Yong Ma

• PhD
• Assistant Research Scientist at University of Michigan

We have designed a new filter pack array to measure angular variations in x-ray spectra during a single shot. The filter pack was composed of repeating identical columns of aluminum and copper filters of varying thicknesses. These columns were located at different positions to measure the spectrum at each corresponding angle. This array was utilize...

Understanding dense fuel hydrodynamics is critical for predicting burning plasma behavior in laser-driven inertial confinement fusion. Traditional diagnostic sources face many limitations in brightness, spatio-temporal resolution, and their ability to capture kinetic effects and electromagnetic fields influencing interaction dynamics. We present a...

We report on an experimental observation of the streaking of betatron x rays in a curved laser wakefield accelerator. The streaking of the betatron x rays was realized by launching a laser pulse into a plasma with a transverse density gradient. By controlling the plasma density and the density gradient, we realized the steering of the laser driver,...

Direct laser acceleration of electrons during a high-energy, picosecond laser interaction with an underdense plasma has been demonstrated to be substantially enhanced by controlling the laser focusing geometry. Experiments using the OMEGA EP facility measured electrons accelerated to maximum energies exceeding 120 times the ponderomotive energy und...

The rapid progress that plasma wakefield accelerators are experiencing is now posing the question as to whether they could be included in the design of the next generation of high-energy electron-positron colliders. However, the typical structure of the accelerating wakefields presents challenging complications for positron acceleration. Despite se...

Ultrafast betatron x-ray emission from electron oscillations in laser wakefield acceleration (LWFA) has been widely investigated as a promising source. Betatron x-rays are usually produced via self-injected electron beams, which are not controllable and are not optimized for x-ray yields. Here, we present a new method for bright hard x-ray emission...

The generation of low emittance electron beams from laser-driven wakefields is crucial for the development of compact x-ray sources. Here, we show new results for the injection and acceleration of quasimonoenergetic electron beams in low amplitude wakefields experimentally and using simulations. This is achieved by using two laser pulses decoupling...

The Zettawatt Equivalent Ultrashort pulse laser System (ZEUS) is a 3-Petawatt user facility funded by the National Science Foundation and is due to be commissioned in late 2023. The facility will explore high-field science and applications.

The formation of plasma waves during laser wakefield acceleration (LWFA) produces time-dependent frequency shifts in the driving laser pulse, extending its spectral content to the infrared. We present direct spectral measurements of multi-mJ infrared pulses from an LWFA. Experimental beam profile measurements and three-dimensional particle-in-cell...

We report on experimental measurements of energy transfer efficiencies in a GeV-class laser wakefield accelerator. Both the transfer of energy from the laser to the plasma wakefield and from the plasma to the accelerated electron beam was diagnosed by simultaneous measurement of the deceleration of laser photons and the acceleration of electrons as...

Laser-wakefield accelerated electron beams have been demonstrated to be a viable alternative to those produced by radio-frequency systems, with unique characteristics including intrinsic femtosecond-scale duration and micron-scale source size. In addition, they present the practical advantage of a generally compact and cost-effective setup inherent...

We report on the first spatial and spectral characterisation of near-GeV positron beams generated in a fully laser-driven configuration. The energy-resolved geometric emittance, source size and spectrum were simultaneously measured for electrons and positrons generated from a laser-wakefield accelerated electron beam impacting on a thin high-Z conv...

Laser wakefield accelerators commonly produce on-axis, low-divergence, high-energy electron beams. However, a high charge, annular shaped beam can be trapped outside the bubble and accelerated to high energies. Here we present a parametric study on the production of low-energy-spread, ultra-relativistic electron ring beams in a two-stage gas cell....

We propose an innovative beam cooling scheme based on laser driven plasma wakefields to address the challenge of high luminosity generation for a future linear collider. For linear colliders, beam cooling is realised by means of damping rings equipped with wiggler magnets and accelerating cavities. This scheme ensures systematic reduction of phase...

We explore the applications of a variety of machine learning techniques in relativistic laser-plasma experiments beyond optimization purposes. With the trained supervised learning models, the beam charge of electrons produced in a laser wakefield accelerator is predicted given the laser wavefront change caused by a deformable mirror. Feature import...

