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In order to understand the charged particle dynamics, e.g. the halo formation, emittance growth, x-y energy transfer and coupling, knowledge of the actual phase space is needed. Other the past decade there is an increasing number of articles who use tomography to map the beam phase space and measure the beam emittance. These studies where performed at high energy facilities where the effect of space charge was neglible and therefore not considered in the analysis. This work extends the tomography technique to beams with space charge. In order to simplify the analysis linear forces where assumed. By carefully modeling the tomography process using the particle-in-cell code WARP we test the validity of our assumptions and the accuracy of the reconstructed phase space. Finally, we report experimental results of phase space mapping at the University of Maryland Electron Ring (UMER) using tomography. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The University of Maryland electron ring (UMER) is a low-energy, high current recirculator for beam physics research with relevance to any applications that rely on intense beams of high quality. We review the space-charge physics issues, both in transverse and longitudinal beam dynamics, which are currently being addressed with UMER: emittance growth and halo formation, strongly asymmetric beams, Montague resonances, equipartitioning, bunch capture and shaping, etc. Furthermore, we report on recent developments in experiments, simulations, and improved diagnostics for space-charge dominated beams. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The University of Maryland Electron Ring (UMER) is a scaled model to investigate the physics of such intense beams. It uses a 10-keV electron beam along with other scaled beam parameters that model the larger machines but at a lower cost. Recently, multi turn operation of the ring (3.6 m diameter) has been achieved. In order to have full current transport of the electron beam, and to increase the number of turns of the beam around the ring, injection of the beam from the straight section into the ring becomes crucial. In this work, we report experimental results from the injection and matching of a space charge dominated beam and an emittance dominated beam. We also describe and analyze two methods of injection of the electron beam from the straight section into the ring. In one of the methods, the two injection quads are fixed to a preset value, while in the other both the injection quads are switched off (Collins injection). © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The University of Maryland Electron Ring (UMER) is a low energy, high current recirculator for beam physics research. Ring construction has been completed for multi-turn operation of beams over a broad range of intensities and initial conditions. The electron beam current is adjustable up to 100 mA and pulse length as long as 100 ns. UMER is addressing issues in beam physics relevant to many applications that require intense beams of high quality, such as advanced concept accelerators, free electron lasers, spallalion neutron sources, and future heavy-ion drivers for inertial fusion. The primary focus of this presentation is experimental results in the area of beam steering and control within the injection line and ring. Unique beam steering algorithms now include measurement of the beam response matrix at each quadrupole and matrix inversion by singular value decomposition (SVD). With these advanced steering methods, transport of an intense beam over 50 turns (3600 full lattice periods) of the ring has been achieved. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Tomography is the technique of reconstructing an image from its projections. It is widely used in the medical community to observe the interior of the human body by processing multiple x-ray images taken at different angles, A few pioneering researchers have adapted tomography to reconstruct detailed phase space maps of charged particle beams. Some questions arise regarding the limitations of tomography technique for space charge dominated beams. For instance is the linear space charge force a valid approximation? Does tomography equally reproduce phase space for complex, experimentally observed, initial particle distributions? Does tomography make any assumptions about the initial distribution? This study explores the use of accurate modeling with the particle-in-cell code WARP to address these questions, using a wide range of different initial distributions in the code. The study also includes a number of experimental results on tomographic phase space mapping performed on the University of Maryland Electron Ring (UMER). © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Previous RF experiments with normal-conducting cavities have demonstrated that there is a significant degradation in maximum gradient when the cavity is subjected to a strong axial magnetic field. We have developed a model suggesting that a cavity with beryllium walls may perform better than copper cavities. In this paper we outline the issues that led us to propose fabricating a Be-wall cavity. We also discuss a concept for fabricating such a cavity and mention some of the manufacturing issues we expect to face. [ABSTRACT FROM AUTHOR]