Optimization of plasma mirror reflectivity and optical quality using double laser pulses

Scott, Graeme; Bagnoud, V.; Brabetz, C.; Clarke, R. J.; Green, J S; Heathcote, R.; Powell, H.; Zielbauer, B.; Arber, T. D.; McKenna, P.; Neely, D.

doi:10.1088/1367-2630/17/3/033027

Cited by 39 publications

(30 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…A double pulse was generated via the same module described in previous work, which investigated the optimisation of plasma mirror reflectivity [21], delivering a prepulse to main pulse energy of 1:10 and with variable delay of up to 100 ps. In total, 72±2 J of laser energy was delivered on target for the shots considered here, giving an average focused main pulse intensity of´-4 10 W cm 18 2 .…”

Section: Experimental Details 21 Methodsmentioning

confidence: 99%

Diagnosis of Weibel instability evolution in the rear surface density scale lengths of laser solid interactions via proton acceleration

et al. 2017

Self Cite

View full text Add to dashboard Cite

It is shown for the first time that the spatial and temporal distribution of laser accelerated protons can be used as a diagnostic of Weibel instability presence and evolution in the rear surface scale lengths of a solid density target. Numerical modelling shows that when a fast electron beam is injected into a decreasing density gradient on the target rear side, a magnetic instability is seeded with an evolution which is strongly dependent on the density scale length. This is manifested in the acceleration of a filamented proton beam, where the degree of filamentation is also found to be dependent on the target rear scale length. Furthermore, the energy dependent spatial distribution of the accelerated proton beam is shown to provide information on the instability evolution on the picosecond timescale over which the protons are accelerated. Experimentally, this is investigated by using a controlled prepulse to introduce a target rear scale length, which is varied by altering the time delay with respect to the main pulse, and similar trends are measured. This work is particularly pertinent to applications using laser pulse durations of tens of picoseconds, or where a micron level density scale length is present on the rear of a solid target, such as proton-driven fast ignition, as the resultant instability may affect the uniformity of fuel energy coupling. 1 2 or » FWTM 1.8 FWHM. The quoted time delay can therefore be considered to be a sample of the intensity profile of a shorter duration FWHM pulse.

show abstract

Section: Experimental Details 21 Methodsmentioning

confidence: 99%

Diagnosis of Weibel instability evolution in the rear surface density scale lengths of laser solid interactions via proton acceleration

et al. 2017

Self Cite

View full text Add to dashboard Cite

show abstract

“…This is consistent with current theoretical models of laser absorption and EMP generation. Scott et al have shown that laser absorption is a strong function of plasma density and scale length [15] , which are both dependent on the pre-pulse delay. The longer the delay between the pre-pulse and main drive, the greater the pre-plasma expansion and the greater the transfer of laser energy to hot electrons.…”

Section: Pre-pulse Delaymentioning

confidence: 99%

EMP control and characterization on high-power laser systems

Bradford

Woolsey

Scott

et al. 2018

High Pow Laser Sci Eng

View full text Add to dashboard Cite

Giant electromagnetic pulses (EMP) generated during the interaction of high-power lasers with solid targets can seriously degrade electrical measurements and equipment. EMP emission is caused by the acceleration of hot electrons inside the target, which produce radiation across a wide band from DC to terahertz frequencies. Improved understanding and control of EMP is vital as we enter a new era of high repetition rate, high intensity lasers (e.g. the Extreme Light Infrastructure). We present recent data from the VULCAN laser facility that demonstrates how EMP can be readily and effectively reduced. Characterization of the EMP was achieved using B-dot and D-dot probes that took measurements for a range of different target and laser parameters. We demonstrate that target stalk geometry, material composition, geodesic path length and foil surface area can all play a significant role in the reduction of EMP. A combination of electromagnetic wave and 3D particle-in-cell simulations is used to inform our conclusions about the effects of stalk geometry on EMP, providing an opportunity for comparison with existing charge separation models.

show abstract

“…This reflectance matches the values previously published with similar contrasts and intensities for s-polarized pulses reflecting from a PM. 7,19,20 Changing the input light's polarization from s-polarized to p-polarized provided a direct comparison of the magnitude A plot showing the published reflectance values from different PM studies and the year they were measured is given in Fig. 11.…”

Section: E Model Fit Parameter Resultsmentioning

confidence: 99%

“…The absorption levels of 18%-19% seen in the study of s-polarized light agree with previously published values from a self-triggered PM. 7,19,20 The absorbed energy directly relates to a drop in reflectance (as shown in Fig. 7(d)), and this parameter is used to vertically shift the plot to match the height of the experimental data.…”

Section: B Determination Of the Plasma Parametersmentioning

confidence: 99%

Reflectance characterization of tape-based plasma mirrors

et al. 2016

View full text Add to dashboard Cite

Articles you may be interested inHigh repetition rate plasma mirror device for attosecond science Rev. Sci. Instrum. 85, 013104 (2014); 10.1063/1.4860035Electromagnetic pulse reflection at self-generated plasma mirrors: Laser pulse shaping and high order harmonic generation Phys. Plasmas 14, 093105 (2007); Specular reflections of relativistic laser pulses from an overdense plasma mirror (PM) were studied experimentally. The pointing stability of the PM and reflectance of the input laser were characterized. The solid material used for the PM was a VHS tape. This study was done for the magnetic and plastic sides of the VHS tape, and for input light of both s and p-polarizations. The laser pulse fluence was varied by changing the focus position relative to the tape surface, which changed the spot size at the tape. The pointing fluctuations of the reflected pulses caused by the PM were ' 1 mrad. A peak reflectance of 82% was obtained from the plastic surface of the VHS tape when focusing s-polarized light 4 mm from the tape surface (the wavefront quality was confirmed to be conserved). An analytic model was developed to understand the physics of the interaction for each tape material and polarization. Fitting of our model parameters to the experimental results allowed an estimate of the key plasma parameters such as plasma expansion velocity, ionization intensity, and fraction of absorbed laser energy. Published by AIP Publishing.

show abstract

Optimization of plasma mirror reflectivity and optical quality using double laser pulses

Cited by 39 publications

References 35 publications

Diagnosis of Weibel instability evolution in the rear surface density scale lengths of laser solid interactions via proton acceleration

Diagnosis of Weibel instability evolution in the rear surface density scale lengths of laser solid interactions via proton acceleration

EMP control and characterization on high-power laser systems

Reflectance characterization of tape-based plasma mirrors

Contact Info

Product

Resources

About