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Phase Control Innovation Leads to Beam Teamwork

October 2019

Beams being combined

More powerful when working together

A breakthrough in phase control of ultrafast lasers is a milestone for a Berkeley Lab effort to develop a high-power laser based on coherently combining many low-power pulses from fiber-optic lasers. This could evolve into a system for powering the next generation of laser-plasma accelerators, such as those of ATAP’s BELLA Center.

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Lasers have progressed tremendously, but one thing remains the same: their applications always seem to need more power with better control.

As ATAP’s Berkeley Lab Laser Accelerator Center (BELLA) looks beyond its current experiments and toward the next generation of its innovative accelerators, it will need a new generation of lasers. They will have to provide significantly more power in shorter pulses at a much higher repetition rate than today’s.

One promising candidate is based on fiber optics. However, the power that can be extracted from each fiber is quite limited: some 10 millijoules. To use fiber technology for a laser suitable for the next generation of laser-plasma accelerators, dubbed “k-BELLA” for its kilohertz/kilowatt performance class, the beams from many fibers would have to be combined, obtaining joule-class output. For a laser-plasma accelerator, they would also have to be combined coherently in space and time so the results are seen by the laser-plasma accelerator as one powerful laser pulse, not as independent pulses in close proximity.

Coherent beam combining concept could be key to unprecedented beam power

This has been an active area of research here and elsewhere. A milestone in the Berkeley Lab effort last year — coherent temporal beam combining — has now been complemented by an innovative beam control technique that holds the key to adding coherent spatial combining. The effort is being led by Qiang Du of the BACI Program and the Engineering Division. Their results were recently published in the journal Optics Letters.

“We’re adding a second dimension to our capabilities,” said Du. The key innovation was realizing that side beams rejected in the diffractive beam-combining elements contain information on phase errors, and that this information can be fed back to the combiner in a system of reasonable performance and complexity.

The researchers are now scaling from a proof-of-principle experiment involving a few beams to an unprecedented 81 channels. The usable information increases along with the number of channels, allowing scaling to the hundreds of beams for joule-class combined output without slowing down the response time of the feedback loop.

The overall beam-combining effort is performed in close collaboration with the University of Michigan, home of a seminal idea and key expertise for coherent beam combining, and Lawrence Livermore National Laboratory.

To learn more…
Qiang Du, Tong Zhou, Lawrence R. Doolittle, Gang Huang, Derun Li, and Russell Wilcox, “Deterministic stabilization of eight-way 2D diffractive beam combining using pattern recognition,” Optics Letters 44, 18 (15 September 2019), pp. 4554-7 (11 September 2019),

It is the third in a series of Optics Letters that the Berkeley Lab researchers have published, following Tong Zhou et al., “Two-dimensional combination of eight ultrashort pulsed beams using a diffractive optic pair,” Optics Letters 43, 14 (11 Jule 2018), pp. 3269-72,, and Tong Zhou et al., “Coherent combination of ultrashort pulse beams using two diffractive optics,” Optics Letters 42, 21 (2 October 2017), pp. 4422-5,

BELLA Center Sets New Laser-Plasma Accelerator Electron Energy Record

February 2019
Computer visualization of acceleration; see linked article for detailsBy accelerating electrons to an energy of 7.8 GeV in just tens of centimeters, BELLA Center researchers have nearly doubled their own previous record for laser-driven particle acceleration, set in 2014 at 4.2 GeV. To learn more about this achievement and the techniques that made it possible, visit the news release from Berkeley Lab Strategic Communications or read the technical article in the journal Physical Review Letters.

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Meet the New Leaders of BELLA Center

February 2019
ATAP Interim Director Thomas Schenkel has named a leadership team for the Berkeley Lab Laser Accelerator Center (BELLA). Eric Esarey is the new Center Director, aided by Deputy Directors Cameron Geddes and Carl Schroeder.

