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Boosting laser-ion acceleration with multi-picosecond pulses

View Article: PubMed Central - PubMed

ABSTRACT

Using one of the world most powerful laser facility, we demonstrate for the first time that high-contrast multi-picosecond pulses are advantageous for proton acceleration. By extending the pulse duration from 1.5 to 6 ps with fixed laser intensity of 1018 W cm−2, the maximum proton energy is improved more than twice (from 13 to 33 MeV). At the same time, laser-energy conversion efficiency into the MeV protons is enhanced with an order of magnitude, achieving 5% for protons above 6 MeV with the 6 ps pulse duration. The proton energies observed are discussed using a plasma expansion model newly developed that takes the electron temperature evolution beyond the ponderomotive energy in the over picoseconds interaction into account. The present results are quite encouraging for realizing ion-driven fast ignition and novel ion beamlines.

No MeSH data available.


Time evolution of the temperature slope obtained with the PIC simulation for the incidence of a single pulse (tL = 1.5 ps, red squares), 2-pulse train (tL = 3 ps, green triangles) and 4-pulse train (tL = 6 ps, blue diamonds).The temporal shape of the incident pulses used in the simulation are shown as dashed lines. The solid lines are determined by least squares fitting with Eq. (17); see the text.
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f2: Time evolution of the temperature slope obtained with the PIC simulation for the incidence of a single pulse (tL = 1.5 ps, red squares), 2-pulse train (tL = 3 ps, green triangles) and 4-pulse train (tL = 6 ps, blue diamonds).The temporal shape of the incident pulses used in the simulation are shown as dashed lines. The solid lines are determined by least squares fitting with Eq. (17); see the text.

Mentions: We have performed 1D PIC simulations using the EPIC code47 to understand the time-dependent heating of plasma electrons depending on the laser pulse duration. Figure 2 shows the temporal variations of electron temperature for 1.5-, 3- and 6-ps pulse durations, corresponding to the incidence of a single pulse, two-pulse train and four-pulse train, respectively. Here, we assume a Gaussian profile for the temporal shape of each laser pulse and set a time of t = 1.5 ps for the arrival timing of the first intensity peak (I = 2.3 × 1018 W cm−2), as shown with dashed lines. The four pulses are separated by a time interval of 1.5 ps between the peaks, making the flattop-like shape of the pulse profile continue for t = 1.5–3 ps for the 2-pulse case and t = 1.5–6 ps for the 4-pulse case.


Boosting laser-ion acceleration with multi-picosecond pulses
Time evolution of the temperature slope obtained with the PIC simulation for the incidence of a single pulse (tL = 1.5 ps, red squares), 2-pulse train (tL = 3 ps, green triangles) and 4-pulse train (tL = 6 ps, blue diamonds).The temporal shape of the incident pulses used in the simulation are shown as dashed lines. The solid lines are determined by least squares fitting with Eq. (17); see the text.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5304168&req=5

f2: Time evolution of the temperature slope obtained with the PIC simulation for the incidence of a single pulse (tL = 1.5 ps, red squares), 2-pulse train (tL = 3 ps, green triangles) and 4-pulse train (tL = 6 ps, blue diamonds).The temporal shape of the incident pulses used in the simulation are shown as dashed lines. The solid lines are determined by least squares fitting with Eq. (17); see the text.
Mentions: We have performed 1D PIC simulations using the EPIC code47 to understand the time-dependent heating of plasma electrons depending on the laser pulse duration. Figure 2 shows the temporal variations of electron temperature for 1.5-, 3- and 6-ps pulse durations, corresponding to the incidence of a single pulse, two-pulse train and four-pulse train, respectively. Here, we assume a Gaussian profile for the temporal shape of each laser pulse and set a time of t = 1.5 ps for the arrival timing of the first intensity peak (I = 2.3 × 1018 W cm−2), as shown with dashed lines. The four pulses are separated by a time interval of 1.5 ps between the peaks, making the flattop-like shape of the pulse profile continue for t = 1.5–3 ps for the 2-pulse case and t = 1.5–6 ps for the 4-pulse case.

View Article: PubMed Central - PubMed

ABSTRACT

Using one of the world most powerful laser facility, we demonstrate for the first time that high-contrast multi-picosecond pulses are advantageous for proton acceleration. By extending the pulse duration from 1.5 to 6 ps with fixed laser intensity of 1018 W cm−2, the maximum proton energy is improved more than twice (from 13 to 33 MeV). At the same time, laser-energy conversion efficiency into the MeV protons is enhanced with an order of magnitude, achieving 5% for protons above 6 MeV with the 6 ps pulse duration. The proton energies observed are discussed using a plasma expansion model newly developed that takes the electron temperature evolution beyond the ponderomotive energy in the over picoseconds interaction into account. The present results are quite encouraging for realizing ion-driven fast ignition and novel ion beamlines.

No MeSH data available.