting anode in the centre. At first electrons will travel perpendicular to the strips until they reach a diagonal. Then they will proceed along this diagonal until they are collected at the centre. Position resolution in two dimensions can be obtained when both the time the electrons need to reach the diagonal and the time they need to reach the centre are measured. The latter is obtained from the collecting anode, the former from a diagonal strip present at the back side of the detector. Compared to common 2D drift detectors this detector offers the advantage of a small amount of readout electronics. It also has the advantage of having just one small collecting anode with a very low capacitance, resulting in low noise and therefore in a good energy resolution. ((orig.))

Development of bipolar pulse accelerator for intense pulsed ion beam acceleration

International Nuclear Information System (INIS)

Fujioka, Y.; Mitsui, C.; Kitamura, I.; Takahashi, T.; Masugata, K.; Tanoue, H.; Arai, K.

2003-01-01

To improve the purity of an intense pulsed ion beams a new type of pulsed ion beam accelerator named 'bipolar pulse accelerator (BPA)' was proposed. In the accelerator purity of the beam is expected. To confirm the principle of the accelerator experimental system was developed. The system utilizes B y type magnetically insulated acceleration gap and operated with single polar negative pulse. A coaxial gas puff plasma gun placed in the grounded anode was used as an ion source, and source plasma (nitrogen) of current density approx. = 25 A/cm 2 , duration approx. = 1.5 μs was injected into the acceleration gap. The ions are successfully accelerated from the grounded anode to the drift tube by applying negative pulse of voltage 180 kV, duration 60 ns to the drift tube. Pulsed ion beam of current density approx. = 40 A/cm 2 , duration approx. 60 ns was obtained at 42 mm downstream from the anode surface. (author)

Effects of focused ion beam milling on the compressive behavior of directionally solidified micro-pillars and the nanoindentation response of an electro-polished surface

International Nuclear Information System (INIS)

Shim, Sang Hoon; Bei, Hongbin; Miller, Michael K; Pharr, George Mathews; George, Easo P

2009-01-01

Focused ion beam (FIB) milling is the typical way in which micro-pillars are fabricated to study small-scale plasticity and size effects in uniaxial compression. However, FIB milling can introduce defects into the milled pillars. To investigate the effects of FIB damage on mechanical behavior, we tested Mo-alloy micro-pillars that were FIB milled following directional solidification, and compared their compressive response to pillars that were not FIB milled. We also FIB milled at glancing incidence a Mo-alloy single-crystal surface, and compared its nanoindentation response to an electro-polished surface of the same crystal. Consequences for the interpretation of data obtained from FIB milled micro-pillars are discussed

Electron Beam Lithography for nano-patterning

DEFF Research Database (Denmark)

Greibe, Tine; Anhøj, Thomas Aarøe; Khomtchenko, Elena

2014-01-01

in a polymer. Electron beam lithography is a suitable method for nano-sized production, research, or development of semiconductor components on a low-volume level. Here, we present electron beam lithography available at DTU Danchip. We expertize a JEOL 9500FZ with electrons accelerated to an energy of 100ke......, the room temperature is controlled to an accuracy of 0.1 degrees in order to minimize the thermally induced drift of the beam during pattern writing. We present process results in a standard positive tone resist and pattern transfer through etch to a Silicon substrate. Even though the electron beam...... of electrons in the substrate will influence the patterning. We present solutions to overcome these obstacles....

Drift Scale THM Model

International Nuclear Information System (INIS)

Rutqvist, J.

2004-01-01

This model report documents the drift scale coupled thermal-hydrological-mechanical (THM) processes model development and presents simulations of the THM behavior in fractured rock close to emplacement drifts. The modeling and analyses are used to evaluate the impact of THM processes on permeability and flow in the near-field of the emplacement drifts. The results from this report are used to assess the importance of THM processes on seepage and support in the model reports ''Seepage Model for PA Including Drift Collapse'' and ''Abstraction of Drift Seepage'', and to support arguments for exclusion of features, events, and processes (FEPs) in the analysis reports ''Features, Events, and Processes in Unsaturated Zone Flow and Transport and Features, Events, and Processes: Disruptive Events''. The total system performance assessment (TSPA) calculations do not use any output from this report. Specifically, the coupled THM process model is applied to simulate the impact of THM processes on hydrologic properties (permeability and capillary strength) and flow in the near-field rock around a heat-releasing emplacement drift. The heat generated by the decay of radioactive waste results in elevated rock temperatures for thousands of years after waste emplacement. Depending on the thermal load, these temperatures are high enough to cause boiling conditions in the rock, resulting in water redistribution and altered flow paths. These temperatures will also cause thermal expansion of the rock, with the potential of opening or closing fractures and thus changing fracture permeability in the near-field. Understanding the THM coupled processes is important for the performance of the repository because the thermally induced permeability changes potentially effect the magnitude and spatial distribution of percolation flux in the vicinity of the drift, and hence the seepage of water into the drift. This is important because a sufficient amount of water must be available within a

Timing calibration of the trigger system for the drift tube detector of the OPERA neutrino oscillation experiment

International Nuclear Information System (INIS)

Lenkeit, Jan

2015-11-01

The OPERA experiment searches for ν μ → ν τ oscillations in an almost pure ν μ beam. The goal is to observe the oscillations in appearance mode by using a large-scale lead/emulsion target to resolve individual ν τ interactions. Magnetic spectrometers measure the charge and momentum of beam induced muons leaving the target sections. The Precision Tracker, a drift tube detector consisting of almost 10000 drift tubes, provides the tracking information inside the spectrometers. The coordinate measurement in the drift tubes is derived from a time measurement relative to an external trigger signal. In order to reach the required momentum resolution of less than 25 % for particle momenta up to 25 GeV, the uncertainty on the trigger timing must not exceed a value of 5 ns. In this thesis, a procedure for the timing calibration of the trigger system is presented. A step-by-step calibration of the corresponding signal paths is described. Applying all calibration results, a spatial resolution of 255 μm is achieved for the Precision Tracker, meeting the specified requirements. Furthermore, a method using the calibrated trigger system for performing time of flight measurements with atmospheric muons is developed. The average error on the measured flight times is ±4.5 ns.

Electron beams by shock waves in the solar corona

International Nuclear Information System (INIS)

Mann, G.; Klassen, A.

2005-07-01

Beams of energetic electrons can be generated by shock waves in the solar corona. At the Sun shock waves are produced either by flares and/or by coronal mass ejections (CMEs). They can be observed as type II bursts in the solar radio radiation. Shock accelerated electron beams appear as rapidly drifting emission stripes (so-called ''herringbones'') in dynamic radio spectra of type II bursts. A large sample of type II bursts showing ''herringbones'' was statistically analysed with respect to their properties in dynamic radio spectra. The electron beams associated with the ''herringbones'' are considered to be generated by shock drift acceleration. Then, the accelerated electrons establish a shifted loss-cone distribution in the upstream region of the associated shock wave. Such a distribution causes plasma instabilities leading to the emission of radio waves observed as ''herringbones''. Consequences of a shifted loss-cone distribution of the shock accelerated electrons are discussed in comparison with the observations of ''herringbones'' within solar type II radio bursts. (orig.)

Fast electron beam charge injection and switching in dielectrics

Energy Technology Data Exchange (ETDEWEB)

Fitting, Hans-Joachim; Schreiber, Erik [Institute of Physics, University of Rostock, Universitaetsplatz 3, 18051 Rostock (Germany); Touzin, Matthieu [Laboratoire de Structure et Proprietes de l' Etat Solide, UMR CNRS 8008, Universite de Lille 1, 59655 Villeneuve d' Ascq (France)

2011-04-15

Basic investigations of secondary electrons (SE) relaxation and attenuation are made by means of Monte Carlo simulations using ballistic electron scattering and interactions with optical and acoustic phonons as well as impact ionization of valence band electrons. Then the electron beam induced selfconsistent charge transport and secondary electron emission in insulators are described by means of an electron-hole flight-drift model (FDM). Ballistic secondary electrons and holes, their attenuation and drift, as well as their recombination, trapping, and field- and temperature-dependent Poole-Frenkel detrapping are included. Whereas the initial switching-on of the secondary electron emission proceeds over milli-seconds due to long-lasting selfconsistent charging, the switching-off process occurs much faster, even over femto-seconds. Thus a rapid electron beam switching becomes possible with formation of ultra-short electron beam pulses offering an application in stroboscopic electron microscopy and spectroscopy. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Fragment separator momentum compression schemes

Energy Technology Data Exchange (ETDEWEB)

Bandura, Laura, E-mail: bandura@anl.gov [Facility for Rare Isotope Beams (FRIB), 1 Cyclotron, East Lansing, MI 48824-1321 (United States); National Superconducting Cyclotron Lab, Michigan State University, 1 Cyclotron, East Lansing, MI 48824-1321 (United States); Erdelyi, Bela [Argonne National Laboratory, Argonne, IL 60439 (United States); Northern Illinois University, DeKalb, IL 60115 (United States); Hausmann, Marc [Facility for Rare Isotope Beams (FRIB), 1 Cyclotron, East Lansing, MI 48824-1321 (United States); Kubo, Toshiyuki [RIKEN Nishina Center, RIKEN, Wako (Japan); Nolen, Jerry [Argonne National Laboratory, Argonne, IL 60439 (United States); Portillo, Mauricio [Facility for Rare Isotope Beams (FRIB), 1 Cyclotron, East Lansing, MI 48824-1321 (United States); Sherrill, Bradley M. [National Superconducting Cyclotron Lab, Michigan State University, 1 Cyclotron, East Lansing, MI 48824-1321 (United States)

2011-07-21

We present a scheme to use a fragment separator and profiled energy degraders to transfer longitudinal phase space into transverse phase space while maintaining achromatic beam transport. The first order beam optics theory of the method is presented and the consequent enlargement of the transverse phase space is discussed. An interesting consequence of the technique is that the first order mass resolving power of the system is determined by the first dispersive section up to the energy degrader, independent of whether or not momentum compression is used. The fragment separator at the Facility for Rare Isotope Beams is a specific application of this technique and is described along with simulations by the code COSY INFINITY.

Fragment separator momentum compression schemes

International Nuclear Information System (INIS)

Bandura, Laura; Erdelyi, Bela; Hausmann, Marc; Kubo, Toshiyuki; Nolen, Jerry; Portillo, Mauricio; Sherrill, Bradley M.

2011-01-01

We present a scheme to use a fragment separator and profiled energy degraders to transfer longitudinal phase space into transverse phase space while maintaining achromatic beam transport. The first order beam optics theory of the method is presented and the consequent enlargement of the transverse phase space is discussed. An interesting consequence of the technique is that the first order mass resolving power of the system is determined by the first dispersive section up to the energy degrader, independent of whether or not momentum compression is used. The fragment separator at the Facility for Rare Isotope Beams is a specific application of this technique and is described along with simulations by the code COSY INFINITY.

Development and characterisation of new high-rate muon drift tube detectors

Energy Technology Data Exchange (ETDEWEB)

Bittner, Bernhard

2012-07-25

With the increase of the LHC luminosity above the design value and the higher background counting rates, detectors in the ATLAS muon spectrometer have to be replaced because the limits of the radiation tolerance will be exceeded. Therefore drift tube chambers with 15 mm tube diameter were developed. The required construction accuracy was verified and the limits of the resolution and efficiency were determined in a muon beam and under gamma irradiation and compared to model expectations.

EFFECT OF ION ∇ B DRIFT DIRECTION ON TURBULENCE FLOW AND FLOW SHEAR

International Nuclear Information System (INIS)

FENZI, C; McKEE, G.R; BURRELL, K.H; CARLSTROM, T.N; FONCK, R.J; GROEBNER, R.J

2003-01-01

The divertor magnetic geometry has a significant effect on the poloidal flow and resulting flow shear of turbulence in the outer region of L-mode tokamak plasmas, as determined via two-dimensional measurements of density fluctuations with Beam Emission Spectroscopy on DIII-D. Plasmas with similar parameters, except that in one case the ion (del)B drift points towards the divertor X-point (lower single-null, LSN), and in the other case, the ion (del)B drift points away from the divertor X-point (upper single-null, USN), are compared. Inside of r/a=0.9, the turbulence characteristics (amplitude, flow direction, correlation lengths) are similar in both cases, while near r/a=0.92, a dramatic reversal of the poloidal flow of turbulence relative to the core flow direction is observed in plasmas with the ion (del)B drift pointing towards the divertor X-point. No such flow reversal is observed in plasmas with the ion (del)B drift pointing away from the divertor X-point. This poloidal flow reversal results in a significantly larger local shear in the poloidal turbulence flow velocity in plasmas with the ion (del)B drift pointing towards the divertor X-point. Additionally, these plasmas locally exhibit significant dispersion, with two distinct and counter-propagating turbulence modes. Likewise, the radial correlation length of the turbulence is reduced in these plasmas, consistent with biorthogonal decomposition measurements of dominant turbulence structures. The naturally occurring turbulence flow shear in these LSN plasmas may facilitate the LH transition that occurs at an input power of roughly one-half to one-third that of corresponding plasmas with the ion (del)B drift pointing away from the X-point

Fast Compressive Tracking.

Science.gov (United States)

Zhang, Kaihua; Zhang, Lei; Yang, Ming-Hsuan

2014-10-01

It is a challenging task to develop effective and efficient appearance models for robust object tracking due to factors such as pose variation, illumination change, occlusion, and motion blur. Existing online tracking algorithms often update models with samples from observations in recent frames. Despite much success has been demonstrated, numerous issues remain to be addressed. First, while these adaptive appearance models are data-dependent, there does not exist sufficient amount of data for online algorithms to learn at the outset. Second, online tracking algorithms often encounter the drift problems. As a result of self-taught learning, misaligned samples are likely to be added and degrade the appearance models. In this paper, we propose a simple yet effective and efficient tracking algorithm with an appearance model based on features extracted from a multiscale image feature space with data-independent basis. The proposed appearance model employs non-adaptive random projections that preserve the structure of the image feature space of objects. A very sparse measurement matrix is constructed to efficiently extract the features for the appearance model. We compress sample images of the foreground target and the background using the same sparse measurement matrix. The tracking task is formulated as a binary classification via a naive Bayes classifier with online update in the compressed domain. A coarse-to-fine search strategy is adopted to further reduce the computational complexity in the detection procedure. The proposed compressive tracking algorithm runs in real-time and performs favorably against state-of-the-art methods on challenging sequences in terms of efficiency, accuracy and robustness.

Injection, compression and confinement of electrons in a magnetic mirror

International Nuclear Information System (INIS)

Fisher, A.

1975-01-01

A Helmholtz coil configuration has been constructed where the magnetic field can be increased to about 10 kGauss in 20 μsec. Electrons are injected from a hot tantalum filament between two plates across which a potential of about 5 keV is applied. The electric field E is perpendicular to the magnetic field B so that the direction of the E x B drift is radial--into the magnetic mirror. About 10 14 electrons were injected and about 10 13 electrons were trapped. The initial electron energy was about 5 keV and after compression 500 keV x-rays were observed. The confinement time is very sensitive to vacuum. Confinement times of milliseconds and good compression were observed at vacuum of 5.10 -5 torr or less. Above 5.10 -5 torr there was no trapping or compression. After a compressed ring of electrons was formed, it was released by a pulse applied to one of the Helmholtz coils that reduced the field. Ejection of the electron ring was observed by x-ray measurements

Study on pulsed-operation of the drift tube quadrupole magnets

International Nuclear Information System (INIS)

Mutou, M.