All three are experienced BELLA Center research leaders, hold the rank of Senior Scientist, and are Fellows of the American Physical Society (Esarey since 1996, Schroeder 2012, Geddes 2016). The three were co-recipients in 2010 of the American Physical Society’s John Dawson Award for Excellence in Plasma Physics Research from the American Physical Society, and each has been twice recognized with the LBNL Outstanding Performance Award.
L-R: BELLA Center Director Eric Esarey and Deputies Carl Schroeder and Cameron Geddes

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Eric Esarey

Eric Esarey has been performing research on intense laser-plasma interactions, advanced accelerator concepts and novel radiation sources for over 30 years. After receiving his PhD in 1986 in plasma physics at MIT, he worked for 12 years at the Naval Research Laboratory. During that time, he and his colleagues pioneered fundamental theory on nonlinear laser-plasma interactions that described the physics of laser-plasma accelerators (LPAs) and carried out groundbreaking experiments on LPAs.

Esarey joined Berkeley Lab in 1998 as a physicist within the theory group of the Center for Beam Physics, where he continued researching LPAs and related phenomena. He helped found the BELLA Center and grow it into the world leading program that it is today. Esarey had previously served as BELLA Center’s Deputy and as Senior Scientific Advisor to the ATAP Division Director. He now succeeds BELLA’s founding director, Wim Leemans, who has left LBNL for a position at DESY.

Schenkel describes Esarey as “a visionary and longtime leader in the field of LPAs with an integrating perspective on the program.”

Esarey’s recent honors include the AAC Prize from the 2018 Advanced Accelerator Concepts Workshop (an event that he will chair in 2020). Among his numerous publications are comprehensive review articles on plasma accelerators that are highly cited within the community. A technical backgrounder accompanying the announcement 2018 Nobel Prize in Physics explained the LPA concept with a diagram originally published in Physics Today by Leemans and Esarey. (See the related article, “2018 Physics Nobel Cites an ATAP Application.”)

Esarey’s deputies are described by Schenkel as “capable, energetic, and with diverse scientific backgrounds,” exemplars of a strong BELLA team “hungry for achievement.”

Carl Schroeder has been a leader of the theoretical and modeling efforts that support BELLA’s experimental work and future applications. After earning his doctorate at UC-Berkeley in 1999, followed by a postdoctoral fellowship at UCLA, he joined LBNL in 2001. His research interests range across BELLA’s intellectual portfolio, including intense laser-plasma interactions, plasma-based accelerators, advanced acceleration concepts, novel radiation sources, and free-electron lasers. “Carl is a theoretical leader not only in BELLA’s current work, but also in the long-term push toward an LPA-based lepton collider,” says Schenkel.

“Ultimately,” he adds, “mastery of laser drive plasma accelerators will enable us to explore physics beyond the Standard Model, and to make strides in understanding the nature of matter and energy, and do so with a much smaller physical and financial footprint than today’s collider technologies. Carl is driving this vision and is laying the foundation for its practical implementation.”

Cameron GeddesCameron Geddes is the lead experimentalist in the new BELLA Center leadership team.

“Cameron has a very strong foundation in high-energy and ultrafast lasers, and since his days as a graduate student has been a driving force and leader in the projects he works on,” says Schenkel.

Geddes has led a variety of the Center’s experimental projects. This includes a new laser facility for one of the many promising near-term applications of laser-plasma accelerators: compact quasi-monoenergetic gamma-ray sources for nuclear nonproliferation and security inspection. He has broad research experience in plasma physics, which at Berkeley Lab has included experimental designs for the PW laser, demonstration of novel concepts in particle injection and beam quality, staging experiments, high energy density science, and large-scale simulations. After working at Lawrence Livermore National Laboratory and Polymath Research on inertial-fusion-related laser-plasma interactions, he earned his doctorate at UC-Berkeley and LBNL in 2005, receiving the Hertz and APS Rosenbluth dissertation prizes. He joined the LBNL staff upon graduation. “Cameron brought a strong foundation in high-energy and ultrafast lasers to us, and since his days as a graduate student has always been a leader in everything he works on,” says Schenkel.

The path forward

BELLA Center is a world leader in the study of intense laser-plasma interactions and advancing the development of LPAs. Research there has demonstrated increasing single-stage electron beam energy gains, now at several GeV, together with lower-energy experiments on staging and on achieving high beam quality.

Going to ever higher energies will require using one LPA stage’s output as the input to the next, achieving more energy than is practical for a single stage. BELLA has achieved a first demonstration of staging. A major next step is to develop and implement a multi-GeV staging experiment. This very exciting and important effort has now been started with funding from DOE High Energy Physics.

