Accelerator Science and Technology Seminar

Titel:

"Exploring Magnetrons as RF Sources for Accelerators and Nuclear Fusion"

Abstract:

A magnetron is a high-efficient (over 80% RF conversion efficiency) and compact high power microwave source, compared with other tubes, such as travelling wave tube (TWT) and klystrons. However, the magnetron is an oscillator in nature, in which the phase and amplitude of the output signal are not easy to be controlled.

We will introduce our design work in the magnetrons in S band and X band with a mega-Watt power level in a medical linear accelerator for generating gamma-rays as a single driving RF source. Also, the magnetrons have been explored to be used in a high energy particle accelerator as multiple driving RF sources. We have developed a novel technique to phase lock these magnetrons with a low power control signal.  On the other hand, we have been motivated to explore a millimetre wave (mmWave) magnetron as an alternative source for the plasma heating in nuclear fusion.

Titel:

"The TYRRHA-accelerator driven system and its accelerator"

Abstract:

After a brief motivation for an Accelerator Driven System (ADS), the requirements on the accelerator are derived.

It then details the MYRRHA design which is based on a 4 mA, 600 MeV CW superconducting proton linac. The construction of the first stage (called MINERVA) by the Belgium Nuclear Research Centre SCK CEN was approved in 2018. It consists of a 100 MeV superconducting RF linac as well as two independent target stations, one for radio-isotope research and production of radio-isotopes for medical purposes, the other one for fusion materials research. 

This contribution presents the main design choices and current status of the overall project parts (civil engineering, particle accelerator and target facilities.

Titel:

"Overview of permanent magnet projects at STFC Daresbury Laboratory"

Abstract:

In recent years the financial and environmental costs of constant electricity consumption have had an increasing effect on facility design and operation. Permanent magnets (PMs) provide an attractive solution to limit the required electrical power. Traditionally PMs produce a fixed field, attempts to alter this generally change field quality. STFC Daresbury Laboratory (UK) has championed the use of PMs to save energy in accelerators and, via the Zero-Power Tuneable Optics (ZEPTO) project, has demonstrated that tuneability of PMs is achievable in a manner suitable for accelerator requirements by moving PM blocks relative to fixed steel structures that define the field, allowing strength to be changed while suitable field homogeneity is maintained.

We present an overview of this project, including a prototype built for Diamond light source and one built for CLARA.   We also present a cautionary story of one of the potential drawbacks of permanent magnet systems, self demagnetization, discussing the design, construction, measurement and troubleshooting of a prototype hybrid Halbach quadrupole magnet. This magnet was significantly under-strength due to local demagnetization in the permanent magnet material. We discuss how this effect was uncovered, measured and reconstructed in simulations.

Titel:

"MAX 4^U: an upgrade of the MAX IV 3 GeV Ring"

Abstract:

The MAX IV 3 GeV storage ring in Lund, Sweden, was the first implementation of a multibend achromat (MBA) lattice fourth-generation light source. Since it started delivery of light to beamlines in 2016, three succeeding MBA-based rings and variants have come on-line: ESRF-EBS, Sirius and APS-U. Several others are being planned, designed, built or commissioned. All of these projects capitalize on the MBA concept and expand it to push the performance in terms of brightness and coherence even further. In order to continue to offer the Swedish and international scientific communities state-of-the-art competitive tools beyond the end of this decade, MAX IV Laboratory launched in 2024 the conceptual design of MAX 4^U , an upgrade of its 3 GeV storage ring aiming at an emittance below 100 pmrad. This performance boost is to be achieved through a minimum-interference upgrade in which localized interventions in selected subsystems and components are carefully chosen to provide the maximum performance increase with minimum cost and, equally important, minimum dark time for MAX IV user community.

This talk outlines the current accelerator physics and engineering concepts in the MAX 4^U conceptual design. 