1982-01-01

The heavy ion linac for NUMATRON project is designed not only as a injector for a synchrotron but also as a supplier of heavy ion beams for experiments with linac beam. In one repetition cycle of the synchrotron (1sec), the linac injects nearly 25 beam pulses with pulse width of 300 μsec and pulse interval of 30 msec. And the ion species can be varied every repetition. On the other hand, when it is off duty of injection to the synchrotron, the linac accelerates the beams that are directly used for the experiments. Also in this case, the ion species should be varied according to the requests of the experiments, for instance every 1 sec. Therefore, the quadrupole magnets installed in the drift tubes of the linac must be excited with pulse mode. The power supply of the quadrupole magnets will consists of two parts, namely pulse-excitation and dc-excitation power sources. The report describes the posibilities on the pulse-operation of the quadrupole magnets with the field gradient of asymptotically equals 10 KG/cm, and the analysis of the power supply of the quadrupole magnets. (author)

Laboratory Course on Drift Chambers

International Nuclear Information System (INIS)

Garcia-Ferreira, Ix-B.; Garcia-Herrera, J.; Villasenor, L.

2006-01-01

Drift chambers play an important role in particle physics experiments as tracking detectors. We started this laboratory course with a brief review of the theoretical background and then moved on to the the experimental setup which consisted of a single-sided, single-cell drift chamber. We also used a plastic scintillator paddle, standard P-10 gas mixture (90% Ar, 10% CH4) and a collimated 90Sr source. During the laboratory session the students performend measurements of the following quantities: a) drift velocities and their variations as function of the drift field; b) gas gains and c) diffusion of electrons as they drifted in the gas

Characteristic parameters of drift chambers calculation

International Nuclear Information System (INIS)

Duran, I.; Martinez-Laso, L.

1989-01-01

We present here the methods we used to analyse the characteristic parameters of drift chambers. The algorithms to calculate the electric potential in any point for any drift chamber geometry are presented. We include the description of the programs used to calculate the electric field, the drift paths, the drift velocity and the drift time. The results and the errors are discussed. (Author) 7 refs

Simple model of electron beam initiated dielectric breakdown

International Nuclear Information System (INIS)

Beers, B.L.; Daniell, R.E.; Delmer, T.N.

1985-01-01

A steady state model that describes the internal charge distribution of a planar dielectric sample exposed to a uniform electron beam was developed. The model includes the effects of charge deposition and ionization of the beam, separate trap-modulated mobilities for electrons and holes, electron-hole recombination, and pair production by drifting thermal electrons. If the incident beam current is greater than a certain critical value (which depends on sample thickness as well as other sample properties), the steady state solution is non-physical

Unstable oscillation of tubular cantilevered beams conveying a compressible fluid

International Nuclear Information System (INIS)

Johnson, R.O.; Stoneking, J.E.; Carley, T.G.

1986-01-01

This paper is concerned with establishing the conditions of stability of a cantilevered tube conveying a compressible fluid. Solutions to Niordson's eigenvalue problem associated with the equations of motion are computed using Muller's method. The effects on critical velocity of compressibility which are accommodated by specifying the tube aspect ratio and fluid sonic velocity are parametrically studied. Aspect ratio is found to have a more pronounced effect on critical velocity than sonic velocity over the parameter range that was considered. (orig.)

Design of low velocity-spread cusp guns for axis encircling beams

International Nuclear Information System (INIS)

Lawson, W.

1987-01-01

The design of a novel electron gun suitable for intense beam cyclotron resonance devices is introduced here. An annular Pierce-type gun is used in conjunction with an unbalanced nonadiabatic field reversal and an adiabatic compression region to produce an axis-encircling beam. This beam is ideally suited for interaction with electromagnetic waves that have strong on-axis electric fields (e.g., the TE 0 /sub 11/ mode). Low velocity spreads are achieved by utilizing the beam self-fields in the compression region and by focusing in the Pierce gun

Generalized drift-flux correlation

International Nuclear Information System (INIS)

Takeuchi, K.; Young, M.Y.; Hochreiter, L.E.

1991-01-01

A one-dimensional drift-flux model with five conservation equations is frequently employed in major computer codes, such as TRAC-PD2, and in simulator codes. In this method, the relative velocity between liquid and vapor phases, or slip ratio, is given by correlations, rather than by direct solution of the phasic momentum equations, as in the case of the two-fluid model used in TRAC-PF1. The correlations for churn-turbulent bubbly flow and slug flow regimes were given in terms of drift velocities by Zuber and Findlay. For the annular flow regime, the drift velocity correlations were developed by Ishii et al., using interphasic force balances. Another approach is to define the drift velocity so that flooding and liquid hold-up conditions are properly simulated, as reported here. The generalized correlation is used to reanalyze the MB-2 test data for two-phase flow in a large-diameter pipe. The results are applied to the generalized drift flux velocity, whose relationship to the other correlations is discussed. Finally, the generalized drift flux correlation is implemented in TRAC-PD2. Flow reversal from countercurrent to cocurrent flow is computed in small-diameter U-shaped tubes and is compared with the flooding curve

The CLEO III drift chamber

CERN Document Server

Peterson, D; Briere, R A; Chen, G; Cronin-Hennessy, D; Csorna, S; Dickson, M; Dombrowski, S V; Ecklund, K M; Lyon, A; Marka, S; Meyer, T O; Patterson, J R; Sadoff, A; Thies, P; Thorndike, E H; Urner, D

2002-01-01

The CLEO group at the Cornell Electron Storage Ring has constructed and commissioned a new central drift chamber. With 9796 cells arranged in 47 layers ranging in radius from 13.2 to 79 cm, the new drift chamber has a smaller outer radius and fewer wires than the drift chamber it replaces, but allows the CLEO tracking system to have improved momentum resolution. Reduced scattering material in the chamber gas and in the inner skin separating the drift chamber from the silicon vertex detector provides a reduction of the multiple scattering component of the momentum resolution and an extension of the usable measurement length into the silicon. Momentum resolution is further improved through quality control in wire positioning and symmetry of the electric fields in the drift cells which have provided a reduction in the spatial resolution to 88 mu m (averaged over the full drift range).

Fast Beam-Based BPM Calibration

International Nuclear Information System (INIS)

Bertsche, Kirk

2012-01-01

The Alignment Diagnostic System (ADS) of the LCLS undulator system indicates that the 33 undulator quadrupoles have extremely high position stability over many weeks. However, beam trajectory straightness and lasing efficiency degrade more quickly than this. A lengthy Beam Based Alignment (BBA) procedure must be executed every two to four weeks to re-optimize the X-ray beam parameters. The undulator system includes RF cavity Beam Position Monitors (RFBPMs), several of which are utilized by an automatic feedback system to align the incoming electron-beam trajectory to the undulator axis. The beam trajectory straightness degradation has been traced to electronic drifts of the gain and offset of the BPMs used in the beam feedback system. To quickly recover the trajectory straightness, we have developed a fast beam-based procedure to recalibrate the BPMs. This procedure takes advantage of the high-precision monitoring capability of the ADS, which allows highly repeatable positioning of undulator quadrupoles. This report describes the ADS, the position stability of the LCLS undulator quadrupoles, and some results of the new recovery procedure.

BATMAN beam properties characterization by the beam emission spectroscopy diagnostic

International Nuclear Information System (INIS)

Bonomo, F.; Ruf, B.; Schiesko, L.; Fantz, U.; Franzen, P.; Riedl, R.; Wünderlich, D.; Barbisan, M.; Pasqualotto, R.; Serianni, G.; Cristofaro, S.

2015-01-01

The ITER neutral beam heating systems are based on the production and acceleration of negative ions (H/D) up to 1 MV. The requirements for the beam properties are strict: a low core beam divergence (< 0.4 °) together with a low source pressure (≤ 0.3 Pa) would permit to reduce the ion losses along the beamline, keeping the stripping particle losses below 30%. However, the attainment of such beam properties is not straightforward. At IPP, the negative ion source testbed BATMAN (BAvarian Test MAchine for Negative ions) allows for deepening the knowledge of the determination of the beam properties. One of the diagnostics routinely used to this purpose is the Beam Emission Spectroscopy (BES): the H α light emitted in the beam is detected and the corresponding spectra are evaluated to estimate the beam divergence and the stripping losses. The BES number of lines of sight in BATMAN has been recently increased: five horizontal lines of sight providing a vertical profile of the beam permit to characterize the negative ion beam properties in relation to the source parameters. Different methods of H α spectra analysis are here taken into account and compared for the estimation of the beam divergence and the amount of stripping. In particular, to thoroughly study the effect of the space charge compensation on the beam divergence, an additional hydrogen injection line has been added in the tank, which allows for setting different background pressure values (one order of magnitude, from about 0.04 Pa up to the source pressure) in the beam drift region

Rectangular drift tube characteristics

International Nuclear Information System (INIS)

Denisov, D.S.; Musienko, Yu.V.

1985-01-01

Results on the study of the characteristics of a 50 x 100 mm aluminium drift tube are presented. The tube was filled with argon-methane and argon-isobutane mixtures. With 16 per cent methane concentration the largest deviation from a linear relation between the drift time and the drift path over 50 mm is less than 2 mm. The tube filled with argon-isobutane mixture is capable of operating in a limited streamer mode

Mechanical features of a 700 MHz bridge-coupled drift tube linac

International Nuclear Information System (INIS)

Liska, D.; Smith, P.; Carlisle, L.; Larkin, T.; Lawrence, G.; Garnett, R.

1992-01-01

Modem linac designs for treating radioactive waste achieve high proton currents through funneling at low energy, typically around 20 MeV. The resulting switch to a high-frequency accelerating structure poses severe performance and fabrication difficulties below 100 MeV. Above 100 MeV, proven coupled-cavity linacs (CCLS) are available. However, at 20 MeV one must choose between a high-frequency drift-tube linac (DTL) or a coupled-cavity linac with very short cells. Potential radiation damage from the CW beam, excessive RF power losses, multipactoring, and fabricability all enter into this decision. At Los Alamos, we have developed designs for a bridge-coupled DTL (BCDTL) that, like a CCL, uses lattice focusing elements and bridge couplers, but that unlike a CCL, accelerates the beam in simple, short, large-aperture DTL modules with no internal quadrupole focusing. Thus, the BCDTL consumes less power than the CCL linac without beam performance and is simpler and cheaper to fabricate in the 20 to 100 MeV range

Effects of γ irradiation on the compression and inter-laminar shear properties of G10 for the BESIII beam pipe supporting flange

Energy Technology Data Exchange (ETDEWEB)

Zheng, Lifang, E-mail: zhenglifang@ustb.edu.cn [University of Science & Technology of Beijing, Beijing, 100083 (China); Qiao, Zhiming [University of Science & Technology of Beijing, Beijing, 100083 (China); Shijiazhuang Mechanical Engineering College, Shijiazhuang, 050003 (China); Xu, Xiaohui; Wang, Li [University of Science & Technology of Beijing, Beijing, 100083 (China)

2017-04-15

Highlights: • After γ irradiation, the epoxy resin matrix in G10 is destroyed; the connection between it and glass fibers loosens. • The compression strength drops. • The fragmentation and expansion of the resin matrix enhance the mutual sliding friction in G10. • The ILSS increases. - Abstract: Given their excellent electrical insulating performance and mechanical properties, G10 epoxy glass cloth-laminated sheets (G10) are used as spare materials for the supporting flange of the Beijing Spectrometer III beam pipe in the Beijing Electron Positron Collider II (BECPII). However, during BECPII operation, the beam pipe suffers a significant amount of γ and neutron irradiation. Studies have demonstrated that when the G10 is exposed to γ irradiation for a sufficiently long time, the material will become damaged, and its mechanical properties will change. In the present work, the compression strength and inter-laminar shear strength (ILSS) of G10 samples were tested. Results showed that after 20 and 200 kGy γ irradiation, the compression strength decreased by 1.26% and 2.15%, respectively, whereas the ILSS increased by 16.17% and 17.95%, respectively. The micro-structural pattern of the samples was investigated by scanning electron microscopy. The firm mesh structure of the epoxy resin matrix was destroyed, and the bonding interface between the glass fibers and the epoxy resin was damaged after γ irradiation. Some microcracks were observed in the glass fibers after γ irradiation. The epoxy resin before and after the irradiation was analyzed by infrared spectroscopy. Results showed that the degradation reaction was dominant during the irradiation compared with the cross-linking reaction in the epoxy resin, leading to the fracture of the molecular chain. The degree of binding between the epoxy resin also decreased.

Pressurizer safety valve serviceability enhancement by spring compression stability

Energy Technology Data Exchange (ETDEWEB)

Ratiu, M.D.; Moisidis, N.T. [California Consulting Engineering and Technology (CALCET), San Leandro, California (United States)

2007-07-01

The proactive maintenance of the spring-loaded-self-actuated Pressurizer Safety Valve (PSV) has caused frequent concerns pertaining the spring self actuated reliability due to set point drift, spurious openings, and seat leakage. The exhaustive testing performed on a Crosby PSV model 6M6 has revealed that the principal cause of these malfunctions is the spring compression elastic instability during service. The spring lateral deformations measurements performed validated the analytical shapes for spring compression: symmetrical bending - for coaxial supported ends - restraining any support displacement, and asymmetrical bending induced by the potential misalignment of the supported top end. The source of the spring compression instability appears on the tested Crosby PSV induced by the top end lateral displacement during long term operation. The testing with restrained displacement at the spring top has shown consistent set-point reproducibility, less than +/- 1 per cent. To eliminate the asymmetrical spring buckling, a design review of the PSV is proposed including the guided fixture at the top and the decrease of spring coil slenderness ratio H/D, corresponding to the general analytical elastic stability for the asymmetrical compression. (authors)

Pressurizer safety valve serviceability enhancement by spring compression stability

International Nuclear Information System (INIS)

Ratiu, M.D.; Moisidis, N.T.

2007-01-01

The proactive maintenance of the spring-loaded-self-actuated Pressurizer Safety Valve (PSV) has caused frequent concerns pertaining the spring self actuated reliability due to set point drift, spurious openings, and seat leakage. The exhaustive testing performed on a Crosby PSV model 6M6 has revealed that the principal cause of these malfunctions is the spring compression elastic instability during service. The spring lateral deformations measurements performed validated the analytical shapes for spring compression: symmetrical bending - for coaxial supported ends - restraining any support displacement, and asymmetrical bending induced by the potential misalignment of the supported top end. The source of the spring compression instability appears on the tested Crosby PSV induced by the top end lateral displacement during long term operation. The testing with restrained displacement at the spring top has shown consistent set-point reproducibility, less than +/- 1 per cent. To eliminate the asymmetrical spring buckling, a design review of the PSV is proposed including the guided fixture at the top and the decrease of spring coil slenderness ratio H/D, corresponding to the general analytical elastic stability for the asymmetrical compression. (authors)

Method of active charge and current neutralization of intense ion beams for ICF

International Nuclear Information System (INIS)

Guiragossian, Z.G.T.; Orthel, J.L.; Lemons, D.S.; Thode, L.E.

