UK Plasma Physics News – Winter 2017.

Welcome to the UK IOP Plasma Physics Group (PPG) e-newsletter. If you have items for inclusion in future newsletters e.g. any meeting announcements or reports, research achievements, new

appointments, facilities, projects, buildings etc. please contact: ken.mcclements@ukaea.uk.

CONTENTS:COMMITTEE NEWSRECENT MEETINGSFORTHCOMING MEETINGSCOMMUNITY NEWSPRIZES AND AWARDS

COMMITTEE NEWS

There have been two committee meetings since the last newsletter. Dr Ken McClements (UKAEA) (ken.mcclements@ukaea.uk) has succeeded Prof Bill Graham (QUB) as the Group Chair. Further details of committee activity and actions are available on the Group website.

RECENT MEETINGS

60 Years on from ZETA

An event entitled ‘60 years on from ZETA’ organised by the IOP Nuclear Industry Group (reported in their September 2017 Newsletter), the IOP Plasma Physics Group, the IOP Nuclear Physics Group and the IOP History of Physics Group was held at Birmingham University on 14 th June 2017. The event’s name was chosen as it was the 60th Anniversary of the Zero Energy Thermonuclear Apparatus (ZETA) fusion experiments. The event also provided a high-level summary of the status of fusion research in the UK, with talks delivered by four leaders from that community.

Chris Warrick (Head of Communications, UKAEA) gave an historical overview on fusion research including ZETA. In 1958 Peter Thonemann’s team at Harwell reported preliminary results from ZETA which included the measurement of neutron emission. The team did not claim that a thermonuclear reaction had been produced. A review article by John Allen, written at the time, makes this clear. Sir John Cockcroft had been led on by the press to say that he was 90 per cent sure that a thermonuclear reaction had been achieved. Later measurements of neutron emission showed that their distribution was non-isotropic and not due to a thermonuclear reaction.

Kate Lancaster (Research Fellow, York Plasma Institute) then gave a ‘whistle-stop tour’ of Inertial Confinement Fusion (ICF), which included discussing what ICF is, who John Nuckolls (LLNL) is (he developed ICF) and the National Ignition Facility (NIF), at LLNL. David Kingham (Chief Executive, Tokamak Energy) went on to talk about compact spherical tokamaks and discussed the work of Tokamak Energy. Finally, Ian Chapman (CEO, UKAEA) talked about the ‘Future Path for Fusion’ discussing fusion in the context of a direct replacement for high carbon energy sources, ITER and MAST. Three of the presentations can be found via the IOP NIG ‘Recent events’ webpage.

Reference: Allen, J.E. Thermonuclear power and the pinch effect, Endeavour, XVII, Number 67, 117. July 1958.

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15th UK Technological Plasma Workshop

The 15th Technological Plasma Workshop (TPW’17) was held in Coventry alongside the Vacuum Symposium at the Vacuum Expo at the Ricoh Arena, on the 11th and 12th of October 2017. The Technological Plasma Workshop is principally a UK-based international forum in science and technology of plasmas and gas discharges. This year it was attended by 60 delegates and the conference programme consisted of 2 invited talks, 17 oral talks and many poster presentations from a mixture of UK and international institutes. TPW’17 was themed on ‘Plasmas and Liquids: Sources, diagnostics, modelling and applications’ with two invited talks on Chemistry induced by atmospheric plasma in aqueous liquids by Dr P Lukes (Czech Academy of Sciences, Czech Republic) and Plasma medicine - beyond the long-lived species by Dr. K Wende (INP, Germany). Other presentations covered diverse topics ranging from chemical probes for plasma diagnostics, atmospheric-pressure plasmas for biomedical, agricultural and environmental applications, computational studies of low-pressure and atmospheric-pressure plasmas, the use of micro-discharges for the production of high current density electron beams for the generation of THz radiation and laser ablation of metal and metal-oxide targets.

Kay Tor of Swansea University was awarded the best student poster prize supported by the Vacuum Symposium for her work on the removal of pharmaceuticals in waste water through non-thermal plasma treatment to impede antimicrobial resistance. A TPW AGM was held on the second day of the conference and it was agreed that TPW 2018 would be collocated with the Vacuum Symposium at the Vacuum Expo at the Ricoh Arena, Coventry.

