Effects of Space Charge and Reactive Wall Impedance on Bunched Beams
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In this article, the authors measured the inductive wall impedance of a stacked beam in the ISR and found that it is |Z|/n z 26 Ohms, which can be explained by the induction impedance up to a certain current.Abstract:
Space charge and reactive wall impedance create longitudinal forces inside the bunch which change the incoherent phase oscillation frequency, the bunch length and the size of the RF-bucket. These effects have been investigated with bunched beams in the ISR. By measuring the shift of the quadrupole mode phase oscillation frequency, the strength of the self-forces was determined. The inductive wall is dominant and its impedance (divided by the mode number) was measured to be |Z|/n z 26 Ohms. An increase of bunch length with current was measured. It can be explained by the inductive impedance up to a certain current; beyond that an excessive, unexplained bunch lengthening occurs. The reduction of the bucket size affects the stacking process. By correcting for it, an increased density of the stacked beam was achieved. Ez = -e az [4 g0 dz (1)read more
Citations
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References
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Journal ArticleDOI
RMS Envelope Equations with Space Charge
TL;DR: In this paper, it was shown that the k-V equations are valid for any charge distribution with elliptical symmetry, provided the beam boundary and emittance are defined by rms (root-meansquare) values.
Journal ArticleDOI
Longitudinal resistive instabilities of intense coasting beams in particle accelerators
V. Kelvin Neil,Andrew M. Sessler +1 more
TL;DR: In this paper, the effect of finite resistance in the vacuum-tank walls on the longitudinal stability of an intense beam of particles in an accelerator is investigated theoretically, and it is shown that even if the particle frequency is an increasing function of particle energy, the wall resistance can render the beam unstable against longitudinal bunching.
Longitudinal resistive instabilities of intense coasting beams in particle accelerators
V. Kelvin Neil,Andrew M. Sessler +1 more
TL;DR: In this article, the longitudinal electromagnetic interaction of an intense coasting beam with itself, including the effect of a resistive vacuum tank, is investigated theoretically, and it is shown that even in the range where the particle frequency is an increasing function of particle energy, the beam can be longitudinally unstable due to resistivity of the vacuum tank walls.
Journal ArticleDOI
Longitudinal Space Charge Effects in Particle Accelerators
C. E. Nielsen,A. M. Sessler +1 more
TL;DR: In this article, the modification of the single particle theory of particles subject to radio-frequency acceleration caused by electrostatic repulsion between particles is calculated and the Boltzmann equation is reduced to a one-dimensional integral equation for the case of a uniform particle density in a limited region of phase space.
Journal ArticleDOI
Stabilization of non-relativistic beams by means of inductive walls
V K Neil,R J Briggs +1 more
TL;DR: In this article, a method for suppressing the negative mass instability in beams of particles with non-relativistic velocity is proposed and investigated theoretically, which involves surrounding the beam with an inductive wall structure incorporating lumped-circuit inductors and does not rely on a velocity spread in the beam.