49 research outputs found
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
Digital simulators of the random processes
The proposed universal digital simulators of random processes based on their Markov models are considered as capable of generating sequences of samples of unlimited duration. It is shown that a simple Markov chain allows generating the random numbers with a specified two-dimensional probability distribution of the neighboring values while a doubly connected Markov model makes it possible to get the three-dimensional random numbers. The parameters of the model are determined from either a known probability density or experimental samples of the simulated random process. It is demonstrated that the simulation algorithms do not require complex mathematical transformations and that they can be implemented using a simple element base. To change the properties of the generated random processes one needs to reload the memory device with a preformed data array. The block diagrams of the simulators are studied and the probabilistic and correlation characteristics of the generated random processes are determined. It is established that with these simulators a high accuracy of convergence of the probability distributions of the selected model and the histograms of the generated sample sequences is ensured. In the common studies, one can hardly find the results that can surpass by their efficiency the ones that the proposed simulation algorithms demonstrate accounting for their non-problematic hardware implementation (the minimum computational costs) and the simplicity of reconfiguring the Markov model based simulators for generating new random processes. The introduced simulators can be used in the design, development and testing of the multi-purpose electronic equipment, with different meters and the devices for simulating radio paths