arXiv subjects

Benjamin Sims

Publications and source records attributed to Benjamin Sims.

4 recordsLinked to original sources

arXiv2025

3D Printing as a Rapid Prototyping Approach for Novel RF Cavity Designs

3D-printing of radiofrequency (RF) cavity resonators could provide a cost-effective solution that enables rapid prototyping and design flexibility compared to traditional fabrication of full-metal cavities. In this work, the feasibility of fabrication of a useful multi-mode GHz cavity is explored. Two kinds of plastics, two slicing approaches and two metal coating techniques were used to build a series of clamped cavities with thin inner copper surface on otherwise 3D printed plastic surface. The cavities were then bench-tested to identify spatial field distributions, operating frequencies and quality factors (Q-factor). Pros and cons of the used fabrication approaches were identified and understood, and the performance of longitudinally sliced painted cavity design demonstrated considerable practicality of 3D-printing approach in designing rf systems.

physics.acc-ph↗

arXiv2024

Dual-mode rf cavity: design, tuning and performance

We present the design and characterization of a dual-mode radiofrequency (rf) cavity, a novel electromagnetic structure with potential benefits such as compactness, efficiency, cost reduction and multifunctionality. The cavity was designed to balance the dual-mode structure considering several factors, such as mode frequencies, quality factor (Q-factor), and minimizing cross talk between couplers. We preformed various tests to verify that this cavity preformed as expected compared to simulated results. As exampled here, a combination of the the fundamental mode TM 010 and the TM 011 mode, tuned to a harmonic of the fundamental, was realized to linearize the off-crest electric field, thereby enabling concurrent bunching and acceleration of charged particle (e.g. electrons) beam in high power systems. The reduction in the number of cavities required to bunch and accelerate promises cost and space savings over conventional approaches. This research lays the foundation for further exploration of multi-mode cavity applications and optimization for specific use cases, with potential implications for a wide range of fields including quantum information platforms.

physics.app-ph↗

arXiv2024

Thermal Emittance Isolation by Cathode Retraction

In this work, a combination of cathode retraction and two-slit emittance measurement technique is proposed as an advanced means to individually modify emittance growth components, specifically, rf injector fringe fields, to isolate and directly measure the thermal emittance, the fundamental beam emittance metric for an electron beam. A case study of the LCLS-II-HE Low Emittance Injector (LEI), a state-of-the-art superconducting radiofrequency (SRF) gun, designed for LCLS-II HE upgrade is used to showcase the power of the two-slit technique. Particularly, it is demonstrated that generating a high resolution phase-space distribution map, dominated by the intrinsic emittance of the electron bunch, is possible. This result goes beyond the normal single-parameter distribution characterizations (e.g. RMS emittance and Twiss parameters) provided by the solenoid scan. One key feature making this technique work (and in the end practically useful) is the ability to retract the cathode, because it provides the ability to compensate for radiofrequency (rf) de-focusing. It is demonstrated how the cathode retraction can serve as an additional optimisation tool for tailoring the routine performance of the photoinjector. We posit that a variable position cathode may be a useful method for optimizing photoinjector performance across multiple parameters regimes.

physics.acc-ph↗

arXiv2023

Emittance Mapping in rf Guns

This paper discusses the trends and trade-offs between transverse sigma x and longitudinal sigma z bunch dimensions, rf injector gradient, bunch charge, and intrinsic electron mean transverse energy (MTE), where all can be chosen to be independent, and the resulting effects on emittance and transverse brightness. Using a practical example of a quarter wave normal conducting photoinjector, it is computationally found that regardless of MTE and bunch charge, there is a universal relation between the gradient E and the aspect ratio of the bunch (sigma x /sigma z ) leading to the highest brightness. This computational result is understood using an analytical formalism consisting of K J Kim's emittance formulation and a two-dimensional space charge model. The results, obtained computationally and interpreted in a robust physical framework, could therefore provide the basis for an express mapping approach for emittance forecasting when used with practical injector system design requirements and limitations.

physics.acc-ph↗