Publications by David McGonegle


X-ray diffraction measurements of plasticity in shock-compressed vanadium in the region of 10-70 GPa

JOURNAL OF APPLIED PHYSICS 122 (2017) ARTN 025117

JM Foster, AJ Comley, GS Case, P Avraam, SD Rothman, A Higginbotham, EKR Floyd, ET Gumbrell, JJD Luis, D McGonegle, NT Park, LJ Peacock, CP Poulter, MJ Suggit, JS Wark


In situ X-ray diffraction measurement of shock-wave-driven twinning and lattice dynamics.

Nature 550 (2017) 496-499

CE Wehrenberg, D McGonegle, C Bolme, A Higginbotham, A Lazicki, HJ Lee, B Nagler, H-S Park, BA Remington, RE Rudd, M Sliwa, M Suggit, D Swift, F Tavella, L Zepeda-Ruiz, JS Wark

Pressure-driven shock waves in solid materials can cause extreme damage and deformation. Understanding this deformation and the associated defects that are created in the material is crucial in the study of a wide range of phenomena, including planetary formation and asteroid impact sites, the formation of interstellar dust clouds, ballistic penetrators, spacecraft shielding and ductility in high-performance ceramics. At the lattice level, the basic mechanisms of plastic deformation are twinning (whereby crystallites with a mirror-image lattice form) and slip (whereby lattice dislocations are generated and move), but determining which of these mechanisms is active during deformation is challenging. Experiments that characterized lattice defects have typically examined the microstructure of samples after deformation, and so are complicated by post-shock annealing and reverberations. In addition, measurements have been limited to relatively modest pressures (less than 100 gigapascals). In situ X-ray diffraction experiments can provide insights into the dynamic behaviour of materials, but have only recently been applied to plasticity during shock compression and have yet to provide detailed insight into competing deformation mechanisms. Here we present X-ray diffraction experiments with femtosecond resolution that capture in situ, lattice-level information on the microstructural processes that drive shock-wave-driven deformation. To demonstrate this method we shock-compress the body-centred-cubic material tantalum-an important material for high-energy-density physics owing to its high shock impedance and high X-ray opacity. Tantalum is also a material for which previous shock compression simulations and experiments have provided conflicting information about the dominant deformation mechanism. Our experiments reveal twinning and related lattice rotation occurring on the timescale of tens of picoseconds. In addition, despite the common association between twinning and strong shocks, we find a transition from twinning to dislocation-slip-dominated plasticity at high pressure (more than 150 gigapascals), a regime that recovery experiments cannot accurately access. The techniques demonstrated here will be useful for studying shock waves and other high-strain-rate phenomena, as well as a broad range of processes induced by plasticity.


Ultrafast X-Ray Diffraction Studies of the Phase Transitions and Equation of State of Scandium Shock Compressed to 82 GPa.

Physical review letters 118 (2017) 025501-

R Briggs, MG Gorman, AL Coleman, RS McWilliams, EE McBride, D McGonegle, JS Wark, L Peacock, S Rothman, SG Macleod, CA Bolme, AE Gleason, GW Collins, JH Eggert, DE Fratanduono, RF Smith, E Galtier, E Granados, HJ Lee, B Nagler, I Nam, Z Xing, MI McMahon

Using x-ray diffraction at the Linac Coherent Light Source x-ray free-electron laser, we have determined simultaneously and self-consistently the phase transitions and equation of state (EOS) of the lightest transition metal, scandium, under shock compression. On compression scandium undergoes a structural phase transition between 32 and 35 GPa to the same bcc structure seen at high temperatures at ambient pressures, and then a further transition at 46 GPa to the incommensurate host-guest polymorph found above 21 GPa in static compression at room temperature. Shock melting of the host-guest phase is observed between 53 and 72 GPa with the disappearance of Bragg scattering and the growth of a broad asymmetric diffraction peak from the high-density liquid.


Inelastic response of silicon to shock compression.

Scientific reports 6 (2016) 24211-

A Higginbotham, PG Stubley, AJ Comley, JH Eggert, JM Foster, DH Kalantar, D McGonegle, S Patel, LJ Peacock, SD Rothman, RF Smith, MJ Suggit, JS Wark

The elastic and inelastic response of [001] oriented silicon to laser compression has been a topic of considerable discussion for well over a decade, yet there has been little progress in understanding the basic behaviour of this apparently simple material. We present experimental x-ray diffraction data showing complex elastic strain profiles in laser compressed samples on nanosecond timescales. We also present molecular dynamics and elasticity code modelling which suggests that a pressure induced phase transition is the cause of the previously reported 'anomalous' elastic waves. Moreover, this interpretation allows for measurement of the kinetic timescales for transition. This model is also discussed in the wider context of reported deformation of silicon to rapid compression in the literature.


Simulations of in situ x-ray diffraction from uniaxially compressed highly textured polycrystalline targets

JOURNAL OF APPLIED PHYSICS 118 (2015) ARTN 065902

D McGonegle, D Milathianaki, BA Remington, JS Wark, A Higginbotham


Prediction of Debye-Scherrer diffraction patterns in arbitrarily strained samples

JOURNAL OF APPLIED PHYSICS 115 (2014) ARTN 174906

A Higginbotham, D McGonegle


Electron-phonon equilibration in laser-heated gold films

PHYSICAL REVIEW B 90 (2014) ARTN 014305

TG White, P Mabey, DO Gericke, NJ Hartley, HW Doyle, D McGonegle, DS Rackstraw, A Higginbotham, G Gregori


Investigations into rapid uniaxial compression of polycrystalline targets using femtosecond X-ray diffraction

18TH APS-SCCM AND 24TH AIRAPT, PTS 1-19 500 (2014) UNSP 112063

D McGonegle, A Higginbotham, E Galtier, EE McBride, MI McMahon, D Milathianaki, HJ Lee, B Nagler, SM Vinko, JS Wark


Femtosecond measurement of shock wave driven twinning and lattice dynamics

Nature (0)

JS Wark, D mcgonegle, M suggit