- Nature, S. Corde et al, august 27th, 2015 - For several years, plasma accelerators have shown their tremendous ability to accelerate particle beams. One objective is to downsize the experimental facilities and to allow the generation of very high energies while keeping the infrastructures within achievable size. To date, plasmas created by laser based on the interaction of an intense femtosecond laser with the matter or plasmas created by electron beams generated from RF accelerators, have accelerated energetic electrons with remarkable properties like ultrafast pulse duration, charge, energy or compactness in the case of lasers.
Sébastien Corde, researcher at LOA, has this time shown (Nature on August 27, 2015) with an international team working on the SLAC-FACET infrastructure at Stanford (USA), how these plasmas can be used to accelerate an other type of particles, the positrons. A positron beam with an initial energy of 20 GeV could gain 5 GeV by capturing about 30% of the energy of the plasma. These results are an important step toward the realisation of the next generation of particle colliders.
- Illustration: Weiming An (UCLA)
- More information:
laser-plasma accelerators at LOA
Victor Malka, CNRS Research Director at LOA (Laboratoire d’Optique Appliquée - École polytechnique, ENSTA Paris-Tech, CNRS) presents in this "Labshot" his work on the laser-plasma accelerators.
Laser-plasma accelerators have potential applications in radiotherapy, in medical imaging and in materials’ science.
Medical X-ray imaging at LOA
A European FET OPEN program on medical x-ray imaging has been awarded to LOA early in March 2015. The project, called VOXEL (Volumetric medical X-ray imaging at extremely low dose) is part of the European framework programme Horizon 2020 on Research and Innovation actions for Future and Emerging Technologies. Coordinated by IST (Portugal), the project gathers research teams from France (LOA, Imagine Optic, LIDyL), Netherland (CWI), Italy (CNR) and Spain (UPM).
Abstract of the project:
Computerized Tomography (CT) has been one of the greatest achievements in medical imaging, but at the cost of a high, potentially harmful, X-ray irradiation dose. The ultimate goal of VOXEL is to provide an alternative to tomography with a disruptive technology enabling 3D X-ray imaging at very low dose. VOXEL aims at prototyping new cameras working in the soft and hard X-rays (< 10 keV) that will combine the X-ray penetration and nanometre spatial resolution, easiness to use, afforded by avoiding the rotation of the source or the sample, and extremely low dose for maximum impact on medicine and biology.
VOXEL relies on the integration of trans-disciplinary fields in medical imaging, optics, X-ray physics, applied mathematics and value to society through foreseeable commercialization. VOXEL aims at prototyping in parallel a soft X-ray “water window” microscope and a hard X-ray 3D camera for medical applications (< 10 keV). While both cameras need groundbreaking development in the underlying physics, only hard X-ray camera has high technological risk (and high societal impact). VOXEL will benefit from the soft X-ray camera thanks to its Biological applications in nano-tomography but also as a test platform for our physical and mathematical models.
The VOXEL team members are leaders in X-ray metrology, wavefront sensing, atomic physic, mathematical computing and 3D medical imaging; with VOXEL we are uniquely positioned to succeed, and to raise the competitiveness of Europe. Doing so by basing the research lead in Portugal with a woman coordinator will be exemplary: beyond the scientific and technological success, thanks to our focus in science and its valorisation, VOXEL will be transformative for scientifically emerging countries.
New ERC Proof of Concept grant at LOA
January 22th, 2015 - An ERC grant Proof of Concept (POC) has been awarded to LOA (V. Malka) on the development of innovative technologies for cancer detection at an early stage. The project includes the scientific developments of several LOA researchers like K. Ta Phuoc, C. Thaury and S. Corde. The most advanced electron beams produced by laser plasma accelerators will be used to radiate a bright, tunable X ray beam to significantly improve the spatial resolution of the imaging technique of low contrast biological objects.
ERC POC grants support high-risk/high-gain research at the frontiers of knowledge to generate unexpected or new opportunities for commercial and societal applications. It helps ERC grant-holders (Advanced grant in this case) to bridge the gap between research and the earliest stage of a marketable innovation.
This is the fifth ERC grant awaded to LOA researchers.
E. Fabre prize for LOA
Stéphane Sebban, CNRS researcher at LOA, won the E. Fabre international award for his pioneering work on X-ray laser developments using intense femtosecond lasers and plasmas. The prize was delivered at the 17th International Congress on Plasma Physics (ICPP 2014) held in Lisbon, Portugal, and is awarded to experienced international researchers having a research activity of less than 15 years after their PhD.
First energetic protons at SAPHIR
First energetic protons at SAPHIR -
SAPHIR project aims at determining the technical and economical viability of laser protons therapy, as an alternative to the classical particle acceleration technics for curing cancer. The final goal of this project is to realize a compact and affordable system to be installed directly in hospitals, thus spreading the use of this treatment.
