Optimising laser driven electron nanobunches from ultrathin foil interactions: Coherent synchrotron emission and relativistic electron mirrors

Lead Research Organisation: Queen's University of Belfast
Department Name: Sch of Mathematics and Physics


Summary of research for a general audience

One of the most exciting frontiers of science is the study of phenomena that take place on the timescale of attoseconds (as, 10^-18 s). To imagine such an incredibly short period of time, consider that light travels from here to the moon in one second, but only travels 0.0003mm in one femtosecond (fs, 10^-15 s). To put it in context, that is about 1/300th the width of a human hair in 10^-15 s (or 1000 as). Attoseconds are the timescales on which atomic processes/transitions occur - for example, an electron circles the hydrogen atom in ~24 as (the so called 'atomic unit of time').

To investigate, and in future control, the dynamics of such ultrafast processes measurement tools of unprecedented quality and precision are required - pulses of light with attosecond duration. This is much shorter than a single cycle of any visible light wave (violet~1.3fs, red~2.5fs), requiring instead extreme-ultraviolet (XUV)/ X-ray radiation to be controlled with clinical accuracy to achieve ultrashort durations. However, the pay-off for this effort is substantial; researchers can investigate the microcosm with a degree of spatial clarity and on shorter time scales than previously possible, thus allowing them to see events that are ordinarily 'blurred' using conventional XUV/X-ray sources such as synchrotrons.

Attosecond pulses must be synthesized using wavelengths shorter than those in the visible region of the spectrum and therein lies a significant problem - wavelengths shorter than the visible spectrum i.e. ultraviolet and X-rays, are strongly absorbed in most materials. It is therefore impossible to build an attosecond laser using conventional laser building techniques. Instead next generation methods are required. Two principle media are currently being studied at laser laboratories around the world - intense laser-gas interactions and relativistic laser plasmas formed using solid density targets - for the production of attosecond pulses.

In the proposed research we focus on the second medium - relativistic laser plasma. The underlying mechanism under investigation for the generation of intense attosecond pulses is the production of relativistic electron nanobunches during high power optical laser interactions with ultrathin carbon foils. This novel concept is based on our recent work showing that dense bunches of electrons with sub 10nm scale (nm = nanometer = 10^-9m) can be formed and rapidly accelerated on the front surface by the relativistically intense driving laser field and subsequently emerge from the rear surface of ultrathin carbon foils. Two resulting mechanisms will be studied in detail in this research - Coherent Synchrotron Emission (CSE) and Relativistic Electron Mirrors (REM). Only recently demonstrated, CSE and REM offer a novel window onto the relativistic laser plasma interaction and our work will not only reveal the microscopic dynamics of these mechanisms but also show a direct path to the generation of bright attosecond pulses.

Planned Impact

Impact Summary

Our work has the potential to impact strongly on both the economy and society. Ultimately with this proposal we are developing our knowledge of the fundamental physics governing intense laser - ultrathin foil interacts with a view to creating novel sources with specific and tailored characteristics for the broader scientific community. Typically history has shown that future applications develop rapidly after a "new tool" has been demonstrated and optimised - the optical laser in 1960 is a case in point.

The use of lasers to produce bright pulses of extreme ultraviolet/X-ray radiation and charged particles is leading the way towards downsizing the current generation of large scale accelerator based facilities. These facilities, such as synchrotrons and linear accelerators, are simply too expensive to have in every university.

One of the key areas of impact of the work in this proposal will be for researchers and users of ultrafast XUV/X-ray and charged particle sources. Our proposal seeks for the first time to perform fully quantitative measurements on beam characteristics (such as efficiency, angular distribution of both XUV and electron beams from ultrathin foils) and how these vary with key interaction parameters so that the wider community can avail of these advances. While this will be achieved through standard methods (academic journals and presentation at conferences) we maintain a proactive stance to bringing our research to the wider scientific community and new audiences via novel multimedia dissemination methods.

Another key area where we will achieve significant impact is through our collaboration with major facilities in the US (Los Alamos National Laboratory (New Mexico), University of Austin (Texas), Ohio State University (Ohio)) and Germany (Helmholtz institute at Jena). All of these high power laser facilities perform high quality, impact-led research and, as evidenced by our statements of support, are very keen to collaborate with us on this project.
Description So far in this award we have demonstrated that it is possible to measure ultrafast bursts of charge particles generated during intense laser matter interactions in real time.

This has resulted in a publication in Nature Communications.

We have also studied the temporal structure of electron nanobunches produced during intense laser matter interactions.

This has been published in Physical Review Letters
Exploitation Route Our new results make it possible for researchers to study ultrafast ion interactions in condensed matter for the first time. Our novel metrology is a crucial step it attaining the ultimate goal of this work - the study of nanobunches of electrons
Sectors Digital/Communication/Information Technologies (including Software),Electronics,Energy,Healthcare,Manufacturing, including Industrial Biotechology

URL http://www.nature.com/ncomms/2016/160210/ncomms10642/full/ncomms10642.html
Description We have used our research and findings to develop a brand new platform for public engagement. Working in collaboration with the Ulster Museum and Northern Ireland Science festival we have based a new exhibition - 'Lasers Live' - which features interactive displays and demonstrations to show how our research is driving light enabled technologies and haw we plan to use this work to develop new sources of radiation for biomedical imaging and radiobiology. The exhibit reached >10,000 people in a 8 day period in February 2015 and >18,000 people in an 11 day stint in February 2016. In the 2016 stint over 500 feedback forms from school students and members of the public were collected and the data form these is currently being collated. In another strand my group was invited to attend the Late Lab sessions as part of the Northern Ireland Science festival in both 2015 and 2016. On each occasion there was over 1000 attendees predominantly in age range 18-35. Again over 100 feedback forms were collected at the 2106 event. The feedback forms will be used to inform and shape future events. These events will continue over the coming years and enhanced impact metrology will be performed to gauge public engagement levels.
Sector Education,Culture, Heritage, Museums and Collections
Impact Types Societal

