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[en] A summary of the talks, papers and discussion sessions presented in the Working Group on Plasma Based Acceleration Concepts is given within the context of the progress towards a 1 GeV laser driven accelerator module. The topics covered within the Working Group were self-modulated laser wakefield acceleration, standard laser wakefield acceleration, plasma beatwave acceleration, laser guiding and wake excitation in plasma channels, plasma wakefield acceleration, plasma lenses and optical injection techniques for laser wakefield accelerators. An overview will be given of the present status of experimental and theoretical progress as well as an outlook towards the future physics and technological challenges for the development of an optimized accelerator module
[en] The focusing system is an essential part of any ion microbeam system and focusing of MeV ion beams is generally accomplished using quadrupole lenses. There are two types of quadrupole lenses requiring the application of either voltage or current to provide the excitation, but there is also the possibility of utilizing lenses constructed from permanent magnets. All of these lens types have different advantages and disadvantages. Most microprobes employ electromagnetic quadrupoles for focusing, however electrostatic lenses have several advantages with respect to electromagnetic lenses, including significantly smaller size, no hysteresis effects, no heating, the utilization of highly stable voltage supplies, focusing which is independent of ion mass, and construction from industrial grade materials. The main advantage of the permanent magnetic lens is that it does not require the application of external power which can significantly reduce the overall lifetime cost. In this presentation, the short probe-forming systems comprised from all these types of quadrupole lenses are compared and the smallest beam spot size and appropriate optimal parameters of these probe-forming systems are determined.
[en] This paper covers the recent work carried out at the Rutherford Appleton Laboratory (RAL) on the ISIS Ion Source Development Rig (ISDR). The development of a retarding potential energy analyzer is described and a measured energy spread of 17.6 eV ± 1.5 eV from the ion source is reported. Variation in energy spread versus discharge current is shown. The development of a pepperpot emittance scanner to study emittance variation along the beam axis is discussed
[en] The possibility of using channeling as a tool for high energy accelerator applications and particle physics has now been extensively investigated. Bent crystals have been used for accelerator extraction and for particle deflection. Applications as accelerating devices have been discussed but have not yet been tried. copyright 1997 American Institute of Physics
[en] We present an introduction to the subjects of emittance and space-charge effects in charged-particle beams. This is followed by a discussion of three important topics that are at the frontier of this field. The first is a simple model, describing space-charge-induced emittance growth, which yields scaling formulas and some physical explanations for some of the surprising results. The second is a discussion of beam halo, an introduction to the particle-core model, and a brief summary of its results. The third topic is an introduction to the hypothesis of equipartitioning for collisionless particle beams. copyright 1996 American Institute of Physics
[en] The application of neutral beams to future power plant devices (DEMO) is dependent on achieving significantly improved electrical efficiency and the most promising route to achieving this is by implementing a photoneutralizer in place of the traditional gas neutralizer. A corollary of this innovation would be a significant reduction in the background gas density through which the beam is transported between the accelerator and the neutralizer. This background gas is responsible for the space charge neutralization of the beam, enabling distances of several metres to be traversed without significant beam expansion. This work investigates the sensitivity of a D- beam to reduced levels of space charge compensation for energies from 100 keV to 1.5 MeV, representative of a scaled prototype experiment, commissioning and full energy operation. A beam transport code, following the evolution of the phase space ellipse, is employed to investigate the effect of space charge on the beam optics. This shows that the higher energy beams are insensitive to large degrees of under compensation, unlike the lower energies. The probable degree of compensation at low gas density is then investigated through a simple, two component beam-plasma model that allows the potential to be negative. The degree of under-compensation is dependent on the positive plasma ion energy, one source of which is dissociation of the gas by the beam. The subsequent space charge state of the beam is shown to depend upon the relative times for equilibration of the dissociation energy and ionization by the beam ions.
[en] A new ion trap for storing fast (keV) ion beams is presented. The trap, which is electrostatic, stores the ions between two electrostatic mirrors. Two different examples of utilization of the trap are given. The first one required the extraction of the trapped particles after storage, in order to study their collision with an external target, while the second example measured the lifetime of the metastable He- levels. The advantage of storage using pure electrostatic fields is discussed
[en] We report formation of a guiding channel for high intensity laser pulses in pure, preionized helium using an axicon focused laser pulse, and demonstrate a single shot technique to measure the temporal and spatial evolution of the plasma channel
[en] The muons in a neutrino factory must be accelerated from the energy of the capture, phase rotation, and cooling systems (around 120 MeV kinetic energy) to the energy of the storage ring (around 25 GeV). This is done with a sequence of accelerators of different types: a linac, one or more recirculating linear accelerators, and finally one or more fixed field alternating gradient accelerators (FFAGs). I discuss the R and D that is needed to arrive at a complete system which we can have confidence will accelerate the beam and for which we can obtain a cost estimate
[en] For high intensity proton runs, emittance blow-up is often accompanied with nontrivial beam loss. It has been suggested that the largest portion of the Booster to AGS (BTA) transfer loss is located in the AGS end. It was also found that the space charge tune spread, immediately after the bunched beam enters the AGS ring, is large enough for the envelope resonance and emittance blow-up. It was decided, in 1997 high intensity proton run, to raise the BTA transfer kinetic energy from 1.54 GeV to 1.9 GeV. The transfer efficiency was increased, as expected. The beam emittance in the AGS ring did not increase, even the AGS acceptance was enlarged, which is probably because of the reduced space charge tune spread