arXiv subjects

Jom Luiten

Publications and source records attributed to Jom Luiten.

6 recordsLinked to original sources

arXiv2025

Permanent Magnet Electron Optics for Low Energy Electron Systems: The Art of Extraordinary Performance from Ordinary Components

Permanent magnet electron optics offer many advantages over electromagnets, and are being increasingly used in high-energy (GeV) electron accelerator designs. Here, we identify the advantages of permanent magnet electron optics for low-energy (keV) electron accelerators. We explore the applications of a class of designs based on axially magnetized permanent magnets, which offer a variety of advantages such as short focal lengths (few mm), while also preventing apparent emittance growth resulting from starting particles in a magnetic field. The proposed design philosophy is applied to an accelerator based on the ultracold electron source. The design is shown to be `emittance preserving' even for very short focal lengths (~5 mm) at an emittance level better than 1 nm-rad, while the short beamline (12 cm) limits space-charge effects. Two remedies for the mitigation of typical manufacturing and alignment challenges are considered. The performance of the design (related to parasitic aberrations) is enhanced by the proposed techniques. Applications of this design philosophy can improve the performance of ultrafast electron diffraction setups with minimal manufacturing effort.

physics.acc-ph↗

arXiv2025

The Coming of Age of the Ultracold Electron Source: A Review

The ultracold electron source is a unique approach to the generation of high-brightness electron beams. We give an overview of its development over the past 20 years, including the underlying physical principles, technical details and recent experiments, and give a flavor of the exciting prospects that the future may hold.

physics.acc-ph↗

arXiv2020

Concept Study of a Compact, High Gradient X-band Travelling Wave RF Photogun with Novel Laser Coupling Scheme

This paper presents the design of a travelling wave RF photogun operating at the European X-band frequency of 11.994 GHz. The design is based on a CLIC prototype structure milled from copper halves and uses the unique gap introduced in the geometry to couple in the laser without obstructing the outgoing electron beam. With a modest peak input power of 19 MW and a fill time of 48 ns, the gun has the ability to operate at very high RF pulse repetition rates in comparison to standing wave RF photoguns. For its nominal input power, the cathode has a peak gradient of 91 MV/m and the entire gun has a gradient of 65 MV/m. The gun is illustrated to provide an 80 pC bunch at a 14.15 MeV with a 0.14 $\%$ RMS energy spread and an emittance of 0.6 mm mrad at a repetition rate of at least 450 Hz.

physics.acc-ph↗

arXiv2020

Addendum to `Mapping electron dynamics in highly transient EUV photon-induced plasmas: a novel diagnostic approach using multi-mode microwave cavity resonance spectroscopy'

A new approach for an in-line beam monitor for ionizing radiation was introduced in a recent publication (Beckers, J., et al. "Mapping electron dynamics in highly transient EUV photon-induced plasmas: a novel diagnostic approach using multi-mode microwave cavity resonance spectroscopy." Journal of Physics D: Applied Physics 52.3 (2018): 034004.). Due to the recent detection and investigation of an additional third decay regime of the afterglow of an extreme ultraviolet photon-induced plasma described in a later article (Platier, B., et al. "Transition from ambipolar to free diffusion in an EUV-induced argon plasma." Applied Physics Letters 116.10 (2020).) there is an additional reason for a minimum number of photons for this approach to work. Near or below this threshold, we explain that the response time of the diagnostic method is a limiting factor. Further, a second limit for the number of photons within a pulse is formalized related to the trapping of highly energetic free electrons.

physics.plasm-ph↗

arXiv2016

Trapped electrons in the quantum degenerate regime

A full strength Coulomb interaction between trapped electrons can be felt only in absence of a neutralizing background. In order to study quantum degenerate electrons without such a background, an external trap is needed to compensate for the strong electronic repulsion. As a basic model for such a system, we study a trapped electron pair in a harmonic trap with an explicit inclusion of its Coulomb interaction. We find the eigenenergy of the ground state, confirming earlier work in the context of harmonium. We extend this to a complete set of properly scaled energies for any value of the trapping strength, including the excited states. The problem is solved either numerically or by making harmonic approximations to the potential. As function of the trapping strength a crossover can be made from the strongly to the weakly-coupled regime, and we show that in both regimes perturbative methods based on a pair-wise electron description would be effective for a many-particle trapped electron system, which resembles a Wigner crystal in the ground state of the strongly coupled limit.

cond-mat.quant-gas↗

arXiv2002

Transverse self-fields within an electron bunch moving in an arc of a circle

As a consequence of motions driven by external forces, self-fields (which are different from the static case) originate within an electron bunch. In the case of magnetic external forces acting on an ultrarelativistic beam, the longitudinal self-interactions are responsible for CSR (Coherent Synchrotron Radiation)-related phenomena, which have been studied extensively. On the other hand, transverse self-interactions are present too. At the time being, existing theoretical analysis of transverse self-forces deal with the case of a bunch moving along a circular orbit only, without considering the situation of a bending magnet with a finite length. In this paper we propose an electrodynamical analysis of transverse self-fields which originate, at the position of a test particle, from an ultrarelativistic electron bunch moving in an arc of a circle. The problem will be first addressed within a two-particle system. We then extend our consideration to a line bunch with a stepped density distribution, a situation which can be easily generalized to the case of an arbitrary density distribution. Our approach turns out to be also useful in order to get a better insight in the physics involved in the case of simple circular motion and in order to address the well known issue of the partial compensation of transverse self-force.

physics.acc-ph↗