accelerating-news-arc.web.cern.ch - EuPRAXIA

Boosting the electron beam brightness: NeXource

Livia Lapadatescu — Fri, 06 Oct 2017 08:19:20 +0000

Boosting the electron beam brightness: NeXource
by Bernhard Hidding (University of Strathclyde)

Particle-in-cell-simulation with VSim: the driver beam propagates to the right and excites the plasma wave, which accelerates the witness bunch while being dechirped by an escort bunch population.(Courtesy: A.F. Habib)

Extremely high-quality electron beams are required to realize knowledge-generating machines in the hard x-ray regime or at the energy frontier. EuPRAXIA, the H2020 project exploring design options for a "European Plasma Research Accelerator with eXcellence In Applications", therefore aims to develop a compact plasma accelerator with superior beam quality. EuPRAXIA researchers at the University of Strathclyde and partners at the University of Hamburg/DESY and UCLA, supported by industry (RadiaBeam, RadiaSoft and Tech-X), have now developed a breakthrough technique which may allow to increase the brightness of electron beams by many orders of magnitude. The study has recently been published in Nature Communications [G. G. Manahan, A. F. Habib, et al., doi: 10.1038/ncomms15705].

While the huge accelerating electric fields of plasma accelerators allow to realize energy gains of many tens of GeV on few cm-scale lengths, the output electron beam quality is also of paramount importance for many key applications. One especially promising approach is the plasma photocathode a.k.a. “Trojan Horse” technique. The concept decouples injection from acceleration, and allows to generate tunable electron beams by controlled ionization injection with a synchronized laser pulse directly inside an electron beam driven plasma wave. This injection mechanism generates witness beams with orders of magnitude better normalized transverse emittance and 5d-brightness, because the laser pulse transfers very low residual transverse momentum to the electrons in statu nascendi. Such plasma photocathodes may have comparable impact as the development of conventional photocathodes, which was a key to realize hard x-ray FEL’s such as the LCLS or the European XFEL in Hamburg. Exploration of the Trojan Horse technique has therefore already been foreseen for large-scale plasma accelerator projects such as SLAC’s FACET-II, BNL’s ATF-II, DESY’s FLASHForward and for EuPRAXIA.

However, it is highly desirable to go even further, and to also tackle the “energy spread” problem. The ultrahigh electric fields in plasmas come at a price: they also produce ultrahigh electric field gradients. Therefore, the head of the accelerated electron beam gains energy at a lower rate than its tail. This leads to an electron beam energy “chirp” which gives rise to various significant problems e.g. during extraction, capture, transport and for applications, where it can be a showstopper e.g. for FEL.

The study in Nature Communications proposes to exploit tailored beam loading by so called “escort” electron bunches, again to be produced by the plasma photocathode technique, in order to flip the accelerating field and hence to obtain longitudinal phase space control over the witness bunch. Most importantly, the technique allows to remove the correlated energy chirp completely, leaving just the uncorrelated, residual energy spread. A discovered scaling law indicates that the relative energy spread of the dechirped bunch can reach sub-0.01%-levels at plasma wavelengths of ~500 µm and electron energies > 2 GeV. This energy spread is approximately two orders of magnitude improved compared to without dechirping.

This would boost the output of plasma accelerators e.g. in terms of 6d-brightness to levels beyond those of even the finest traditional accelerators. For example, the combination of low emittance, ultrahigh brightness and low energy spread may allow to beat the FEL Pellegrini criterion and the FEL Pierce parameter at the same time, and to harness ultrahigh gain.

Claudio Pellegrini (not involved in the study), one of the key figures in the history of the LCLS, said: "The path towards realizing the LCLS required a fundamental improvement of the electron beam quality obtainable from conventional accelerators. The approach Manahan et al. suggest now is very promising as regards obtaining a further step change in electron beam quality, this time to be enabled with plasma accelerators. This holds great prospects for the construction of future compact hard x-ray FEL's".