In addition to electron beam acceleration, BELLA is exploring the applications of laser-plasma accelerated electron beams, e.g., with programs to develop compact radiation sources based on LPA electron beams.

Higher average laser power will be required for a lepton collider and also for many near-term LPA applications, and the BELLA Center is performing R&D to advance the development of these lasers. Fiber-based laser systems are among the candidates for this key enabling technology.

“Eric, Cameron, and Carl are all distinguished individuals and team leaders in their disciplines, and have been working together for many years to keep BELLA at the forefront of laser-plasma acceleration,” Schenkel says, adding, “BELLA is sure to enjoy continued growth and achievement under their leadership.”

Berkeley Lab Joins LaserNetUS

To help foster the broad applicability of high-intensity lasers, Berkeley Lab is a partner in a new research network called LaserNetUS. The network will provide U.S. scientists increased access to the unique high-intensity laser facilities at BELLA Center and at eight other institutions nationwide operating high-intensity, ultra­fast lasers.

LaserNetUS has had its first call for research proposals. It is anticipated that the winning proposals for this initial “Run 1” will be announced in mid-2019, with experiments to ensue through the remainder of calendar 2019.

The BELLA facilities available to outside users through LaserNetUS are described in detail here.

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Expanding access to key capabilities
“High-intensity and ultrafast lasers have come to be essential tools in many of the sciences, and in engineering applications as well,” said James Symons, Berkeley Lab’s associate laboratory director for its Physical Sciences Area.

Such lasers have a broad range of uses in basic research, manufacturing, and medicine. For example, they can be used to recreate some of the most extreme conditions in the universe, such as those found in supernova explosions and near black holes. They can generate high-energy particles for high-energy physics research (being explored at the BELLA Center) or intense X-ray pulses to probe matter as it evolves on ultrafast timescales. Laser-based systems can also cut materials precisely, generate intense neutron bursts to evaluate aging aircraft components, and potentially deliver tightly focused radiation therapy to tumors, among other uses.

The petawatt-class lasers of the LaserNetUS partners generate light with at least 1 million billion watts of power. A petawatt is nearly 100 times the output of all the world’s power plants, and yet these lasers achieve this threshold in the briefest of bursts. Using a technology called “chirped pulse amplification,” which was pioneered by two of the winners of this year’s Nobel Prize in physics, these lasers fire off bursts of light shorter than a tenth of a trillionth of a second.

Maintaining U.S. leadership in a fast-moving global endeavor
The U.S. was the dominant innovator and user of high-intensity laser technology in the 1990s, but now Europe and Asia have taken the lead, according to a recent report from the National Academies of Sciences, Engineering, and Medicine titled “Opportunities in Intense Ultrafast Lasers: Reaching for the Brightest Light.” Currently, 80 to 90 percent of the world’s high-intensity ultrafast laser systems are overseas, and all of the highest-power research lasers that are currently in construction or have already been built are also overseas. The report’s authors recommended establishing a national network of laser facilities to emulate successful efforts in Europe.

LaserNetUS is holding a nationwide call for proposals that will allow any researcher in the U.S. to request time on one of the high-intensity lasers at the LaserNetUS host institutions.. The proposals, due March 18, will be peer reviewed by an independent proposal review panel. This call will allow any researcher in the U.S. to apply for time on one of the high intensity lasers at the LaserNetUS host institutions. The initial “Run 1” experiments are expected to take place in the second half of calendar 2019.


A message from Associate Laboratory Director James Symons

Part of two-page spread from Nobel Prize background document, showing cover and BELLA discussion
Click here
for a larger picture, or here for a PDF of the entire document
Dear colleagues,

This year’s Nobel Prize in Physics was shared by three pioneers in the science, technology, and applications of lasers. Two of the laureates — Gérard Mourou and his then doctoral student Donna Strickland — won for a breakthrough that (among its many other benefits) made our Berkeley Lab Laser Accelerator Center possible.