Here, we investigate the effects of laser polarization and wavelength on electron injection dynamics in a laser wakefield accelerator. During the ionization process, electrons gain residual momentum and kinetic energy via above threshold ionization, which has a strong dependence on laser polarization. A circularly polarized laser pulse results in a...

We report on a study of highly controllable, quasi-static hollow plasma channels generated by ion motion following a laser–plasma interaction via numerical simulations. These channels are generated by ion motion in a nonlinear wakefield, which has an asymmetry between focusing and defocusing periods. Such plasma channels, driven by a fs duration, 1...

Experimental measurements using the OMEGA EP laser facility demonstrated direct laser acceleration (DLA) of electron beams to (505 ± 75) MeV with (140 ± 30) nC of charge from a low-density plasma target using a 400 J, picosecond duration pulse. Similar trends of electron energy with target density are also observed in self-consistent two-dimensiona...

Experimental measurements using the OMEGA EP laser facility demonstrated direct laser acceleration (DLA) of electron beams to (505 $\pm$ 75) MeV with (140 $\pm$ 30)~nC of charge from a low-density plasma target using a 400 J, picosecond duration pulse. Similar trends of electron energy with target density are also observed in self-consistent two-di...

Zettawatt Equivalent Ultrashort pulse laser System ( ZEUS ): The National Science Foundation’s mid-scale 3PW laser facility for exploration of relativistic plasmas, nonlinear quantum electrodynamics, and other extreme high-field phenomena is described.

We report on high efficiency energy transfer in a GeV-class laser wakefield accelerator. Both the transfer of energy from the laser to the plasma wakefield, and from the plasma to the accelerated electron beam were diagnosed experimentally by simultaneous measurement of the deceleration of laser photons and the accelerated electrons as a function o...

We report on the experimental observation of a decreased self-injection threshold by using laser pulses with circular polarization in laser wakefield acceleration experiments in a nonpreformed plasma, compared to the usually employed linear polarization. A significantly higher electron beam charge was also observed for circular polarization compare...

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Building on past support, NSF has funded the Zetawatt Equivalent Ultrashort pulse laser System (ZEUS), a mid-scale 3PW multi-beam user facility, to explore nonlinear quantum electrodynamics, relativistic plasmas, and other phenomena in High-Field Science.

Single-shot absorption measurements have been performed using the multi-keV x rays generated by a laser-wakefield accelerator. A 200 TW laser was used to drive a laser-wakefield accelerator in a mode which produced broadband electron beams with a maximum energy above 1 GeV and a broad divergence of ≈15 mrad FWHM. Betatron oscillations of these elec...

Magnetic reconnection is a process that contributes significantly to plasma dynamics and energy transfer in a wide range of plasma and magnetic field regimes, including inertial confinement fusion experiments, stellar coronae, and compact, highly magnetized objects like neutron stars. Laboratory experiments in different regimes can help refine, exp...

Single-shot absorption measurements have been performed using the multi-keV X-rays generated by a laser wakefield accelerator. A 200 TW laser was used to drive a laser wakefield accelerator in a mode which produced broadband electron beams with a maximum energy above 1 GeV and a broad divergence of $\approx15$ miliradians FWHM. Betatron oscillation...

There has been growing interest both in studying high intensity ultrafast laser plasma interactions with adaptive control systems as well as using long wavelength driver beams. We demonstrate the coherent control of the dynamics of laser-wakefield acceleration driven by ultrashort (∼ 100 fs) mid-infrared (∼ 3.9 μm) laser pulses. The critical densit...

Laser-wakefield accelerators (LWFAs) are high acceleration-gradient plasma-based particle accelerators capable of producing ultra-relativistic electron beams. Within the strong focusing fields of the wakefield, accelerated electrons undergo betatron oscillations, emitting a bright pulse of X-rays with a micrometer-scale source size that may be used...

Thin-film compression (TFC) and the focusability of high-power laser pulses after self-phase modulation in thin films at transport intensities (∼1 TW∕cm 2) for petawatt laser systems is demonstrated. High-energy (∼296 mJ) laser pulses are compressed from ∼55 fs to ∼31 fs. Additionally, the focusability of high-power (∼45-55 TW) flat-top laser pulse...

