Home OALib Journal OALib PrePrints Submit Ranking News My Lib FAQ About Us Follow Us+
 Title Keywords Abstract Author All
Search Results: 1 - 10 of 100 matches for " "
 Page 1 /100 Display every page 5 10 20 Item
 Physics , 2010, DOI: 10.1088/1748-0221/6/02/P02004 Abstract: In many applications of the simple three-element einzel lens, such as injecting a low energy ion beam into a high-field Penning trap, there is a need for small-angle steering as well as focusing of the beam. We have analyzed a diagonalslit cylinder serving as the middle electrode of such a lens and have shown that such an electrode configuration significantly diminishes the aberration associated with such a deflection.
 Science Diliman , 1999, Abstract: The ion beam produced from a plasma sputter-type negative ion source with Zr target was analyzed, and the negative ion beam current was increased by focusing with an electrostatic Einzel lens. An Ar-N2 plasma at 7.0x 10-3 Torr (20%N2) with discharge current voltage=-20 V and discharge current=1.0 A was produced for sputter formation of negative ions in the ion source. The Zr target immersed in the plasma was biased at -200 V. The ion beam was analyzed with a retarding potential electrostatic energy analyzer. Lens potentials of 20.0 V for the outer electrodes and -80.3 V for the inner electrode resulted in the highest negative ion beam current, increasing the ion current to 0.5 nA (from 0.28 nA when not using the lens), and reduced the beam spot size to 25 mm (from 35 mm for the unfocused beam).
 Physics , 2015, Abstract: We investigate the motion of the primary beam outside the light cylinder in the pulsar wind. Inside the light cylinder both primary and secondary plasma move along dipole magnetic field lines where their energies can be arbitrary. But at larger distances the theory predicts quasi-radial motion with the velocity exactly corresponding to the drift velocity which cannot be the same for primary and secondary plasma. Hence, the deceleration of the primary beam is to take place simultaneously resulting in the acceleration of the secondary plasma. We investigate this process in the three-fluid MHD approximation and demonstrate that for most pulsars the energy of the beam remains practically unchanged. Only for young radio pulsars (Crab, Vela) essential deceleration up to the energy of the secondary plasma takes place outside the fast magnetosonic surface $r_{\rm F} \sim (10$-$100) R_{\rm L}$, the energy of secondary plasma itself increasing insufficiently.
 Physics , 2009, DOI: 10.1103/PhysRevSTAB.13.101303 Abstract: With the increasing development of laser accelerators, the electron energy is already beyond GeV and even higher in near future. Conventional beam dump based on ionization or radiation loss mechanism is cumbersome and costly, also has radiological hazards. We revisit the stopping power of high-energy charged particles in matter and discuss the associated problem of beam dump from the point of view of collective deceleration. The collective stopping length in an ionized gas can be several orders of magnitude shorter than the Bethe-Bloch and multiple electromagnetic cascades' stopping length in solid. At the mean time, the tenuous density of the gas makes the radioactivation negligible. Such a compact and non-radioactivating beam dump works well for short and dense bunches, which is typically generated from laser wakefield accelerator.
 Physics , 2005, DOI: 10.1088/0953-4075/39/19/S18 Abstract: We report on the production of a pulsed molecular beam of metastable NH ($a ^1\Delta$) radicals and present first results on the Stark deceleration of the NH ($a ^1\Delta, J=2, M\Omega=-4$) radicals from 550 m/s to 330 m/s. The decelerated molecules are excited on the spin-forbidden $A ^3\Pi \leftarrow a ^1\Delta$ transition, and detected via their subsequent spontaneous fluorescence to the $X ^3\Sigma^{-}, v"=0$ ground-state. These experiments demonstrate the feasibility of our recently proposed scheme [Phys. Rev. A 64 (2001) 041401] to accumulate ground-state NH radicals in a magnetic trap.
 Physics , 2007, Abstract: The plasma lens concept is examined as an alternative to focusing horns and solenoids for a neutrino beam facility. The concept is based on a combined high-current lens/target configuration. Current is fed at an electrode located downstream from the beginning of the target where pion capturing is needed. The current is carried by plasma outside the target. A second plasma lens section, with an additional current feed, follows the target. The plasma is immersed in a relatively small solenoidal magnetic field to facilitate its current profile shaping to optimize pion capture. Simulations of the not yet fully optimized configuration yielded a 25% higher neutrino flux at a detector situated at 3 km from the target than the horn system for the entire energy spectrum and a factor of 2.5 higher flux for neutrinos with energy larger than 3 GeV. A major advantage of plasma lenses is in background reduction. In antineutrino operation, neutrino background is reduced by a factor of close to 3 for the whole spectrum, and for energy larger than 3 GeV, neutrino background is reduced by a factor of 3.6. Plasma lenses have additional advantages: larger axial currents, high signal purity: minimal neutrino background in antineutrino runs. The lens medium consists of plasma, consequently, particle absorption and scattering is negligible. Withstanding high mechanical and thermal stresses in a plasma is not an issue.
 Physics , 2013, Abstract: Current wires are considered for compensation of long-range beam-beam interactions for the High Luminosity upgrade (HL-LHC) of the Large Hadron Collider at CERN. In this note, we demonstrate the advantage of using Electron Lens for this purpose instead of a conventional current-bearing wire.
 Physics , 2015, Abstract: In this article we investigate the Fresnel diffraction characteristics of the hybrid optical element which is a combination of a spiral phase plate (SPP) with topological charge p and a thin lens with focal length f, named the helical lens (HL). As incident a Gaussian laser beam is treated, having its waist a distance from the HL plane and its axis passing through the centre of the HL. It is shown that the SPP introduces a phase singularity of p-th order to the incident beam, while the lens transforms the beam characteristic parameters. The output light beam is analyzed in detail: its characteristic parameters and focusing properties, amplitude and intensity distributions and the vortex rings profiles and radii, at any z distance behind the HL plane, as well as in the near and far field.
 Physics , 2014, DOI: 10.1103/PhysRevA.81.013419 Abstract: We study the dynamics of a supersonic molecular beam in a low-finesse optical cavity and demonstrate that most molecules in the beam can be decelerated to zero central velocity by the intracavity optical field in a process analogous to electrostatic Stark deceleration. We show that the rapid switching of the optical field for slowing the molecules is automatically generated by the cavity-induced dynamics. We further show that $\sim1\%$ of the molecules can be optically trapped at a few millikelvin in the same cavity.
 Brazilian Journal of Physics , 2009, DOI: 10.1590/S0103-97332009000300005 Abstract: the characteristics of the ion beam extracted from an ion sources were investigated using computer code simion 3 d version 7.0. it has been used to evaluate the extraction system in order to produce an ion beam with high current and low beam emittance. the results show that the shape of the extraction electrode plays an important role in ion beam formation. comparison has been made between two extraction systems, pierce extraction electrode and spherical extraction electrode. the results show that the spherical extraction system yields ion extraction beam with lower emittance and radius than that the pierce system. the simulation can provide the basis for optimizing the extraction system and the acceleration gap for ion source.
 Page 1 /100 Display every page 5 10 20 Item