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Author: Dongsu Du Publisher: ISBN: Category : Languages : en Pages : 204
Book Description
Since 2004, table-top laser-plasma accelerators (LPAs) driven by ~30fs terwatt laser pulses have produced colimated, nearly mono-energetic eletron bunches with energy up to 1 GeV in laboratories around the world. Large-scale computer simulations show that LPAs can scale to higher energy while retaining high beam quality, but will require laser pulses of higher energy and longer duration than current LPAs. The group of Prof. Mike Downer, in collaboration with the Texas Petawatt (TPW) laser team headed by Prof. Todd Ditmire, is setting up an experiment that uses the TPW laser (1.1 PW, 150 fs) to drive the world's first multi-GeV LPA. This thesis provides a general overview of the TPW-LPA project, including several diagnostic systems for the beam, plasma and laser pulse. Special attention is given to three of the diagnostic systems: (1)A transverse interferometry diagnostic of the plasma density profile created by the TPW laser pulse; (2)A Thomson scattering diagnostic of the self-guided path of the TPW laser pulse through the plasma; (3)An optical transition radiation diagnostic of the accelerated electron bunch exiting the plasma. In each case, basic principles, theoretical background, calculation and simulation results, and preliminary experimental results will be presented.
Author: Dongsu Du Publisher: ISBN: Category : Languages : en Pages : 204
Book Description
Since 2004, table-top laser-plasma accelerators (LPAs) driven by ~30fs terwatt laser pulses have produced colimated, nearly mono-energetic eletron bunches with energy up to 1 GeV in laboratories around the world. Large-scale computer simulations show that LPAs can scale to higher energy while retaining high beam quality, but will require laser pulses of higher energy and longer duration than current LPAs. The group of Prof. Mike Downer, in collaboration with the Texas Petawatt (TPW) laser team headed by Prof. Todd Ditmire, is setting up an experiment that uses the TPW laser (1.1 PW, 150 fs) to drive the world's first multi-GeV LPA. This thesis provides a general overview of the TPW-LPA project, including several diagnostic systems for the beam, plasma and laser pulse. Special attention is given to three of the diagnostic systems: (1)A transverse interferometry diagnostic of the plasma density profile created by the TPW laser pulse; (2)A Thomson scattering diagnostic of the self-guided path of the TPW laser pulse through the plasma; (3)An optical transition radiation diagnostic of the accelerated electron bunch exiting the plasma. In each case, basic principles, theoretical background, calculation and simulation results, and preliminary experimental results will be presented.
Author: Stefan Bedacht Publisher: ISBN: Category : Languages : en Pages : 244
Book Description
An overview of the beam diagnostics for the laser wakefield acceleration project at the Texas Petawatt Laser facility is presented. In this experiment, short and intense laser pulses of 165 fs and up to 190 J will be used to accelerate electrons up to the GeV energy range using laser wakefield acceleration. The density variation of the plasma generated in a helium gas cell will be measured with different optical detection systems such as frequency domain holography. Spectra of the transmitted laser beam and optical transition radiation will yield information about the energy transfer to the plasma and the energy of the electrons, respectively. In addition, a calorimeter will measure accelerated electron energies. Prior to the final experiment, preliminary frequency shift measurements and simulations on optical transition radiation were performed.
Author: Yen-Yu Chang Publisher: ISBN: Category : Languages : en Pages : 206
Book Description
We demonstrated single shot diagnostics of laser-plasma accelerators (LPAs). We observed the structure and the evolving process of the blow-out region, the nonlinear waves (plasma bubble) induced by the driving beam using the Faraday rotation diagnostic. We obtained the evolution of the plasma bubble in single shot using Faraday rotation diagnostic with multiple probe beams. The diameter of the bubble changed from 300 [micrometer] to 50 [micrometer] in 2 cm, which revealed the transition of the acceleration stages from ”bubble expanding mode” to ”bubble stabilizing mode”. Moreover, we demonstrated the broad bandwidth frequency domain streak camera (B-FDSC), which can resolve the dynamics of LPAs in single shot. We improved the temporal resolution of B-FDSC to 10 fs by broadening the bandwidth of the probe beam to 100 nm using supercontinuum generation, and we performed a prototype experiment to show that B-FDSC was capable of resolving the evolution of pulse self-steepening and temporal splitting in a single shot.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
The electron energy dependence of a scintillating screen (Lanex Fast) was studied with sub-nanosecond electron beams ranging from 106 MeV to 1522 MeV at the Lawrence Berkeley National Laboratory Advanced Light Source (ALS) synchrotron booster accelerator. The sensitivity of the Lanex Fast decreased by 1percent per 100 MeV increase of the energy. The linear response of the screen against the charge was verified with charge density and intensity up to 160 pC/mm2 and 0.4 pC/ps/mm2, respectively. For electron beams from the laser plasma accelerator, a comprehensive study of charge diagnostics has been performed using a Lanex screen, an integrating current transformer, and an activation based measurement. The charge measured by each diagnostic was found to be within +/-10 percent.
