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Alexey Burov

Publications and source records attributed to Alexey Burov.

At least 19 recordsLinked to original sources
arXiv2026

The Unreasonable Effectiveness of Physics in Biology

We demonstrate that the system of fine-tuning constraints for life is overdetermined: the number of inequalities is too large relative to the number of free parameters in the chemical sector and likely not only there. This entails that life-permitting conditions are secured at the level of physics not only by the fine-tuned fundamental constants, but also by a very special form of the laws. In 1960, Eugene Wigner published his essay "The Unreasonable Effectiveness of Mathematics in the Natural Sciences," summarizing his reflections on the miraculous comprehensibility of the mathematical structure of physical laws. The present paper points to another, no less remarkable, aspect of this structure, which may be called as our title suggests.

physics.hist-ph↗
arXiv2021

Longitudinal Modes of Bunched Beams with Weak Space Charge

Longitudinal collective modes of a bunched beam with a repulsive inductive impedance (the space charge below transition or the chamber inductance above it) are analytically described by means of reduction of the linearized Vlasov equation to a parameter-less integral equation. For any multipolarity, the discrete part of the spectrum is found to consist of infinite number of modes with real tunes, which limit point is the incoherent zero-amplitude frequency. In other words, notwithstanding the RF bucket nonlinearity and potential well distortion, the Landau damping is lost. Hence, even a tiny coupled-bunch interaction makes the beam unstable; such growth rates for all the modes are analytically obtained for arbitrary multipolarity. In practice, however, the finite threshold of this loss of Landau damping is set either by the high-frequency impedance roll-off or intrabeam scattering. Above the threshold, growth of the leading collective mode should result in persistent nonlinear oscillations.

physics.acc-ph↗
arXiv2021

Comment on "Fast-slow mode coupling instability for coasting beams in the presence of detuning impedance"

In this comment we show untenability of key points of the recent article of N. Biancacci, E. Metral and M. Migliorati [Phys. Rev. Accel. Beams 23, 124402 (2020)], hereafter the Article and the Authors. Specifically, the main Eqs. (23), suggested to describe mode coupling, are shown to be unacceptable even as an approximation. The Article claims the solution of this pair of equations to be in "excellent agreement" with the pyHEADTAIL simulations for CERN PS, which is purportedly demonstrated by Fig. 6. Were it really so, it would be a signal of a mistake in the code. However, the key part of the simulation results is not actually shown, and the demonstrated agreement has all the features of an illusion.

physics.acc-ph↗
arXiv2020

Space Charge Effects for Transverse Collective Instabilities in Circular Machines

A brief historical review is presented of progressing understanding of transverse coherent instabilities of charged particles beams in circular machines when both Coulomb and wake fields are important. The paper relates to a talk given at ICFA Workshop on Mitigation of Coherent Beam Instabilities in Particle Accelerators, 23-27 September 2019 in Zermatt, Switzerland.

physics.acc-ph↗
arXiv2019

Transverse Microwave Convective Instability at Transition Crossing

An analytical model of transverse convective instability of a bunch at transition crossing is presented for the microwave case, when the wake is sufficiently short compared with the bunch length. The space charge is assumed to be strong, as it typically is for the low and medium energy synchrotrons. A simple formula for the intensity threshold is obtained and its prediction is compared with available CERN PS data; without a single fitting parameter, a good agreement is demonstrated.

