Optimisation and control of high intensity laser accelerated ion beams

Olivier Tresca

Research output: ThesisDoctoral Thesis

Abstract

The interaction of a laser pulse of relativistic intensity (≥1×1018 Wcm−2) with a solid target results in the creation of a quasi-electrostatic field at the rear surface of the target. This field is strong enough (TVm−1) to ionise and accelerate ions from the target surface via the Target Normal Sheath Acceleration (TNSA) mechanism. The resulting beam has many desirable properties for a large range of potential applications. The work presented in this thesis aims at optimising and controlling the ion beam properties.
Firstly, an investigation of laser driven ion acceleration using ultrahigh contrast (1010), ultrashort (50 fs) laser pulses focused to intensities up to 1021 Wcm−2 on thin foil targets is presented. It is found that irradiation at normal (0◦) incidence produces higher energy ions than oblique incidence (35◦), contrasting sharply with previous work at lower intensities. These findings are confirmed by 1D boosted PIC simulations and can be explained by the acceleration of fast electrons being dominated by a new absorption process. The effects of target composition and thickness on the acceleration of carbon ions are also discussed and compared to calculations using analytical models of ion acceleration. Next, an investigation of the transverse refluxing of fast electrons in targets
of limited lateral size is reported. The targets were irradiated by high intensity (∼1×1019 Wcm−2), picosecond laser pulses. The maximum energy of the resulting TNSA proton beams is found to increase with decreasing target surface area. This is explained by the presence of a laterally spreading electron population that reflects off the target edges and enhances the TNSA accelerating field. In addition it is demonstrated that this laterally refluxing electron population can be used to control the spatial intensity distribution of the TNSA proton beam, by changing the geometry of the target. This technique offers encouraging prospects for many applications of laser accelerated ions.
Finally, a characterisation study of debris emission generated by the interaction of high power laser pulses with solid targets is presented. Targets of thickness ranging from 1 mm to 5 nm were irradiated by high intensity (∼1×1020 Wcm−2), picosecond laser pulses. The resulting debris emission is found to be directed along the target normal axis at both the rear and front of the target. The front emission profile is found to be similar to a plasma expansion profile. Hollow debris depositions of radius increasing with target thickness are measured from the target rear surface. This emission profile is explained by the propagation and breakout of a laser driven shock at the rear of the target.
LanguageEnglish
QualificationPhD
Awarding Institution
  • University Of Strathclyde
Supervisors/Advisors
  • McKenna, Paul, Supervisor
Place of PublicationGlasgow
Publisher
Publication statusPublished - 2012

Fingerprint

high power lasers
ion beams
optimization
sheaths
lasers
debris
pulses
ions
proton beams
electrons
profiles
incidence
target thickness
theses

Keywords

  • laser accelerated ion beams
  • laser pulse
  • ion beam properties

Cite this

Tresca, O. (2012). Optimisation and control of high intensity laser accelerated ion beams. Glasgow: University of Strathclyde.
Tresca, Olivier. / Optimisation and control of high intensity laser accelerated ion beams. Glasgow : University of Strathclyde, 2012. 178 p.
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title = "Optimisation and control of high intensity laser accelerated ion beams",
abstract = "The interaction of a laser pulse of relativistic intensity (≥1×1018 Wcm−2) with a solid target results in the creation of a quasi-electrostatic field at the rear surface of the target. This field is strong enough (TVm−1) to ionise and accelerate ions from the target surface via the Target Normal Sheath Acceleration (TNSA) mechanism. The resulting beam has many desirable properties for a large range of potential applications. The work presented in this thesis aims at optimising and controlling the ion beam properties.Firstly, an investigation of laser driven ion acceleration using ultrahigh contrast (1010), ultrashort (50 fs) laser pulses focused to intensities up to 1021 Wcm−2 on thin foil targets is presented. It is found that irradiation at normal (0◦) incidence produces higher energy ions than oblique incidence (35◦), contrasting sharply with previous work at lower intensities. These findings are confirmed by 1D boosted PIC simulations and can be explained by the acceleration of fast electrons being dominated by a new absorption process. The effects of target composition and thickness on the acceleration of carbon ions are also discussed and compared to calculations using analytical models of ion acceleration. Next, an investigation of the transverse refluxing of fast electrons in targetsof limited lateral size is reported. The targets were irradiated by high intensity (∼1×1019 Wcm−2), picosecond laser pulses. The maximum energy of the resulting TNSA proton beams is found to increase with decreasing target surface area. This is explained by the presence of a laterally spreading electron population that reflects off the target edges and enhances the TNSA accelerating field. In addition it is demonstrated that this laterally refluxing electron population can be used to control the spatial intensity distribution of the TNSA proton beam, by changing the geometry of the target. This technique offers encouraging prospects for many applications of laser accelerated ions.Finally, a characterisation study of debris emission generated by the interaction of high power laser pulses with solid targets is presented. Targets of thickness ranging from 1 mm to 5 nm were irradiated by high intensity (∼1×1020 Wcm−2), picosecond laser pulses. The resulting debris emission is found to be directed along the target normal axis at both the rear and front of the target. The front emission profile is found to be similar to a plasma expansion profile. Hollow debris depositions of radius increasing with target thickness are measured from the target rear surface. This emission profile is explained by the propagation and breakout of a laser driven shock at the rear of the target.",
keywords = "laser accelerated ion beams, laser pulse, ion beam properties",
author = "Olivier Tresca",
year = "2012",
language = "English",
publisher = "University of Strathclyde",
school = "University Of Strathclyde",

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Tresca, O 2012, 'Optimisation and control of high intensity laser accelerated ion beams', PhD, University Of Strathclyde, Glasgow.