The support of IOP Plasma Physics Group, the IOP Dielectric and

Electrostatic Group and the Vacuum Expo which had over 120 delegates presenting at the symposium subsidised the two day conference and their support is greatly appreciated. The workshop based within the wider Vacuum Symposium was used as a forum for exploring collaborative opportunities between the academic and industrial communities. The Ricoh Arena is an excellent venue with high quality attendees and provided the ideal meeting place for the next generation of researchers in this field to engage with leading researchers in both academia and in the wider plasma and vacuum based industries. We look forward to seeing you at TPW 2018 at the Ricoh Arena, Coventry UK on the 10th and 11th of October 2018.

Computational Plasma Physics Conference

The Computational Plasma Physics Conference took place between the 20-22 November 2017 at Kings Manor in York (the archaeology department for York University). It was organised by the IOP Plasma Physics Group, IOP Computational Physics Group, and CCP-Plasma (who gave travel and accommodation bursaries to PhD students attending).

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The aim of this conference was to provide a snapshot of the state-of-the-art; examining the development, testing and optimisation of numerical techniques which are not only accurate but also fast, efficient and scalable on modern supercomputing platforms. It was also a forum for those developing and using plasma physics codes in academia and industry to discuss best practice. While the focus of the meeting was on applications to laboratory plasmas, there were also talks on atmospheric/astrophysical plasmas.

The morning of the first day was dedicated to introducing the algorithms, tools, codes and supporting infrastructure available to researchers new to the field of computational plasma physics, with nine invited talks. The remainder of the conference was split into eight sessions, each consisting of an invited talk and one to three contributed talks. There were seven invited talks and 14 contributed talks for the main conference, along with 21 posters.

The poster session, sponsored by AWE, was held on the Monday night. The best student poster prize, also sponsored by AWE, was awarded to Dominic Hill from Imperial College London for his work on ‘2D Vlasov-Fokker-Planck Simulations of Laser-Ablated Plasmas under ICF Relevant Conditions’. Henry Watkins and Stefan Mijin, both from Imperial College London, were poster prize runners-up for their work on ‘Modelling Laser Propagation with Magnetised Transport in Plasmas’ and ‘Development of a Fully Implicit Kinetic Code for Parallel Electron Transport in the Tokamak Scrape-Off Layer’, respectively.

It was a worthwhile conference, which sparked quite a few conversations between attendees and brought together physicists and computer scientists from both the UK and further afield including University of Warwick, UCL, ECMWF, Tech-X, RAL, Imperial College London, AWE, University of Leeds, CCFE, University of York, DESY, University of Bristol, and Arm.

45th IOP Plasma Physics Conference

The 45th IOP Plasma Physics conference was recently held at Queen's University Belfast from 9 th – 12th April 2018. The meeting was well attended and a fuller report will be in the next Newsletter.

FORTHCOMING MEETINGS

TPW 2018: 10-11 October 2018 at Ricoh Arena, Coventry, UK. Early registration and abstract submission deadline: 1 September 2018.

International Conference on High Energy Density Science (ICHED) 2019: 31 March-5 April 2019 at University College, Oxford, UK. Abstract submission deadline: 7 December 2018.

46th IOP Plasma Physics Conference: 23-26 April 2019 at Holywell Park, Loughborough, Leicestershire, UK. Details to follow.

COMMUNITY NEWS

AWE

Professional Technician Registration at AWE

Following the launch event of the Professional Technician Registration scheme with the Science Council last year several of AWE’s Orion technicians have now completed the process successfully.

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Once achieving registration, through the Science Council, the candidates are assessed through the appropriate scientific institute for membership; in the case of the Orion technicians the Institute of Physics (IOP). Eight of Orion’s technicians have now fully completed professional registration having either achieved the standard of Registered Scientist (RSci) and Member of the IOP (MInstP); or having achieved the standard of Registered Scientific Technician (RSciTech) and Associate Member of the IOP. All of those who have gained professional registration should be incredibly proud of their achievements and for helping AWE to pioneer this new initiative. AWE hopes that other technicians would be inspired to become professionally recognised for the tremendous work that they do.

Orion Technician Rich Thompson on receiving his RSciTech certificate said:

“After deciding that the world of academia wasn’t what I wanted I felt pretty certain that professional registration was well and truly out of my reach. I’d always thought it was something reserved for people with Bachelors, Masters or PhDs. So, it was refreshing to hear that the Science Council are recognising people not just on academic awards but also on the merit of their work in their day to day activities and the knowledge they gain from this.”