1981-01-01

Methods of generating the beam neutralization electrons with required properties are given in the context of a Light Ion Fusion Experiment (LIFE) designed accelerator. Recently derived envelope equations for neutralized and ballistically focused intense ion beams are applied to the LIFE geometry in which 10 MeV He + multiple beamlets coalesce and undergo 45:1 radial compression while beam pulses experience a 20:1 axial compression in the propagation range of 10 m. Both active and auto-neutralization methods are examined and found to produce initial electron temperatures consistent with the requirement of the envelope equation for both radial and axial adiabatic beam pulse compressions. The stability of neutralized beam propagation is also examined concerning the Pierce type electrostatic instability and for the case of LIFE beams it is found to have insignificant effect. A scaled experimental setup is presented which can serve to perform near term tests on the ballistically focused propagation of neutralized light ion beams

Drift-modeling and monitoring comparisons

International Nuclear Information System (INIS)

Chen, N.C.J.; Hanna, S.R.

1977-01-01

Congress is looking into the conglomeration of nuclear reactors into energy centers of limited area. Drift from cooling towers can corrode and damage structures in the immediate vicinity of the towers, cause a public nuisance if located near parking lots or high-density traffic areas, and endanger local vegetation. The estimation of salt deposition has relied primarily on predictions from a variety of models, with very few direct measurements. One of the major efforts in our program is to evaluate the assumptions, limitations, and applicabilities of various analytical models for drift deposition prediction. Several drift deposition models are compared using a set of standard input conditions. The predicted maximum drift deposition differs by two orders of magnitude, and the downwind locations of the maximum differ by one order of magnitude. The discrepancies are attributed mainly to different assumptions in the models regarding the initial effective height of the droplets. Current programs in which drift characteristics at the tower mouth and drift deposition downwind of the tower are being measured are summarized. At the present time, drift deposition measurements, sufficiently comprehensive for model verifications, are unavailable. Hopefully, the Chalk Point Program will satisfy this need

Drifting oscillations in axion monodromy

Energy Technology Data Exchange (ETDEWEB)

Flauger, Raphael [Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213 (United States); McAllister, Liam [Department of Physics, Cornell University, Ithaca, NY 14853 (United States); Silverstein, Eva [Stanford Institute for Theoretical Physics, Stanford University, Stanford, CA 94305 (United States); Westphal, Alexander, E-mail: flauger@physics.ucsd.edu, E-mail: mcallister@cornell.edu, E-mail: evas@stanford.edu, E-mail: alexander.westphal@desy.de [Theory Group, Deutsches Elektronen-Synchrotron DESY, D-22603 Hamburg (Germany)

2017-10-01

We study the pattern of oscillations in the primordial power spectrum in axion monodromy inflation, accounting for drifts in the oscillation period that can be important for comparing to cosmological data. In these models the potential energy has a monomial form over a super-Planckian field range, with superimposed modulations whose size is model-dependent. The amplitude and frequency of the modulations are set by the expectation values of moduli fields. We show that during the course of inflation, the diminishing energy density can induce slow adjustments of the moduli, changing the modulations. We provide templates capturing the effects of drifting moduli, as well as drifts arising in effective field theory models based on softly broken discrete shift symmetries, and we estimate the precision required to detect a drifting period. A non-drifting template suffices over a wide range of parameters, but for the highest frequencies of interest, or for sufficiently strong drift, it is necessary to include parameters characterizing the change in frequency over the e-folds visible in the CMB. We use these templates to perform a preliminary search for drifting oscillations in a part of the parameter space in the Planck nominal mission data.

Drifting oscillations in axion monodromy

International Nuclear Information System (INIS)

Flauger, Raphael; Westphal, Alexander

2014-12-01

We study the pattern of oscillations in the primordial power spectrum in axion monodromy inflation, accounting for drifts in the oscillation period that can be important for comparing to cosmological data. In these models the potential energy has a monomial form over a super-Planckian field range, with superimposed modulations whose size is model-dependent. The amplitude and frequency of the modulations are set by the expectation values of moduli fields. We show that during the course of inflation, the diminishing energy density can induce slow adjustments of the moduli, changing the modulations. We provide templates capturing the effects of drifting moduli, as well as drifts arising in effective field theory models based on softly broken discrete shift symmetries, and we estimate the precision required to detect a drifting period. A non-drifting template suffices over a wide range of parameters, but for the highest frequencies of interest, or for sufficiently strong drift, it is necessary to include parameters characterizing the change in frequency over the e-folds visible in the CMB. We use these templates to perform a preliminary search for drifting oscillations in a part of the parameter space in the Planck nominal mission data.

Style drift in private equity

NARCIS (Netherlands)

Cumming, D.; Fleming, G.; Schwienbacher, A.

2009-01-01

We introduce the concept of style drift to private equity investment. We present theory and evidence pertaining to style drifts in terms of a fund manager's stated focus on particular stages of entrepreneurial development. We develop a model that derives conditions under which style drifts are less

Collisional drift fluid equations and implications for drift waves

International Nuclear Information System (INIS)

Pfirsch, Dieter; Correa-Restrepo, Dario

1996-01-01

The usual theoretical description of drift-wave turbulence (considered to be one possible cause of anomalous transport in a plasma), e.g. the Hasegawa-Wakatani theory, makes use of various approximations, the effects of which are extremely difficult to assess. This concerns in particular the conservation laws for energy and momentum. The latter law is important in relation to charge separation and the resulting electric fields, which are possibly related to the L-H transition. Energy conservation is crucial to the stability behaviour, it will be discussed by means of an example. New collisional multi-species drift-fluid equations were derived by a new method which yields, in a transparent way, conservation of energy and total angular momentum and the law for energy dissipation. Both electrostatic and electromagnetic field variations are considered. The only restriction involved is the validity of the drift approximation; in particular, there are no assumptions restricting the geometry of the system. The method is based primarily on a Lagrangian for dissipationless fluids in the drift approximation with isotropic pressures. The dissipative terms are introduced by adding corresponding terms to the ideal equations of motion and of the pressures. The equations of motion, of course, no longer result from a Lagrangian via Hamilton's principle. However, their relation to the ideal equations also implies a relation to the ideal Lagrangian, which can be used to advantage. Instead of introducing heat conduction one can also assume isothermal behaviour, e.g. T v (x) = constant. Assumptions of this kind are often made in the literature. The new method of introducing dissipation is not restricted to the present kind of theory; it can equally well be applied to theories such as multi-fluid theories without using the drift approximation of the present paper. (author)

Dynamic neutral beam current and voltage control to improve beam efficacy in tokamaks

Science.gov (United States)

Pace, D. C.; Austin, M. E.; Bardoczi, L.; Collins, C. S.; Crowley, B.; Davis, E.; Du, X.; Ferron, J.; Grierson, B. A.; Heidbrink, W. W.; Holcomb, C. T.; McKee, G. R.; Pawley, C.; Petty, C. C.; Podestà, M.; Rauch, J.; Scoville, J. T.; Spong, D. A.; Thome, K. E.; Van Zeeland, M. A.; Varela, J.; Victor, B.

2018-05-01

An engineering upgrade to the neutral beam system at the DIII-D tokamak [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] enables time-dependent programming of the beam voltage and current. Initial application of this capability involves pre-programmed beam voltage and current injected into plasmas that are known to be susceptible to instabilities that are driven by energetic ( E ≥ 40 keV) beam ions. These instabilities, here all Alfvén eigenmodes (AEs), increase the transport of the beam ions beyond a classical expectation based on particle drifts and collisions. Injecting neutral beam power, P beam ≥ 2 MW, at reduced voltage with increased current reduces the drive for Alfvénic instabilities and results in improved ion confinement. In lower-confinement plasmas, this technique is applied to eliminate the presence of AEs across the mid-radius of the plasmas. Simulations of those plasmas indicate that the mode drive is decreased and the radial extent of the remaining modes is reduced compared to a higher beam voltage case. In higher-confinement plasmas, this technique reduces AE activity in the far edge and results in an interesting scenario of beam current drive improving as the beam voltage reduces from 80 kV to 65 kV.

Reproducible and controllable induction voltage adder for scaled beam experiments

Energy Technology Data Exchange (ETDEWEB)

Sakai, Yasuo; Nakajima, Mitsuo; Horioka, Kazuhiko [Department of Energy Sciences, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8502 (Japan)

2016-08-15

A reproducible and controllable induction adder was developed using solid-state switching devices and Finemet cores for scaled beam compression experiments. A gate controlled MOSFET circuit was developed for the controllable voltage driver. The MOSFET circuit drove the induction adder at low magnetization levels of the cores which enabled us to form reproducible modulation voltages with jitter less than 0.3 ns. Preliminary beam compression experiments indicated that the induction adder can improve the reproducibility of modulation voltages and advance the beam physics experiments.

Drift chamber performance in the field of a superconducting magnet: measurement of the drift angle

International Nuclear Information System (INIS)

Sanders, G.H.; Sherman, S.; McDonald, K.T.; Smith, A.J.S.; Thaler, J.J.

1977-01-01

Results are presented of the first measurements in a study of drift chamber performance in magnetic fields up to 6 tesla. The angle of the electron drift was measured as a function of electric and magnetic field intensity. It appears that even at the high fields of superconducting magnets (3 to 6 tesla) the drift angle induced by the Lorentz force can be corrected for with tilted electric drift fields and/or the use of Xenon gas. At 3 tesla a drift field tilted at 45 0 with a magnitude of 3.5 kV/cm should restore normal operating conditions. At 4 tesla, a 45 0 tilt field would have a magnitude 5 kV/cm

XTR detection by means of 20 μm resolution drift chamber

International Nuclear Information System (INIS)

Baskakov, V.I.; Dolgoshein, B.A.; Lebedenko, V.N.

1977-01-01

The possibility to separate spatially the ionization losses of a relativistic charged particle and XTR quanta generated by the same particle in the laminated medium in detector was investigated. A double electroluminescent drift chamber filled with xenon at 10 atm pressure was constructed for this purpose. A detailed examination of the chamber characteristics was carried out on 3.5 GeV energy electron beam. The obtained results demonstrated the possibility to separate XTR and particle ionization spatially by means of the described method

Computer controlled drifting of Si(Li) detectors

International Nuclear Information System (INIS)

Landis, D.A.; Wong, Y.K.; Walton, J.T.; Goulding, F.S.

1989-01-01

A relatively inexpensive computer-controlled system for performing the drift process used in fabricating Si(Li) detectors is described. The system employs a small computer to monitor the leakage current, applied voltage and temperature on eight individual drift stations. The associated computer program initializes the drift process, monitors the drift progress and then terminates the drift when an operator set drift time has elapsed. The improved control of the drift with this system has been well demonstrated over the past three years in the fabrication of a variety of Si(Li) detectors. A few representative system responses to detector behavior during the drift process are described

Local Trigger Electronics for the CMS Drift Tubes Muon detector

CERN Document Server

Travaglini, R

2003-01-01

In the CMS detector in preparation for the CERN LHC collider, the Drift Tubes Muon Chambers are equipped with mini-crates hosting custom electronics for fast data processing and local trigger generation. In particular the Trigger Server of a DTC consists of Track Sorter Slave ASICs and a Track Sorter Master system. The trigger electronics boards are in production, to be ready for the muon detector installation in the CMS barrel starting at the end of 2003.In this work, the performance of the Trigger Server will be discussed, on the basis both of high-statistics tests with predefined patterns and of test beam data collected at CERN, where a DTC was exposed to a muon beam having an LHC-like bunch structure. Finally, some system performance expectations, concerning radiation tolerance and signal transmission issues during LHC running, will be also discussed.

Modeling concept drift

DEFF Research Database (Denmark)

Borchani, Hanen; Martinez, Ana Maria; Masegosa, Andrés R.

2015-01-01

An often used approach for detecting and adapting to concept drift when doing classification is to treat the data as i.i.d. and use changes in classification accuracy as an indication of concept drift. In this paper, we take a different perspective and propose a framework, based on probabilistic ...... data set from a Spanish bank....

The Drift Burst Hypothesis

OpenAIRE

Christensen, Kim; Oomen, Roel; Renò, Roberto

2016-01-01

The Drift Burst Hypothesis postulates the existence of short-lived locally explosive trends in the price paths of financial assets. The recent US equity and Treasury flash crashes can be viewed as two high profile manifestations of such dynamics, but we argue that drift bursts of varying magnitude are an expected and regular occurrence in financial markets that can arise through established mechanisms such as feedback trading. At a theoretical level, we show how to build drift bursts into the...

RF-field generation in wide frequency range by electron beam

International Nuclear Information System (INIS)

Bogdanovich, B.; Nesterovich, A.; Minaev, S.

1996-01-01

A simple device for generating powerful RF oscillations in the frequency range of 100-250 MHz is considered. The two-gaps cavity is based on the quarter-wavelength coaxial line loaded by drift tubes. Frequency tuning is accomplished by using the movable shorting plunger. A permanent electron beam being modulated at the first gap return the energy at the second one. The additional tube with the permanent decelerating potential, introduced into the main drift tube, allows to decrease the drift tube length and keep the excitation conditions in frequency tuning. Both autogeneration and amplification modes are under consideration. RF-parameters of the cavity and experimental results are described. (author)

Field investigation of the drift shadow

International Nuclear Information System (INIS)

Su, Grace W.; Kneafsey, Timothy J.; Ghezzehei, Teamrat A.; Marshall, Brian D.; Cook, Paul J.

