Nicholas John Hartley

Dr. Nicholas John Hartley

orcid

Research Focus & Metrics

Academic Career Length

13Years (2014-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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21 August 2017 in Nature Astronomy
Verified
Journal Article
Closed access
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DKD. Kraus
D. Kraus
JVJan Vorberger
Jan Vorberger
APA. Pak
A. Pak
NHNicholas John Hartley
Nicholas John Hartley
LFL. B. Fletcher
L. B. Fletcher
RFR. W. Falcone
R. W. Falcone

24 July 2017 in High Power Laser Science and Engineering
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Journal Article
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IPI. Prencipe
I. Prencipe
JFJulien Fuchs
Julien Fuchs
SPS. Pascarelli
S. Pascarelli
DSD. W. Schumacher
D. W. Schumacher
RSR. B. Stephens
R. B. Stephens
TCT. E. Cowan
T. E. Cowan
A number of laser facilities coming online all over the world promise the capability of high-power laser experiments with shot repetition rates between 1 and 10 Hz. Target availability and technical issues related to the interaction environment could become a bottleneck for the exploitation of such facilities. In this paper, we report on target needs for three different classes of experiments: dynamic compression physics, electron transport and isochoric heating, and laser-driven particle and radiation sources. We also review some of the most challenging issues in target fabrication and high repetition rate operation. Finally, we discuss current target supply strategies and future perspectives to establish a sustainable target provision infrastructure for advanced laser facilities.

13 November 2018 in Plasma Physics and Controlled Fusion
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Journal Article
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DKD Kraus
D Kraus
BBB Bachmann
B Bachmann
BBB Barbrel
B Barbrel
RFR W Falcone
R W Falcone
LFL B Fletcher
L B Fletcher
TDT Döppner
T Döppner
We discuss the possibility of obtaining highly precise measurements of the ionization potential depression in dense plasmas with spectrally resolved x-ray scattering, while simultaneously determining the electron temperature and the free electron density. A proof-of-principle experiment at the Linac Coherent Light Source, probing isochorically heated carbon samples, demonstrates the capabilities of this method and motivates future experiments at x-ray free electron laser facilities.

23 July 2014 in Physical Review B
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TWT. G. White
T. G. White
PMP. Mabey
P. Mabey
DGD. O. Gericke
D. O. Gericke
NHNicholas John Hartley
Nicholas John Hartley
HDH. W. Doyle
H. W. Doyle
GGG. Gregori
G. Gregori
By irradiating a thin metal foil with an intense short-pulse laser, we have created a uniform system far from equilibrium. The deposited energy is initially deposited only within the electronic subsystem, and the subsequent evolution of the system is determined by the details of the electron-phonon coupling. Here, we measure the time evolution of the lattice parameter through multilayer Bragg diffraction and compare the result to classical molecular dynamic simulations to determine the lattice temperature. The electron-ion coupling constant for gold is then determined by comparison with the evolution of a two-temperature electron-phonon system.

10 April 2014 in Physical Review Letters
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Journal Article
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TWT. G. White
T. G. White
NHNicholas John Hartley
Nicholas John Hartley
BBB. Borm
B. Borm
BCB. J. B. Crowley
B. J. B. Crowley
JHJ. W. O. Harris
J. W. O. Harris
GGG. Gregori
G. Gregori
We have employed fast electrons produced by intense laser illumination to isochorically heat thermal electrons in solid density carbon to temperatures of $$\sim${}10\text{ }000\text{ }\text{ }\mathrm{K}$. Using time-resolved x-ray diffraction, the temperature evolution of the lattice ions is obtained through the Debye-Waller effect, and this directly relates to the electron-ion equilibration rate. This is shown to be considerably lower than predicted from ideal plasma models. We attribute this to strong ion coupling screening the electron-ion interaction.

26 May 2020 in Nature Communications
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Journal Article
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SFS. Frydrych
S. Frydrych
JVJ. Vorberger
J. Vorberger
NHNicholas John Hartley
Nicholas John Hartley
ASA. K. Schuster
A. K. Schuster
KRK. Ramakrishna
K. Ramakrishna
DKD. Kraus
D. Kraus
The gas and ice giants in our solar system can be seen as a natural laboratory for the physics of highly compressed matter at temperatures up to thousands of kelvins. In turn, our understanding of their structure and evolution depends critically on our ability to model such matter. One key aspect is the miscibility of the elements in their interiors. Here, we demonstrate the feasibility of X-ray Thomson scattering to quantify the degree of species separation in a 1:1 carbon–hydrogen mixture at a pressure of ~150 GPa and a temperature of ~5000 K. Our measurements provide absolute values of the structure factor that encodes the microscopic arrangement of the particles. From these data, we find a lower limit of $$2{4}_{-7}^{+6}$$ 2 4 − 7 + 6 % of the carbon atoms forming isolated carbon clusters. In principle, this procedure can be employed for investigating the miscibility behaviour of any binary mixture at the high-pressure environment of planetary interiors, in particular, for non-crystalline samples where it is difficult to obtain conclusive results from X-ray diffraction. Moreover, this method will enable unprecedented measurements of mixing/demixing kinetics in dense plasma environments, e.g., induced by chemistry or hydrodynamic instabilities.