In a plasma with a transverse density gradient, laser wavefront tilt develops gradually due to phase velocity differences in different plasma densities. The wavefront tilt leads to a parabolic trajectory of the plasma wakefield and hence the accelerated electron beam, which leads to an angular streaking of the emitted betatron radiation. In this wa...

High intensity short pulse laser plasma interaction experiments were performed to investigate laser wakefield acceleration (LWFA) in the 'bubble' regime. Using a specially designed phase plate, two high intensity laser focal spots were generated adjacent to each other with a transverse spacing of 70 μm and were focused onto a low density plasma tar...

One order of magnitude energy enhancement of the target surface electron beams with central energy at 11.5 MeV is achieved by using a 200 TW, 500 fs laser at an incident angle of 72° with a prepulse intensity ratio of 5 × 10 − 6 . The experimental results demonstrate the scalability of the acceleration process to high electron energy with a longer...

Compact acceleration of a tightly collimated relativistic electron beam with high charge from a laser-plasma interaction has many unique applications. However, currently the well-known schemes, including laser wakefield acceleration from gases and vacuum laser acceleration from solids, often produce electron beams either with low charge or with lar...

Significance In the last three decades, the laser–plasma accelerator (LPA) has shown a rapid development owing to its super–high-accelerate gradients, which makes it a very promising compact accelerator and light source. Acceleration of a high-quality electron beam with divergence angle as small as possible and beam charge as high as possible has b...

Betatron radiation from laser wakefield accelerated electrons and X-rays scattered off a counter-propagating relativistic electron bunch are collimated and hold the potential to extend the energy range to hard X-ray or gamma ray band. The peak brightness of these incoherent radiations could reach the level of the brightest synchrotron light sources...

Compact acceleration of a tightly collimated relativistic electron beam with high charge from a laser-plasma interaction has many unique applications. However, currently the well-known schemes, including laser wakefield acceleration from gases and vacuum laser acceleration from solids, often produce electron beams either with low charge or with lar...

We present the experimentally generated electron bunch from laser-wakefield acceleration (LWFA) with a charge of 620 pC and a maximum energy up to 0.6 GeV by irradiating 80 TW laser pulses at a 3 mm Helium gas jet. The charge of injected electrons is much larger than the normal scaling laws of LWFA in bubble regime. We also got a quasi-monoenergeti...

Scientific Reports 6 : Article number: 30491 10.1038/srep30491 ; published online: 26 July 2016 ; updated: 02 September 2016 This Article contains errors in Figure 3a and 3d where the y axes ‘y (μm)’ is incorrectly given as ‘y (mm)’. The correct Figure 3 appears below as Figure 1 .

The promising ability of a plasma wiggler based on laser wakefield acceleration to produce betatron X-rays with photon energies of a few keV to hundreds of keV and a peak brilliance of 1022–1023 photons/s/mm2/mrad2/0.1%BW has been demonstrated, providing an alternative to large-scale synchrotron light sources. Most methods for generating betatron r...

Neutron energy is directly correlated with the energy of the incident ions in experiments involving laser-driven nuclear reactions. Using high-energy incident ions reduces the energy concentration of the generated neutrons. A novel “laser-collider” method was used at the Shenguang II laser facility to produce monoenergetic neutrons via 7Li (d, n) n...

Betatron x-ray source generated in the process of laser wakefield acceleration has been studied in IOP using different species of gas. For helium plasmas, the generation of bright betatron radiation in electron acceleration via self-injection was studied in experiment and simulation. Two electron bunches with different qualities were injected seque...

Betatron radiation from the transverse oscillation of laser-wakefield accelerated electrons is very promising for a wide range of applications. Currently, the main limitation of this radiation source is the x-ray photon yield. We present our recent progress in achieving higher photon flux using a clustering gas target instead of the normal gas jet,...

By adjusting the focus geometry of a spatially structured laser pulse, single, double, and treble quasi-monoenergetic electron beams were generated, respectively, in laser-wakefield acceleration. Single electron beam was produced as focusing the laser pulse to a single spot. While focusing the laser pulse to two spots that are approximately equal i...