2005-01-01

A drift shadow is an area immediately beneath an underground void that, in theory, will be relatively drier than the surrounding rockmass. Numerical and analytical models of water flow through unsaturated rock predict the existence of a drift shadow, but field tests confirming its existence have yet to be performed. Proving the existence of drift shadows and understanding their hydrologic and transport characteristics could provide a better understanding of how contaminants move in the subsurface if released from waste emplacement drifts such as the proposed nuclear waste repository at Yucca Mountain, Nevada. We describe the field program that will be used to investigate the existence of a drift shadow and the corresponding hydrological process at the Hazel-Atlas silica-sandmine located at the Black Diamond Mines Regional Preserve in Antioch, California. The location and configuration of this mine makes it an excellent site to observe and measure drift shadow characteristics. The mine is located in a porous sandstone unit of the Domengine Formation, an approximately 230 meter thick series of interbedded Eocene-age shales, coals, and massive-bedded sandstones. The mining method used at the mine required the development of two parallel drifts, one above the other, driven along the strike of the mined sandstone stratum. This configuration provides the opportunity to introduce water into the rockmass in the upper drift and to observe and measure its flow around the underlying drift. The passive and active hydrologic tests to be performed are described. In the passive method, cores will be obtained in a radial pattern around a drift and will be sectioned and analyzed for in-situ water content and chemical constituents. With the active hydrologic test, water will be introduced into the upper drift of the two parallel drifts and the flow of the water will be tracked as it passes near the bottom drift. Tensiometers, electrical resistance probes, neutron probes, and ground

FIELD INVESTIGATION OF THE DRIFT SHADOW

International Nuclear Information System (INIS)

G.W. Su; T.J. Kneafsey

2006-01-01

A drift shadow is an area immediately beneath an underground void that, in theory, will be relatively drier than the surrounding rock mass. Numerical and analytical models of water flow through unsaturated rock predict the existence of a drift shadow, but field tests confirming the existence of the drift shadow have yet to be performed. Proving the existence of drift shadows and understanding their hydrologic and transport characteristics could provide a better understanding of how contaminants move in the subsurface if released from waste emplacement drifts such as the proposed nuclear waste repository at Yucca Mountain, Nevada. We describe the field program that will be used to investigate the existence of a drift shadow--and the corresponding hydrological process at the Hazel-Atlas silica-sand mine located at the Black Diamond Mines Regional Preserve in Antioch, California. The location and configuration of this mine makes it an excellent site to observe and measure drift shadow characteristics. The mine is located in a porous sandstone unit of the Domengine formation, an approximately 230 meter thick series of interbedded Eocene-age shales, coals, and massive-bedded sandstones. The mining method used at the mine required the development of two parallel drifts, one above the other, driven along the strike of the mined sandstone stratum. This configuration provides the opportunity to introduce water into the rock mass in the upper drift and to observe and measure its flow around the underlying drift. The passive and active hydrologic tests to be performed are described. In the passive method, cores will be obtained in a radial pattern around a drift and will be sectioned and analyzed for in-situ water content using a gravimetric technique, as well as analyzed for chemistry. With the active hydrologic test, water will be introduced into the upper drift of the two parallel drifts and the flow of the water will be tracked as it passes near the bottom drift

An Obliquely Propagating Electromagnetic Drift Instability in the Lower Hybrid Frequency Range

International Nuclear Information System (INIS)

Hantao Ji; Russell Kulsrud; William Fox; Masaaki Yamada

2005-01-01

By employing a local two-fluid theory, we investigate an obliquely propagating electromagnetic instability in the lower hybrid frequency range driven by cross-field current or relative drifts between electrons and ions. The theory self-consistently takes into account local cross-field current and accompanying pressure gradients. It is found that the instability is caused by reactive coupling between the backward propagating whistler (fast) waves in the moving electron frame, and the forward propagating sound (slow) waves in the ion frame when the relative drifts are large. The unstable waves we consider propagate obliquely to the unperturbed magnetic field and have mixed polarization with significant electromagnetic components. A physical picture of the instability emerges in the limit of large wave number characteristic of the local approximation. The primary positive feedback mechanism is based on reinforcement of initial electron density perturbations by compression of electron fluid via induced Lorentz force. The resultant waves are qualitatively consistent with the measured electromagnetic fluctuations in reconnecting current sheet in a laboratory plasma

CTF Void Drift Validation Study

Energy Technology Data Exchange (ETDEWEB)

Salko, Robert K. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Gosdin, Chris [Pennsylvania State Univ., University Park, PA (United States); Avramova, Maria N. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Gergar, Marcus [Pennsylvania State Univ., University Park, PA (United States)

2015-10-26

This milestone report is a summary of work performed in support of expansion of the validation and verification (V&V) matrix for the thermal-hydraulic subchannel code, CTF. The focus of this study is on validating the void drift modeling capabilities of CTF and verifying the supporting models that impact the void drift phenomenon. CTF uses a simple turbulent-diffusion approximation to model lateral cross-flow due to turbulent mixing and void drift. The void drift component of the model is based on the Lahey and Moody model. The models are a function of two-phase mass, momentum, and energy distribution in the system; therefore, it is necessary to correctly model the ow distribution in rod bundle geometry as a first step to correctly calculating the void distribution due to void drift.

A doublet of 3" cylindrical silicon drift detectors in the CERES/NA45 experiment

CERN Document Server

Faschingbauer, U; Baur, R; Ceretto, F; Drees, A; Fraenkel, Zeev; Fuchs, C; Gatti, E; Glässel, P; Hemberger, M; Pérez de los Heros, C; Hess, F; Holl, P; Irmscher, D; Jacob, C; Kemmer, J; Minaev, Yu I; Panebratsev, Yu A; Pfeiffer, A; Ravinovich, I; Razin, S V; Rehak, P; Sampietro, M; Schükraft, Jürgen; Shimansky, S S; Socol, E; Specht, H J; Tel-Zur, G; Tserruya, Itzhak; Ullrich, T S; Voigt, C A; Wurm, J P; Yurevich, V I

1995-01-01

We report on the performance of a doublet of 3" cylindrical silicon drift detectors installed as an upgrade of the CERES/NA45 electron pair spectrometer for the Pb-beam at the CERN SPS. The silicon detectors provide external particle tracking and background rejection of conversions and close Dalitz pairs. Results on vertex reconstruction and rejection from Pb test-run in 1994 are presented.

Performance of Drift-Tube Detectors at High Counting Rates for High-Luminosity LHC Upgrades

CERN Document Server

Bittner, Bernhard; Kortner, Oliver; Kroha, Hubert; Manfredini, Alessandro; Nowak, Sebastian; Ott, Sebastian; Richter, Robert; Schwegler, Philipp; Zanzi, Daniele; Biebel, Otmar; Hertenberger, Ralf; Ruschke, Alexander; Zibell, Andre

2016-01-01

The performance of pressurized drift-tube detectors at very high background rates has been studied at the Gamma Irradiation Facility (GIF) at CERN and in an intense 20 MeV proton beam at the Munich Van-der-Graaf tandem accelerator for applications in large-area precision muon tracking at high-luminosity upgrades of the Large Hadron Collider (LHC). The ATLAS muon drifttube (MDT) chambers with 30 mm tube diameter have been designed to cope with and neutron background hit rates of up to 500 Hz/square cm. Background rates of up to 14 kHz/square cm are expected at LHC upgrades. The test results with standard MDT readout electronics show that the reduction of the drift-tube diameter to 15 mm, while leaving the operating parameters unchanged, vastly increases the rate capability well beyond the requirements. The development of new small-diameter muon drift-tube (sMDT) chambers for LHC upgrades is completed. Further improvements of tracking e?ciency and spatial resolution at high counting rates will be achieved with ...

Some results of observations of solar radio bursts of the ''drift pairs'' type near 25 and 12.5 MHz

International Nuclear Information System (INIS)

Abranin, Eh.P.; Bazelyan, L.L.; Goncharov, N.Yu.; Zajtsev, V.V.; Zinichev, V.A.; Levin, B.N.; Rapoport, V.O.; Tsybko, Ya.G.; Gor'kovskij Gosudarstvennyj Univ.

1977-01-01

The drift pairs in the frequency range of 12-13 MHz and 24-26 MHz are considered. It is shown that double bursts may be observed both at the second and at the first harmonics. The time interval between the elements of the double burst remains practically unchanged. This fact creates difficulties when interpreting double bursts due to the radio echo in the solar corona. It is suggested that the double (and generally multiple) structure of burst may be associated with the successive transmission of a fast electron beam in regions of double plasma resonance. It is considered that the radiation occurs due to cyclotron instability at the forward front of the electron beam travelling along the decreasing magnetic field of the coronal ray. It is shown that the properties of these burst can be explained by the proposed mechanism of drift pairs formation

IBEX - annular beam propagation experiment

International Nuclear Information System (INIS)

Mazarakis, M.G.; Miller, R.B.; Shope, S.L.; Poukey, J.W.; Ramirez, J.J.; Ekdahl, C.A.; Adler, R.J.

1983-01-01

IBEX is a 4-MV, 100-kA, 20-ns cylindrical isolated Blumlein accelerator. In the experiments reported here, the accelerator is fitted with a specially designed foilless diode which is completely immersed in a uniform magnetic field. Several diode geometries have been studied as a function of magnetic field strength. The beam propagates a distance of 50 cm (approx. 10 cyclotron wavelengths) in vacuum before either striking a beam stop or being extracted through a thin foil. The extracted beam was successfully transported 60 cm downstream into a drift pipe filled either with 80 or 640 torr air. The main objectives of this experiment were to establish the proper parameters for the most quiescent 4 MV, 20 to 40 kA annular beam, and to compare the results with available theory and numerical code simulations

Active beam position stabilization of pulsed lasers for long-distance ion profile diagnostics at the Spallation Neutron Source (SNS).

Science.gov (United States)

Hardin, Robert A; Liu, Yun; Long, Cary; Aleksandrov, Alexander; Blokland, Willem

2011-02-14

A high peak-power Q-switched laser has been used to monitor the ion beam profiles in the superconducting linac at the Spallation Neutron Source (SNS). The laser beam suffers from position drift due to movement, vibration, or thermal effects on the optical components in the 250-meter long laser beam transport line. We have designed, bench-tested, and implemented a beam position stabilization system by using an Ethernet CMOS camera, computer image processing and analysis, and a piezo-driven mirror platform. The system can respond at frequencies up to 30 Hz with a high position detection accuracy. With the beam stabilization system, we have achieved a laser beam pointing stability within a range of 2 μrad (horizontal) to 4 μrad (vertical), corresponding to beam drifts of only 0.5 mm × 1 mm at the furthest measurement station located 250 meters away from the light source.

Beam dynamics simulation of the Spallation Neutron Source linear accelerator

International Nuclear Information System (INIS)

Takeda, H.; Billen, J.H.; Bhatia, T.S.

1998-01-01

The accelerating structure for Spallation Neutron Source (SNS) consists of a radio-frequency-quadrupole-linac (RFQ), a drift-tube-linac (DTL), a coupled-cavity-drift-tube-linac (CCDTL), and a coupled-cavity-linac (CCL). The linac is operated at room temperature. The authors discuss the detailed design of linac which accelerates an H - pulsed beam coming out from RFQ at 2.5 MeV to 1000 MeV. They show a detailed transition from 402.5 MHz DTL with a 4 βλ structure to a CCDTL operated at 805 MHz with a 12 βλ structure. After a discussion of overall feature of the linac, they present an end-to-end particle simulation using the new version of the PARMILA code for a beam starting from the RFQ entrance through the rest of the linac. At 1000 MeV, the beam is transported to a storage ring. The storage ring requires a large (±500-keV) energy spread. This is accomplished by operating the rf-phase in the last section of the linac so the particles are at the unstable fixed point of the separatrix. They present zero-current phase advance, beam size, and beam emittance along the entire linac

Formal solution for the fields within a beam-bug calibrator

International Nuclear Information System (INIS)

Fessenden, T J.

1998-01-01

For some time I was bothered by the fact that measurements of offsets in the various bug calibration setups never agreed with the simple formulae (2) used for determining electron beam position in the Livermore induction linacs and transport systems. About 1983 I realized that the discrepancy arises from the way the bug calibrator simulates an electron beam in a conducting pipe. At that time I solved the problem using the method presented here. Unfortunately, I did not write it up at that time. After considerable effort, I was able to repeat the calculation. Since I have little confidence that after a few years I could ever do it again, I felt obliged to write it up in some detail. Our beam bug calibrator consists of two conducting cylinders, nominally concentric, that simulate the electron beam within a drift tube. The radii of the larger cylinder is 2.3 times that of the smaller giving an electrical impedance of 50 Ohms to the coaxial combination. To simulate a beam off-axis within a drift tube, the inner tube is moved relative to the outer tube. This only approximately simulates the motion of a beam because the surface current on the inner tube redistributes in response to the translation. Fortunately, the fields of the translated inner cylinder can be found exactly using complex variable theory (1)

Study of negative hydrogen ion beam optics using the 3D3V PIC model

International Nuclear Information System (INIS)

Miyamoto, K.; Nishioka, S.; Goto, I.; Hatayama, A.; Hanada, M.; Kojima, A.

2015-01-01

The mechanism of negative ion extraction under real conditions with the complex magnetic field is studied by using the 3D PIC simulation code. The extraction region of the negative ion source for the negative ion based neutral beam injection system in fusion reactors is modelled. It is shown that the E x B drift of electrons is caused by the magnetic filter and the electron suppression magnetic field, and the resultant asymmetry of the plasma meniscus. Furthermore, it is indicated that that the asymmetry of the plasma meniscus results in the asymmetry of negative ion beam profile including the beam halo. It could be demonstrated theoretically that the E x B drift is not significantly weakened by the elastic collisions of the electrons with neutral particles

Study of negative hydrogen ion beam optics using the 3D3V PIC model

Energy Technology Data Exchange (ETDEWEB)

Miyamoto, K., E-mail: kmiyamot@naruto-u.ac.jp [Naruto University of Education, 748 Nakashima, Takashima, Naruto-cho, Naruto-shi, Tokushima, 772-8502 (Japan); Nishioka, S.; Goto, I.; Hatayama, A. [Faculty of Science and Technology, Keio University, 3-14-1, Hiyoshi, Kohoku-ku, Yokohama, 223-8522 (Japan); Hanada, M.; Kojima, A. [Japan Atomic Energy Agency, 801-1,Mukoyama, Naka, 319-0913 (Japan)

2015-04-08

The mechanism of negative ion extraction under real conditions with the complex magnetic field is studied by using the 3D PIC simulation code. The extraction region of the negative ion source for the negative ion based neutral beam injection system in fusion reactors is modelled. It is shown that the E x B drift of electrons is caused by the magnetic filter and the electron suppression magnetic field, and the resultant asymmetry of the plasma meniscus. Furthermore, it is indicated that that the asymmetry of the plasma meniscus results in the asymmetry of negative ion beam profile including the beam halo. It could be demonstrated theoretically that the E x B drift is not significantly weakened by the elastic collisions of the electrons with neutral particles.

Recent US advances in ion-beam-driven high energy density physics and heavy ion fusion

International Nuclear Information System (INIS)

Logan, B.G.; Bieniosek, F.M.; Celata, C.M.; Coleman, J.; Greenway, W.; Henestroza, E.; Kwan, J.W.; Lee, E.P.; Leitner, M.; Roy, P.K.; Seidl, P.A.; Vay, J.-L.; Waldron, W.L.; Yu, S.S.; Barnard, J.J.; Cohen, R.H.; Friedman, A.; Grote, D.P.; Kireeff Covo, M.; Molvik, A.W.; Lund, S.M.; Meier, W.R.; Sharp, W.; Davidson, R.C.; Efthimion, P.C.; Gilson, E.P.; Grisham, L.; Kaganovich, I.D.; Qin, H.; Sefkow, A.B.; Startsev, E.A.; Welch, D.; Olson, C.

2007-01-01

During the past two years, significant experimental and theoretical progress has been made in the US heavy ion fusion science program in longitudinal beam compression, ion-beam-driven warm dense matter, beam acceleration, high brightness beam transport, and advanced theory and numerical simulations. Innovations in longitudinal compression of intense ion beams by >50X propagating through background plasma enable initial beam target experiments in warm dense matter to begin within the next two years. We are assessing how these new techniques might apply to heavy ion fusion drivers for inertial fusion energy

Vibrations And Stability Of Bernoulli-Euler And Timoshenko Beams On Two-Parameter Elastic Foundation

Directory of Open Access Journals (Sweden)

Obara P.

2014-12-01

Full Text Available The vibration and stability analysis of uniform beams supported on two-parameter elastic foundation are performed. The second foundation parameter is a function of the total rotation of the beam. The effects of axial force, foundation stiffness parameters, transverse shear deformation and rotatory inertia are incorporated into the accurate vibration analysis. The work shows very important question of relationships between the parameters describing the beam vibration, the compressive force and the foundation parameters. For the free supported beam, the exact formulas for the natural vibration frequencies, the critical forces and the formula defining the relationship between the vibration frequency and the compressive forces are derived. For other conditions of the beam support conditional equations were received. These equations determine the dependence of the frequency of vibration of the compressive force for the assumed parameters of elastic foundation and the slenderness of the beam.

