Accelerator Science and Technology Seminar

Title:

TRIBs with 1.75 GHz beating - an end game idea for BESSY II

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"The SSMB Proof-of-Principle Experiment at the MLS - Status and Perspective"

Abstract: 

The Steady-State Microbunching (SSMB) Proof-of-Principle Experiment

(PoP) at the MLS has first successfully shown coherent synchrotron radiation on the second undulator harmonic in 2019. Since then, as part of a Master's thesis, a first harmonic detection setup was commissioned and is used successfully to investigate the storage ring state necessary for coherent emission.

This talk will give an overview of the SSMB-PoP project, the current status and an outlook on future planned phases of the PoP experiment.

Title:

Status of the Sealab facility at HZB, a new perspective for bERLinPro

Abstract: 

Since end of the year 2020 the energy recovery project bERLinPro is officially completed. But what is the status of this facility, the next scientific goals in the framework of accelerator physics at HZB, what are the perspectives? To reflect the continuation of this endeavor and the eventually broaden application of this machine from high current SRF based energy recovery concept to an ultrafast electron diffraction facility producing shortest electron pulses, the facility is now named Sealab, Srf Electron Accelertor Laboratory. In this talk, an overview of the status of the machine, the coming set up and commissioning steps with an outlook to midterm and future applications will be given.

Title:

Machine learning for particle accelerators

Abstract: 

The last few years have seen a strong increase in uptake of machine learning (ML) techniques in the domain of particle accelerators. ML techniques have been used in a number of applications, from anomaly detection to surrogate modelling, virtual diagnostics, tuning and control as well as advanced data analysis. This talk will explore the different applications where ML is becoming an increasingly valuable tool to meet new demands for beam energy, brightness, reliability and stability, and will review several successful case studies in a number of particle accelerator facilities.

Title:

Multi-alkali antimonide photocathode development for high brightness beams (Status of photocathode R&D for ARD)

Abstract: 

Photocathode R&D at the Helmholtz-Zentrum Berlin is driven by the motivation to produce high brightness electron beams for the SRF photoinjector test facility currently under construction at HZB. To deliver high quality photocathodes, the working group at HZB have developed the necessary infrastructure comprising several ultra-high vacuum systems for the production, analysis and transportation of bi-alkali antimonide photocathodes. In this talk, the following topics will be covered: a status update of the photocathode lab, lessons learned from the growth and characterization of Cs-K-Sb photocathodes, and first steps towards developing a growth procedure for Na-K-Sb photocathodes. Finally, results from collaborative work with a solid-state physics theory group aiming at an ab-initio description of the
photoemission process will be presented

Titel:

"Smalltalk on Accelerator Toolkits (ATs)"

Abstract: 

A summary of the LEGO (modular) approach employed for the Python interface to the Tracy-2 Hamiltonian and symplectic integrator. For a perspective on predictable results for synchrotron light sources, the talk will also provide an outline on the origin and experimental validation of the underlying model, which has not changed since then. I.e., the implementation of an on-line model for model-based control to guide the commissioning of the Advanced Light Source, Berkeley, in the early 1990s. A straightforward exercise in Hamiltonian dynamics; by applying systematic analytical methods developed  for celestial mechanics a century ago.

Titel:

"CBETA: Challenges and Lessons Learned"

Abstract: 

CBETA, the Cornell Brookhaven ERL Test Accelerator, was the first multi-pass SRF ERL, and was commissioned at low average current from 2019-2020. In addition to being an 8 pass ERL (4 energy increasing and 4 decreasing passes), it also used a single return loop for all 4 beam energies, made possible with FFA (Fixed Field Alternating-gradient) magnets with a wide energy acceptance. In this talk, I will describe the challenges of commissioning such a machine, and the lessons learned from our initial operations period. 

Titel:

"Low-Alpha Storage Ring Design for Steady-State Microbunching"

Abstract: 

A new concept is proposed for minimizing the longitudinal emittance of a low momentum compaction factor (low-alpha) storage ring, which has the capability to stably store sub-femtosecond electron bunches for the first time. This storage ring is designed for Steady-State microbunching (SSMB) to generate kW level average power EUV radiation. The proposed design approach can be applied to any quasi-isochronous storage rings to yield very high radiation power due to longitudinal coherence of the radiation. We obtain an optimal lattice design by minimizing global and local momentum compaction factors simultaneously.

We have studied nonlinear optimization for this low-alpha storage ring, which is different from the normal storage ring. The main differences come from two parts: one is that the second order momentum compaction factor need to correct, another is that SSMB ring will use 1 μm  laser modulator to replace traditional RF cavity (equivalent wavelength is about 1 m). So the high order transverse-longitudinal coupling will limit the 6D dynamic aperture. We have done some preliminary study on 6D dynamic aperture optimization for SSMB ring.

Title:  

 "PERLE: A novel facility for ERL development and application in multi-turn configuration and high-powered regime"

Abstract:

The development of ERLs has been recognized as one of the five main pillars of accelerators R&D in support of the European Strategy for Particle Physics (ESPP).  The ERL Roadmap Panel recognized PERLE project as “a central part of the roadmap for the development of energy-recovery Linacs”, with milestones to be achieved by the next ESPP in 2026.

PERLE at Orsay is a project aiming at the construction of a novel ERL machine for the development and application of the energy recovery technique in multi-turn configuration, large current and large energy regime. It will operate in a 3-turns mode, first at 250 MeV, then upgraded to 500 MeV with 20mA beam current. Such challenging parameters make PERLE a unique multi-turn ERL facility operating at an unexplored operational power regime (10MW), studying and validating a broad range of accelerator phenomena, paving the way for the future larger scale ERLs.

