Glauber coherence of single electron sources

Recently demonstrated solid state single electron sources generate different quantum states depending on their operation condition. For adiabatic and non-adiabatic sources we determine the Glauber correlation function in terms of the Floquet scattering matrix of the source. The correlation function provides full information on the shape of the state, on its time-dependent amplitude and phase, which makes the coherence properties of single electron states essential for the production of quantum multi-particle states.Comment: 4+ pages, 4 figure

Quantum description and properties of electrons emitted from pulsed nanotip electron sources

We present a quantum calculation of the electron degeneracy for electron sources. We explore quantum interference of electrons in the temporal and spatial domain and demonstrate how it can be utilized to characterize a pulsed electron source. We estimate effects of Coulomb repulsion on two-electron interference and show that currently available nano tip pulsed electron sources operate in the regime where the quantum nature of electrons can be made dominant

Recent Advances in Electron and Positron Sources

Recent advances in electron and positron sources have resulted in new capabilities driven in most cases by the increasing demands of advanced accelerating systems. Electron sources for brighter beams and for high average-current beams are described. The status and remaining challenges for polarized electron beams are also discussed. For positron sources, recent activity in the development of polarized positron beams for future colliders is reviewed. Finally, a new proposal for combining laser cooling with beam polarization is presented.Comment: 9 pages, 3 figures, contributed to the AAC 2000 Worksho

Electron Beam Ion Sources

Electron beam ion sources (EBISs) are ion sources that work based on the principle of electron impact ionization, allowing the production of very highly charged ions. The ions produced can be extracted as a DC ion beam as well as ion pulses of different time structures. In comparison to most of the other known ion sources, EBISs feature ion beams with very good beam emittances and a low energy spread. Furthermore, EBISs are excellent sources of photons (X-rays, ultraviolet, extreme ultraviolet, visible light) from highly charged ions. This chapter gives an overview of EBIS physics, the principle of operation, and the known technical solutions. Using examples, the performance of EBISs as well as their applications in various fields of basic research, technology and medicine are discussed.Comment: 37 pages, contribution to the CAS-CERN Accelerator School: Ion Sources, Senec, Slovakia, 29 May - 8 June 2012, edited by R. Baile

Electron density diagnostics in atmospheric pressure radio frequency dielectric barrier discharge and discharge with bare electrode

Electron densities in two types of atmospheric pressure radio frequency plasma sources: dielectric barrier discharge (DBD) and discharge with bare electrode (DBE) are investigated by analysis of Stark broadening of Hydrogen Balmer (Hβ) lines. Voigt fitting is firstly employed to obtain the electron density below the theoretical lower limit of 1020 m-3. Fine-structure fitting method is further applied to verify the electron density for both plasma sources. When injecting power from 4 W to 20 W, the electron densities are found in the range of 2.9-6.1×1019 m-3 and 3.6-8.6×1019 m-3 for DBD and DBE, respectively. The electron density study aims to gain more insight of the physics of cold atmospheric pressure radio frequency helium plasma

Single-Shot Electron Diffraction using a Cold Atom Electron Source

Cold atom electron sources are a promising alternative to traditional photocathode sources for use in ultrafast electron diffraction due to greatly reduced electron temperature at creation, and the potential for a corresponding increase in brightness. Here we demonstrate single-shot, nanosecond electron diffraction from monocrystalline gold using cold electron bunches generated in a cold atom electron source. The diffraction patterns have sufficient signal to allow registration of multiple single-shot images, generating an averaged image with significantly higher signal-to-noise ratio than obtained with unregistered averaging. Reflection high-energy electron diffraction (RHEED) was also demonstrated, showing that cold atom electron sources may be useful in resolving nanosecond dynamics of nanometre scale near-surface structures.Comment: This is an author-created, un-copyedited version of an article published in Journal of Physics B: Atomic, Molecular and Optical Physics. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at http://dx.doi.org/10.1088/0953-4075/48/21/21400

High-Brightness Photocathode Electron Sources

Most present and future electron accelerators require bright sources. Invented less than ten years ago, the photo-injector the principle of which is briefly recalled, has already demonstrated that it can provide very bright beams. In this paper, the most advanced photo-injector projects are reviewed, their specific features are outlined, and their major issues are examined. The state-of-the-art in photocathode and laser technologies is presented. Beam dynamics issues are also considered since they are essential in the production of bright beams. Finally, the question of the maturity of photo-injector technology is addressed.Comment: PostScript uuencoded file, 18 pages, 5 figure

On-demand entanglement generation using dynamic single-electron sources

We review our recent proposals for the on-demand generation of entangled few-electron states using dynamic single-electron sources. The generation of entanglement can be traced back to the single-electron entanglement produced by quantum point contacts acting as electronic beam splitters. The coherent partitioning of a single electron leads to entanglement between the two outgoing arms of the quantum point contact. We describe our various approaches for generating and certifying entanglement in dynamic electronic conductors and we quantify the influence of detrimental effects such as finite electronic temperatures and other dephasing mechanisms. The prospects for future experiments are discussed and possible avenues for further developments are identified.Comment: Published version, 11 pages, 7 figures, short review for focus issue on 'Single-electron control in solid-state devices'. in Phys. Status Solidi B (2016

Implications for electron acceleration and transport from non-thermal electron rates at looptop and footpoint sources in solar flares

The interrelation of hard X-ray (HXR) emitting sources and the underlying physics of electron acceleration and transport presents one of the major questions in the high energy solar flare physics. Spatially resolved observations of solar flares often demonstrate the presence of well separated sources of bremsstrahlung emission, so-called coronal and foot-point sources. Using spatially resolved X-ray observations by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and recently improved imaging techniques, we investigate in detail the spatially resolved electron distributions in a few well observed solar flares. The selected flares can be interpreted as having a standard geometry with chromospheric HXR foot-point sources related to thick-target X-ray emission and the coronal sources characterised by a combination of thermal and thin-target bremsstrahlung. Using imaging spectroscopy technique, we deduce the characteristic electron rates and spectral indices required to explain the coronal and foot-points X-ray sources. We found that, during the impulsive phase, the electron rate at the loop-top is several times (a factor of 1.7-8) higher than at the foot-points. The results suggest sufficient number of electrons accelerated in the loop-top to explain the precipitation into the foot-points and implies electrons accumulation in the loop-top. We discuss these results in terms of magnetic trapping, pitch-angle scattering and injection properties. Our conclusion is that the accelerated electrons must be subject to magnetic trapping and/or pitch-angle scattering, keeping a fraction of the population trapped inside the coronal loops. These findings put strong constraints on the particle transport in the coronal source, and provide a quantitative limits on deka-keV electron trapping/scattering in the coronal source