Fabrication of Multi-Harmonic Buncher for Pulsed Proton Beam Generation

Energy Technology Data Exchange (ETDEWEB)

Kim, H. S.; Kwon, H. J.; Cho, Y. S. [Korea Multipurpose Accelerator Complex, Gyeongju (Korea, Republic of)

2015-05-15

Fast neutrons with a broad spectrum can be generated by irradiating the proton beams on target materials. To measure the neutron energy by time of flight (TOF) method, the short pulse width of the proton beam is preferred because the neutron energy uncertainty is proportional to the pulse width. In addition, the pulse repetition rate should be low enough to extend the lower limit of the available neutron energy. Pulsed proton beam generation system is designed based on an electrostatic deflector and slit system as shown in Fig. 1. In a simple deflector with slit system, most of the proton beam is blocked by slit, especially when the beam pulse width is short. The ideal field pattern inside the buncher cavity is saw-tooth wave. To make the field pattern similar to the saw-tooth waveform, we adopted a multi-harmonic buncher (MHB). The design for the multi-harmonic buncher including 3D electromagnetic calculation has been performed. Based on the design, a multi-harmonic buncher cavity was fabricated. It consists of two resonators, two drift tubes and a vacuum chamber. The resonator is a quarter-wave coaxial resonator type. The drift tube is connected to the resonator by using a coaxial vacuum feedthrough. Design summary and detailed fabrication method of the multi-harmonic buncher is presented in this paper. A multi-harmonic buncher for a proton beam chopper system to generate a short pulse neutron beam was designed, fabricated and assembled.

Distributed drift chamber design for rare particle detection in relativistic heavy ion collisions

CERN Document Server

Bellwied, R; Bernardo, V; Caines, H; Christie, W; Costa, S; Crawford, H J; Cronqvist, M; Debbe, R; Dinnwiddie, R; Engelage, J; Flores, I; Fuzesy, R Z; Greiner, L; Hallman, T; Hoffmann, G; Huang, H Z; Jensen, P; Judd, E G; Kainz, K; Kaplan, M; Kelly, S; Lindstrom, P J; Llope, W J; Lo Curto, G; Longacre, R; Milosevich, Z; Mitchell, J T; Mitchell, J W; Mogavero, E; Mutchler, G S; Paganis, S; Platner, E; Potenza, R; Rotondo, F; Russ, D; Sakrejda, I; Saulys, A; Schambach, J; Sheen, J; Smirnoff, N; Stokely, C L; Tang, J; Trattner, A L; Trentalange, S; Visser, G; Whitfield, J P; Witharm, F; Witharm, R; Wright, M

2002-01-01

This report describes a multi plane drift chamber that was designed and constructed to function as a topological detector for the BNL AGS E896 rare particle experiment. The chamber was optimized for good spatial resolution, two track separation, and a high uniform efficiency while operating in a 1.6 T magnetic field and subjected to long term exposure from a 11.6 GeV/nucleon beam of 10 sup 6 Au ions per second.

Conceptual design report for the SDC barrel and intermediate muon detectors based on a jet-type drift chamber

International Nuclear Information System (INIS)

Arai, Y.; Funahashi, Y.; Higashi, Y.

1992-04-01

We propose a jet-type drift chamber for the barrel and intermediate muon detectors of SDC. The chamber system consists of large multiwire drift chambers having a simple box-type frame structure: 2. 5 x 0.4 m 2 in cross section and maximum 9 m in length. A chamber module consists of double layers of small jet cells. The drift cell is composed of a wire plane, including 3 sense wires, and cathode plates parallel to the wire plane. The two layers in a chamber are staggered to each other by half a cell width. The jet cell is tilted such that its principle axis points to the interaction point. Such an arrangement, together with a constant drift velocity of the jet cell, allows us to design a simple and powerful trigger system for high momentum muons utilizing a drift time sum between a pair of staggered cells. The multi-hit capability will be helpful to distinguish high momentum muon tracks from associated electromagnetic debris as has been demonstrated by the Fermilab beam test T816. The maximum drift time fulfills the SDC requirement. A preliminary FEM analysis of the chamber module verified the excellent structural stiffness. It makes the support structure and the alignment system relatively simple. These features will reduce the total cost as well as ensure a good performance of the chamber system. (J.P.N.)

Space charge effects and aberrations on electron pulse compression in a spherical electrostatic capacitor.

Science.gov (United States)

Yu, Lei; Li, Haibo; Wan, Weishi; Wei, Zheng; Grzelakowski, Krzysztof P; Tromp, Rudolf M; Tang, Wen-Xin

2017-12-01

The effects of space charge, aberrations and relativity on temporal compression are investigated for a compact spherical electrostatic capacitor (α-SDA). By employing the three-dimensional (3D) field simulation and the 3D space charge model based on numerical General Particle Tracer and SIMION, we map the compression efficiency for a wide range of initial beam size and single-pulse electron number and determine the optimum conditions of electron pulses for the most effective compression. The results demonstrate that both space charge effects and aberrations prevent the compression of electron pulses into the sub-ps region if the electron number and the beam size are not properly optimized. Our results suggest that α-SDA is an effective compression approach for electron pulses under the optimum conditions. It may serve as a potential key component in designing future time-resolved electron sources for electron diffraction and spectroscopy experiments. Copyright © 2017 Elsevier B.V. All rights reserved.

Neutral beam injection system design for KSTAR tokamak

Energy Technology Data Exchange (ETDEWEB)

Choi, B.H.; Lee, K.W.; Chung, K.S.; Oh, B.H.; Cho, Y.S.; Bae, Y.D.; Han, J.M. [Korea Atomic Energy Research Institute, Taejon (Korea)

1998-06-01

The NBI system for KSTAR (Korean Superconducting Tokamak Advanced Research) has been designed based on conventional positive ion beam technology. One beam line consists of three ion sources, three neutralizers, one bending magnet, and one drift tube. This system will deliver 8 MW deuterium beam to KSTAR plasma in normal operation to support the advanced experiments on heating, current drive and profile control. The key technical issues in this design were high power ion source(120 kV, 65 A), long pulse operation (300 seconds; world record is 30 sec), and beam rotation from vertical to horizontal direction. The suggested important R and D points on ion source and beam line components are also included. (author). 7 refs., 27 figs., 1 tab.

Results of Preliminary Tests of PAR Bunch Cleaning

CERN Document Server

Yao, Chihyuan; Grelick, Arthur; Lumpkin, Alex H; Sereno, Nicholas S

2005-01-01

A particle accumulator ring (PAR) is used at the Advanced Photon Source (APS) to collect multiple linac bunches and compress them into a 0.3-ns (rms) single bunch for booster injection. A 9.77-MHz fundamental rf system and a 117.3-MHz harmonic rf system are employed for initial beam capture and bunch length compression. Satellite bunches with very low charge form due to rf phase drifts or beam loading change. These satellites, when injected into the booster and then into the storage ring (SR), cause bunch impurity at three buckets from the target bucket. Storage ring and booster bunch cleaning was tried but proved to be difficult due to the top-up mode of operation in the storage ring and tune drift in the booster synchrotron. Recently we implemented a PAR bunch-cleaning system with tune-modulated harmonic rf knockout. Preliminary tests gave a measured SR bunch purity of better than 10

Evaluation of intensity drift correction strategies using MetaboDrift, a normalization tool for multi-batch metabolomics data.

Science.gov (United States)

Thonusin, Chanisa; IglayReger, Heidi B; Soni, Tanu; Rothberg, Amy E; Burant, Charles F; Evans, Charles R

2017-11-10

In recent years, mass spectrometry-based metabolomics has increasingly been applied to large-scale epidemiological studies of human subjects. However, the successful use of metabolomics in this context is subject to the challenge of detecting biologically significant effects despite substantial intensity drift that often occurs when data are acquired over a long period or in multiple batches. Numerous computational strategies and software tools have been developed to aid in correcting for intensity drift in metabolomics data, but most of these techniques are implemented using command-line driven software and custom scripts which are not accessible to all end users of metabolomics data. Further, it has not yet become routine practice to assess the quantitative accuracy of drift correction against techniques which enable true absolute quantitation such as isotope dilution mass spectrometry. We developed an Excel-based tool, MetaboDrift, to visually evaluate and correct for intensity drift in a multi-batch liquid chromatography - mass spectrometry (LC-MS) metabolomics dataset. The tool enables drift correction based on either quality control (QC) samples analyzed throughout the batches or using QC-sample independent methods. We applied MetaboDrift to an original set of clinical metabolomics data from a mixed-meal tolerance test (MMTT). The performance of the method was evaluated for multiple classes of metabolites by comparison with normalization using isotope-labeled internal standards. QC sample-based intensity drift correction significantly improved correlation with IS-normalized data, and resulted in detection of additional metabolites with significant physiological response to the MMTT. The relative merits of different QC-sample curve fitting strategies are discussed in the context of batch size and drift pattern complexity. Our drift correction tool offers a practical, simplified approach to drift correction and batch combination in large metabolomics studies

Experimental Study on Voided Reinforced Concrete Beams with Polythene Balls

Science.gov (United States)

Sivaneshan, P.; Harishankar, S.

2017-07-01

The primary component in any structure is concrete, that exist in buildings and bridges. In present situation, a serious problems faced by construction industry is exhaustive use of raw materials. Recent times, various methods are being adopted to limit the use of concrete. In structural elements like beams, polythene balls can be induced to reduce the usage of concrete. A simply supported reinforced concrete beam has two zones, one above neutral axis and other below neutral axis. The region below neutral axis is in tension and above neutral axis is in compression. As concrete is weak in tension, steel reinforcements are provided in tension zone. The concrete below the neutral axis acts as a stress transfer medium between the compression zone and tension zone. The concrete above the neutral axis takes minimum stress so that we could partially replace the concrete above neutral axis by creating air voids using recycled polythene balls. Polythene balls of varying diameters of 75 mm, 65 mm and 35 mm were partially replaced in compression zone. Hence the usage of concrete in beams and self-weight of the beams got reduced considerably. The Load carrying capacity, Deflection of beams and crack patterns were studied and compared with conventional reinforced concrete beams.

Generation of intense, high-energy ion pulses by magnetic compression of ion rings

International Nuclear Information System (INIS)

Kapetanakos, C.A.

1981-01-01

A system based on the magnetic compression of ion rings, for generating intense (High-current), high-energy ion pulses that are guided to a target without a metallic wall or an applied external magnetic field includes a vacuum chamber; an inverse reflex tetrode for producing a hollow ion beam within the chamber; magnetic coils for producing a magnetic field, bo, along the axis of the chamber; a disc that sharpens a magnetic cusp for providing a rotational velocity to the beam and causing the beam to rotate; first and second gate coils for producing fast-rising magnetic field gates, the gates being spaced apart, each gate modifying a corresponding magnetic mirror peak (Near and far peaks) for trapping or extracting the ions from the magnetic mirror, the ions forming a ring or layer having rotational energy; a metal liner for generating by magnetic flux compression a high, time-varying magnetic field, the time-varying magnetic field progressively increasing the kinetic energy of the ions, the magnetic field from the second gate coil decreasing the far mirror peak at the end of the compression for extracting the trapped rotating ions from the confining mirror; and a disc that sharpens a magnetic half-cusp for increasing the translational velocity of the ion beam. The system utilizes the self-magnetic field of the rotating, propagating ion beam to prevent the beam from expanding radially upon extraction

Spiral silicon drift detectors

International Nuclear Information System (INIS)

Rehak, P.; Gatti, E.; Longoni, A.; Sampietro, M.; Holl, P.; Lutz, G.; Kemmer, J.; Prechtel, U.; Ziemann, T.

1988-01-01

An advanced large area silicon photodiode (and x-ray detector), called Spiral Drift Detector, was designed, produced and tested. The Spiral Detector belongs to the family of silicon drift detectors and is an improvement of the well known Cylindrical Drift Detector. In both detectors, signal electrons created in silicon by fast charged particles or photons are drifting toward a practically point-like collection anode. The capacitance of the anode is therefore kept at the minimum (0.1pF). The concentric rings of the cylindrical detector are replaced by a continuous spiral in the new detector. The spiral geometry detector design leads to a decrease of the detector leakage current. In the spiral detector all electrons generated at the silicon-silicon oxide interface are collected on a guard sink rather than contributing to the detector leakage current. The decrease of the leakage current reduces the parallel noise of the detector. This decrease of the leakage current and the very small capacities of the detector anode with a capacitively matched preamplifier may improve the energy resolution of Spiral Drift Detectors operating at room temperature down to about 50 electrons rms. This resolution is in the range attainable at present only by cooled semiconductor detectors. 5 refs., 10 figs

Drift-based scrape-off particle width in X-point geometry

Science.gov (United States)

Reiser, D.; Eich, T.

2017-04-01

The Goldston heuristic estimate of the scrape-off layer width (Goldston 2012 Nucl. Fusion 52 013009) is reconsidered using a fluid description for the plasma dynamics. The basic ingredient is the inclusion of a compressible diamagnetic drift for the particle cross field transport. Instead of testing the heuristic model in a sophisticated numerical simulation including several physical mechanisms working together, the purpose of this work is to point out basic consequences for a drift-dominated cross field transport using a reduced fluid model. To evaluate the model equations and prepare them for subsequent numerical solution a specific analytical model for 2D magnetic field configurations with X-points is employed. In a first step parameter scans in high-resolution grids for isothermal plasmas are done to assess the basic formulas of the heuristic model with respect to the functional dependence of the scrape-off width on the poloidal magnetic field and plasma temperature. Particular features in the 2D-fluid calculations—especially the appearance of supersonic parallel flows and shock wave like bifurcational jumps—are discussed and can be understood partly in the framework of a reduced 1D model. The resulting semi-analytical findings might give hints for experimental proof and implementation in more elaborated fluid simulations.

Compression and expansion in central collisions

International Nuclear Information System (INIS)

Danielewicz, P.

1997-01-01

Dynamics of central collisions of heavy nuclei in the energy range from few tens of MeV/nucleon to a couple of GeV/nucleon is discussed. As the beam energy increases and/or the impact parameter decreases, the maximum compression increases. It is argued that the hydrodynamic behaviour of matter sets in the vicinity of balance energy. At higher energies shock fronts are observed to form within head-on reaction simulations, perpendicular to beam axis and separating hot compressed matter from cold. In the semi-central reactions a weak tangential discontinuity develops in-between these fronts. The hot compressed matter exposed to the vacuum in directions parallel to the shock front begin to expand collectively into these directions. The expansion affects particle angular distributions and mean energy components and further shapes of spectra and mean energies of particles emitted into any one direction. The variation of slopes and the relative yields measured within the FOPI collaboration are in a general agreement with the results of simulations. As to the FOPI data on stopping, they are consistent with the preference for transverse over the longitudinal motion in the head-on Au + Au collisions. Unfortunately, though, the data can not be used to decide directly on that preference due to acceptance cuts. Tied to the spatial and temporal changes in the reactions are changes in the entropy per nucleon. (authors)

Mechanical features of a 700-MHz bridge-coupled drift-tube linac

International Nuclear Information System (INIS)

Liska, D.; Smith, P.; Carlisle, L.; Larkin, T.; Lawrence, G.; Garnett, R.

