Laser Electron Accelerator

A method for generating large-amplitude nonlinear plasma waves, which utilizes an optimized train of independently adjustable, intense laser pulses, is analyzed in I-D both theoretically and numerically (using both Maxwell-fluid and particle-in-cell codes). Optimal pulse widths and interpulse spacings are computed for pulses with either square or finite-risetime sine shapes. A resonant region of the plasma wave phase space is found where the plasma wave is driven by the laser most efficiently. The width of this region, and thus the optimal finiterisetime laser pulse width, was found to decrease with increasing plasma density and plasma wave amplitude, while the nonlinear plasma wavelength, and thus the optimal interpulse spacing, was found to increase. Also investigated are the resonance sensitivities to variations in the laser and plasma parameters. Nonlinear Landau damping of the wave by trapped background electrons is found to be important. Resonant excitation by this method is shown to more advantageous for electron acceleration than either the single pulse wakefield or the plasma beatwave concepts, because comparable plasma wave amplitudes may be generated at lower plasma densities, thus reducing electron-phase detuning, or at lower laser intensities, thus reducing laser-plasma instabilities. Practical experimental methods for producing the required pulse trains are discussed.

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1995

Critical aspects of high-gradient electron acceleration by laser-driven relativistic electron plasma waves have been studied experimentally. A number of important features incorporated into the design of the experimental facility make it possible to obtain controlled injection of high-energy electrons into the plasma and make reliable measurements of electron acceleration. Effective accelerating electric field gradients of approximately 1.7 GeVim have been obtained in centimeter-length plasmas.

Nature Communications, 2021

Plasma wakefield accelerators are capable of sustaining gigavolt-per-centimeter accelerating fields, surpassing the electric breakdown threshold in state-of-the-art accelerator modules by 3-4 orders of magnitude. Beam-driven wakefields offer particularly attractive conditions for the generation and acceleration of high-quality beams. However, this scheme relies on kilometer-scale accelerators. Here, we report on the demonstration of a millimeter-scale plasma accelerator powered by laser-accelerated electron beams. We showcase the acceleration of electron beams to 128 MeV, consistent with simulations exhibiting accelerating gradients exceeding 100 GV m−1. This miniaturized accelerator is further explored by employing a controlled pair of drive and witness electron bunches, where a fraction of the driver energy is transferred to the accelerated witness through the plasma. Such a hybrid approach allows fundamental studies of beam-driven plasma accelerator concepts at widely accessible ...

IEEE Transactions on Plasma Science

Physics of Plasmas, 2005

The interaction of high intensity laser pulses with underdense plasma is investigated experimentally using a range of laser parameters and energetic electron production mechanisms are compared. It is clear that the physics of these interactions changes significantly depending not only on the interaction intensity but also on the laser pulse length. For high intensity laser interactions in the picosecond pulse duration regime the production of energetic electrons is highly correlated with the production of plasma waves. However as intensities are increased the peak electron acceleration increases beyond that which can be produced from single stage plasma wave acceleration and direct laser acceleration mechanisms must be invoked. If, alternatively, the pulse length is reduced such that it approaches the plasma period of a relativistic electron plasma wave, high power interactions can be shown to enable the generation of quasimonoenergetic beams of relativistic electrons.

Nature, 2004

Nature Communications, 2013

Laser-plasma accelerators of only a centimetre's length have produced nearly monoenergetic electron bunches with energy as high as 1 GeV. Scaling these compact accelerators to multigigaelectronvolt energy would open the prospect of building X-ray free-electron lasers and linear colliders hundreds of times smaller than conventional facilities, but the 1 GeV barrier has so far proven insurmountable. Here, by applying new petawatt laser technology, we produce electron bunches with a spectrum prominently peaked at 2 GeV with only a few per cent energy spread and unprecedented sub-milliradian divergence. Petawatt pulses inject ambient plasma electrons into the laser-driven accelerator at much lower density than was previously possible, thereby overcoming the principal physical barriers to multi-gigaelectronvolt acceleration: dephasing between laser-driven wake and accelerating electrons and laser pulse erosion. Simulations indicate that with improvements in the laser-pulse focus quality, acceleration to nearly 10 GeV should be possible with the available pulse energy.

Nature, 2006

In laser-plasma-based accelerators 1 , an intense laser pulse drives a large electric field (the wakefield) which accelerates particles to high energies in distances much shorter than in conventional accelerators. These high acceleration gradients, of a few hundreds of gigavolts per metre, hold the promise of compact high-energy particle accelerators. Recently, several experiments have shown that laser-plasma accelerators can produce high-quality electron beams, with quasi-monoenergetic energy distributions at the 100 MeV level 2-4 . However, these beams do not have the stability and reproducibility that are required for applications. This is because the mechanism responsible for injecting electrons into the wakefield is based on highly nonlinear phenomena 5 , and is therefore hard to control. Here we demonstrate that the injection and subsequent acceleration of electrons can be controlled by using a second laser pulse 6 . The collision of the two laser pulses provides a pre-acceleration stage which provokes the injection of electrons into the wakefield. The experimental results show that the electron beams obtained in this manner are collimated (5 mrad divergence), monoenergetic (with energy spread ,10 per cent), tuneable (between 15 and 250 MeV) and, most importantly, stable. In addition, the experimental observations are compatible with electron bunch durations shorter than 10 fs. We anticipate that this stable and compact electron source will have a strong impact on applications requiring short bunches, such as the femtolysis of water 7 , or high stability, such as radiotherapy with high-energy electrons 8,9 or radiography 10 for materials science.

Plasma Physics and Controlled Fusion, 2007

A few years ago, several experiments showed that laser-plasma accelerators can produce high-quality electron beams, with quasi-monoenergetic energy distributions at the 100 MeV level. These experiments were performed by focusing a single ultra-short and ultraintense laser pulse into an underdense plasma. Here, we report on recent experimental results of electron acceleration using two counter-propagating ultra-short and ultraintense laser pulses. We demonstrate that the use of a second laser pulse provides enhanced control over the injection and subsequent acceleration of electrons into plasma wakefields. The collision of the two laser pulses provides a pre-acceleration stage which provokes the injection of electrons into the wakefield. The experimental results show that the electron beams obtained in this manner are collimated (5 mrad divergence), monoenergetic (with relative energy spread <10%), tuneable (between 50 and 250 MeV) and, most importantly, stable.

2007 IEEE Particle Accelerator Conference (PAC), 2007

A relativistically intense laser pulse is focused into a gas jet and quasi-monoenergetic electrons emitted at a 37 degree angle with respect to the laser axis are observed. The average energy of the electrons was between 1 and 2 MeV and the total accelerated charge was about 1 nC emitted into a 10 degree cone angle. The electron characteristics were sensitive to plasma density. The results are compared with three dimensional particle-incell simulations. This electron acceleration mechanism might be useful as a source of injection electrons in a laser wakefield accelerator.