This title appears in the Scientific Report :
2009
Please use the identifier:
http://dx.doi.org/10.1103/PhysRevE.80.026404 in citations.
Please use the identifier: http://hdl.handle.net/2128/9322 in citations.
Optimized K alpha x-ray flashes from femtosecond-laser-irradiated foils
Optimized K alpha x-ray flashes from femtosecond-laser-irradiated foils
We investigate the generation of ultrashort K alpha pulses from plasmas produced by intense femtosecond p-polarized laser pulses on Copper and Titanium targets. Particular attention is given to the interplay between the angle of incidence of the laser beam on the target and a controlled prepulse. It...
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Personal Name(s): | Lu, W. |
---|---|
Nicoul, M. / Shymanovich, U. / Tarasevitch, A. / Zhou, P. / Sokolowski-Tinten, K. / von der Linde, D. / Masek, M. / Gibbon, P. / Teubner, U. | |
Contributing Institute: |
Jülich Supercomputing Center; JSC |
Published in: | Physical Review E Physical review / E, 80 80 (2009 2009) 2 2, S. 026404 026404 |
Imprint: |
College Park, Md.
APS
2009
2009-08-27 2009-08-01 |
Physical Description: |
026404 |
DOI: |
10.1103/PhysRevE.80.026404 |
Document Type: |
Journal Article |
Research Program: |
Scientific Computing |
Series Title: |
Physical Review E
80 |
Subject (ZB): | |
Link: |
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Publikationsportal JuSER |
Please use the identifier: http://hdl.handle.net/2128/9322 in citations.
We investigate the generation of ultrashort K alpha pulses from plasmas produced by intense femtosecond p-polarized laser pulses on Copper and Titanium targets. Particular attention is given to the interplay between the angle of incidence of the laser beam on the target and a controlled prepulse. It is observed experimentally that the K alpha yield can be optimized for correspondingly different prepulse and plasma scale-length conditions. For steep electron-density gradients, maximum yields can be achieved at larger angles. For somewhat expanded plasmas expected in the case of laser pulses with a relatively poor contrast, the K alpha yield can be enhanced by using a near-normal-incidence geometry. For a certain scale-length range (between 0.1 and 1 times a laser wavelength) the optimized yield is scale-length independent. Physically this situation arises because of the strong dependence of collisionless absorption mechanisms-in particular resonance absorption-on the angle of incidence and the plasma scale length, giving scope to optimize absorption and hence the K alpha yield. This qualitative description is supported by calculations based on the classical resonance absorption mechanism and by particle-in-cell simulations. Finally, the latter simulations also show that even for initially steep gradients, a rapid profile expansion occurs at oblique angles in which ions are pulled back toward the laser by hot electrons circulating at the front of the target. The corresponding enhancement in K alpha yield under these conditions seen in the present experiment represents strong evidence for this suprathermal shelf formation effect. |