Furthermore, PERLE machine opens a new frontier for the physics of “the electromagnetic probe”. It will be the first ERL dedicated to Nuclear Physics for studying the eN interaction with radioactive nuclei. PERLE is also the necessary demonstrator for the future HEP machine (LHeC / FCC-eh) (same technological choices & beam parameters). PERLE could also host elastic ep scattering experiments and experiments on Nuclear Photonics using inverse Compton scattering gammas.

In this seminar, we will present the PERLE project, focusing on the challenges on accelerator physics and presenting the possible physics applications. We will also show the project structuration in an international collaboration and a timeline for the TDR phase and the following staged construction steps toward the PERLE machine at its nominal performances.

Title: 

"Digital Shadow for BESSY II"

Abstract: 

Accelerator development has been directly linked to computational tools for studying the designed machines and forecasting their performance. In early days computer modelling was disjoint from conducting on the experiments. Conversions from engineering space (e.g. power converter currents) to accelerator physics space (e.g. angles produced by correctors) was typically a semiautomatic process. Today’s available computing power –  next to consistent interfaces to libraries and tools – call for a connection: i.e. a digital model of the machine that follows the current machine settings (digital shadow). 

This talk will outline the proposed design and its implementation. It will show how conversion is split off from physics calculation. Finally it will describe the development of commissioning tools based on bluesky, which are developed and tested using the digital shadow and the machine.

Title: 

"Superconducting solenoid fields measurement and optimization for SRF Gun-III at ELBE HZDR"

Abstract: 
 

In order to reduce the projected transverse beam emittance, a solenoid is usually used at normal conducting as well as superconducting radiofrequency (SRF) photoinjectors. At the ELBE SRF Gun-II, a superconducting solenoid is located inside the gun’s cryomodule about 0.1 m far from the end of the gun cavity. The aberration of the solenoid field, such as the quadrupole component, will influence the beam symmetry and enlarge the projected transverse emittance. The influence of the quadrupole field on emittance is studied, and the correctors have been used to cancel this multipole field. The SC solenoid for SRF Gun-III is optimized to reduce the spherical aberration. The fields measurement of the new solenoid has to be conducted. The multipole components of the field are analysed by a formalism fitting method, and the results agree with the simulation.

Titel:

"Superconducting Thin Films for Next-Generation SRF Cavities"

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Title: 

"Fast Reactive Turner SRF Modules and Other CERN SRF Activities"

Abstract: 

A Ferro-Electric fast Reactive Tuner (FE-FRT) is a novel type of RF cavity tuner containing a low loss ferroelectric material. FE-FRTs have no moving parts, can be placed outside of liquid helium environment and allow cavity frequencies to be changed extremely quickly (on the timescale of 100s of ns). FE-FRTs can be used for a wide variety of use cases including microphonics suppression, RF switching, and transient beam loading compensation.

This talk will discuss compensation of microphonics, which in low beam loading machines or erls such as BerlinPro can allow a dramatic reduction in RF power requirements.

Title: 

"The Multiturn ERL at S-DALINAC"

Abstract: 

The superconducting recirculating electron accelerator S-DALINAC at TU Darmstadt is established since 1991 and mainly developed and operated by students. Besides conventional single-pass or multi-pass acceleration schemes serving various nuclear-physics experiments, the accelerator can also be operated as an energy-recovery LINAC (ERL) in different setups:

a single-turn ERL was realized in 2017 and a twofold ERL with shared beam transport in 2021.

In this talk, we will present results of those energy-recovery modes at the S-DALINAC and will focus on the challenges to realize and investigate them.

Title: 

"Status of the Linac Coherent Light Source II and the path to high power Free Electron Lasers"

Abstract: 

Following a short introduction to Stanford University and the SLAC National Accelerator Laboratory, the presentation will give an overview of the achievements of major FEL facilities around the world. Afterwards a discussion of plans to improve and / or increase brightness, spectral cleanliness, peak power, energy per pulse and photon energy reach will follow. The presentation will attempt to define the term “High Power” in the context of future developments, and what other systems are necessary to support maximum science output. 

In 2009 the Linac Coherent Light Source was the world’s first successfully delivered hard x-ray FEL and immediately started a worldwide race, which caused the construction of several new next generation FEL’s. A proposal to use the core capabilities from various major DOE labs resulted in the 2013 change of course of the SLAC National Accelerator Laboratory and the construction of the world’s most powerful cw x-ray FEL, which is now under commissioning. The seemingly impossible task was implemented through a multilab collaboration, which had to overcome many obstacles to bring LCLS-II to this point. Lessons learned, the present commissioning status and future ambitions will be discussed.

Title: 

"VELA / CLARA activities"

Abstract: 

Compact Linear Accelerator for Research and Applications (CLARA) is an accelerator test facility located at Daresbury Laboratory in the United Kingdom. The facility has delivered high brightness beam for several novel proof of principle experiments in the area of novel acceleration, deflection, Very High Energy Electron (VHEE) radiotherapy, novel diagnostics and accelerator technology developments. This talk will describe the accelerator facility, will briefly mention the experiments till date and will outline future user exploitation possibilities when the facility will be upgraded to full energy of 250 MeV in 2024.

Title: 

"The LightHouse Accelerator for Tc Production"

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