Their Nobel-winning research brought “chirped pulse amplification,” a method of generating high-intensity, ultra-short pulses, to lasers. In a mere three pages, their 1985 paper “Compression of Amplified Chirped Optical Pulses” (Optics Communications 56, 3 (1 December 1985), pp. 219-221) sparked a revolution. The concept was implemented widely and almost immediately, ending a decade-long plateau in laser performance.

Today, CPA and follow-on developments are used near-universally at the peak-power frontier of very large research lasers, and also to increase the peak power of relatively small lasers for a wide variety of industrial and medical applications as well as research. (To take just one of many examples, some of you may be reading this with vision corrected by LASIK surgery, a technology made feasible for widespread use by CPA.)

We were immensely gratified to see laser-plasma acceleration, and specifically the multi-GeV electron beams obtained at the BELLA facility, mentioned as one of the examples of the benefits of CPA in the Nobel committee’s scientific background document. The BELLA Petawatt system is a 1 Hz repetition rate Ti:sapphire laser based on the CPA technique pioneered by Strickland and Mourou. In addition to the discussion, the Nobel backgrounder used a conceptual diagram of the LPA principle from the 2010 White Paper of the ICFA/ICUIL Joint Task Force on High Power Laser Technology for Accelerators —a figure that had originally appeared in an article by Wim Leemans and Eric Esarey in the March 2009 issue of Physics Today.

The white paper was produced by a joint task force, chaired by ATAP Division Director Wim Leemans, of the International Committee on Future Accelerators and International Committee on Ultra-high Intensity Lasers, and was based on a workshop series held first at GSI and then here at LBNL. The notional BELLA follow-on, which we call k-BELLA for its kilohertz repetition rate / kilowatt average power performance class, is an example of such a next-generation laser.

CPA is also one of the techniques used in an exciting collaborative project being conducted through our Berkeley Accelerator Controls and Instrumentation (BACI) Center: development of a laser system that uses “coherent combining” to achieve both high peak power and high average power from arrays of fiber-optic lasers.

Please join me in offering congratulations on the scientific stature and the widespread, ongoing societal impact of the research by Drs. Mourou and Strickland, as well as their co-laureate Dr. Arthur Ashkin. (He is a pioneer of laser trapping and the inventor of “optical tweezers” that use lasers to grasp tiny physical particles such as bacteria or viruses. His work had already figured into the 1997 Nobel Prize in Physics for our former Lab director and Secretary of Energy Steven Chu, who had worked with Ashkin at Bell Labs.) Their achievements have given us both game-changing tools and inspiration. This is a time for all of us to be proud of the important role we play as research pioneers and the resulting benefit to humankind.

James Symons
Associate Lab Director
Physical Sciences Area

Study Points to Laser-Electron Collider As Potential Gamma-Ray Source

An international team of researchers, including Stepan Bulanov, a theorist with ATAP’s Berkeley Lab Laser Accelerator (BELLA) Center, has calculated that collisions between powerful lasers and high-energy electron beams could provide an attractive new way to generate gamma rays. Their results were published July 17 in the journal Physical Review Letters.

The study was prompted by the accessibility of today’s petawatt-class laser systems (including BELLA) and the near-future prospects for multi-PW facilities, at least five of which are being planned worldwide. Such facilities, the study found, can create laser fields strong enough to interact with high-energy electron beams and convert the electrons into multi-GeV photons (gamma rays). In order to favor the emission of high-energy photons and minimize their decay into electron-positron pairs, which is very probable in the fields of high intensity lasers, the fields must not only be sufficiently strong, but also well localized. The photons emitted could have energies of more than half the electron-beam energy, and more than 18% of the electrons would be converted into photons.

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Conceptual diagram of laser-electron collider as source of GeV photons

Conceptual visualization of the setup, where high-energy electrons (blue) are injected along the axis of an intense dipole wave. In this field, the electrons will emit large amounts of high-energy photons (yellow). The polarization of the field shown here is that of an electric dipole, with a poloidal electric field (red) and a toroidal magnetic field (green).

The electron beam could be provided by either a conventional accelerator or a laser-plasma accelerator such as BELLA. Among the findings of the study was that the optimum power for the scattering laser would be around 0.4 PW, with higher powers actually being detrimental to the goal of producing high-energy photons. This suggests that a future laser of the 10-PW class might be able to provide the scattering beam while also driving a laser-plasma accelerator to provide the electron beam.

