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Title: Laser power density dependence on charge state distribution of Ta ion laser plasma

Abstract

Laser power density per pulse, which is commonly expressed with the unit of “W/cm2,” is an important parameter to characterize ablation plasma. To match a design charge state of heavy ion beam induced by a laser ion source, a laser power density must be carefully chosen. Above around 108 W/cm2 of laser power density, laser ablation plasma is emitted from the surface of solid material. Then, up to 109 W/cm2, the most abundant charge state is 1+. Because the ionization energy increases with higher charge states, increasing the laser intensity leads to the charge state distribution shifting higher. Increasing the density to increase charge states also results in lower time of flight due to higher velocities. The maximum laser power density is obtained by the smallest available laser spot size on the target material which is determined by the quality of the laser beam. For many accelerator applications, higher charge state beams are preferred. In particular cases, singly charge ion beams are demanded. Therefore, production of intermediate charge state beams has not been investigated well. In this study, we selected Ta4+ as an example demanded beam and tried to clarify how the transition of charge state distribution depends on lasermore » power density. Conclusively, the possible specification of a laser ion source for Ta4+ delivery was elucidated.« less

Authors:
ORCiD logo; ORCiD logo; ORCiD logo; ORCiD logo; ORCiD logo; ORCiD logo
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1593486
Grant/Contract Number:  
SC0012704
Resource Type:
Publisher's Accepted Manuscript
Journal Name:
Review of Scientific Instruments
Additional Journal Information:
Journal Name: Review of Scientific Instruments Journal Volume: 91 Journal Issue: 1; Journal ID: ISSN 0034-6748
Publisher:
American Institute of Physics
Country of Publication:
United States
Language:
English

Citation Formats

Okamura, Masahiro, Tamis, Andrew, Whelan, Tommy, Kanesue, Takeshi, Ikeda, Shunsuke, and Cannavò, Antonino. Laser power density dependence on charge state distribution of Ta ion laser plasma. United States: N. p., 2020. Web. doi:10.1063/1.5129530.
Okamura, Masahiro, Tamis, Andrew, Whelan, Tommy, Kanesue, Takeshi, Ikeda, Shunsuke, & Cannavò, Antonino. Laser power density dependence on charge state distribution of Ta ion laser plasma. United States. https://doi.org/10.1063/1.5129530
Okamura, Masahiro, Tamis, Andrew, Whelan, Tommy, Kanesue, Takeshi, Ikeda, Shunsuke, and Cannavò, Antonino. Thu . "Laser power density dependence on charge state distribution of Ta ion laser plasma". United States. https://doi.org/10.1063/1.5129530.
@article{osti_1593486,
title = {Laser power density dependence on charge state distribution of Ta ion laser plasma},
author = {Okamura, Masahiro and Tamis, Andrew and Whelan, Tommy and Kanesue, Takeshi and Ikeda, Shunsuke and Cannavò, Antonino},
abstractNote = {Laser power density per pulse, which is commonly expressed with the unit of “W/cm2,” is an important parameter to characterize ablation plasma. To match a design charge state of heavy ion beam induced by a laser ion source, a laser power density must be carefully chosen. Above around 108 W/cm2 of laser power density, laser ablation plasma is emitted from the surface of solid material. Then, up to 109 W/cm2, the most abundant charge state is 1+. Because the ionization energy increases with higher charge states, increasing the laser intensity leads to the charge state distribution shifting higher. Increasing the density to increase charge states also results in lower time of flight due to higher velocities. The maximum laser power density is obtained by the smallest available laser spot size on the target material which is determined by the quality of the laser beam. For many accelerator applications, higher charge state beams are preferred. In particular cases, singly charge ion beams are demanded. Therefore, production of intermediate charge state beams has not been investigated well. In this study, we selected Ta4+ as an example demanded beam and tried to clarify how the transition of charge state distribution depends on laser power density. Conclusively, the possible specification of a laser ion source for Ta4+ delivery was elucidated.},
doi = {10.1063/1.5129530},
journal = {Review of Scientific Instruments},
number = 1,
volume = 91,
place = {United States},
year = {2020},
month = {1}
}

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