1992-01-01

Modern linac designs for treating radioactive waste achieve high proton currents through funneling at low energy, typically around 20 MeV. The resulting switch to a high-frequency accelerating structure poses severe performance and fabrication difficulties below 100 MeV. Above 100 MeV, proven coupled-cavity linacs (CCLs) are available. However, at 20 MeV one must choose between a high-frequency drift-tube linac (DTL) or a coupled-cavity linac with very short cells. Potential radiation damage from the CW beam, excessive RF power losses, multipactoring, and fabricability all enter into this decision. At Los Alamos, we have developed designs for a bridge-coupled DTL (BCDTL) that, like a CCL, uses lattice focusing elements and bridge couplers, but that unlike a CCL, accelerates the beam in simple, short, large-aperture DTL modules with no internal quadrupole focusing. Thus, the BCDTL consumes less power than the CCL linac without beam performance and is simpler and cheaper to fabricate in the 20 to 100 MeV range. (Author) ref., tab., 3 figs

Tabulated In-Drift Geometric and Thermal Properties Used In Drift-Scale Models for TSPA-SR

International Nuclear Information System (INIS)

N.D. Francis

2000-01-01

The objective of this calculation is to provide in-drift physical properties required by the drift-scale models (both two- and three-dimensional) used in total system performance assessments (TSPA). The physical properties include waste package geometry, waste package thermal properties, emplacement drift geometry including backfill and invert geometry and properties (both thermal and hydrologic), drip shield geometry and thermal properties, all tabulated in a single source

Implementation of vertically asymmetric toroidal-field ripple for beam heating of tokamak reactor plasmas

International Nuclear Information System (INIS)

Jassby, D.L.; Sheffield, G.V.; Towner, H.H.; Weissenburger, D.W.

1976-10-01

The neutral-beam energy required for adequate penetration of tokamak plasmas of high opacity can be reduced by a large factor if the beam is injected vertically into a region of large TF (toroidal-field) ripple. Energetic ions are trapped in local magnetic wells and drift vertically toward the midplane (z = 0). If the ripple is made very small on the opposite side of the midplane, drifting ions are detrapped and thermalized in the central plasma region. This paper discusses design considerations for establishing the required vertically asymmetric ripple. Examples are given of special TF-coil configurations, and of the use of auxiliary coil windings to create the prescribed ripple profiles

Argus drift chamber

Energy Technology Data Exchange (ETDEWEB)

Danilov, M; Nagovizin, V; Hasemann, H; Michel, E; Schmidt-Parzefall, W; Wurth, R; Kim, P

1983-11-15

The ARGUS detector came into operation at the DORIS-II e/sup +/s/sup -/ storage ring at the end of 1982. Its two meter long drift chamber contains 5940 sense and 24588 field wires organized in uniform 18x18.8 mm/sup 2/ drift cells filling the whole volume. These cells form 36 layers, 18 of which provide stereo views. Each sense wire is equipped with a single hit TDC and ADC for coordinate and dE/dx measurements. The chamber is operated with propane to improve momentum and dE/dx resolution. The drift chamber design and initial performance are presented. With a very crude space-time relation approximation and without all the necessary corrections applied a spatial resolution of about 200 ..mu..m was obtained for half of the drift cell volume. Further corrections should improve this result. An intrinsic dE/dx resolution of 4.2% and an actual resolution of 5% were obtained for cosmic muons and also for Bhabha scattered electrons. An actual dE/dx resolution of 5.6% was obtained for pions from e/sup +/e/sup -/ annihilation data with almost no track selection. A relativistic rise of 30% was observed in good agreement with theory. The long-term stability is still to be investigated.

Study of the performance of ATLAS muon drift-tube chambers in magntic fields and at high irradiation rates

Energy Technology Data Exchange (ETDEWEB)

Valderanis, Chrysostomos

2012-07-26

The performance of ATLAS muon drift-tube (MDT) chambers has been studied in detail using high-energy muon beams. The measurements of the drift tube properties in magnetic fields showed that inelastic collisions of the drifting electrons with the CO{sub 2} molecules in the Ar:CO{sub 2} (93:7) gas mixture of the MDT chambers have to be taken into account in the simulation of the drift properties. Such inelastic collisions are now correctly treated by the Garfield simulation programme from version 9 providing an accurate description of the behaviour of the ATLAS muon drift tubes, in particular in the magnetic field. Measurements at the Gamma Irradiation Facility at CERN were performed to study the performance of the MDT chambers in the presence of high {gamma} ray background fluences. The chambers have a spatial resolution better than 40 {mu}m at the nominal background rates expected at the Large Hadron Collider design luminosity of 10{sup 34} cm{sup -2}s{sup -1} and a resolution better than 50 {mu}m for up to five times higher background rates. Efficient muon detection up to background counting rates of 500 kHz per tube corresponding to 35% occupancy was demonstrated.

Magnetic compression into Brillouin flow

International Nuclear Information System (INIS)

Becker, R.

1977-01-01

The trajectories of beam edge electrons are calculated in the transition region between an electrostatic gun and an increasing magnetic field for various field shapes, transition length, and cathode fluxes, assuming that the resultant beam is of Brillouin flow type. The results give a good physical interpretation to the axial gradient of the magnetic field being responsible for the amount of magnetic compression and also for the proper injection conditions. Therefore it becomes possible to predict from the known characteristics of any fairly laminary electrostatic gun the necessary axial gradient of the magnetic field and the axial position of the gun with respect to the field build-up. (orig.) [de

Development of bipolar-pulse accelerator for intense pulsed ion beam acceleration

Energy Technology Data Exchange (ETDEWEB)

Masugata, Katsumi [Department of Electrical and Electronic System Engineering, Toyama University, 3190 Gofuku, Toyama 930-8555 (Japan)]. E-mail: masugata@eng.toyama-u.ac.jp; Shimizu, Yuichro [Department of Electrical and Electronic System Engineering, Toyama University, 3190 Gofuku, Toyama 930-8555 (Japan); Fujioka, Yuhki [Department of Electrical and Electronic System Engineering, Toyama University, 3190 Gofuku, Toyama 930-8555 (Japan); Kitamura, Iwao [Department of Electrical and Electronic System Engineering, Toyama University, 3190 Gofuku, Toyama 930-8555 (Japan); Tanoue, Hisao [National Institute of Advanced Industry Science and Technology, 1-1-1, Umezono, Tsukuba-shi, Ibaraki 305-8568 (Japan); Arai, Kazuo [National Institute of Advanced Industry Science and Technology, 1-1-1, Umezono, Tsukuba-shi, Ibaraki 305-8568 (Japan)

2004-12-21

To improve the purity of intense pulsed ion beams, a new type of pulsed ion beam accelerator named 'bipolar pulse accelerator' was proposed. To confirm the principle of the accelerator a prototype of the experimental system was developed. The system utilizes By type magnetically insulated acceleration gap and operated with single polar negative pulse. A coaxial gas puff plasma gun was used as an ion source, which was placed inside the grounded anode. Source plasma (nitrogen) of current density {approx}25A/cm2, duration {approx}1.5{mu}s was injected into the acceleration gap by the plasma gun. The ions were successfully accelerated from the grounded anode to the drift tube by applying negative pulse of voltage 240kV, duration 100ns to the drift tube. Pulsed ion beam of current density {approx}40A/cm2, duration {approx}50ns was obtained at 41mm downstream from the anode surface. To evaluate the irradiation effect of the ion beam to solid material, an amorphous silicon thin film of thickness {approx}500nm was used as the target, which was deposited on the glass substrate. The film was found to be poly-crystallized after 4-shots of the pulsed nitrogen ion beam irradiation.

Seepage Model for PA Including Drift Collapse

International Nuclear Information System (INIS)

Li, G.; Tsang, C.

2000-01-01

The purpose of this Analysis/Model Report (AMR) is to document the predictions and analysis performed using the Seepage Model for Performance Assessment (PA) and the Disturbed Drift Seepage Submodel for both the Topopah Spring middle nonlithophysal and lower lithophysal lithostratigraphic units at Yucca Mountain. These results will be used by PA to develop the probability distribution of water seepage into waste-emplacement drifts at Yucca Mountain, Nevada, as part of the evaluation of the long term performance of the potential repository. This AMR is in accordance with the ''Technical Work Plan for Unsaturated Zone (UZ) Flow and Transport Process Model Report'' (CRWMS M andO 2000 [153447]). This purpose is accomplished by performing numerical simulations with stochastic representations of hydrological properties, using the Seepage Model for PA, and evaluating the effects of an alternative drift geometry representing a partially collapsed drift using the Disturbed Drift Seepage Submodel. Seepage of water into waste-emplacement drifts is considered one of the principal factors having the greatest impact of long-term safety of the repository system (CRWMS M andO 2000 [153225], Table 4-1). This AMR supports the analysis and simulation that are used by PA to develop the probability distribution of water seepage into drift, and is therefore a model of primary (Level 1) importance (AP-3.15Q, ''Managing Technical Product Inputs''). The intended purpose of the Seepage Model for PA is to support: (1) PA; (2) Abstraction of Drift-Scale Seepage; and (3) Unsaturated Zone (UZ) Flow and Transport Process Model Report (PMR). Seepage into drifts is evaluated by applying numerical models with stochastic representations of hydrological properties and performing flow simulations with multiple realizations of the permeability field around the drift. The Seepage Model for PA uses the distribution of permeabilities derived from air injection testing in niches and in the cross drift to

'Pipetron' beam dynamics with noise

International Nuclear Information System (INIS)

Shiltsev, V.D.

1996-10-01

Extra-large hadron collider, ''Pipetron'', at 100 TeV energy is currently under consideration. In this article we study the Pipetron transverse and longitudinal beam dynamics under influence of external noises. The major effects are growths of transverse and longitudinal emittances of the beam caused by noisy forces which vary over the revolution period or synchrotron oscillation period, respectively; and closed orbit distortions induced by slow drift of magnet positions. Based on analytical consideration of these phenomena, we estimate tolerable levels of these noises and compare them with available experimental data. Although it is concluded that transverse and, probably, longitudinal feedback systems are necessary for the emittance's preservation, and sophisticated beam-based orbit correction methods should be used at the Pipetron, we observe no unreasonable requirements which present and impenetrable barrier to the project

Transmission and compression of an intense relativistic electron beam produced by a converging annular diode with return current feedback through the cathode. Pt. 2. The experiments

International Nuclear Information System (INIS)

Kelly, J.G.; Schuch, R.L.

1976-02-01

The complete results of the experiments with the converging annular diode within return current fedback through the cathode (Triax) are reported herein. The diode was designed to focus a relativistic high-current electron beam to a small focus. It did confirm the Triaxial theory detailed in Part I, and it did achieve a factor of 10 areal compression with 50% efficiency (which was below expectations). There were two principal reasons for this shortfall. First, the rapid diode plasma motion of 10 cm/μsec that was discovered necessitated the use of larger A-K gaps than expected and led to thicker beam sheets than are needed for good focusing. Second, the intrinsic angular spread of the electrons, even from the best cathode surfaces, introduced excessive angular momentum into the beam so that only a minor portion of the electrons could reach the axis. However, the yield of useful information about diode physics in general and about the influence of prepulse, the role of diode plasmas, the motion of energetic beams within conducting boundaries, diode emission properties, and diode diagnostic techniques in particle has had a significant and useful impact on the electron beam program at Sandia

Seepage into drifts with mechanical degradation

International Nuclear Information System (INIS)

Li, Guomin; Tsang, Chin-Fu

2002-01-01

Seepage into drifts in unsaturated tuff is an important issue for the long-term performance of the potential nuclear waste repository at Yucca Mountain, Nevada. Drifts in which waste packages will potentially be emplaced are subject to degradation in the form of rockfall from the drift ceiling induced by stress relief, seismic, or thermal effects. The objective of this study is to calculate seepage rates for various drift-degradation scenarios and for different values of percolation flux for the Topopah Spring middle nonlithophysal (Tptpmn) and the Topopah Spring lower lithophysal (Tptpll) units. Seepage calculations are conducted by (1) defining a heterogeneous permeability model on the drift scale that is consistent with field data, (2) selecting calibrated parameters associated with the Tptpmn and Tptpll units, and (3) simulating seepage on detailed degraded-drift profiles, which were obtained from a separate rock mechanics engineering analysis. The simulation results indicate (1) that the seepage threshold (i.e., the percolation flux at which seepage first occurs) is not significantly changed by drift degradation, and (2) the degradation-induced increase in seepage above the threshold is influenced more by the shape of the cavity created by rockfall than the rockfall volume

Compressive and fatigue behavior of beta-type titanium porous structures fabricated by electron beam melting

International Nuclear Information System (INIS)

Liu, Y.J.; Wang, H.L.; Li, S.J.; Wang, S.G.; Wang, W.J.; Hou, W.T.; Hao, Y.L.; Yang, R.; Zhang, L.C.

2017-01-01

β-type titanium porous structure is a new class of solution for implant because it offers excellent combinations of high strength and low Young's modulus. This work investigated the influence of porosity variation in electron beam melting (EBM)-produced β-type Ti2448 alloy samples on the mechanical properties including super-elastic property, Young's modulus, compressive strength and fatigue properties. The relationship between the misorientation angle of adjacent grains and fatigue crack deflection behaviors was also observed. The super-elastic property is improved as the porosity of samples increases because of increasing tensile/compressive ratio. For the first time, the position of fatigue crack initiation is defined in stress-strain curves based on the variation of the fatigue cyclic loops. The unique manufacturing process of EBM results in the generation of different sizes of grains, and the apparent fatigue crack deflection occurs at the grain boundaries in the columnar grain zone due to substantial misorientation between adjacent grains. Compared with Ti-6Al-4V samples, the Ti2448 porous samples exhibit a higher normalized fatigue strength owing to super-elastic property, greater plastic zone ahead of the fatigue crack tip and the crack deflection behavior. - Highlights: • The super-elastic property is improved with increasing porosity of Ti2448 porous samples. • The position of fatigue crack initiation on the strain curve is defined. • The unique EBM-produced microstructure leads to apparent fatigue crack deflection occurring at columnar grain boundary. • Ti2448 porous samples display only half of the Young's modulus of Ti-6Al-4V porous samples at same fatigue strength level.

About a method for compressing x-ray computed microtomography data

Science.gov (United States)

Mancini, Lucia; Kourousias, George; Billè, Fulvio; De Carlo, Francesco; Fidler, Aleš

2018-04-01

The management of scientific data is of high importance especially for experimental techniques that produce big data volumes. Such a technique is x-ray computed tomography (CT) and its community has introduced advanced data formats which allow for better management of experimental data. Rather than the organization of the data and the associated meta-data, the main topic on this work is data compression and its applicability to experimental data collected from a synchrotron-based CT beamline at the Elettra-Sincrotrone Trieste facility (Italy) and studies images acquired from various types of samples. This study covers parallel beam geometry, but it could be easily extended to a cone-beam one. The reconstruction workflow used is the one currently in operation at the beamline. Contrary to standard image compression studies, this manuscript proposes a systematic framework and workflow for the critical examination of different compression techniques and does so by applying it to experimental data. Beyond the methodology framework, this study presents and examines the use of JPEG-XR in combination with HDF5 and TIFF formats providing insights and strategies on data compression and image quality issues that can be used and implemented at other synchrotron facilities and laboratory systems. In conclusion, projection data compression using JPEG-XR appears as a promising, efficient method to reduce data file size and thus to facilitate data handling and image reconstruction.

