Investigation of ultrashort pulse laser propulsion using time-resolved shadowgraphy and torsion pendulum

Xiao-nong Zhu; Nan Zhang

doi:10.1117/12.839584

28 August 2009 Investigation of ultrashort pulse laser propulsion using time-resolved shadowgraphy and torsion pendulum

Xiao-nong Zhu, Nan Zhang

Proceedings Volume 7382, International Symposium on Photoelectronic Detection and Imaging 2009: Laser Sensing and Imaging; 738208 (2009) https://doi.org/10.1117/12.839584
Event: International Symposium on Photoelectronic Detection and Imaging 2009, 2009, Beijing, China

Abstract

Laser pulses with different pulse durations between 50 fs and 12 ps are used to ablate different types of solid targets. With the help of time-resolved shadowgraphy, the ultrafast dynamics associated with femtosecond laser ablation of solid materials is experimentally investigated based on the commonly used pump-probe technique. It is revealed that both photothermal and photomechanical mechanisms exist in the ablation processes for laser fluence far above the target ablation threshold. From the recorded shadowgraphs, it is revealed that the material ejection due to femtosecond laser ablation of solid materials has a typical velocity of 10⁵ - 10⁴ m/s. Such high jet velocities can lead to specific impulse of 10⁴ - 10³ s, which is much higher than the upper limit of the specific impulse of chemical propulsion (500 s). The so-called ablative laser propulsion with high specific impulse can be thus realized. Momentum coupling coefficient is determined through using a homemade torsion pendulum with a minimum measurable momentum of ~2x10^-9 N·s. The dependence of the ultrashort laser ablation generated momentum is investigated on laser energy fluence and pulse width. The main findings include: 1) As the pulse width increases, the laser generated momentum first increases rapidly and then remains almost constant; 2) For 50 fs pulses, optimal laser fluence exists that leads to the maximum momentum for aluminum and copper targets. At the optimal laser fluence, it is mostly the photomechanical mechanism that is responsible for material removal, and in this case the ablated material also has relatively lower jet velocity.

Citation Download Citation

Xiao-nong Zhu and Nan Zhang "Investigation of ultrashort pulse laser propulsion using time-resolved shadowgraphy and torsion pendulum", Proc. SPIE 7382, International Symposium on Photoelectronic Detection and Imaging 2009: Laser Sensing and Imaging, 738208 (28 August 2009); https://doi.org/10.1117/12.839584

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available