Ion time-of-flight signals from nanosecond laser ablation plasmas excited in constricted cavities

Ion time-of-flight spectra from nanosecond pulse laser ablation at 1064 nm wavelength of a graphite target under repeated 10 Hz pulse repetition are investigated. By injecting focused laser beams at 12° from the surface normal, the ablated target formed a vertical cavity as the target is rotated con...

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Bibliographic Details
Published in:AIP conference proceedings 2021-07, Vol.2373 (1)
Main Authors: Hernandez, J. E., Wada, M.
Format: Article
Language:English
Subjects:
Ablation
Electric potential
Electrons
Holes
Ion extraction
Ions
Laser ablation
Laser beams
Lasers
Nanosecond pulses
Negative ions
Plasmas (physics)
Positive ions
Voltage
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Summary:Ion time-of-flight spectra from nanosecond pulse laser ablation at 1064 nm wavelength of a graphite target under repeated 10 Hz pulse repetition are investigated. By injecting focused laser beams at 12° from the surface normal, the ablated target formed a vertical cavity as the target is rotated continuously. For increasing number of pulses, decrease in positive signals for positive ion extraction while increase in negative signals for both 5 and 20 GW/cm2 laser power densities at −3 kV extraction voltage were observed. Increase in voltage onto a positive ion retardation plate installed in front of the Faraday cup array showed distinct negative ion peaks with decrease in positive ion signal intensity. Time-of- flight signals under increased number of pulses with the positively biased retardation plate showed less pronounced negative ion peaks for 5 GW/cm2 at -3 kV extraction, whereas the peaks persisted for 20 GW/cm2 laser power density. The influence of target cavity development on the negative ion formation is discussed.
ISSN:0094-243X
1551-7616
DOI:10.1063/5.0057437