physics.acc-ph↗
arXiv2019

Convective Instabilities of Bunched Beams with Space Charge

For a single hadron bunch in a circular accelerator at zero chromaticity, without multi-turn wakes and without electron clouds and other beams, only one transverse collective instability is possible, the mode-coupling instability, or TMCI. For sufficiently strong space charge (SC), the instability threshold of the wake-driven coherent tune shift normally increases linearly with the SC tune shift, as independently concluded by several authors using different methods. This stability condition has, however, a very strange feature: at strong SC, it is totally insensitive to the number of particles. Thus, were it correct, such a beam with sufficiently strong SC, being stable at some intensity, would remain stable at higher intensity, regardless of how much higher! This paper suggests a resolution of this conundrum: while SC suppresses TMCI, it introduces head-to-tail convective amplifications, which could make the beam even less stable than without SC, even if all the coherent tunes are real, i.e. all the modes are stable in the conventional {\it absolute} meaning of the word. This is done using an effective new method of analysis of the beam's transverse spectrum for arbitrary space charge and wake fields. Two new types of beam instabilities are introduced: the {\it saturating convective instability}, SCI, and the {\it absolute-convective instability}, ACI.

physics.acc-ph↗
arXiv2018

Coupled-Beam and Coupled-Bunch Instabilities

A problem of coupled-beam instability is solved for two multibunch beams with slightly different revolution frequencies, as in the Fermilab Recycler Ring (RR). Sharing of the inter-bunch growth rates between the intra-bunch modes is described. The general analysis is applied to the RR; possibilities to stabilize the beams by means of chromaticity and feedback are considered.

physics.acc-ph↗
arXiv2018

Transverse Instabilities of a Bunch with Space Charge, Wake and Feedback

When a resistive feedback and single-bunch wake act together, it is known that some head-tail modes may become unstable even without space charge. This feedback-wake instability, FWI, modified by space charge to a certain degree, is shown to have a special single-maximum increasing- dropping pattern with respect to the gain. Also, at sufficiently large Coulomb and wake fields, as well as the feedback gain, a new type of transverse mode-coupling instability is shown to take place, 3FMCI, when head-to-tail amplified positive modes couple and the growth rate saturates with the gain.

physics.acc-ph↗
arXiv2018

Core-Halo Collective Instabilities

At strong space charge, transverse modes of the bunch core may effectively couple with those of the halo, leading to instabilities well below the core-only transverse mode-coupling threshold.

physics.acc-ph↗
arXiv2018

TMCI with Resonator Wakes

Transverse mode-coupling instability (TMCI) with a high-frequency resonator wake is examined by the Nested Head-Tail Vlasov solver (NHT), where a Gaussian bunch in a parabolic potential (GP model) is represented by concentric rings in the longitudinal phase space. It is shown that multiple mode couplings and decouplings make impossible an unambiguous definition of the threshold, unless Landau damping is taken into account. To address this problem, instead of a single instability threshold, an interval of thresholds is suggested, bounded by the low and high intensity ones. For the broadband impedance model, the high intensity threshold is shown to follow Zotter's scaling, but smaller by about a factor of two. The same scaling, this time smaller than Zotter's by a factor of four, is found for the ABS model (Air Bag Square well).

physics.acc-ph↗
arXiv2018

Efficiency versus instability in plasma accelerators

Plasma wake-field acceleration is one of the main technologies being developed for future high-energy colliders. Potentially, it can create a cost-effective path to the highest possible energies for e+e- or γ-γ colliders and produce a profound effect on the developments for high-energy physics. Acceleration in a blowout regime, where all plasma electrons are swept away from the axis, is presently considered to be the primary choice for beam acceleration. In this paper, we derive a universal efficiency-instability relation, between the power efficiency and the key instability parameter of the trailing bunch for beam acceleration in the blowout regime. We also show that the suppression of instability in the trailing bunch can be achieved through BNS damping by the introduction of a beam energy variation along the bunch. Unfortunately, in the high efficiency regime, the required energy variation is quite high, and is not presently compatible with collider-quality beams. We would like to stress that the development of the instability imposes a fundamental limitation on the acceleration efficiency, and it is unclear how it could be overcome for high-luminosity linear colliders. With minor modifications, the considered limitation on the power efficiency is applicable to other types of acceleration.