Orion’s Steve Fell-Lee on being awarded RSci said:

“The Science Council registration proves your value as a practicing scientist or science technician through the work you do by applying your knowledge, working with others, taking personal responsibility, personal integrity and professional development. I am extremely proud to have been awarded RSci, and would highly recommend professional registration to all.”

Orion’s Long Pulse Front-end Upgraded

As part of the programme of continual improvements to AWE’s Orion laser system the two Dual Operation Diode Amplifiers (DODA) have been upgraded to support 10 ns pulses, a great enhancement to Orion’s capability. The two Pre-Amplifier Modules (PAM) each have a DODA providing the first stage of pulse amplification in the long pulse beam lines.

The DODA consist of a linear cavity where an injected laser pulse circulates between two end mirrors. The pulse passes through the gain medium twice on each round trip through the cavity. The entry and exit of the pulse is controlled via its polarisation state. Once the pulse is injected into the cavity at a polariser, an electro-optic device utilising the Pockels effect is activated. This Pockels Cell keeps the pulse trapped in the cavity, passing through the gain medium around fifty times. At the point where the gain and loss in the cavity balance out the Pockels Cell is switched off and the pulse exits the cavity, this provides optimal energy stability.

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In addition to amplifying pulses the cavity can switch to a continuous wave (CW) mode, via an insertable mirror and additional end mirror. In CW mode the cavity is self-seeded and the polarisation state at the polariser set such that the leakage from the cavity is optimised for maximum power extraction. The use of the cavity in this way provides both an alignment source for amplification.

The cavity is ≈ 3.3 m long with a 22 ns round trip time allowing for a 10 ns pulse to be amplified without any overlap with itself with the gain medium. This is folded up onto a 1.2 by 0.6 m optical breadboard making it a modular item. The modular nature of the DODA allows offline development and optimisation of the design before it is used on the main system. Maximising operational efficiency when an upgrade takes place.

The upgrade of the two DODAs was carefully planned in to minimise any disruption to other laser maintenance activities on the long pulse system, de-risking any over run from the changes to the highly complex system. The removal and installation of the DODAs was under taken on a maintenance day with the excellent support of the Orion technicians. The alignment and commissioning then took a further day of lasers on time to bring the DODA to an operational state. Several PAM rod shots where then fired to confirm its operation and timing. The first DODA to be upgraded was on PAM01 last year, the PAM02 DODA has recently been installed completing the upgrade.

CCFE

£86 million boost for UK nuclear fusion programme

An £86 million Government investment in the nuclear fusion research programme at Culham was announced in December 2017. This investment will fund the building and operation of a National Fusion Technology Platform at Culham Science Centre, expected to open in 2020. The new facilities will support British industry and help to secure around £1 billion in contracts from the key international fusion research experiment ITER, now being built in France, and other global fusion projects. Looking further ahead, they will enable CCFE and its operator the UK Atomic Energy Authority to develop technology for the first nuclear fusion power plants and put UK industry in a strong position to exploit the commercialisation of this highly promising low-carbon energy source. The National Fusion Technology Platform comprises two new centres of excellence:

Hydrogen-3 Advanced Technology (H3AT) will research how to process and store tritium, one of the fuels that will power commercial fusion reactors;

Fusion Technology Facilities (FTF) will carry out thermal, mechanical, hydraulic and electromagnetic tests on prototype components under the conditions experienced inside fusion reactors.

The National Fusion Technology Platform will enhance the UK's expertise in critical areas of fusion research, with significant benefits to the economy as part of the Government's industrial strategy. It will also provide a powerful signal of the UK's intent to continue its participation in international science collaboration after leaving the European Union. So far, 38 UK companies have won contracts totalling over €500 million on the €14 billion ITER experiment – the stepping stone to fusion power stations.

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H3AT and FTF will work closely with the industrial supply chain to create knowledge to position them for the next phase of ITER procurements in areas including the tritium plant, Hot Cell, measurement systems, assembly, maintenance and reactor materials. The National Fusion Technology Platform is expected to create around 100 jobs at Culham Science Centre and many more in the wider nuclear industry supply chain. Head of CCFE, Professor Ian Chapman, said:

“Fusion is entering the delivery era, with an increasing focus on the key technologies that will be needed for the first power stations. The National Fusion Technology Platform will help British industry to maximise growth from opportunities provided by ITER. In the longer term it means the UK will be at the forefront of developing fusion and bringing cleaner energy to the world.”

The investment will add to Culham's existing facilities for mechanical testing (top image) and tritium handling (bottom image).