Uses of these concentrated gamma-ray beams include nuclear and quark-gluon physics and astrophysics. Gamma ray beams are already available to researchers, but this new concept offers potential advantages. The combination of photon energy and intense concentration would be unique, and would exceed parameters available from Compton backscattering sources. The output would also be free of the neutrons and other heavy particles that come from bremsstrahlung sources. Polarization could be among the other beam attributes useful to researchers.

The study was conducted by researchers from Chalmers University of Technology and the University of Gothenburg in Sweden; Japan’s Kansai Photon Science Institute; and the ELI-Beamlines Project in Europe’s Extreme Light Infrastructure, as well as Berkeley Lab.

To learn more…

New laser physics achieves energy at astronomical levels,” news release, Carolina Svensson, University of Gothenburg.

Laser-Particle Collider for Multi-GeV Photon Production,” J. Magnusson, A. Gonoskov, M. Marklund, T. Zh. Esirkepov, J.K. Koga, K. Kondo, M. Kando, S.V. Bulanov, G. Korn, and S.S. Bulanov, Phys. Rev. Lett. 122, 254801 (17 June 2019).

BELLA’s Eric Esarey honored with Advanced Accelerator Concepts Prize

Eric Esarey, a senior scientist in Berkeley Lab’s Accelerator Technology and Applied Physics Division (ATAP), has been awarded the 2018 Advanced Accelerator Concepts Prize “for his pioneering theoretical research in the physics of laser-plasma accelerators.”

The prize, which recognizes outstanding contributions to the science and technology of advanced accelerator concepts, is awarded at the biennial Advanced Accelerator Concepts Workshop. Esarey joins a who’s who of researchers in cutting-edge approaches to particle acceleration, including ATAP Director Wim Leemans, who was honored in 2012.

Esarey came to Berkeley Lab 20 years ago, bringing plasma-theory expertise to the burgeoning effort in laser-plasma accelerators that is now known as BELLA Center. Previously he had worked for 12 years at the Naval Research Laboratory after earning his doctorate from MIT.

Theory and experiment have been partners in BELLA from the outset in the understanding of how intense lasers and plasmas interact, how an electron beam can “surf” the resulting electromagnetic wave, and how the promise of practical accelerators based on this principle might be fulfilled. Esarey serves as BELLA Center’s deputy, leading the theoretical and computational work that guides and supports the experimental efforts, and is also senior scientific advisor of ATAP Division.

Esarey was elected a Fellow of the American Physical Society (APS) in 1996 for “seminal scientific contributions to the physics of intense laser-plasma interaction.” In 2010, the APS honored him with the John Dawson Award for Excellence in Plasma Physics Research “for experiments and theory leading to the demonstration of high-quality electron beams from laser-plasma accelerators.”

AAC 2018 student-poster honors for BELLA’s Liona Fan-Chiang

BELLA Center and UC-Berkeley graduate student Liona Fan-Chiang was one of eight student poster honorees at the Advanced Accelerator Concepts Workship, winning for “Planar Laser-Induced Fluorescence for Custom Laser Plasma Accelerator Targets.”

Liona Fan-Chiang
Click for larger version
Liona Fan-Chiang previewed her award-winning presentation when DOE’s General Accelerator R&D Program Comparative Review came to LBNL in August 2018. Leemans and staff scientist Hann-Shin Mao collaborated with her on the work described in the poster.

The win continues an emerging tradition: Kelly Swanson of BELLA and UCB, who like Fan-Chiang is one of Leemans’s students, won student-poster honors at AAC 2016, as did Manuel Kirchen, a BELLA visitor from the University of Hamburg and DESY.

Berkeley Lab’s fruitful association with AAC continues

Fan-Chiang’s presentation was part of a strong Berkeley Lab presence (28 participants, who among them gave 20 orals, including three invited plenaries; three working-group summaries; and six posters) at the Workshop.

In 2020, the AAC Workshop will be hosted by Berkeley Lab (which had co-organized the 2008 AAC, together with UC-Berkeley). Esarey will chair the 2020 event.

