Energy Loss of a High Charge Bunched Electron Beam in Plasma

There has been much interest in the blowout regime of plasma wakefield acceleration (PWFA), which features ultra-high fields and nonlinear plasma motion. Using an exact analysis, we examine here a fundamental limit of nonlinear PWFA excitation, by an infinitesimally short, relativistic electron beam. The beam energy loss in this case is shown to be linear in charge even for nonlinear plasma response, where a normalized, unitless charge exceeds unity. The physical basis for this effect is discussed, as are deviations from linear behavior observed in simulations with finite length beams.Comment: Submitted to Physical Review Letter

High-Efficiency Resonant Cavity Quadrupole Moment Monitor

Measurement of the beam quadrupole moment at several locations can be used to reconstruct the beam envelope and emittance parameters. The measurements can be performed in a non-intercepting way using a set of quadrupole-mode cavities. We present a cavity design with an optimized quadrupole moment shunt impedance. The cavity properties can be characterized using a wire test method to insure symmetry about the central axis, and alignment to nearby position sensing cavities. The design and characterization of the prototype structure is discussed

Natural noise and external wake field seeding in a proton-driven plasma accelerator

We discuss the level of natural shot noise in a proton bunch-driven plasma accelerator. The required seeding for the plasma wake field must be larger than the cumulative shot noise. This is the necessary condition for the axial symmetry of the generated wake and the acceleration quality. We develop an analytical theory of the noise field and compare it with multi-dimensional simulations. It appears that the natural noise wake field generated in plasma by the available at CERN super-protons-synchrotron (SPS) bunches is very low, at the level of a few 10 kV/m. This fortunate fact eases the requirements on the seed. Our three dimensional simulations show that even a few tens MeV electron bunch precursor of a very moderate intensity is sufficient to seed the proton bunch self-modulation in plasma.Comment: 5 pages, 5 figure

Generation of angular-momentum-dominated electron beams from a photoinjector

Various projects under study require an angular-momentum-dominated electron beam generated by a photoinjector. Some of the proposals directly use the angular-momentum-dominated beams (e.g. electron cooling of heavy ions), while others require the beam to be transformed into a flat beam (e.g. possible electron injectors for light sources and linear colliders). In this paper, we report our experimental study of an angular-momentum-dominated beam produced in a photoinjector, addressing the dependencies of angular momentum on initial conditions. We also briefly discuss the removal of angular momentum. The results of the experiment, carried out at the Fermilab/NICADD Photoinjector Laboratory, are found to be in good agreement with theoretical and numerical models.Comment: 8 pages, 7 figures, submitted to Phys. Rev. ST Accel. Beam

Generation of angular-momentum-dominated electron beams from a photoinjector

Various projects under study require an angular-momentum-dominated electron beam generated by a photoinjector. Some of the proposals directly use the angular-momentum-dominated beams (e.g., electron cooling of heavy ions), while others require the beam to be transformed into a flat beam (e.g., possible electron injectors for light sources and linear colliders). In this paper we report our experimental study of an angular-momentum-dominated beam produced in a photoinjector, addressing the dependencies of angular momentum on initial conditions. We also briefly discuss the removal of angular momentum. The results of the experiment, carried out at the Fermilab/NICADD Photoinjector Laboratory, are found to be in good agreement with theoretical and numerical models

THE WORLDWIDE UNIVERSITIES NETWORK: DEVELOPMENT PROSPECTS

The article is devoted to the urgent problem of the development of inter-university cooperation of Worldwide Universities Network participants. The Net unites 23 universities from different countries. Changes of the modern world, connected with the growing economic cooperation and humanitarian integration among countries, as well as growth of intercultural communication, are actively affecting the education sector and have led to a new phenomenon in the field of education - university networks. Traditionally, network universities are created within existing political and economic associations, but the Worldwide Universities Network project is an exception, as the universities from 14 countries belonging to different regions of the world and different cultures participate in it. This article analyses the experience of interuniversity cooperation of its participants in the context of the possibilities for institutionalizing the ideas of the "dialogue of cultures". The growth of scientific and educational cooperation between WUN universities, numerous joint projects and programs significantly influenced the formation of the "global educational system". Uniqueness of the Network University lies in the successful synchronization of the educational process and the formation of uniform standards of education. However, the different models of education existing in the countries participating in the system of universities create difficulties for more intensive development of cooperation among the parties. However, interaction within WUN contributes to international social and humanitarian integration, convergence of national education systems and development of intercultural communication. Expanding the activities of the university network and studying the most promising areas of its development has become the subject of special scientific interest of the authors of this article