Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 1905.07688

Probability of radiation of twisted photons by cold relativistic particle bunches

O. V. Bogdanov·P. O. Kazinski·G. Yu. Lazarenko
View original source ↗Read source document ↗Export metadata ↓

Abstract

The probability to record a twisted photon produced by a cold relativistic particle bunch of charged particles is derived. The radiation of twisted photons by such particle bunches in stationary electromagnetic fields and in propagating electromagnetic waves is investigated. It is shown that the incoherent radiation by bunches of particles traversing normally an isotropic dispersive medium (the edge, transition, and Vavilov-Cherenkov radiations) and by bunches moving in a helical undulator does not depend on the azimuthal distribution of particles in the bunch and is the same as for round bunches. As for planar undulators, the incoherent radiation by particle bunches is the same as for the bunches symmetric under reflection with respect to the axis of a twisted photon detector. At high energies of recorded twisted photons, this property is universal and holds for the forward incoherent radiation by any cold relativistic particle bunch. The coherent radiation of twisted photons by such particle bunches obeys the property that we call the addition rule. This rule provides a simple means to describe the properties of coherent radiation of twisted photons. Furthermore, the strong addition rule is established for the coherent radiation by sufficiently long helical bunches. The use of this rule allows one to elaborate superradiant pure sources of twisted photons. The coherent radiation by helical bunches is considered for the edge, transition, and Vavilov-Cherenkov processes and for particles moving in undulators and plane laser waves with circular polarization. In these cases, the sum rules are deduced for the total probability to record a twisted photon and for the projection of the total angular momentum per photon. The explicit expressions for both incoherent and coherent interference factors are derived for several simple bunch profiles.

Explore related subjects

physics.acc-phphysics.optics

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

O. V. Bogdanov, P. O. Kazinski, G. Yu. Lazarenko. 2019-05-19. Probability of radiation of twisted photons by cold relativistic particle bunches. https://doi.org/10.1016/j.aop.2020.168116

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Production of a Titanium Ion Beam Using Fluorides and Fluorine-Forming Precursors in an ECR Ion Source

The production of multiply charged titanium ions is of significant interest for accelerator-based experiments, surface modification technologies, and applications in nuclear physics. Due to the low saturated vapor pressure of titanium at temperatures below 1000 °C, the generation of titanium ion beams from an electron cyclotron resonance ion source (ECRIS) remains a challenging task. The choice of titanium vapor injection methods into the ECR plasma plays a key role in achieving high ionization efficiency, plasma stability, and reliable long-term source operation. In this work, alternative approaches for the injection of neutral titanium atoms into the ECR plasma are investigated, focusing on the use of fluorine-containing compounds. Titanium fluorides (TiF3, TiF4) possess a relatively high saturated vapor pressure at moderate temperatures, allowing to use standard resistively heated ovens operating up to 1000 °C. Another method involves the in-situ formation of titanium fluorides inside the plasma chamber via chemical reactions between metal titanium and the dissociation products of sulfur hexafluoride (SF6). These approaches enable controlled and efficient titanium injection into the ECRIS plasma with satisfactory extracted ion beam stability.

physics.acc-ph↗
arXiv2026

Three Dimensional Theory of the Ion Channel Laser

The ion channel laser (ICL) is a plasma-based alternative to the free electron laser (FEL) that uses the electric field of a uniform-density ion channel rather than the magnetic field of an undulator to induce transverse oscillations of electrons in an ultrarelativistic bunch and thereby produce coherent radiation via a collective electromagnetic instability. The powerful focusing of the ion channel generally yields significantly higher gain parameters in the ICL as compared to the FEL. This permits lasing in extremely short distances using electron bunches with an energy spread as large as a few percent; a value readily achievable with current plasma-based accelerators. ICLs, however, impose stringent transverse phase space requirements on the electron bunch beyond what is required in FELs. In this work, we present a novel 3D theory of the planar off-axis configuration of the ICL that accounts for a number of effects including diffraction, transverse radiation profile, frequency and betatron phase detuning, and nonzero spread in energy and undulator parameter. We derive the ICL pendulum and field equations, which we use to write down the 3D Maxwell-Klimontovich equations. After linearizing, we obtain an integro-differential equation describing the $z$-evolution of the radiation field. The 3D ICL dispersion relation is obtained using a Van Kampen normal mode expansion. We numerically solve the $z$-evolution equation to compute radiation power growth rates and transverse radiation profiles over a range of different ICL parameters. We examine the gain reduction due to 3D effects, energy spread, and emittance. Electron bunch phase space and emittance requirements for lasing are derived. Finally, we make general observations about the performance and feasibility of the ICL and discuss future prospects.

physics.acc-ph↗
arXiv2026

Integration of Retrieval-Augmented Generation for Knowledge Access in the ELBE Accelerator Control System

The efficient operation of accelerator facilities increas- ingly relies on rapid access to heterogeneous operational knowledge, including logbooks, interlock reports, machine parameters, and historical archive data. At ELBE, we pro- posed a Retrieval-Augmented Generation (RAG) frame- work that integrates facility documentation and operational records into a unified AI-assisted support tool for operators. The system is expected to index electronic logbooks, ma- chine archive time-series data, and subsystem manuals using domain-adapted embeddings stored in a vector database. User queries will be expected to be processed through a large language model that retrieves the most relevant oper- ational context and generates structured, operator-oriented responses with traceable source references. This contribu- tion presents the system architecture, data integration strat- egy, and challenges toward real-time AI-assisted accelerator operation

physics.acc-ph↗