Report on Laser Technology for k-BELLA and Beyond Available

Click to download Report of Workshop on Laser Technology for k-BELLA and Beyond (September 2017).

The report comes from a workshop, held at LBNL May 9-11, on near- and long-term technology prospects for ultrafast lasers that could operate in the multi-kW to even tens-of-kW average power range. Such laser performance is needed for k-BELLA, further stepping stones to a laser-plasma accelerator relevant to high-energy physics, and spinoff benefits en route.

Leemans Wins IEEE’s Particle Accelerator Science & Technology Award

Brookhaven’s Ilan Ben-Zvi (l.) presents the award to Leemans
Dr. Wim Leemans, BELLA Center and Accelerator Technology and Applied Physics Division Director, was recognized with the IEEE Particle Accelerator Science and Technology Award. He received the award in an October 13, 2016 ceremony at the North American Particle Accelerator Conference (NA-PAC 2016).

Leemans was honored “for pioneering development of laser-plasma accelerators.” One of the leaders in the field, he is director of ATAP’s Berkeley Lab Laser Accelerator (BELLA) Center as well as of ATAP. He had already been elected a Fellow of the IEEE.

At each NA-PAC, the IEEE Nuclear and Plasma Sciences Society gives this award to two individuals who have made outstanding contributions to the development of particle accelerator science and technology.

“It’s quite an honor to be in such company,” says Leemans of the accelerator science and technology luminaries who have been recognized with the PAST Award. He joins four previous recipients from ATAP and its predecessor organizations, starting with inaugural winner L. Jackson Laslett and including Ronald M. Scanlan, Ka-Ngo Leung, and Alpert Garren.

BELLA Center’s Cameron Geddes Named a Fellow of the American Physical Society

CGRGeddes_150x180y_28July2015 BELLA Center’s Dr. Cameron Geddes has joined the ranks of Fellows of the APS. Geddes was honored in 2016 “for research demonstrating the production of high quality electron beams from laser plasma accelerators.”

APS Fellows are recognized by their peers “for exceptional contributions to the physics enterprise; e.g., outstanding physics research, important applications of physics, leadership in or service to physics, or significant contributions to physics education.” Geddes joins 25 other present and former staff members of ATAP and its predecessor organization, the Accelerator and Fusion Research Division, to be so honored. Six other researchers associated with Berkeley Lab also received the distinction in 2016.

Early Career Research Program Award for BELLA Center’s Jeroen van Tilborg

JVanTilborg_75x90y BELLA scientist Jeroen van Tilborg has received a DOE Early Career Research Program Award. He joins Chad Mitchell of the ATAP Division’s Center for Beam Physics among LBNL’s five 2016 recipients. They were among 49 winners nationwide out of 720 applicants in this prestigious Office of Science program for researchers who have received their PhD within the last 10 years. Click here for an LBNL Public Affairs story about the May 3 announcement.

BELLA Center Demonstrates Staging; Major Proof of Concept On Road to Future Laser-Plasma Accelerators

Staging_sim_cookie_150x149y Many laser-plasma accelerator (LPA) applications will require far more beam energy than is reasonable to achieve in a single accelerating stage. BELLA Center researchers have recently demonstrated coupling of an accelerated beam from one LPA stage into another. This is considered an essential technique for the future of LPA Their work is described in an article published February 1, 2016 in Nature.

In addition to being a pathway to higher energies, staging can also be used to decelerate an electron beam that has served its purpose, rather than sending it to a beam dump that must be shielded against the radiation that would result. This could further improve the compactness of, say, future light sources, or portable applications in homeland security or medical treatment.

To learn more, see the February 2016 edition of the ATAP Newsletter.

LPA_FEL_100x67y   Moore Foundation Backs BELLA FEL with $2.4M Grant

BELLA researchers will receive $2.4 million from the Gordon and Betty Moore Foundation to develop compact free-electron lasers that will serve as powerful, affordable x-ray sources for scientific discovery. This new technology could lead to portable and high-contrast imaging with x-ray accelerators to observe chemical reactions, visualize the flow of electrons, or watch biological processes unfold. To learn more, see the February 2016 edition of the ATAP Newsletter.