Electronics for proportional drift tubes

International Nuclear Information System (INIS)

Fremont, G.; Friend, B.; Mess, K.H.; Schmidt-Parzefall, W.; Tarle, J.C.; Verweij, H.; CERN-Hamburg-Amsterdam-Rome-Moscow Collaboration); Geske, K.; Riege, H.; Schuett, J.; CERN-Hamburg-Amsterdam-Rome-Moscow Collaboration); Semenov, Y.; CERN-Hamburg-Amsterdam-Rome-Moscow Collaboration)

1980-01-01

An electronic system for the read-out of a large number of proportional drift tubes (16,000) has been designed. This system measures deposited charge and drift-time of the charge of a particle traversing a proportional drift tube. A second event can be accepted during the read-out of the system. Up to 40 typical events can be collected and buffered before a data transfer to a computer is necessary. (orig.)

Velocity and Magnetic Compressions in FEL Drivers

CERN Document Server

Serafini, L

2005-01-01

We will compare merits and issues of these two techniques suitable for increasing the peak current of high brightness electron beams. The typical range of applicability is low energy for the velocity bunching and middle to high energy for magnetic compression. Velocity bunching is free from CSR effects but requires very high RF stability (time jitters), as well as a dedicated additional focusing and great cure in the beam transport: it is very well understood theoretically and numerical simulations are pretty straightforward. Several experiments of velocity bunching have been performed in the past few years: none of them, nevertheless, used a photoinjector designed and optimized for that purpose. Magnetic compression is a much more consolidated technique: CSR effects and micro-bunch instabilities are its main drawbacks. There is a large operational experience with chicanes used as magnetic compressors and their theoretical understanding is quite deep, though numerical simulations of real devices are still cha...

Simulating non-Kolmogorov turbulence phase screens based on equivalent structure constant and its influence on simulations of beam propagation

Directory of Open Access Journals (Sweden)

Ming Chen

Full Text Available Gaussian distribution is used to describe the power law along the propagation path and phase screen of the non-Kolmogorov turbulence is proposed based on the equivalent refractive-index structure constants. Various simulations of Gaussian beam propagation in Kolmogorov and non-Kolmogorov turbulence are used for telling the difference between isotropic and anisotropic turbulence. The results imply that the non-Kolmogorov turbulence makes a great influence on the simulations via power law in spectrum and the number of phase screens. Furthermore, the influence is mainly reflected in light intensity and beam drift. Statistics suggest that when Gaussian beam propagate through single phase screen of non-Kolmogorov, maximum and uniformity of light intensity increase first and then decrease with power law, and beam drift firstly increases and then to stabilize. When Gaussian beam propagate through multiple phase screens, relative errors of beam drift decrease with the number of phase screens. And scintillation indices in non-Kolmogorov turbulence is larger than that in Kolmogorov turbulence when the number is small. When the number is big, the scintillation indices in non-Kolmogorov turbulence is smaller than that in Kolmogorov turbulence. The results shown in this paper demonstrate the effect of the non-Kolmogorov turbulence on laser atmospheric transmissions. Thus, this paper suggests a possible direction of the improvement of the laser transmission accuracy over a long distance through the atmosphere.

Simulation of the development and interaction of instabilities in a relativistic electron beam under variation of the beam wall thickness

Energy Technology Data Exchange (ETDEWEB)

Badarin, A. A.; Kurkin, S. A. [Saratov State University (Russian Federation); Koronovskii, A. A. [Yuri Gagarin State Technical University (Russian Federation); Rak, A. O. [Belorussian State University of Informatics and Radioelectronics (Belarus); Hramov, A. E., E-mail: hramovae@gmail.com [Saratov State University (Russian Federation)

2017-03-15

The development and interaction of Bursian and diocotron instabilities in an annular relativistic electron beam propagating in a cylindrical drift chamber are investigated analytically and numerically as functions of the beam wall thickness and the magnitude of the external uniform magnetic field. It is found that the interaction of instabilities results in the formation of a virtual cathode with a complicated rotating helical structure and several reflection regions (electron bunches) in the azimuthal direction. It is shown that the number of electron bunches in the azimuthal direction increases with decreasing beam wall thickness and depends in a complicated manner on the magnitude of the external magnetic field.

Performance of the CMS drift-tube chamber local trigger with cosmic rays

CERN Document Server

Chatrchyan, S; Sirunyan, A M; Adam, W; Arnold, B; Bergauer, H; Bergauer, T; Dragicevic, M; Eichberger, M; Erö, J; Friedl, M; Frühwirth, R; Ghete, V M; Hammer, J; Hänsel, S; Hoch, M; Hörmann, N; Hrubec, J; Jeitler, M; Kasieczka, G; Kastner, K; Krammer, M; Liko, D; Magrans de Abril, I; Mikulec, I; Mittermayr, F; Neuherz, B; Oberegger, M; Padrta, M; Pernicka, M; Rohringer, H; Schmid, S; Schöfbeck, R; Schreiner, T; Stark, R; Steininger, H; Strauss, J; Taurok, A; Teischinger, F; Themel, T; Uhl, D; Wagner, P; Waltenberger, W; Walzel, G; Widl, E; Wulz, C E; Chekhovsky, V; Dvornikov, O; Emeliantchik, I; Litomin, A; Makarenko, V; Marfin, I; Mossolov, V; Shumeiko, N; Solin, A; Stefanovitch, R; Suarez Gonzalez, J; Tikhonov, A; Fedorov, A; Karneyeu, A; Korzhik, M; Panov, V; Zuyeuski, R; Kuchinsky, P; Beaumont, W; Benucci, L; Cardaci, M; De Wolf, E A; Delmeire, E; Druzhkin, D; Hashemi, M; Janssen, X; Maes, T; Mucibello, L; Ochesanu, S; Rougny, R; Selvaggi, M; Van Haevermaet, H; Van Mechelen, P; Van Remortel, N; 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Gomez Ceballos, G; Hahn, K A; Harris, P; Jaditz, S; Kim, Y; Klute, M; Lee, Y J; Li, W; Loizides, C; Ma, T; Miller, M; Nahn, S; Paus, C; Roland, C; Roland, G; Rudolph, M; Stephans, G; Sumorok, K; Sung, K; Vaurynovich, S; Wenger, E A; Wyslouch, B; Xie, S; Yilmaz, Y; Yoon, A S; Bailleux, D; Cooper, S I; Cushman, P; Dahmes, B; De Benedetti, A; Dolgopolov, A; Dudero, P R; Egeland, R; Franzoni, G; Haupt, J; Inyakin, A; Klapoetke, K; Kubota, Y; Mans, J; Mirman, N; Petyt, D; Rekovic, V; Rusack, R; Schroeder, M; Singovsky, A; Zhang, J; Cremaldi, L M; Godang, R; Kroeger, R; Perera, L; Rahmat, R; Sanders, D A; Sonnek, P; Summers, D; Bloom, K; Bockelman, B; Bose, S; Butt, J; Claes, D R; Dominguez, A; Eads, M; Keller, J; Kelly, T; Kravchenko, I; Lazo-Flores, J; Lundstedt, C; Malbouisson, H; Malik, S; Snow, G R; Baur, U; Iashvili, I; Kharchilava, A; Kumar, A; Smith, K; Strang, M; Alverson, G; Barberis, E; Boeriu, O; Eulisse, G; Govi, G; McCauley, T; Musienko, Y; Muzaffar, S; Osborne, I; Paul, T; Reucroft, S; 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Andelin, D; Arenton, M W; Balazs, M; Boutle, S; Buehler, M; Conetti, S; Cox, B; Hirosky, R; Ledovskoy, A; Neu, C; Phillips II, D; Ronquest, M; Yohay, R; Gollapinni, S; Gunthoti, K; Harr, R; Karchin, P E; Mattson, M; Sakharov, A; Anderson, M; Bachtis, M; Bellinger, J N; Carlsmith, D; Crotty, I; Dasu, S; Dutta, S; Efron, J; Feyzi, F; Flood, K; Gray, L; Grogg, K S; Grothe, M; Hall-Wilton, R; Jaworski, M; Klabbers, P; Klukas, J; Lanaro, A; Lazaridis, C; Leonard, J; Loveless, R; Magrans de Abril, M; Mohapatra, A; Ott, G; Polese, G; Reeder, D; Savin, A; Smith, W H; Sourkov, A; Swanson, J; Weinberg, M; Wenman, D; Wensveen, M; White, A

2010-01-01

The performance of the Local Trigger based on the drift-tube system of the CMS experiment has been studied using muons from cosmic ray events collected during the commissioning of the detector in 2008. The properties of the system are extensively tested and compared with the simulation. The effect of the random arrival time of the cosmic rays on the trigger performance is reported, and the results are compared with the design expectations for proton-proton collisions and with previous measurements obtained with muon beams.

CesrTA Retarding Field Analyzer Measurements in Drifts, Dipoles, Quadrupoles and Wigglers

International Nuclear Information System (INIS)

Calvey, J.R.; Li, Y.; Livezey, J.A.; Makita, J.; Meller, R.E.; Palmer, M.A.; Schwartz, R.M.; Strohman, C.R.; Harkay, K.; Calatroni, S.; Rumolo, G.; Kanazawa, K.; Suetsugu, Y.; Pivi, M.; Wang, L.

2010-01-01

Over the course of the CesrTA program, the Cornell Electron Storage Ring (CESR) has been instrumented with several retarding field analyzers (RFAs), which measure the local density and energy distribution of the electron cloud. These RFAs have been installed in drifts, dipoles, quadrupoles, and wigglers; and data have been taken in a variety of beam conditions and bunch configurations. This paper will provide an overview of these results, and give a preliminary evaluation of the efficacy of cloud mitigation techniques implemented in the instrumented vacuum chambers.

Technology choices for the Integrated Beam Experiment (IBX)

Energy Technology Data Exchange (ETDEWEB)

Leitner, M.A.; Celata, C.M.; Lee, E.P.; Sabbi, G.; Waldron, W.L.; Barnard, J.J.

2002-10-31

Over the next three years the research program of the Heavy Ion Fusion Virtual National Laboratory (HIF-VNL), a collaboration among LBNL, LLNL, and PPPL, is focused on separate scientific experiments in the injection, transport and focusing of intense heavy ion beams at currents from 100 mA to 1 A. As a next major step in the HIF-VNL program, we aim for a complete ''source-to-target'' experiment, the Integrated Beam Experiment (IBX). By combining the experience gained in the current separate beam experiments IBX would allow the integrated scientific study of the evolution of a single heavy ion beam at high current ({approx}1 A) through all sections of a possible heavy ion fusion accelerator: the injection, acceleration, compression, and beam focusing. This paper describes the main parameters and technology choices of the planned IBX experiment. IBX will accelerate singly charged potassium or argon ion beams up to 10 MeV final energy and a longitudinal beam compression ratio of 10, resulting in a beam current at target of more than 10 Amperes. Different accelerator cell design options are described in detail: Induction cores incorporating either room temperature pulsed focusing-magnets or superconducting magnets.

First beam in Linac4 DTL

CERN Multimedia

Katarina Anthony

2014-01-01

Following the installation of the Linac4 Drift Tube Linac (DTL) earlier this summer (see here), the first DTL tank saw beams at 12 MeV on 5 August.   Transverse emittance measured at 12 MeV after the DTL tank1 using a temporary slit-and-grid emittance device. You never forget your first beam. That was especially true for the Linac4 DTL team, as it followed years of design, construction and vigorous testing. "We performed countless measurements of the geometry, vacuum and magnet polarisation of the DTL tanks while we were in the workshop," says Suitbert Ramberger, project engineer for the Linac4 DTL. "Add that preparation to the excellent RF conditioning that we carried out in the weeks before the beam tests and I was confident that the acceleration with beam would fully meet expectations!" Indeed it did. Beam commissioning tests ran until 21 August and found the DTL operating with nominal transmission. This successful run has confirmed the innovative design ...

Application of Deformable Templates for Recognizing Tracks Detected with High Pressure Drift Tubes

International Nuclear Information System (INIS)

Baginyan, S.; Baranov, S.; Glazov, A.; Ososkov, G.

1994-01-01

The modification of the deformable template method (DTM) application to the problem of track finding and track parameter determination for data detected with high pressure drift tubes (HPDT) in the design of ATLAS for the muon spectrometer experiment is proposed. Our DTM applications consist of two parts, according to two stages of the study. The first part relates to the stage of HPDT study on the CERN muon beam (BEAM-TEST) with the simplest one-prong events without noise signals, where the main obstacle is the left-right ambiguities for each tube. In the second part more complicated HPDT data are to be handled with noise signals. It was shown that the suggested DTM development solves the problem of track recognition and track parameter determination for both noiseless and noise data. Results are obtained on the real beam test data and on data simulating the muon spectrometer on the basis of HPDT. 14 refs., 10 figs

Automatic tracking of the intersection of a laser and electron beam

International Nuclear Information System (INIS)

Turko, B.T.; Fuzesy, R.Z.; Pripstein, D.A.; Kowitt, M.; Chamberlain, O.; Shapiro, G.; Hughes, E.

1990-05-01

For the Compton Polarimeter experiment at the Stanford Linear Accelerator the crossing point of a laser beam and an electron beam must be kept accurate and stable. An electronic system is described for the automatic tracking and correcting of the beam crossing. A remote CCD camera, relatively insensitive to electromagnetic disturbance, records small displacements of the pulsed laser beam. Video signals are analyzed at a remote station, the amount of drift from a selected reference point determined and the appropriate correction commands sent to the motorized mirror deflecting the laser beam. A description of the system, its performance and the test results are presented. 2 refs., 4 figs

Properties of H- and D- beams from magnetron and Penning sources

International Nuclear Information System (INIS)

Sluyters, T.; Kovarik, V.

1979-01-01

The quality of negative hydrogen isotope beams are evaluated after extraction from magnetron and Penning sources. The general conclusions of these measurements are that: (a) the beam quality from these plasma sources are adequate for the transport of high current negative ion beams in bending magnets; (b) there is evidence of practically complete space charge neutralization in the drift space beyond the extractor; (c) the beam performance from the Penning source appears to be better compared with the magnetron source; and (d) it is likely that the high electric field gradient and a concave ion emission boundary are responsible for a beam cross-over near the anode aperture, which causes beam divergence practically independent of the extraction geometry

Time-resolved ion beam induced charge collection (TRIBICC) in micro-electronics

International Nuclear Information System (INIS)

Schoene, H.; Walsh, D.S.; Sexton, F.W.; Doyle, B.L.; Aurand, J.F.; Dodd, P.E.; Flores, R.S.; Wing, N.

1998-01-01

The entire current transient induced by single 12 MeV Carbon ions was measured at a 5GHz analog bandwidth. A focused ion micro-beam was used to acquire multiple single ion transients at multiple locations of a single CMOS transistor. The current transients reveal clear and discernible contributions of drift and diffusive charge collection. Transients measured for drain and off-drain ion strikes compare well to 3D DAVINCI calculations. Estimates are presented for the drift assisted funneling charge collection depth

Efficient Injection of Electron Beams into Magnetic Guide Fields

International Nuclear Information System (INIS)

Chorny, V.; Cooperstein, G.; Dubyna, V.; Frolov, O.; Harper-Slaboszewicz, V.; Hinshelwood, D.; Schneider, R.; Solovyov, V.; Tsepilov, H.; Vitkovitsky, I.; Ware, K.

