Energy transport in short-pulse-laser-heated targets measured using extreme ultraviolet laser backlighting

TY - JOUR

T1 - Energy transport in short-pulse-laser-heated targets measured using extreme ultraviolet laser backlighting

AU - Wilson, L. A.

AU - Tallents, G. J.

AU - Pasley, J.

AU - Whittaker, D. S.

AU - Rose, S. J.

AU - Guilbaud, O.

AU - Cassou, K.

AU - Kazamias, S.

AU - Daboussi, S.

AU - Pittman, M.

AU - Delmas, O.

AU - Demailly, J.

AU - Neveu, O.

AU - Ros, D.

PY - 2012/8/28

Y1 - 2012/8/28

N2 - The accurate characterization of thermal electron transport and the determination of heating by suprathermal electrons in laser driven solid targets are both issues of great importance to the current experiments being performed at the National Ignition Facility, which aims to achieve thermonuclear fusion ignition using lasers. Ionization, induced by electronic heat conduction, can cause the opacity of a material to drop significantly once bound-free photoionization is no longer energetically possible. We show that this drop in opacity enables measurements of the transmission of extreme ultraviolet (EUV) laser pulses at 13.9 nm to act as a signature of the heating of thin (50 nm) iron layers with a 50-nm thick parylene-N (CH) overlay irradiated by 35-fs pulses at irradiance 3 x 10(16) Wcm(-2). Comparing EUV transmission measurements at different times after irradiation to fluid code simulations shows that the target is instantaneously heated by hot electrons (with approximately 10% of the laser energy), followed by thermal conduction with a flux limiter of approximate to 0.05.

AB - The accurate characterization of thermal electron transport and the determination of heating by suprathermal electrons in laser driven solid targets are both issues of great importance to the current experiments being performed at the National Ignition Facility, which aims to achieve thermonuclear fusion ignition using lasers. Ionization, induced by electronic heat conduction, can cause the opacity of a material to drop significantly once bound-free photoionization is no longer energetically possible. We show that this drop in opacity enables measurements of the transmission of extreme ultraviolet (EUV) laser pulses at 13.9 nm to act as a signature of the heating of thin (50 nm) iron layers with a 50-nm thick parylene-N (CH) overlay irradiated by 35-fs pulses at irradiance 3 x 10(16) Wcm(-2). Comparing EUV transmission measurements at different times after irradiation to fluid code simulations shows that the target is instantaneously heated by hot electrons (with approximately 10% of the laser energy), followed by thermal conduction with a flux limiter of approximate to 0.05.

UR - http://www.scopus.com/inward/record.url?scp=84865578164&partnerID=8YFLogxK

U2 - 10.1103/PhysRevE.86.026406

DO - 10.1103/PhysRevE.86.026406

M3 - Article

SN - 1539-3755

VL - 86

SP - 1

EP - 7

JO - Physical Review E

JF - Physical Review E

IS - 2

M1 - 026406

ER -