Workshops forge aspects of plasma accelerator futures

A pair of workshops hosted by ATAP Division in January, with results that are feeding into higher-level strategic-planning processes in the plasma-based-accelerator and laser-technology communities, will have implications for the next moves of BELLA and the future of accelerators. The Plasma-Based Accelerator Concepts for Colliders Workshop was intended to “identify the key physics and technology R&D needed to realize a plasma-based collider, and to formulate a nationally and internationally coordinated roadmap for carrying out this research over the next two decades.”

Besides electrons, the present and future BELLA lasers and laser-plasma acceleration concepts also offer the prospect of compact, efficient acceleration of ions. The repetition rate, spot size, and intensity of BELLA lasers could open new doors for discovery science related to plasma physics, high-energy-density physics, and nuclear physics, with spinoff prospects including cancer treatment and nuclear security. The Workshop on High Energy Density Physics with BELLA-i discussed this unique opportunity for discovery science as well as applications.

Visit the April 2016 ATAP Newsletter for more information on these workshops.

BELLA reaches 4.2 GeV, a record energy for laser-plasma accelerators

Nine-cm-long capillary discharge waveguide used to generate multi-GeV electron beams. Plasma plume made more prominent with HDR photography. (LBNL photo by Roy Kaltschmidt.) DECEMBER 2014 — BELLA has set a new energy record for these compact accelerators by reaching 4.2 giga-electron-volts in the nine-inch capillary discharge waveguide shown here. In this photo by LBNL's Roy Kaltschmidt, the plasma plume has been made more prominent with HDR photography. More…

BELLA Center study points to easing of laser-pulse quality requirements for pulse combining in LPAs

3D map of the longitudinal wakefield generated by the incoherent combination of 208 low-energy laser beamlets MAY 2014 — One attractive approach to producing powerful laser pulses, as required in laser-plasma accelerators, involves combining many lower-powered pulses. Theory-guided modeling at the BELLA Center suggests that when the destination is the plasma of an LPA, the similarity of these pulses does not need to be as rigorous as previously thought—welcome news for the cost and complexity of LPA systems. Their work is the cover story in the May 2014 issue of Physics of Plasmas, and is summarized and interpreted in this news release by American Institute of Physics staff and this story by LBNL Public Affairs.

BELLA Team honored with Secretary of Energy Achievement Award

From left, Sergio Zimmermann of Engineering, who was the Project Manager; Wim Leemans, who was Project Director and is now Center Director; Suzanne Suskind, the DOE Federal Project Director for BELLA; David Klaus, Deputy Under Secretary for Management and Performance; and Ted Lavine, the DOE Office of Science Program Manager for BELLA.
L-R: Sergio Zimmermann, Wim Leemans, Suzanne Suskind, David Klaus, and Ted Lavine at the award presentation.
APRIL 2014 — The project team behind BELLA has been commended by Energy Secretary Ernest Moniz for “outstanding ingenuity and exceptional project performance” resulting in a facility that is now “operating at unprecedented performance levels and enabling breakthrough advances”. On hand to accept the award at the recent DOE Project Management Workshop were (from left) Wim Leemans of AFRD, who was Project Director and is now Center Director, and Sergio Zimmermann of Engineering, who was the Project Manager; Suzanne Suskind, the DOE Federal Project Director for BELLA; David Klaus, Deputy Under Secretary for Management and Performance; and Ted Lavine, the DOE Office of Science Program Manager for BELLA.

BELLA Laser achieves world record power at one pulse per second

The BELLA laser bay at a late stage of construction, "front end" in foreground
BELLA laser bay at a late stage of construction, "front end" in foreground
July 20, 2012 — On this night the BELLA laser system delivered a petawatt of power in a pulse just 40 femtoseconds long at a pulse rate of one hertz — one pulse every second. A petawatt is 1015 watts, a quadrillion watts, and a femtosecond is 10-15 second, a quadrillionth of a second. No other laser system has achieved this peak power at this rapid pulse rate. For further information, see the LBNL press release and this Scientific American news item.

Wim Leemans wins AAC 2012 Prize

Leemans ca. 2012

JUNE 14, 2012 — The third Advanced Accelerator Concepts (AAC) Prize was awarded to Dr. Wim Leemans of Lawrence Berkeley National Laboratory (LBNL), head of the BELLA Center, “for outstanding contributions to the science and technology of laser-plasma accelerators.” More information can be found at the AAC 2012 website.

