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CO<sub>2</sub> Laser Absorption in Ablation Plasmas

Eckel, Hans-Albert and Tegel, Jochen and Schall, Wolfgang (2005) CO<sub>2</sub> Laser Absorption in Ablation Plasmas. Fourth International Symposium on Beamed Energy Propulsion, 2005-11-15 - 2005-11-18, Nara, Japan.

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Abstract

The impulse formation by laser ablation is limited by the premature absorption of the incident laser radiation in the initially produced cloud of ablation products. The power fraction of a CO<sub>2</sub> laser pulse transmitted through a small hole in a POM sample for pulse energies of 35 to 150 J focused on a spot of 2 cm<sup>2</sup> has been compared with the incident power. The plasma formation in vacuum and in air of 3500 Pa and the spread of the shock wave with velocities of 1.6 to 2.4 km/s in the low pressure air was observed by Schlieren photography. A sharp edged dark zone with a maximum extension of 10 to 12 mm away from the target surface develops within 5 µs independently of the pressure and is assumed to be a plasma. In order to find out, if this is also the zone where the majority of the incident laser radiation is absorbed, a CO<sub>2</sub> probe laser beam was directed through the expansion cloud parallel to and at various distances from the sample surface. The time behavior of the absorption signal of the probe beam has been measured and an absorption wave could be observed.

Document Type:Conference or Workshop Item (Speech)
Title:CO<sub>2</sub> Laser Absorption in Ablation Plasmas
Authors:
AuthorsInstitution or Email of Authors
Eckel, Hans-AlbertUNSPECIFIED
Tegel, JochenUNSPECIFIED
Schall, WolfgangUNSPECIFIED
Date:2005
Refereed publication:No
In SCOPUS:No
In ISI Web of Science:No
Status:Accepted
Keywords:Laser propulsion, plasma diagnostics
Event Title:Fourth International Symposium on Beamed Energy Propulsion
Event Location:Nara, Japan
Event Type:international Conference
Event Dates:2005-11-15 - 2005-11-18
Organizer:Tokyo Institute of Technology
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Aeronautics
HGF - Program Themes:Aircraft Research
DLR - Research area:Aeronautics
DLR - Program:L AR - Aircraft Research
DLR - Research theme (Project):L - Laser Research and Technology
Location: Stuttgart
Institutes and Institutions:Institute of Technical Physics
Deposited By: Dr.rer.nat. Hans-Albert Eckel
Deposited On:10 Feb 2006
Last Modified:14 Jan 2010 20:56

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