Laboratory visualization of laser-driven plasma accelerators in the bubble regime


Laboratory visualization of laser-driven plasma accelerators in the bubble regime

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dc.contributor.advisor Downer, Michael Coffin
dc.creator Dong, Peng 2011-08-01T19:52:55Z 2011-08-01T19:52:55Z 2010-08 2011-08-01 August 2010
dc.description.abstract Accurate single-shot visualization of laser wakefield structures can improve our fundamental understanding of plasma-based accelerators. Previously, frequency domain holography (FDH) was used to visualize weakly nonlinear sinusoidal wakes in plasmas of density n[subscript e] < 0.6 × 10¹⁹/cm³ that produced few or no relativistic electrons. Here, I address the more challenging task of visualizing highly nonlinear wakes in plasmas of density n[subscript e] ~ 1 to 3× 10¹⁹/cm³ that can produce high-quality relativistic electron beams. Nonlinear wakes were driven by 30 TW, 30 fs, 800 nm pump pulses. When bubbles formed, part of a 400 nm, co-propagating, overlapping probe pulse became trapped inside them, creating a light packet of plasma wavelength dimensions--that is, an optical "bullet"--that I reconstruct by FDH methods. As ne increased, the bullets first appeared at 0.8 × 10¹⁹/cm³, the first observation of bubble formation below the electron capture threshold. WAKE simulations confirmed bubble formation without electron capture and the trapping of optical bullets at this density. At n[subscript] >1× 10¹⁹/cm³, bullets appeared with high shot-to-shot stability together with quasi-monoenergetic relativistic electrons. I also directly observed the temporal walk-off of the optical bullet from the beam-loaded plasma bubble revealed by FDH phase shift data, providing unprecedented visualization of the electron injection and beam loading processes. There are five chapters in this thesis. Chapter 1 introduces general laser plasma- based accelerators (LPA). Chapter 2 discusses the FDH imaging technique, including the setup and reconstruction process. In 2006, Dr. N. H. Matlis used FDH to image a linear plasma wakefield. His work is also presented in Chapter 2 but with new analyses. Chapter 3, the main part of the thesis, discusses the visualization of LPAs in the bubble regime. Chapter 4 presents the concept of frequency domain tomography. Chapter 5 suggests future directions for research in FDH.
dc.format.mimetype application/pdf
dc.language.iso eng
dc.subject Lasers
dc.subject Plasma accelerators
dc.subject Electrons
dc.subject Holography
dc.subject Laser wakefield structures
dc.subject Plasma-based accelerators
dc.subject Direct laser acceleration
dc.subject Laser-plasma electron acceleration
dc.subject Frequency-domain holography
dc.title Laboratory visualization of laser-driven plasma accelerators in the bubble regime 2011-08-01T19:53:43Z
dc.identifier.slug 2152/ETD-UT-2010-08-1881
dc.contributor.committeeMember Becker, Michael
dc.contributor.committeeMember Ditmire, Todd
dc.contributor.committeeMember Lang, Karol
dc.contributor.committeeMember Shvets, Gennady
dc.description.department Physics
dc.type.genre thesis
dc.type.material text Physics Physics University of Texas at Austin Doctoral Doctor of Philosophy

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