1999-01-01

Preliminary experimental and modeling study of injection and transport of high current electron beams in current-neutralized background gas has been performed. Initial analysis of the results indicates that high current triaxial ring diode operates very reproducibly in the pinch mode. High current density beam can be injected efficiently into the drift region, using azimuthal guide field with reduced intensity near the injection region. This was shown to improve the effectiveness of capturing the beam for the transport. The transport length was insufficient to measure losses, such as would arise from scattering with the background gas

Drift reversal capability in helical systems

International Nuclear Information System (INIS)

Yokoyama, M.; Itoh, K.; Okamura, S.

2002-10-01

The maximum-J (J is the second adiabatic invariant) capability, i.e., the drift reversal capability, is examined in quasi-axisymmetric (QAS) stellarators and quasi-poloidally symmetric (QPS) stellarators as a possible mechanism for turbulent transport suppression. Due to the existence of non-axisymmetry of the magnetic field strength in QAS configurations, a local maximum of J is created to cause the drift reversal. The increase of magnetic shear in finite beta equilibria also has favorable effect in realizing the drift reversal. The radial variation of the uniform magnetic field component plays a crucial role for the drift reversal in a QPS configuration. Thus, the drift reversal capability and its external controllability are demonstrated for QAS and QPS stellarators, by which the impact of magnetic configuration on turbulent transport can be studied in experiments. (author)

Drift reversal capability in helical systems

International Nuclear Information System (INIS)

Yokoyama, M.; Itoh, K.; Okamura, S.; Matsuoka, K.; Nakajima, N.; Itoh, S.-I.; Neilson, G.H.; Zarnstorff, M.C.; Rewoldt, G.

2003-01-01

The maximum-J (J is the second adiabatic invariant) capability, i.e., the drift reversal capability, is examined in quasi-axisymmetric (QAS) stellarators and quasi-poloidally symmetric (QPS) stellarators as a possible mechanism for turbulent transport suppression. Due to the existence of non-axisymmetry of the magnetic field strength in QAS configurations, a local maximum of J is created to cause the drift reversal. The increase of magnetic shear in finite beta equilibria also has favorable effect in realizing the drift reversal. The radial variation of the uniform magnetic field component plays a crucial role for the drift reversal in a QPS configuration. Thus, the drift reversal capability and its external controllability are demonstrated for QAS and QPS stellarators, by which the impact of magnetic configuration on turbulent transport can be studied in experiments. (author)

The Diagonal Compression Field Method using Circular Fans

DEFF Research Database (Denmark)

Hansen, Thomas

2005-01-01

This paper presents a new design method, which is a modification of the diagonal compression field method, the modification consisting of the introduction of circular fan stress fields. The traditional method does not allow changes of the concrete compression direction throughout a given beam...... if equilibrium is strictly required. This is conservative, since it is not possible fully to utilize the concrete strength in regions with low shear stresses. The larger inclination (the smaller -value) of the uniaxial concrete stress the more transverse shear reinforcement is needed; hence it would be optimal...... if the -value for a given beam could be set to a low value in regions with high shear stresses and thereafter increased in regions with low shear stresses. Thus the shear reinforcement would be reduced and the concrete strength would be utilized in a better way. In the paper it is shown how circular fan stress...

Calibration of the CMS Drift Tube Chambers and Measurement of the Drift Velocity with Cosmic Rays

CERN Document Server

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Yoo, H D; Zheng, Y; Jindal, P; Parashar, N; Cuplov, V; Ecklund, K M; Geurts, F J M; Liu, J H; Maronde, D; Matveev, M; Padley, B P; Redjimi, R; Roberts, J; Sabbatini, L; Tumanov, A; Betchart, B; Bodek, A; Budd, H; Chung, Y S; de Barbaro, P; Demina, R; Flacher, H; Gotra, Y; Harel, A; Korjenevski, S; Miner, D C; Orbaker, D; Petrillo, G; Vishnevskiy, D; Zielinski, M; Bhatti, A; Demortier, L; Goulianos, K; Hatakeyama, K; Lungu, G; Mesropian, C; Yan, M; Atramentov, O; Bartz, E; Gershtein, Y; Halkiadakis, E; Hits, D; Lath, A; Rose, K; Schnetzer, S; Somalwar, S; Stone, R; Thomas, S; Watts, T L; Cerizza, G; Hollingsworth, M; Spanier, S; Yang, Z C; York, A; Asaadi, J; Aurisano, A; Eusebi, R; Golyash, A; Gurrola, A; Kamon, T; Nguyen, C N; Pivarski, J; Safonov, A; Sengupta, S; Toback, D; Weinberger, M; Akchurin, N; Berntzon, L; Gumus, K; Jeong, C; Kim, H; Lee, S W; Popescu, S; Roh, Y; Sill, A; Volobouev, I; Washington, E; Wigmans, R; Yazgan, E; Engh, D; Florez, C; Johns, W; Pathak, S; Sheldon, P; Andelin, D; Arenton, M W; Balazs, M; Boutle, S; Buehler, M; Conetti, S; Cox, B; Hirosky, R; Ledovskoy, A; Neu, C; Phillips II, D; Ronquest, M; Yohay, R; Gollapinni, S; Gunthoti, K; Harr, R; Karchin, P E; Mattson, M; Sakharov, A; Anderson, M; Bachtis, M; Bellinger, J N; Carlsmith, D; Crotty, I; Dasu, S; Dutta, S; Efron, J; Feyzi, F; Flood, K; Gray, L; Grogg, K S; Grothe, M; Hall-Wilton, R; Jaworski, M; Klabbers, P; Klukas, J; Lanaro, A; Lazaridis, C; Leonard, J; Loveless, R; Magrans de Abril, M; Mohapatra, A; Ott, G; Polese, G; Reeder, D; Savin, A; Smith, W H; Sourkov, A; Swanson, J; Weinberg, M; Wenman, D; Wensveen, M; White, A

2010-01-01

This paper describes the calibration procedure for the drift tubes of the CMS barrel muon system and reports the main results obtained with data collected during a high statistics cosmic ray data-taking period. The main goal of the calibration is to determine, for each drift cell, the minimum time delay for signals relative to the trigger, accounting for the drift velocity within the cell. The accuracy of the calibration procedure is influenced by the random arrival time of cosmic muons. A more refined analysis of the drift velocity was performed during the offline reconstruction phase, which takes into account this feature of cosmic ray events.

Wavefront Tilt And Beam Walk Correction For A Pulsed Laser System

Science.gov (United States)

Bartosewcz, Mike; Tyburski, Joe

1986-05-01

The Lockheed Beam Alignment Assembly (BAA) is designed to be a space qualifiable, long life, low bandwidth beam stabilization system. The BAA will stabilize a wandering pulsed laser beam with an input beam tilt of ±750 microradians and translation of ±2.5 mm by two orders of magnitude at the bandwidth of interest. A bandwidth of three hertz was selected to remove laser and optical train thermal drifts and launch induced strain effects. The lambda over twenty RMS wavefront will be maintained in the optics at full power under vacuum test, to demonstrate space qualifiability and optical performance.

Comparison of electrostatic and electromagnetic synchronization of drift waves and suppression of drift wave turbulence in a linear device

Energy Technology Data Exchange (ETDEWEB)

Brandt, C; Grulke, O; Klinger, T, E-mail: christian.brandt@lpmi.uhp-nancy.f [Max-Planck-Institute for Plasma Physics, EURATOM Association, Wendelsteinstrasse 1, D-17491 Greifswald (Germany)

2010-05-15

Experiments in a cylindrical magnetized plasma on the control of drift waves by means of two different spatiotemporal open-loop control systems-an electrostatic and an electromagnetic exciter-are reported. The drift wave dynamics is controlled by a mode-selective signal created with azimuthal arrangements of eight electrodes and eight saddle coils, respectively. Nonlinear interaction between the control signals and drift waves is observed, leading to synchronization of coherent drift waves and suppression of broadband drift wave turbulence. The cross-phase between density and potential fluctuations reduces from {approx}{pi}/2 in turbulence to {approx}0 in controlled turbulence. Hence, the cross-field transport is reduced to the level of coherent drift waves. For both control systems the coupling to the drift wave can be ascribed to the drive of parallel currents, on the one hand via direct electric contact and, on the other hand, via electromagnetic induction.

Drift chamber data readout system

International Nuclear Information System (INIS)

Basiladze, S.G.; Lokhonyai, L.

1980-01-01

An electronic system for processing drift chamber signals is described. The system consists of 4-channel fast amplifier-discriminators of low threshold, 16-channel time-expanders transforming 0.5 μs time intervals to 10 μs and a 9-bit time-to-digital converter (TDC) recording up to 16 expanded time intervals. If the average track multiplicity is small, TDC is capable to process signals from 4 time-expanders (i.e., 64 drift gaps). In order to record multiple tracks per drift gap discriminator outputs can be connected to a number of time-expander channels. The fast clear input enables the system to be cleared within 0.5 μs. Efficient readout from TDC is facilated by reading only those channels which contain non-zero data (9 bits - drift time; 6 bits - wire number)

Ponderomotive enhancement of charged particle beam limiting current

International Nuclear Information System (INIS)

Grebogi, C.; Uhm, H.S.

1987-01-01

The space charge limiting current problem is investigated for a magnetized particle beam propagating in a cylindrical drift tube and in presence of a waveguide mode. It is shown that with a proper choice of a waveguide mode, the limiting current can be greatly enhanced due to ponderomotive effects. Physically, this is accomplished by using the ponderomotive energy to reduce the potential depression due to the beam's self space charge field. Formulas for the limiting current as a function of beam energy and waveguide r.f. field for solid and hollow beams are derived. It is found from these formulas that, in appropriate parameter regimes, the space charge limiting current, say, of a 250kV bem can be enhanced by 70%

An electrodeless drift chamber

International Nuclear Information System (INIS)

Allison, J.; Barlow, R.J.; Bowdery, C.K.; Duerdoth, I.; Rowe, P.G.

1982-01-01

We describe a chamber in which the drift field is controlled by the deposition of electrostatic charge on an insulating surface. The chamber operates with good efficiency and precision for observed drift distances of up to 45 cm, promises to be extremely robust and adaptable and offers a very cheap way of making particle detectors. (orig.)

Thoughts of fast beam aborts for the international linear collider

International Nuclear Information System (INIS)

Mattison, T.

2006-01-01

The ILC beam is potentially very destructive, and a fast beam abort system is useful as part of the machine-protection strategy. Scaling laws for kicker pulse power and length optimization are presented. Kicker reference designs for the ILC with full linac aperture, and limited aperture, are presented. Power levels are of order 10 8 W for 100 nsec filling times, and length scales are of order 100 m. Design issues for beam transport to a dump are considered. Separation of the beams at the defining obstruction and energy bandwidth force either a long drift after the septum bend or long quads with large apertures for dispersion control. (author)

Recent DIII-D neutral beam calibration results

International Nuclear Information System (INIS)

Wight, J.; Hong, R.M.; Phillips, J.

1991-10-01

Injected DIII-D neutral beam power is estimated based on three principle quantities: the fraction of ion beam that is neutralized in the neutralizer gas cell, the beamline transmission efficiency, and the fraction of beam reionized in the drift duct. System changes in the past few years have included a new gradient grid voltage operating point, ion source arc regulation, routine deuterium operations and new neutralizer gas flow controllers. Additionally, beam diagnostics have been improved and better calibrated. To properly characterize the beams the principle quantities have been re-measured. Two diagnostics are primarily used to measure the quantities. The beamline waterflow calorimetry system measures the neutralization efficiency and the beamline transmission efficiency, and the target tile thermocouples measure the reionization loss. An additional diagnostic, the target tile pyrometer, confirmed the reionization loss measurement. Descriptions and results of these measurements will be presented. 4 refs., 5 figs., 2 tabs

In-Drift Microbial Communities

Energy Technology Data Exchange (ETDEWEB)

D. Jolley

2000-11-09

As directed by written work direction (CRWMS M and O 1999f), Performance Assessment (PA) developed a model for microbial communities in the engineered barrier system (EBS) as documented here. The purpose of this model is to assist Performance Assessment and its Engineered Barrier Performance Section in modeling the geochemical environment within a potential repository drift for TSPA-SR/LA, thus allowing PA to provide a more detailed and complete near-field geochemical model and to answer the key technical issues (KTI) raised in the NRC Issue Resolution Status Report (IRSR) for the Evolution of the Near Field Environment (NFE) Revision 2 (NRC 1999). This model and its predecessor (the in-drift microbial communities model as documented in Chapter 4 of the TSPA-VA Technical Basis Document, CRWMS M and O 1998a) was developed to respond to the applicable KTIs. Additionally, because of the previous development of the in-drift microbial communities model as documented in Chapter 4 of the TSPA-VA Technical Basis Document (CRWMS M and O 1998a), the M and O was effectively able to resolve a previous KTI concern regarding the effects of microbial processes on seepage and flow (NRC 1998). This document supercedes the in-drift microbial communities model as documented in Chapter 4 of the TSPA-VA Technical Basis Document (CRWMS M and O 1998a). This document provides the conceptual framework of the revised in-drift microbial communities model to be used in subsequent performance assessment (PA) analyses.

In-Drift Microbial Communities

International Nuclear Information System (INIS)

Jolley, D.

2000-01-01

As directed by written work direction (CRWMS M and O 1999f), Performance Assessment (PA) developed a model for microbial communities in the engineered barrier system (EBS) as documented here. The purpose of this model is to assist Performance Assessment and its Engineered Barrier Performance Section in modeling the geochemical environment within a potential repository drift for TSPA-SR/LA, thus allowing PA to provide a more detailed and complete near-field geochemical model and to answer the key technical issues (KTI) raised in the NRC Issue Resolution Status Report (IRSR) for the Evolution of the Near Field Environment (NFE) Revision 2 (NRC 1999). This model and its predecessor (the in-drift microbial communities model as documented in Chapter 4 of the TSPA-VA Technical Basis Document, CRWMS M and O 1998a) was developed to respond to the applicable KTIs. Additionally, because of the previous development of the in-drift microbial communities model as documented in Chapter 4 of the TSPA-VA Technical Basis Document (CRWMS M and O 1998a), the M and O was effectively able to resolve a previous KTI concern regarding the effects of microbial processes on seepage and flow (NRC 1998). This document supercedes the in-drift microbial communities model as documented in Chapter 4 of the TSPA-VA Technical Basis Document (CRWMS M and O 1998a). This document provides the conceptual framework of the revised in-drift microbial communities model to be used in subsequent performance assessment (PA) analyses

Drive beam stabilisation in the CLIC Test Facility 3

Science.gov (United States)

Malina, L.; Corsini, R.; Persson, T.; Skowroński, P. K.; Adli, E.

2018-06-01

The proposed Compact Linear Collider (CLIC) uses a high intensity, low energy drive beam to produce the RF power needed to accelerate a lower intensity main beam with 100 MV/m gradient. This scheme puts stringent requirements on drive beam stability in terms of phase, energy and current. The consequent experimental work was carried out in CLIC Test Facility CTF3. In this paper, we present a novel analysis technique in accelerator physics to find beam drifts and their sources in the vast amount of the continuously gathered signals. The instability sources are identified and adequately mitigated either by hardware improvements or by implementation and commissioning of various feedbacks, mostly beam-based. The resulting drive beam stability is of 0.2°@ 3 GHz in phase, 0.08% in relative beam energy and about 0.2% beam current. Finally, we propose a stabilisation concept for CLIC to guarantee the main beam stability.