The combination of ultralow emittance and reduced energy spread may allow to realize next generation electron beam sources with ultrahigh 6D-brightness, an approach which the team calls the “NeXource” technique. Bernhard Hidding, who led the study and presented some of the results at IPAC’17, said that the novel concept could hardly come at a better time: “We have just seen first experimental signatures of the plasma photocathode in the ‘E210: Trojan Horse’ programme at SLAC FACET. Fascinatingly, it looks like the complex beam-plasma physics involved support each other to facilitate the mechanism. This is highly encouraging for future R&D along the NeXource approach.”


Residual energy spread scaling law: reducing the plasma wavelength and increasing the electron energy can reduce the residual relative energy spread to sub-0.01% levels already at 2-3 GeV, an energy which is today routinely reached by plasma accelerators. (Courtesy: A.F. Habib and G.G. Manahan)	The diagram indicates the projected 6d-brightness performance of the plasma-based NeXource approach in a couple of variations and at different energies when compared to state-of-the-art accelerators. (Courtesy: A.F. Habib and G.G. Manahan)

Strathclyde’s Research & Knowledge Exchange Services office has patented the approach and is now working with well-known accelerator product SME RadiaBeam Technologies to further develop and commercialize the technology. The technology may enable future compact free-electron lasers with a shot-by-shot performance substantially better than today obtainable even from the best of today’s large machines, and may have transformative effect on this and other important areas of research in natural, life and material sciences. It may be a unique path forward for EuPRAXIA to realize the goal of compact hard x-ray free-electron-lasers, and to fertilize plasma-based linear collider and high energy physics efforts.

EuPRAXIA

electron beams

FELs

plasma accelerators

issue 22

EuPRAXIA baseline parameters established

Jennifer Toes — Mon, 05 Dec 2016 15:01:16 +0000

EuPRAXIA baseline parameters established
by Dr. Ricardo Torres (University of Liverpool)

Photograph of the participants at the 1st Yearly Meeting of EuPRAXIA
(Image:Copyright Pieyre Sylvaine, LLR)

The First Yearly Meeting of the EuPRAXIA consortium took place at the École Polytechnique in Paris, over 26-28th October. Ralph Assmann, Project Coordinator, and Arnd Specka, Deputy Project Coordinator and Host of the meeting, welcomed 59 registered participants from partner institutes, associate partners, and industry.

The Yearly Meeting discussed the fruitful first year of the project, which included the forming of the collaboration board, hiring of new personnel, investigation of facility parameters and a total of eleven workshops and special work package meetings. Scientific results from these events covering all aspects of the project were reported, and included interesting new insights and future directions.

One of the highlights of the meeting was the presentation and approval of the preliminary study concept of EuPRAXIA. The report summarized the scientific input for the preliminary study concept of EuPRAXIA which has been received over the past year. All work packages contributed to this report with summary reports of topical workshops held during 2016.

One such workshop was the European Plasma Accelerator meeting held in Pisa in June 2016, where more than 120 scientists gathered and discussed the various technical approaches and requirements for the collaboration over three days. Another workshop on laser technology which lead to the 100-cube laser challenge (100J / 100fs / 100Hz) has become one of the baseline components of the EuPRAXIA design.

The preliminary study concept report presents the outcome of all these discussions, condensed into flow diagrams and technical tables. The graphical diagrams show the main concepts, their interplay and the connections to relevant applications. Included in the report are the agreed baseline parameters, the parameter ranges to be explored and the technical goals for the next step of the EuPRAXIA conceptual design work.

The values of the parameters were first derived from scaling laws and refined by simulations. The parameter ranges documented in the report will ensure that work done in different locations by the project partners will be focused on the same targets and operating under the same assumptions. This common baseline for parameters and their study range will also ensure that results can be compared for beam quality, tolerances, layout footprints and costs.

At this stage, the study will contemplate multiple paths for obtaining high-quality multi-GeV electron beams. Such concepts considered include: Laser Wakefield Acceleration (LWFA) with internal or external injection and direct or staged acceleration to 5 GeV; beam-driven Plasma Wakefield Acceleration (PWFA) to 1 GeV or 5 GeV; and a hybrid scheme including LWFA and staging using PWFA to a multi-GeV electron beam.

By keeping these common baseline parameters and goals in mind, the work packages of EuPRAXIA can further investigate the techniques and approaches required.

In addition, the report contained the requirements for the plasma-based accelerator and its experimental user areas tailored for the two main applications foreseen by EuPRAXIA. Firstly, High Energy Physics and other pilot applications, and secondly, a Free Electron Laser (FEL) for ultrafast photon science.

The values for the FEL requirements were determined during several workshops held over the last six months. The requirements for the HEP applications in terms of beam parameters and infrastructure were defined by the participants of a workshop on Pilot Applications of Electron Plasma Accelerators (PAEPA) in mid-October 2016.

In the next phase of the project, the technical work will use the parameters from the preliminary study to provide a more refined table of parameters for incoming and outgoing beam and laser properties, realistic estimates of performance, basic values for tolerances and stability requirements, basic layouts (footprints) of the technical components, and a further iteration of specifications for the science applications.

The future outcome from the work packages could be used to rank the various solutions towards the final proposal, due in 2019. This ranking will define the optimal combination of technologies for the conceptual design of a EuPRAXIA facility.

EuPRAXIA

issue 19

Plasma Accelerator Consortium met in Pisa

Panagiotis Charitos — Thu, 15 Sep 2016 10:25:41 +0000

Plasma Accelerator Consortium met in Pisa

by Prof. Carsten Welsch (University of Liverpool)

EuPRAXIA and EuroNNAc members gather for the meeting in Pisa, Italy (Image courtesy of EuPRAXIA)

Particle accelerator experts from around the world joined experts from the laser and novel accelerator communities to discuss the design of an innovative European plasma accelerator within the framework of the EuPRAXIA and EuroNNAc projects.

The workshop took place between June 29th and July 1st at the Area della Ricerca in Pisa, Italy and was hosted by the Istituto Nazionale di Ottica – CNR.

The local organiser, Leo Gizzi said: “It has been an absolute pleasure to see the vibrant discussions amongst participants. The definition of the key parameters of such an international facility with global reach and impact is one of the most exciting things a researcher can be part of. The event gave us the opportunity to reflect on the state-of-the-art and at the same time outline the R&D programme required to reach our goals by the end of the design study.”

The design and science cases of advanced plasma accelerators are subject of intense studies around the world. Progress in proof-of-principle experiments has led to the expectation that ground-breaking applications of plasma accelerators will become available in the next few years.

Ralph Assmann gives a speech to attendees at Pisa meeting (Image courtesy of EuPRAXIA)

More than 120 delegates discussed the parameters and technical specifications required at the interfaces between lasers and plasmas, plasmas and particle beams, as well as particle beams and other applications such as Free Electron Lasers, High Energy Physics detectors and ultra-compact X ray devices. Discussions also covered the specific requirements in beam diagnostics, laser technology and underpinning simulation codes.

The aim of the meeting was to collect the input from all interested parties in order to define a full parameter set that will be used as the core of a conceptual design for a European plasma accelerator with industry beam quality that shall now be developed by the project partners until the end of 2019. Targeted workshops will now be organised by each of the EuPRAXIA work packages in order to build up on the Pisa discussions and further refine all parameters.

All presentations and further information can be found on the workshop’s indico page. For more information about EuPRAXIA, please refer to the project website.

Lasers to shine even brighter

Panagiotis Charitos — Thu, 23 Jun 2016 09:55:31 +0000

EuPRAXIA consortium paves way for next generation laser technology

by Alexandra Welsch (University of Liverpool)

The Horizon 2020 Design Study EuPRAXIA targets the preparation of a conceptual design report for the world’s first plasma-based accelerator at 5 GeV with industrial beam quality and two user areas. The laser systems to be used as drivers for the laser-driven plasma acceleration process and as part of the laser injector are crucial for the success of the project. Their development and optimization are addressed within Work Package 4 of this pan-European project. On 18 May 2016 experts from within this Work Package held a first Topical Workshop on the laser system at the synchrotron SOLEIL in France.