Obituary - Dr Don Sweetman

Dr Don Sweetman, who died just before Christmas 2017 aged 87, was a former director at Culham’s fusion research laboratory. Don started work with UKAEA in the nuclear research team at AWRE Aldermaston in Berkshire in 1955. Two years later he went to the USA as a Commonwealth Research Fellow at the Massachusetts Institute of Technology. On his return to Aldermaston in 1958, he joined the rapidly developing fusion activity there and led the team building the Phoenix mirror machine.

In 1962 he moved with members of his Phoenix team to Culham just after the laboratory been established to build an upgrade to Phoenix - ‘Phoenix II’. With a stint at Princeton Plasma Physics Laboratory in the USA also under his belt, Don returned to Culham where in 1971 he became Deputy Head of Experimental Division B with responsibility for both Phoenix and the Levitron. Under Don’s leadership and with his strong scientific involvement during the 1970s, the Levitron produced the first experimental results demonstrating that neutral beam and electron cyclotron wave heating could drive currents in the plasma, and that the observed currents agreed with theoretical predictions. During this time Don became a strong proponent and advocate of the use of neutral beam heating.

In 1979 Don was appointed Head of Experimental Division A where his remit included the DITE and CLEO machines and then in 1981 he became Head of the Experimental Division at Culham on the merger of Experimental Divisions A and B. He took over as Authority Programme Director for Fusion in 1987 on the retirement of Bas Pease – a title which changed to Director of UKAEA Fusion in 1993 - and he carried on in that role until his retirement in 1996. He was succeeded at Culham by Derek Robinson.

During his time at Culham, Don sustained a vibrant research programme in the face of substantial funding cuts to the UK’s nuclear fusion budget. Despite the difficult financial climate, he managed to find funds for the START device in the 1980s, which rapidly proved the promise of the spherical tokamak. Subsequently in the early 1990s Don was a key figure in getting Government and European approval for the construction of the spherical tokamak experiment MAST (Mega Amp Spherical

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Tokamak) at Culham. This was a significant achievement at a time when fusion funding was being questioned and it laid the foundations for CCFE’s current MAST Upgrade programme.

Don was widely respected amongst the UK and international fusion community. He was a member of the JET Council and Scientific Council among other international committees.

CLF

EPSRC-funded collaboration to assess shock ignition route to fusion and develop Odin code

As it stands, efforts to achieve energy gain via laser fusion are yet to be successful, but a recently proposed method called 'Shock Ignition' is looking very promising. In principle, this method is more efficient than conventional ICF schemes, so energy gain should be possible with a significantly smaller laser system than current multi-billion dollar laser fusion systems.

The coupled, non-linear nature of the physics of laser fusion, means simulation models are critical for designing and interpreting the experiments. Unfortunately, current simulation models are not sufficiently accurate to predict the observed experimental behaviour. A leading hypothesis for the causes of these inaccuracies are kinetic laser plasma interaction instabilities (LPIs). These alter the experiments in ways that are both hard to measure experimentally, and hard to model. The issue we face, is that current simulation codes used to design the laser fusion experiments do not account for LPIs and the changes they cause. This makes it very difficult to account for their effects, precluding the design of experiments with sufficient accuracy for energy gain.

In an attempt to address this problem, which is particularly important in the context of Shock Ignition, EPSRC has awarded a three year, £1.3 million grant led by Dr Robbie Scott (CLF) in conjunction with co-PI's Prof Nigel Woolsey (University of York), and Prof Tony Arber (University of Warwick). The project is being performed within a wider international collaboration involving the AWE, the University of Bordeaux (Prof Dimitri Batani, Prof Vladimir Tikhonchuk, Dr Alexis Casner), General Atomics (Dr M. Wei), UCSD (Prof F. Beg), MIT (Prof C. Li), and the Laboratory for Laser Energetics, Rochester, USA (Prof Riccardo Betti, Dr Wolfgang Theobald, Dr S. Regan).

Dr Robbie Scott said about this project:

“Over the next 3 years our team - and international collaborative partners - will perform a robust evaluation of the viability of the shock ignition approach to laser fusion. Current theoretical models indicate the shock ignition approach would require a significantly smaller, and cheaper, laser system than existing laser fusion ignition facilities."