State-of-the-Art Beams From Table-Top Accelerators

Diagram of spectroscopy apparatus - click for larger version
Diagram of spectroscopy apparatus. Click for larger version.
AUGUST 2010 — Laser-plasma accelerators can produce high-energy electron beams with an emittance as good as beams from state-of-the-art conventional accelerators for free electron lasers and gamma-ray sources. The emittance of LPA beams has been measured using a new technique based on single-shot x-ray spectroscopy. The research appears in Physical Review Letters: “Low-emittance electron bunches from a laser-plasma accelerator measured using single-shot x-ray spectroscopy,” by G.R. Plateau, C.G.R. Geddes, D.B. Thorn, M. Chen, C. Benedetti, E. Esarey, A. J. Gonsalves, N.H. Matlis, K. Nakamura, C. B. Schroeder, S. Shiraishi, T. Sokollik, J. van Tilborg, Cs. Toth, S. Trotsenko, T. S. Kim, M. Battaglia, Th. Stöhlker, and W.P. Leemans, August 2010. For more information, see this LBNL press release. The technical paper is available here.

BELLA Center Members Win 2010 Dawson Award

L-R: Csaba Toth, Eric Esarey, Wim Leemans, Cameron Geddes, and Carl Schroeder
L-R: Toth, Esarey, Leemans, Geddes, Schroeder
JULY 12, 2010 — “For experiments and theory leading to the demonstration of high-quality electron beams from laser-plasma accelerators,” the American Physical Society’s 2010 John Dawson Award for Excellence in Plasma Physics Research has been given to (from left) Csaba Toth, Eric Esarey, Wim Leemans, Cameron Geddes, and Carl Schroeder of the BELLA Center, which Leemans heads. Simon Hooker of Oxford University collaborated in the research that inspired the award, and shares the prize. The award was presented at the APS Division of Plasma Physics meeting in Chicago, November 8-12, 2010. To learn more, see this issue of Today at Berkeley Lab.

Wim Leemans Wins 2009 E.O. Lawrence Award

Leemans ca. 2012

DECEMBER 16, 2009 — Wim Leemans, head of the BELLA Center, is one of six 2009 recipients of the U.S. Department of Energy’s highest honor, the Ernest Orlando Lawrence Award, for his pioneering research with laser wakefield accelerators.
For more information, see the LBNL press release.

GeV electron beams from a cm-scale accelerator

Data from GeV-on-cm-scale paper

1 GeV in only 3.3 cm

OCTOBER 2006 — BELLA Center researchers, together with colleagues from the University of Oxford, have accelerated electrons to more than 1 GeV in only 3.3 cm. This is the highest energy achieved with laser-wakefield acceleration, which harnesses the electric field of a plasma wave driven by a laser beam. Results have been published in “GeV electron beams from a cm-scale accelerator”, W. P. Leemans, B. Nagler, A. J. Gonsalves, Cs. Toth, K. Nakamura, C.G.R. Geddes, E. Esarey, C.B. Schroeder, and S.M. Hooker, Nature Physics 2 (October 2006), pp. 696-699. More information can be found in this LBNL press release. The technical paper describing the achievement is nphys418.

High-quality electron beams from a laser wakefield accelerator using plasma-channel guiding

High-quality 100 MeV beams
SEPTEMBER 2004 — High-quality electron beams have been obtained by first shaping a channel through hydrogen gas with powerful, precisely timed laser pulses, then accelerating bunches of electrons through the plasma inside the channel. Because of the controlled accelerator length and the characteristics of the channel, there are several billion electrons in each bunch within a few percent of the same high energy, more than 80 MeV. Results have been published in “High-quality electron beams from a laser wakefield accelerator using plasma-channel guiding”, C.G.R. Geddes, Cs. Toth, J. van Tilborg, E. Esarey, C. Schroeder, D. Bruhwiler, C. Nieter, J. Cary, and W.P. Leemans, Nature 431 (September 2004), pp. 538-541. For more information, see the LBNL press release. The technical journal article is here.