Optimisation and control of high intensity laser accelerated ion beams. / Tresca, Olivier.

Glasgow : University of Strathclyde, 2012. 178 p.

Research output: ThesisDoctoral Thesis

TY - THES

T1 - Optimisation and control of high intensity laser accelerated ion beams

AU - Tresca, Olivier

PY - 2012

Y1 - 2012

N2 - The interaction of a laser pulse of relativistic intensity (≥1×1018 Wcm−2) with a solid target results in the creation of a quasi-electrostatic field at the rear surface of the target. This field is strong enough (TVm−1) to ionise and accelerate ions from the target surface via the Target Normal Sheath Acceleration (TNSA) mechanism. The resulting beam has many desirable properties for a large range of potential applications. The work presented in this thesis aims at optimising and controlling the ion beam properties.Firstly, an investigation of laser driven ion acceleration using ultrahigh contrast (1010), ultrashort (50 fs) laser pulses focused to intensities up to 1021 Wcm−2 on thin foil targets is presented. It is found that irradiation at normal (0◦) incidence produces higher energy ions than oblique incidence (35◦), contrasting sharply with previous work at lower intensities. These findings are confirmed by 1D boosted PIC simulations and can be explained by the acceleration of fast electrons being dominated by a new absorption process. The effects of target composition and thickness on the acceleration of carbon ions are also discussed and compared to calculations using analytical models of ion acceleration. Next, an investigation of the transverse refluxing of fast electrons in targetsof limited lateral size is reported. The targets were irradiated by high intensity (∼1×1019 Wcm−2), picosecond laser pulses. The maximum energy of the resulting TNSA proton beams is found to increase with decreasing target surface area. This is explained by the presence of a laterally spreading electron population that reflects off the target edges and enhances the TNSA accelerating field. In addition it is demonstrated that this laterally refluxing electron population can be used to control the spatial intensity distribution of the TNSA proton beam, by changing the geometry of the target. This technique offers encouraging prospects for many applications of laser accelerated ions.Finally, a characterisation study of debris emission generated by the interaction of high power laser pulses with solid targets is presented. Targets of thickness ranging from 1 mm to 5 nm were irradiated by high intensity (∼1×1020 Wcm−2), picosecond laser pulses. The resulting debris emission is found to be directed along the target normal axis at both the rear and front of the target. The front emission profile is found to be similar to a plasma expansion profile. Hollow debris depositions of radius increasing with target thickness are measured from the target rear surface. This emission profile is explained by the propagation and breakout of a laser driven shock at the rear of the target.

AB - The interaction of a laser pulse of relativistic intensity (≥1×1018 Wcm−2) with a solid target results in the creation of a quasi-electrostatic field at the rear surface of the target. This field is strong enough (TVm−1) to ionise and accelerate ions from the target surface via the Target Normal Sheath Acceleration (TNSA) mechanism. The resulting beam has many desirable properties for a large range of potential applications. The work presented in this thesis aims at optimising and controlling the ion beam properties.Firstly, an investigation of laser driven ion acceleration using ultrahigh contrast (1010), ultrashort (50 fs) laser pulses focused to intensities up to 1021 Wcm−2 on thin foil targets is presented. It is found that irradiation at normal (0◦) incidence produces higher energy ions than oblique incidence (35◦), contrasting sharply with previous work at lower intensities. These findings are confirmed by 1D boosted PIC simulations and can be explained by the acceleration of fast electrons being dominated by a new absorption process. The effects of target composition and thickness on the acceleration of carbon ions are also discussed and compared to calculations using analytical models of ion acceleration. Next, an investigation of the transverse refluxing of fast electrons in targetsof limited lateral size is reported. The targets were irradiated by high intensity (∼1×1019 Wcm−2), picosecond laser pulses. The maximum energy of the resulting TNSA proton beams is found to increase with decreasing target surface area. This is explained by the presence of a laterally spreading electron population that reflects off the target edges and enhances the TNSA accelerating field. In addition it is demonstrated that this laterally refluxing electron population can be used to control the spatial intensity distribution of the TNSA proton beam, by changing the geometry of the target. This technique offers encouraging prospects for many applications of laser accelerated ions.Finally, a characterisation study of debris emission generated by the interaction of high power laser pulses with solid targets is presented. Targets of thickness ranging from 1 mm to 5 nm were irradiated by high intensity (∼1×1020 Wcm−2), picosecond laser pulses. The resulting debris emission is found to be directed along the target normal axis at both the rear and front of the target. The front emission profile is found to be similar to a plasma expansion profile. Hollow debris depositions of radius increasing with target thickness are measured from the target rear surface. This emission profile is explained by the propagation and breakout of a laser driven shock at the rear of the target.

KW - laser accelerated ion beams

KW - laser pulse

KW - ion beam properties

M3 - Doctoral Thesis

PB - University of Strathclyde

CY - Glasgow

ER -

Tresca O. Optimisation and control of high intensity laser accelerated ion beams. Glasgow: University of Strathclyde, 2012. 178 p.