Laboratory visualization of laser-driven plasma accelerators in the bubble regime
MetadataShow full item record
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.
Showing items related by title, author, creator and subject.
Proton acceleration experiment by high intensity laser pulse interaction with solid density target at the Texas Petawatt Laser Facility Kuk, Donghoon (2011-12)In recent, high intensity laser pulse interaction with solid density matter has been studied in several laboratory and facilities. Multi-MeV proton and ion beams from plasma produced by this interaction is one important ...
Gaul, E.; Toth, C. (2012-06)Laser Technology has long been the limiting and the enabling step for laser plasma accelerators. The work presented here addressed the current and near future laser technology relevant to particle acceleration as well as ...
Quasi-monoenergetic laser-plasma acceleration of electrons beyond 1 GeV at the Texas Petawatt Laser Fazel, Neil Behzad; 0000-0002-8178-3371 (2015-08)Laser-plasma accelerators first produced 1 GeV electrons with few percent energy spread and high beam quality in 2006. The goal of laser-plasma acceleration experiments conducted at the Texas Petawatt (TPW) laser starting ...