Volumetric creation of ultra-high-energy-density plasma by irradiation of ordered nanowire arrays

Creating appreciable volumes of Ultra-High-Energy Density (UHED) matter in the laboratory is a challenge. Recent developments in the fabrication of vertically aligned nanowire array targets, in coordination with ultra-high-contrast femtosecond laser pulses focused to relativistic intensity, have opened the door to creating UHED matter using compact laser facilities with laser pulses of ~ 0.6 J. These high aspect ratio, vertically aligned nanostructure targets allow the laser energy to penetrate deep into the near-solid density material and heat plasmas to keV temperatures, generating Gbar pressures that are only surpassed in the laboratory by the central hot-spot of highly compressed thermonuclear fusion plasmas. The depth of the heated volume is key in governing the properties of these new UHED plasmas, and is reported here for the first time in vertically aligned nanowire arrays using a buried-tracer technique. In this study, arrays of 55 nm diameter nanowires, manufactured with a variable length segment of nickel on top of a buried cobalt segment, were irradiated with relativistic femtosecond laser pulses of (4±1) x 1019 W cm-2 intensity. Buried Co atoms are observed to ionize to the He-like state for depths greater than 4 μm, in good agreement with particle-in-cell simulations. The measured heat penetration demonstrates that the UHED plasma regime can be accessed with small high repetition rate lasers.

Name thesis:degree_name

Master of Science (M.S.)

Level thesis:degree_level

Masters

Discipline thesis:degree_discipline

Electrical and Computer Engineering

Grantor dc:publisher

Colorado State University. Libraries

Year dc:date.issued

2016

Authors dc:creator

• Bargsten, Clayton, author
• Rocca, Jorge J., advisor
• Marconi, Mario C., committee member
• Roberts, Jacob L., committee member

• high energy density
• plasma physics
• volumetric heating
• nanowires
• gigabar
• ultrafast

Statement dc:rights

• Copyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.

Language dc:language.iso

eng, English

Identifier URI

https://doi.org/10.25675/3.018831

OAI identifier oai:identifier

oai:mountainscholar.org:10217/173462