Description Air Force Basic Technology grant
Amount $150,000 (USD)
Organisation United States Air Force 
Sector Public
Country United States
Start 12/2013 
End 12/2017
Description EPSRC equipment upgrade
Amount £1,000,000 (GBP)
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 05/2015 
End 10/2016
Description Erasmus Plus
Amount £150,000 (GBP)
Organisation European Union 
Sector Public
Country European Union (EU)
Start 10/2017 
End 10/2019
Description Marie Curie International Training Network
Amount £168,000 (GBP)
Organisation Marie Sklodowska-Curie Actions 
Sector Academic/University
Country Global
Start 03/2016 
End 03/2020
Description CEA Saclay collaboration 
Organisation Saclay Nuclear Research Centre
Country France 
Sector Public 
PI Contribution WE performed and designed experiments on both the Gemini laser system at RAL and the ultrafast laser system at CEA Saclay
Collaborator Contribution Provide staff and expertise for experiments and dedicated access to a world class laser facility
Impact 3 papers ( 1 PRL, 1 Nature Communications, I New Journal of Phyiscs) Invitations to further experiments
Start Year 2010
Description Lund collabortation 
Organisation Lund University
Country Sweden 
Sector Academic/University 
PI Contribution Performed experiments and led the Scientific case on the Phelix laser at GSI Darmstadt
Collaborator Contribution PhD and Postdoc support on experiments
Impact Currently 5 publications in preparation 2 publications accepted for publictaion
Start Year 2013
Description Partnership with Class 5 lasers DESY hamburg 
Organisation Deutsches Electronen-Synchrotron (DESY)
Country Germany 
Sector Academic/University 
PI Contribution We have aided in developing novel x-ray sources for deployment at free electron lasers
Collaborator Contribution They have provided access to expertise and engineering
Impact 3 publications accepted, two publications pending
Start Year 2012
Description Partrnership with CALA in Munich 
Organisation Ludwig Maximilian University of Munich (LMU Munich)
Country Germany 
Sector Academic/University 
PI Contribution Expertise in ultrafast laser ion interactions with matter
Collaborator Contribution Access to cutting edge laser facilities
Impact Not applicable yet - early stage of collaboration
Start Year 2016
Description Texas Petawatt, Austin Texas U.S. 
Organisation University of Texas at Austin
Country United States 
Sector Academic/University 
PI Contribution We are working on novel diagnostics for studying laser driven electrons and ions
Collaborator Contribution Access has been granted to laser experimental area and target fabrication
Impact As a very new collaboration the outcomes are currently in preparation, but we anticipate
Start Year 2015
Description Incredible power of light roadshow 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact We hosted and provided full time staffing for the Incredible power of light roadshow from the STFC in the Ulster Museum during February and March 2015. Our active participation in this public out reach event saw over 10,000 members of the public and over 1000 pupils from regional (Northern Ireland) schools. We demonstrated the exhibits and informed attendees about how to pursue careers in science, technology engineering and mathematics with particular emphasis on laser and light based technologies. Since this was the first year it was difficult to directly measure impact. However our success saw my group invited to return to present the exhibits again the following year (2016).

Also the impact on regional schools was tangible with over 10 requests from individual school groups to provide year round displays in public forums with dedicated exhibitors such as those provided by my group.
Year(s) Of Engagement Activity 2015
Description Lasers live demonstration, Northern Ireland Science festival 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact In 2015 the inaugural Northern Ireland Science festival was held. Following our successful collaboration with Ulster museum with the STFCs Incredible Power of Light roadshow we were invited to build and demonstrate a Laser's Live exhibition in the Foyer of the Ulster Museum. This highly visible location saw nearly 11,000 members of the public attend live demonstrations of how light energy can be harnessed over an 9 day period in 2015.

This was so successful the Ulster Museum invited us to return for an extended period in 2016, extending our reach beyond that of the Northern Ireland Science festival for a 12 day residence in the Foyer. This saw > 18,000 attendees to the museum visit our live demonstrations

We performed detailed metrology in 2016 with over 1000 questionnaires completed by school students and members of the public with ages ranging from 3 - >60 years. The results of these questionnaires are currently being processed but the response has been overwhelming.

All numbers for attendance are official numbers of the Ulster Museum.
Year(s) Of Engagement Activity 2015,2016
Description Lasers live demonstration, Northern Ireland Science festival 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact Over 20,000 members of the public attended our Lasers live event held in the Ulster museum as part of Northern Ireland Science festival.
Year(s) Of Engagement Activity 2018
Description Late Lab 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact As part of the Northern Ireland Science festival we have presented live demonstrations at the Late Lab showcase event of how light can be used to change our world to members of the public. On both occasions over 1000 members of the public attended our stands and interacted with our demonstrators in a 1 -1 basis in an very different setting to what is normal of a scientific setting.
Year(s) Of Engagement Activity 2015,2016
URL https://www.youtube.com/watch?v=oFN3JCAgj58
Description Northern ireland Science Festival 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact Over 20,000 members of the public attended our Lasers live event held in the Ulster museum as part of Northern Ireland Science festival.
Year(s) Of Engagement Activity 2016,2017