Author: Alexander Ross Meadows Publisher: ISBN: Category : Languages : en Pages : 276
Book Description
A two-year experimental campaign is described during which diamond-like carbon and plastic targets with thicknesses from 20 nanometers to 15 micrometers were irradiated by the Texas Petawatt Laser. Target composition and thickness were varied to modify the specifics of the laser-matter interaction. Plasma mirrors were selectively implemented to affect the contrast of the laser system and provide additional control of the physical processes under investigation. A number of particle diagnostics were implemented to measure the distribution of laser accelerated ions and electrons. In addition, optical diagnostics were fielded to measure the intensity profile of the laser and measure the density of the target pre-plasma. The results of these experiments suggest that the Texas Petawatt laser pulse has pre-pulse and pedestal features with intensities at least 10−8 of the main pulse. Micronscale targets were able to survive these features and maintain a relatively sharp density gradient until the arrival of the main laser pulse, allowing for ion acceleration. Electron spectra measured in this configuration show an average temperature of 10 MeV, with no v angular dependence out to at least 60 degrees. By contrast, interferometric plasma density measurements and a lack of any observable ion acceleration suggest that nanoscale targets were destroyed well before the main pulse. In this case, the peak of the laser pulse interacted with a cloud of plasma between 10−3 and 10−2 of critical density. The contrast improvement offered by the implementation of plasma mirrors was seen to increase the maximum energy of laser accelerated protons from targets thicker than 1 micrometer. In addition, the plasma mirrors allowed nanoscale targets to survive pre-pulse and pedestal features and support the production of ion beams. Proton spectra show that ions were accelerated to greater maximum energies from nanoscale targets than from more traditional micron-scale targets. This effect can be attributed to a reduction in the target pre-plasma scale length upon the introduction of plasma mirrors. These results indicate that the manipulation of target properties and laser contrast can significantly affect the interaction between an ultrahigh intensity laser and a target.
Author: Publisher: ISBN: 9780496121625 Category : Lasers Languages : en Pages : 77
Book Description
An interferometric laser optical diagnostic was developed to analyze plasma behavior and properties in Magnetically Insulated Transmission Lines (MITL) and other high energy density experiments. The diagnostic produces interferograms needing to be analyzed to achieve quantitative data from experiments. Research focused on analyzing interferograms by using Quick Fringe, a commercial software package, showing the plasma density field in experimental interferograms. Issues in analysis included benchmarking Quick Fringe, exploration of vibration effects on reference interferograms used to retrieve data from interferograms containing data, and revealing program limitations. Benchmarking of Quick Fringe shows that interferograms of a lens could be analyzed successfully by utilizing various methods to calculate the lens geometry within +/-0.05 waves. Vibration issues were mitigated by either creating a reference interferogram, or averaging multiple reference interferograms. Quick Fringe calculated the results of the MITL interferogram to have a maximum fringe shift to be ∼0.5 to ∼0.7 waves, which correlates to a plasma density of >2--3 · 1016 cm-3.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
We present an overview of diagnostic techniques for measuring key parameters of electron bunches from Laser Plasma Accelerators (LPAs). The diagnostics presented here were chosen because they highlight the unique advantages (e.g., diverse forms of electromagnetic emission) and difficulties (e.g., shot-to-shot variability) associated with LPAs. Non destructiveness and high resolution (in space and time and energy) are key attributes that enable the formation of a comprehensive suite of simultaneous diagnostics which are necessary for the full characterization of the ultrashort, but highly-variable electron bunches from LPAs.
Author: Dongsu Du
Author: Dongsu Du
Author: Stefan Bedacht
Author: Yen-Yu Chang
Author: 
Author: Alexander Ross Meadows
Author: Jan-Niclas Gruse
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Author: 
Author: Barney Richard Walton
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