106 research outputs found
Semi-analytical description of the modulator section of the coherent electron cooling
In the coherent electron cooling, the modern hadron beam cooling technique,
each hadron receives an individual kick from the electric field of the
amplified electron density perturbation created in the modulator by this hadron
in a co-propagating electron beam. We developed a method for computing the
dynamics of these density perturbations in an infinite electron plasma with any
equilibrium velocity distribution -- a possible model for the modulator. We
derived analytical expressions for the dynamics of the density perturbations in
the Fourier-Laplace domain for a variety of 1D, 2D, and 3D equilibrium
distributions of the electron beam. To obtain the space-time dynamics, we
employed the fast Fourier transform (FFT) algorithm. We also found an
analytical solution in the space-time domain for the 1D Cauchy equilibrium
distribution, which serves as a benchmark for our general approach based on
numerical evaluation of the integral transforms and as a fast alternative to
the numerical computations. We tested the method for various distributions and
initial conditions.Comment: 11 pages, 5 figure
On Compensating Tune Spread Induced by Space Charge in Bunched Beams
Space charge effects play significant role in modern-day accelerators. These
effects frequently constrain attainable beam parameters in an accelerator - or
- in an accelerator chain. They also could limit the luminosity of hadron
colliders operating either at low energies or with a sub-TeV high brightness
hadron beams. A number of schemes for compensating space charge effects in a
coasting (e.g. continuous) hadron beam were proposed and some of them had been
tested. But all of these methods do not address the issue of tune spread
compensation of a bunched hadron beam, e.g. the tune shift dependence on the
longitudinal position inside the bunch. In this paper we propose and evaluate a
novel idea of using a co-propagating electron bunch with miss-matched
longitudinal velocity to compensate the space charge induced tune-shift and
tune spread. We present a number of practical examples of such system.Comment: 40 pages, 12 figure
Digital demodulator of the quadrature amplitude modulation signals
In this paper, the digital algorithm and the device for the demodulation of the quadrature amplitude modulation signals are considered. The fundamental advantages of our approach are simple hardware implementation, minimal number of arithmetic operations required over the signal period as well as the potential interference immunity in the presence of Gaussian noise. The expressions have been found for the error probability and their inaccuracy has been estimated. By means of the statistical simulation methods, the practical interference immunity of the introduced demodulator, together with the influence of phase locking errors have been tested. The introduced demodulator can be implemented either as a device independent from the programmable logic devices, or as an installation unit of the receiver equipment
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