Solving the mystery of why comets emit X-rays

A team of scientists including members of STFC’s Central Laser Facility and RAL Space have been able to unravel the mystery of why comets travelling through Space give off X-ray emissions. To investigate how X-rays can be emitted from a comet, a team of scientists from 15 research institutes performed experiments at the Laboratoire pour L'Utilisation des Lasers Intenses (LULI) in Paris where they replicated the interaction of the Solar-wind with a comet. The results of their experiment were analogous to many astrophysical systems, including the interaction of a comet with the solar wind. In order to learn more about this mystery, the international group created a model system by firing laser beams onto a plastic foil. This caused the foil to explode which led to the expulsion of a stream of ions and electrons which formed a high speed flow of ionized gas like the Solar wind. Prof Bob Bingham remarks:

“These experimental results are important as they provide direct laboratory evidence that objects moving through magnetized plasmas can be sites of electron acceleration- a very general situation in

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astrophysics that takes place not only in comets, but also in planetary magnetospheres, such as our own Earth, or even in supernova remnants, where the ejected material moves across the interstellar gas. The experiments also confirm theoretical models developed by the team."

The full publication is available to view in Nature Physics.

Gemini laser creates artificial gamma ray burst in the laboratory for the first time

A team, led by Queen's University Belfast, have used the Gemini laser at the CLF to recreate a mini gamma ray burst (GRB) - one of the most powerful explosions in the universe. Their experiment will further our understanding of black holes and pulsar emissions, and even fuel the search for extra-terrestrial life. They created a unique state of matter known as ‘neutral electron-positron plasma’ for the first time. In order to generate a beam containing equal amounts of electrons and positrons, called an EPB, the scientists channelled an intense laser pulse through a chamber filled with helium. Whilst the research group had generated a similar beam in previous experiments, never before has anyone been able to analyse their kinetics. By measuring the behaviour of the EPB, they revealed unprecedented insight into fundamental phenomena in basic pair plasma physics.

Lead scientist Dr Gianluca Sarri remarks:

"In our experiment, we were able to observe, for the first time, some of the key phenomena that play a major role in the generation of gamma ray bursts, such as the self-generation of magnetic fields that lasted for a long time. These were able to confirm some major theoretical predictions of the strength and distribution of these fields. In short, our experiment independently confirms that the models currently used to understand gamma ray bursts are on the right track.”

The research was supported by EPSRC and STFC and the full publication is available to view in Physical Review Letters.

PRIZES AND AWARDS

Fusion Power Associates 2017 Excellence in Fusion Engineering Award and Early Career Research Program award

Adam Sefkow, an assistant professor of mechanical engineering at the University of Rochester and senior scientist at the University’s Laboratory for Laser Energetics, is being recognized with two awards for his research in high-energy density physics and inertial confinement fusion. He has received a prestigious Early Career Research Program award from the US Department of Energy to develop a hybrid fluid-kinetic multi-physics simulation code to help interpret data acquired from high-energy-density physics and inertial confinement fusion experiments.

Sefkow will also receive the Fusion Power Associates 2017 Excellence in Fusion Engineering Award in recognition of his scientific contributions on a range of topics, including magneto-inertial fusion, short-pulse and long-pulse laser-plasma interaction physics, and intense charged-particle

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beam transport. He received his PhD from Princeton University in 2007, was a principal member of the technical staff in the Pulsed Power Sciences Center at Sandia National Laboratories before joining the University of Rochester in 2016.

Rutherford Prize for the Communication of Plasma Physics 2018 (sponsored by STFC)

Congratulations to Dr Jena Meinecke who is the 2018 winner of the Rutherford Prize for the Communication of Plasma Physics. Jena was the lead organiser for 2017 Royal Society Summer Exhibition stand ‘How to Make a Supernova’, featuring plasma research conducted on large laser facilities (focused on AWE’s Orion laser) to recreate astrophysical environments in the lab.

Jena led a collaborative team of 34 physicists from Imperial, Oxford and AWE and scored highly on presentation, scientific accuracy, impact, awareness, media skills and innovation and was noted for encompassing many outreach and media elements into the activity. The stand was visited by general public, school groups and VIP guests, with over 10,000 people attending the exhibition over the week.

Now time to think who you are going to nominate for the 2019 prize. Self-nominations are welcome and there’s no time limit as to when the activity took place.

Malcolm Haines Early Career Plasma Physics Prize

Thanks to a gift from his family, there will be a new IOP Prize for ‘Early Career Plasma Physicists’, remembering the major contributions Professor Malcolm Haines made to our subject. Full details will follow.

Photo credit: Kate Lancaster

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