A new scheme for bright hard x-ray emission from laser wakefield electron accelerator is reported, where pure nitrogen gas is adopted. Intense Betatron x-ray beams are generated from ionization injected K-shell electrons of nitrogen into the accelerating wave bucket. The x-ray radiation shows synchrotron-like spectrum with total photon yield 8$\tim...

Neutron yields have direct correlation with the energy of incident deuterons in experiments of laser deuterated target interaction [Roth et al., Phys. Rev. Lett. 110, 044802 (2013) and Higginson et al., Phys. Plasmas 18, 100703 (2011)], while deuterated plasma density is also an important parameter. Experiments at the Shenguang II laser facility ha...

Optimized-quality monoenergetic target surface electron beams at MeV level with low normalized emittance (0.03π mm mrad) and high charge (30 pC) per shot have been obtained from 3 TW laser-solid interactions at a grazing incidence. The 2-Dimension particle-in-cell simulations suggest that electrons are wake-field accelerated in a large-scale, near-...

Rayleigh scattering method can be used to investigate the cluster size and the cluster formation process, and its advantages are that it is easy to perform and non-disruptive. In this paper, by measuring the Rayleigh scattering intensities of clusters generated respectively in pure xenon gas and hydrogen-xenon gas mixture, the relationships of Rayl...

Upon the interaction of 60 TW Ti: sapphire laser pulses with 4 mm long supersonic nitrogen gas jet, a directional x-ray emission was generated along with the generation of stable quasi-monoenergetic electron beams having a peak energy of 130 MeV and a relative energy spread of ∼ 20%. The betatron x-ray emission had a small divergence of 7.5 mrad an...

We report an efficient Mo Kα x-ray source produced by interaction of femtosecond Ti: sapphire laser pulses with a solid Molybdenum target working at 1 kHz repetition rate. The generated Mo Kα x-ray intensity reaches to 4.7 × 10(10) photons sr(-1) s(-1), corresponding to an average power of 0.8 mW into 2π solid angle. The spatial resolution of this...

We present an indirect method to diagnose the electron beam behaviors and bubble dynamic evolution in a laser-wakefield accelerator. Four kinds of typical bubble dynamic evolution and, hence, electron beam behaviors observed in Particle-In-Cell simulations are identified correspondingly by simultaneous measurement of distinct angular distributions...

We report the generation of a 6 pC, 23 MeV electron bunch with the energy spread ± 3.5% by using 2 TW, 80 fs high contrast laser pulses interacting with helium gas targets. Within the optimized experimental condition, we obtained quasi-monoenergetic electron beam with an ultra-small normalized divergence angle of 92 mrad, which is at least 5 times...

Significance Desktop laser plasma acceleration is able to generate monoenergetic electron beams, and such electron beams can oscillate in the plasma bubble, which results in the collimated X-rays with ability of femtosecond temporal resolution. However, high-flux X-ray emission and high-quality electron beams have not been obtained simultaneously b...

X-ray radiation with an average flux of 1.3 x 10(7) photons sr(-1) . s(-1) is generated by the interaction between ultra-short laser and solid target working at 1 kHz repetition rate. A knife edge is introduced to measure the source size. The X-ray emission shows obvious dependences on the laser contrast and intensity. It is discovered that at lowe...

A quasi-monoenergetic electron beam with divergence of 3° and energy peak of 1 MeV is observed along the target surface from interaction of a bulk Cu target and an intense relativistic laser pulse of 1 TW and 70 fs at a grazing incident angle. A preplasma formed by high-contrast picosecond prepulse plays a crucial role. Particle-in-cell simulations...

Hard X-ray sources from femtosecond (fs) laser-produced plasmas, including the betatron X-rays from laser wakefield-accelerated electrons, have compact sizes, fs pulse duration and fs pump-probe capability, making it promising for wide use in material and biological sciences. Currently the main problem with such betatron X-ray sources is the limite...

Bright betatron x-ray has been generated using an Ar clustering gas jet target irradiated with a 3 TW ultra-high contrast laser. The measured emission flux with photon energy > 2.4 keV reaches 2\times10^8 photons/shot. It is ten-fold enhancement comparing to the emission flux produced by using gas target in the same laser parameters. Observation sh...