Mathias Vogt, DESY-MFL
“The Free-Electron Laser FLASH and the FLASH2020+ Upgrade Project” 

In the last 2-3 decades Free-Electron Lasers (FELs) have become an essential class of large scale facilities for photon based studies of matter. FLASH, the “Free-electron LASer in Hamburg'' at DESY is an XUV /soft X-ray FEL with two FEL beamlines plus an experimental beamline, driven by a common RF photo-cathode gun and a common superconducting linac.
 Currently FLASH is undergoing a substantial upgrade program called  “FLASH2020+''. Here I will briefly introduce the basic principles of SASE and seeded FELs, describe FLASH and the FLASH2020+ project and smoothly move towards intrinsic FEL-specific collective issues and thereby into the next talk by Ph. Amstutz.

Philipp Amstutz, TU Dortmund 
“Advances in a perturbation theory and semi-Lagrangian simulation of microbunching for FLASH2020+ and laser-heater based bunch shaping methods”

As one of the leading mechanisms limiting the quality of high-brightness electron bunches driving free-electron lasers, the microbunching instability continues to be in the focus of much attention. Due to its collective, non-linear nature, analysis of the microbunching instability poses significant challenges, both theoretically and numerically.
 This talk will give an introduction to two promising methods to address these challenges:
•    a perturbation theory based on the Fréchet-Taylor expansion
•    of collective Perron-Frobenius propagation operators;
•    and a tree-based domain-decomposition approach allowing
•    efficient semi-Lagrangian simulation of exotic phase-space densities.
 These methods are employed to assess the suppression of the microbunching  instability via a laser heater installed at FLASH as part of the FLASH2020+  upgrade project. Finally, an advanced operation mode of the laser heater is presented, which  aims to taylor FEL pulse profiles by manipulating the longitudinal charge density of electron bunches.

Titel:

''Interactive Modeling of Accelerator Machines: A Strategic Approach to Tackling Future Challenges in Particle Accelerator Design''

Abstract: 

In this presentation, I will share insights from my past experiences in designing critical components for some of pioneering accelerator facilities, including CERN and DESY. The focus will be on the advanced modeling approaches I developed to overcome design complexities and optimize performance. By illustrating these methods, I will highlight how interactive modeling can streamline the design process, enhance reliability, and reduce development time.

The presentation will specifically explore semi-analytical methods developed for the design of high-brightness electron sources, including thermionic and radio-frequency electron guns, from the perspectives of electromagnetic interactions and beam dynamics. Additionally, two fast particle tracking codes currently under development will be introduced, demonstrating their applications in machine learning-based optimization and real-time modeling of particle accelerators.

Titel:

"Linear Optics and Nonlinear Dynamics of Lattice Design for MLS II"

Abstract:

The Metrology Light Source (MLS) is a 630 MeV electron storage ring as a synchrotron radiation source for the terahertz (THz) to the extreme UV spectral range. Its upgrade project MLS II is defined as a compact 0.8 GeV storage ring with multiple operation modes, which pursues lower emittance (<50 nm) in standard user mode and preserves the strong capability of MLS to manipulate the momentum compaction and its higher-order terms for low-alpha mode. As MLS has been successfully conducting numerous source-based calibrations of space instruments utilizing calculable synchrotron radiation, a homogeneous dipole field is an essential requirement for MLS II. Moreover, at least two straight sections with lengths of around 4–5 meters each are required for RF cavities and injection elements, while at least two more straight sections can be filled with insertion devices (IDs). To fulfil these requirements, lattice options based on double-bend achromat (DBA) and quadruple-bend achromat (QBA) have been designed and developed. The linear optics and nonlinear beam dynamics of four different lattices will be presented in this seminar.

Titel:

"Development of Nb₃Sn Thin Films on Copper for the SRF Cavities of the Future Particle Accelerators"

Abstract: 

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Titel:

"Accelerator research at the University of the Basque Country"

Abstract:

The University of the Basque country is a public university in the north of Spain, we will present the work on accelerator that is currently at the Research group on Instrumentation and Experimental Control of the University, including already ongoing collaborations with HZB. There are two main projects related to the particle accelerators, the first one is the design and construction of a low current compact 7 MeV proton accelerator, that is partially constructed. The second project is the design and construction of an ion source based compact neutron generator, that uses the D-D fusion reaction to produce neutrons. Subjects related to these projects are the object of the currently ongoing collaborations with HZB, these include LLRF systems for superconducting cavities and a possible project on high efficiency magnetrons as power amplifiers for cavities.