Teddy Borger

Quasi-monoenergetic laser-plasma acceleration of electrons to 2 GeV

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 multi-gigaelectronvolt 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.

Full-aperture backscatter diagnostics and applications at the Texas Petawatt Laser facility

In this paper, we present the development and application of a full-aperture backscatter diagnostics system at the Texas Petawatt Laser (TPW) facility. The diagnostic system includes three independent diagnostic stations. With this system, we obtained TPW on-shot focus properties, and high-harmonic spectral emission from solid foils (e.g., Cu and Al) and their Si substrate in an experiment to study laser hole boring, which show the hole-boring mechanism at relativistic intensities. The measured on-target full-power focal spots from ultrathin film targets help determine the optimum target thickness at certain laser contrast parameters for particle acceleration and neutron generation experiment, which is also a relative measurement of shot-toshot intensity fluctuations.

Pulse Contrast Measurements of the Texas Petawatt Laser

Temporal contrast of the Texas Petawatt laser is presented. The contrast is influenced by pencil beam prepulses on the timescale up to 110ns and by parametric fluorescence on the timescale of the OPCPA pump laser.

The Texas petawatt laser and current experiments

The Texas Petawatt Laser is operational with experimental campaigns executed in both F/40 and F3 target chambers. Recent improvements have resulted in intensities of >2×1021 W/cm2 on target. Experimental highlights include, accelerated electron energies of >2 GeV, DD fusion ion temperatures >25 keV and isochorically heated solids to 10-50 eV.

Generation of dark-current-free quasi-monoenergetic 1.25 GeV electrons by laser wakefield acceleration

We report electron acceleration to 1.25 GeV by petawatt-laser-driven wakefield acceleration at plasma density 5×1017 cm3. Electron beams are dark-current-free, quasi-monoenergetic, highly collimated (<;1mrad divergence), contain tens of pC and have excellent pointing stability.

Self-injected petawatt laser-driven plasma electron acceleration in 10 17 cm −3 plasma

We report observation of electron self-injection and acceleration in a plasma accelerator driven by the Texas petawatt laser at 1017 cm−3 plasma density, an order of magnitude lower density than previous self-injected laser-plasma accelerators.

Adaptive optics on petawatt lasers: current performance of the Texas Petawatt Laser

In this paper, we report on current developments aimed at improving the focusability of the Texas Petawatt Laser. Two major campaigns have been commissioned that address the issue of focusability. First, we implemented a closed loop, 32 actuator bi-moprh deformable mirror (DFM) to compensate for aberrations in the optical train and second, a color corrector lens assembly was installed that compensates for chromatic errors accumulated in broadband (>15 nm), large aperture (>20 cm) laser systems. We will present in detail, pre and post correction results with the DFM and describe challenges faced when one activates a single shot, high energy closed loop system. Secondly, we will provide modeling and experimental results of our color correction system. This is a novel approach to a problem only seen in high energy, broadband, large aperture laser pulses. By using color correction optics we have demonstrated a 6X increase in focal intensity. With the installation of the DFM, the rms wavefront error in the system was reduced from 2.4 waves to .131 waves, further increasing intensities seen at focus by 1 order of magnitude.

GeV Electrons and High brightness Betatron X-rays from Petawatt-Laser-Driven Plasma Accelerators

We identify three regimes of correlated GeV-electron/keV-betatron-X-ray generation by a laser-plasma accelerator driven by the Texas Petawatt laser, and relate them to variations in strength of blowout, injection geometry and beam loading.

Petawatt lasers based on hybrid, OPCPA-Nd:glass amplification

A Petawatt laser [1] based on hybrid optical parametric chirped pulse amplification (OPCPA) and mixed Nd:glass has been demonstrated [2]. This concept enables peak powers which can be scaled significantly beyond one petawatt. Higher power lasers enable access to unprecedented scientific research in the studies of high intensity physics. In this paper we discuss the laser, the potential of scaling to higher peak power and the first experiments.