physics.acc-ph↗
arXiv2017

Parametric Landau damping of space charge modes

Landau damping is the mechanism of plasma and beam stabilization; it arises through energy transfer from collective modes to the incoherent motion of resonant particles. Normally this resonance requires the resonant particle's frequency to match the collective mode frequency. We have identified an important new damping mechanism, {\it parametric Landau damping}, which is driven by the modulation of the mode-particle interaction. This reveals new possibilities for stability control through manipulation of both particle and mode-particle coupling spectra. We demonstrate the existence of parametric Landau damping in a simulation of transverse coherent modes of bunched accelerator beams with space charge.

physics.acc-ph↗
arXiv2017

Landau Damping with Electron Lenses in Space-Charge Dominated Beams

Progress on the Intensity Frontier of high energy physics critically depends on record high intensity charged particles accelerators. Beams in such machines become operationally limited by coherent beam instabilities, particularly enhanced in the regime of strong space charge (SC). Usual methods to control the instabilities, such as octupole magnets, beam feedback dampers and employment of chromatic effects, become less effective and insufficient. In [1] it was proposed to employ electron lenses for introduction of sufficient spread in particle oscillation frequencies needed for beam stabilization and in [2] it was shown that electron lenses are uniquely effective for Landau damping of transverse beam instabilities in high energy particle accelerators and their employment does not compromise incoherent (single particle) stability, dynamic aperture and the beam lifetime. Here we consider an important issue of effectiveness of the Landau damping with electron lenses in space-charge dominated beams and demonstrate that the desired stability can be assured with proper choice of the electron beam parameters and current distributions.

physics.acc-ph↗
arXiv2017

TMCI and Space Charge

Transverse mode-coupling instability (TMCI) is known to limit bunch intensity. Since space charge (SC) changes the spectra of the collective modes, it affects the TMCI threshold as well. In agreement with results of M. Blaskiewicz and V. Balbekov, we found that, when the wake is negative or it essentially negative, the instability threshold increases as fast as the space charge tune shift when the latter is large enough. In contrast, for oscillating wakes, when the oscillations are sufficiently pronounced, the threshold dependence on SC is non-monotonic; at sufficiently high SC tune shift the threshold goes inversely proportional to that.

physics.acc-ph↗
arXiv2017

Landau Damping of Beam Instabilities by Electron Lenses

Modern and future particle accelerators employ increasingly higher intensity and brighter beams of charged particles and become operationally limited by coherent beam instabilities. Usual methods to control the instabilities, such as octupole magnets, beam feedback dampers and use of chromatic effects, become less effective and insufficient. We show that, in contrast, Lorentz forces of a low-energy, a magnetically stabilized electron beam, or "electron lens", easily introduces transverse nonlinear focusing sufficient for Landau damping of transverse beam instabilities in accelerators. It is also important that, unlike other nonlinear elements, the electron lens provides the frequency spread mainly at the beam core, thus allowing much higher frequency spread without lifetime degradation. For the parameters of the Future Circular Collider, a single conventional electron lens a few meters long would provide stabilization superior to tens of thousands of superconducting octupole magnets.

physics.acc-ph↗
arXiv2017

Luminosity Limitations in Linear Colliders Based on Plasma Acceleration

Particle acceleration in plasma creates a possibility of exceptionally high accelerating gradients and appears as a very attractive option for future linear electron-positron and/or photon-photon colliders. These high accelerating gradients were already demonstrated in a number of experiments. However, a linear collider requires exceptionally high beam brightness which still needs to be demonstrated. In this article we discuss major phenomena which limit the beam brightness of accelerated beam and, consequently, the collider luminosity.

physics.acc-ph↗
arXiv2016

Efficiency of feedbacks for suppression of transverse instabilities of bunched beams

Which gain and phase have to be set for a bunch-by-bunch transverse damper, and at which chromaticity it is better to stay? These questions are considered for three models: the two-particle model with possible quadrupole wake, the author's Nested Head-Tail Vlasov solver with a broadband impedance, and the same with the LHC impedance model.

physics.acc-ph↗