5 laboratories and French institutions (LOA , CPO / Institut Curie , Institut Gustave Roussy , CEA DAM / LIRM IRAMIS and CEA Saclay ) and 4 industrial partners (Amplitude Technologies, Dosisoft , Imagine Optic and Propulse SAS) are involved in SAPHIR. This interdisciplinary project connects physics, biology , oncology, and is largely devoted to technology transfer from basic research to industry.
The experimental system is installed on the site of the LOA at Palaiseau. It has recently been commissioned and the first energetic protons were produced to validate the experimental setup. 5 MeV protons have been generated with a laser energy of about 3J on target and a pulse length of 40 fs. The upgrade of the laser power will allow to study the parameters for efficient production of protons of several hundred MeVs.
Image Caption : Thomson parabola data showing accelerated protons from a solid target
( 6 microns thick) and four traces of carbon ions ( C +, C4 + ) .
ERC Senior Grant awarded at LOA
Victor Malka, head of the research group SPL at LOA has been awarded the prestigious 2013 European ERC grant. The objective of the so called X-5 project is to demonstrate the feasibility of the 5th generation of high energy radiation sources, which are expected to be compact, to lower the costs, and to meet the growing demand of the scientific community. These novel sources will be produced using laser-based high-energy electron accelerators coupled to magnetic permanent magnet undulators or plasma wigglers. The project includes a strong collaboration with teams from the Synchrotron SOLEIL. This is the 4th ERC grant awarded to LOA teams.
ERC Advanced Grants allow exceptional established research leaders of any nationality and any age to pursue ground-breaking, high-risk projects that open new directions in their respective research fields or other domains.
The ERC Advanced Grant funding targets researchers who have already established themselves as independent research leaders in their own right.
The upgraded Salle Jaune Laser shines again
After 1 year and a half break and an intense work of the technical support and researchers teams to carry out a huge upgrade program, the LOA laser Facility "Salle Jaune" and the related experimental sites have just done their first shots on target.
First experiments of laser-matter interaction have been performed successfully on the acceleration of energetic electrons (image: 3 electron spectra around 400 MeV from 3 consecutive laser shots) and the generation of ultrashort X-rays. It is remarkable that these first results were obtained only a few minutes after re-focusing the laser on target for the first time since the stop of the facility 18 months ago, indicating a very high quality of the laser beam properties and of the interaction parameters.
The laser now delivers a power of 120 TW on target splitted on multiple beams. Three fully equiped experimental sites are now available to perform complex plasma physics experiments thanks to the multiple beams spatially and temporally synchronized.
This project was funded by ENSTA, Ecole Polytechnique, CNRS and numerous contracts including a ERC European project and few ANR programs from the french Ministery of Research.
Rainbow pattern from laser-plasmas
Intense light pulses that can precisely sculpt solid materials also generate dazzling rainbow patterns that reveal information about the surface.
Not just a pretty face. This colorful pattern of light scattered from a solid surface being hit with laser pulses can convey details of the surface damage, such as the size of the laser-generated crater.
A spectacular sunburst of colored light produced as a laser beam bores into a solid surface could reveal information about the damage the light causes, according to a report in Physical Review Letters. The authors observed the rainbow pattern as they blasted a series of transparent materials such as glass and quartz with intense laser pulses. The team says that this effect, surprisingly overlooked until now, could offer a way of monitoring laser ablation, a technique used in fields as varied as dental surgery and art preservation.
- Ciliary White Light: Optical Aspect of Ultrashort Laser Ablation on Transparent Dielectrics
Yi Liu, Yohann Brelet, Zhanbing He, Linwei Yu, Sergey Mitryukovskiy, Aurélien Houard, Benjamin Forestier, Arnaud Couairon, and André Mysyrowicz
Phys. Rev. Lett. 110, 097601 (2013)
Improved stability of laser-plasma electron beam
Laser-plasma accelerators can produce high quality electron beams, up to giga-electronvolts in energy, from a centimeter scale device. The properties of the electron beams and the accelerator stability are largely determined by the injection stage of electrons into the ac- celerator. The simplest mechanism of injection is self-injection, in which the wakefield is strong enough to trap cold plasma electrons into the laser wake. The main drawback of this method is its lack of shot-to-shot stability. Researchers from LOA have demonstrated the existence of two different self-injection mechanisms. Transverse self-injection is shown to lead to low stability and poor quality electron beams, because of a strong dependence on the intensity profile of the laser pulse. In contrast, longitudinal in- jection, which is unambiguously observed for the first time, is shown to lead to much more stable acceleration and higher quality electron beams. These results are published in Nature Communications, February 19th, 2013.