At the beginning of the event highlights from current and future laser development projects, including the Extreme Light Infrastucture (ELI) project, the APOLLON, and the ILIL PW facilities were presented. These lasers shall cover energies ranging from ten Joule up to kilo-Joule, pulse durations from attoseconds to hundred femtoseconds, and repetition rates from one shot per minute to 10 Hz. It was emphasized that these projects needed tremendous investments and major developments in new materials arising from research projects launched as early as 2006.

A wide range of laser technologies and quite different architectures emerged from this overview, suggesting a range of potential solutions for the development of the future EuPRAXIA laser concept. A “100 cube” operating point was considered, providing 100 Joule, 100 fs pulses at 100 Hz, with a contrast of 1010 at 10 ps. Whilst ambitious for a scientific laser issued in 2025, it was found a generally realistic scenario, with warnings about a potentially longer timescale needed to attain an "industrial" version of such a system. The key parameters and overall design will now be further investigated within the Design Study.

These ongoing developments will now be put into a bigger context. EuPRAXIA is organizing a Workshop on a European Plasma Accelerator in Pisa, Italy between 29 June to 1 July 2016 at Area della Ricerca del CNR, Pisa, Italy hosted by Istituto Nazionale di Ottica - CNR. This event will be open to the communities of conventional facilities, lasers and novel accelerators, to discuss the unique scientific and industry opportunities arising from the EuPRAXIA design.

EuPRAXIA

plasma accelerators

issue 17

Compact modern accelerators for big science

Alessia Barachetti — Thu, 19 Nov 2015 13:38:31 +0000

Compact modern accelerators for big science
By Carsten Welsch(UNILIV)

On 1 November 2015 a new European Design Study called EuPRAXIA (“European Plasma Research Accelerator with eXcellence In Applications”) started. 3 M€ of funding has been awarded to 16 laboratories and universities from 5 EU member states within the European Union’s Horizon 2020 programme. They will be joined by 18 associated partners that make additional in-kind contributions.

The goal of this ambitious project is to design accelerator technology, laser systems and feedbacks for improving the quality of plasma-accelerated electron beams. Two user areas will be developed for a novel free-electron laser, for high-energy physics and for other applications. An implementation model will also be proposed, including a comparative study of possible sites in Europe, a cost estimate and a model for distributed construction but installation at one central site.

Novel and small plasma accelerator compared to the FLASH accelerator. Credit: Heiner Müller-Elsner/Desy

EuPRAXIA has a total of 14 work packages that address specific scientific challenges. R&D in eight of them will be directly supported by the design study. This includes extensive simulation studies across the consortium to optimize the plasma, laser and electron beam parameters for both, the plasma injector and the accelerating modules. These investigations will target the achievable beam characteristics, including maximum energy and bunch charge, but also energy spread and transverse emittance of the electron bunches. It is hoped that they will also provide valuable information about acceptable tolerance levels with regards to error sources such as laser intensity and plasma density. Another work package aims at identifying a reliable and stable solution to build the injector and plasma accelerator stages. It will design the plasma structures that are required for both tasks and define optimum regimes of operation. Studies will also include the design of suitable diagnostics required to monitor the shot-to-shot operation of plasma structures and a complete set of instrumentation for the electron injector and laser plasma stage.

EuPRAXIA is the important intermediate step between proof-of-principle experiments and ground-breaking, ultra-compact accelerators for science, industry, medicine or the energy frontier. The design study was endorsed by the European Steering Group on Accelerator R&D (ESGARD) and developed with support from the EuroNNAc network. It aims at establishing a revolutionary design of a plasma-based accelerator with superior beam quality. The study shall help put this new type of particle accelerator on the roadmap for future science facilities with a significantly reduced footprint and hence much lower costs.

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