Walter Scott, Jr. College of Engineering

Graduate Exam Abstract

Reed Hollinger
Ph.D. Final
Dec 03, 2018, 2:00 pm - 5:00 pm
ERC Electronic Classroom
Highly relativistic laser interactions with ordered nanostructures
Abstract: Heating solid density matter to extreme temperatures has been one of the primary motivations
behind the construction of large laser facilities around the world. The creation of simultaneously
hot (multi-keV) and dense (on the order of a solid) plasma is a difficult problem in the laboratory
due to the barrier that the critical electron density imposes to optical lasers, typically heating a
very thin surface laser with a majority of the energy not being absorbed. Experiments conducted
at Colorado State University have demonstrated the efficient volumetric heating of nanowire
arrays using high contrast, relativistic laser pulses to multi-keV temperatures at an intensity of
5x10^18 W/cm^2. These large volume plasmas have longer hydrodynamic cooling times while the
radiative cooling time is greatly decreased due to the near solid electron densities when compared
to solid, flat targets. This results in very efficient conversion of optical laser light into x-rays since
the plasma is able to radiate away more of its' energy as x-rays before cooling due to
hydrodynamic expansion. With this technique, an x-ray conversion efficiency of over 20% was
measured for photon energies greater than 1keV. After a significant upgrade to the laser, these
interactions were explored at highly relativistic intensities (nearly 1000 times higher intensity than
initial experiments), exceeding 10^21 W/cm^2. Careful measurements of the energy deposition
dynamics and the volume of the nanowire plasma were carried out in comparison to solid targets.
At these intensities, it is possible to generate extreme degrees of ionization never before seen at a
small scale, table top laser facility, such as H-like Ni (27 times ionized) and Ne-like Au (69 times
Adviser: Jorge Rocca
Co-Adviser: n/a
Non-ECE Member: Amy Prieto
Member 3: Mario Marconi
Addional Members: Carmen Menoni
R. Hollinger, C. Bargsten, V. Shlyaptsev, V. Kaymak, A. Pukhov, M. Capeluto, S. Wang, A. Rockwood, Y. Wang, A. Townsend, A. Prieto, P. Stockton, A. Curtis, J.J. Rocca, “Efficient picosecond x-ray pulse generation from plasmas in the radiation dominated regime,” Optica, 4 11 p.1344 (2017).

A. Curtis, C. Calvi, J. Tinsley, R. Hollinger, V. Kaymak, A. Pukhov, S. Wang, A. Rockwood, Y. Wang, V. Shlyaptsev, J.J. Rocca, “Micro-scale fusion in dense relativistic nanowire array plasmas,” Nature Communications, Accepted 2018.

C. Bargsten, R. Hollinger, M. G. Capeluto, V. Kaymak, A. Pukhov, S.Wang, A. Rockwood, Y. Wang, D. Keiss, R. Tommasini, R. London,J. Park, M. Busquet, M. Klapisch, V. N. Shlyaptsev, and J. J. Rocca, “Energy penetration into arrays of aligned nanowires irradiated with relativistic intensities: scaling to terabar pressures,” Science Advances, 3 1 e1601558 (2017).

Y. Wang, S. Wang, A. Rockwood, B. Luther, R. Hollinger, A. Curtis, C. Calvi, C. Menoni, J.J. Rocca, “0.85 PW laser operation at 3.3 Hz and high contrast ultrahigh intensity 400nm second harmonic beamline ,” Optics Letters, 42 19 p3828 (2017).

M. Purvis, V. Shlyaptsev, R. Hollinger, C. Bargsten, A. Pukhov, A. Prieto, Y. Wang, B. Luther, L. Yin, S.Wang, J.J. Rocca, “Relativistic plasma nanophotonics for ultrahigh energy density physics,” Nature Photonics, 7 10 p.796 (2013).

Program of Study: