A Laser-Plasma Ion Beam Booster Based on Hollow-Channel Magnetic Vortex Acceleration

Laser-driven ion acceleration can provide ultra-short, high-charge, low-emittance beams. Although undergoing extensive research, demonstrated maximum energies for laser-ion sources are non-relativistic, complicating injection into high-$\beta$ accelerator elements and stopping short of desirable energies for pivotal applications, such as proton tumor therapy. In this work, we decouple the efforts towards relativistic beam energies from a single laser-plasma source via a proof-of-principle concept, boosting the beam into this regime through only a few plasma stages. We employ full 3D particle-in-cell simulations to demonstrate the capability for capture of high-charge beams as produced by laser-driven sources, where both source and booster stages utilize readily available laser pulse parameters.Comment: 4 pages, 4 figures, submitted for peer revie

Exploring novel concepts of x-ray radiation generation

Laser Wakefield Acceleration (LWFA) is a promising technique for the development of com- pact particle accelerators. The resulting electron beams have useful characteristics such as short temporal duration and high brightness. LWFA can also generate x-ray radiation, which can be tailored by properties of the interaction such as target density profile and laser polarization.This work will discuss the theoretical regime of x-ray driven WFA in a nanotube. In this novel regime, the acceleration gradient is predicted to be on the order of TeV/cm and this is confirmed by modeling x-ray pulses in a nanotube. In this work, we include the effects of ionic motion explicitly and investigate the possibility that the lattice force could couple with the formation of a stable wake structure. We show that wakefield formation and electron acceleration processes are not influenced by the presence of polaritons. The present work indicates the acceleration gradient on the order of TeV/cm, which agrees well with wakefield theory and is consistent with previous findings without the lattice effect. This amounts to the validation by computation of the concept of the solid state plasma wakefield in nanomaterials.This thesis also includes experimental work designed to study the wavelength scaling of LWFA as the wavelength is decreased. An experimental platform was built in a new labo- ratory at UCI. The laser system is a commercial system with mJ scale energy and operates at kHz repetition rate. Generation of a sub-relativistic electron beam was confirmed by de- tection of bremsstrahlung radiation. This platform can be used to study electron beam and radiation generation with a near single cycle pulse as well as 2ω and 3ω of the laser pulse.A series of LWFA experiments conducted using the HERCULES laser system are also pre- sented. The results demonstrate that wakefield temperature and dynamics can be determined by the soft x-ray spectra of the interaction. Plasma conditions, the signature of bubble for- mation and electron injection are imprinted in the xuv data. A decreased self-injection threshold was observed with a circularly polarized laser pulse revealing that self-injection is polarization dependent. A different injection mechanism for a circularly polarized laser pulse is discussed

Exploring novel concepts of x-ray radiation generation

Laser Wakefield Acceleration (LWFA) is a promising technique for the development of com- pact particle accelerators. The resulting electron beams have useful characteristics such as short temporal duration and high brightness. LWFA can also generate x-ray radiation, which can be tailored by properties of the interaction such as target density profile and laser polarization.This work will discuss the theoretical regime of x-ray driven WFA in a nanotube. In this novel regime, the acceleration gradient is predicted to be on the order of TeV/cm and this is confirmed by modeling x-ray pulses in a nanotube. In this work, we include the effects of ionic motion explicitly and investigate the possibility that the lattice force could couple with the formation of a stable wake structure. We show that wakefield formation and electron acceleration processes are not influenced by the presence of polaritons. The present work indicates the acceleration gradient on the order of TeV/cm, which agrees well with wakefield theory and is consistent with previous findings without the lattice effect. This amounts to the validation by computation of the concept of the solid state plasma wakefield in nanomaterials.This thesis also includes experimental work designed to study the wavelength scaling of LWFA as the wavelength is decreased. An experimental platform was built in a new labo- ratory at UCI. The laser system is a commercial system with mJ scale energy and operates at kHz repetition rate. Generation of a sub-relativistic electron beam was confirmed by de- tection of bremsstrahlung radiation. This platform can be used to study electron beam and radiation generation with a near single cycle pulse as well as 2ω and 3ω of the laser pulse.A series of LWFA experiments conducted using the HERCULES laser system are also pre- sented. The results demonstrate that wakefield temperature and dynamics can be determined by the soft x-ray spectra of the interaction. Plasma conditions, the signature of bubble for- mation and electron injection are imprinted in the xuv data. A decreased self-injection threshold was observed with a circularly polarized laser pulse revealing that self-injection is polarization dependent. A different injection mechanism for a circularly polarized laser pulse is discussed

Paraneoplastic syndromes revealing ovarian teratoma in young and menopausal women: report of two cases

Paraneoplastic syndromes are a heterogeneous group of clinical and biological manifestations caused by underling neoplasms. They can reveal ovarian teratoma which express neuroendocrine proteins, or contain mature or immature neural tissue inducing an autoimmune response. The etiological investigation is then crucial to early identification of the tumor in order to optimize the prognosis and to limit neurological sequelae. In case of ovarian teratoma, management is essentially based on surgical resection sometimes associated with immunotherapie. We report two new cases of ovarian teratoma revealed by paraneoplastic syndromes in young and menopausal woman.The Pan African Medical Journal 2016;2

High-Density Dynamics of Laser Wakefield Acceleration from Gas Plasmas to Nanotubes

The electron dynamics of laser wakefield acceleration (LWFA) is examined in the high-density regime using particle-in-cell simulations. These simulations model the electron source as a target of carbon nanotubes. Carbon nanotubes readily allow access to near-critical densities and may have other advantageous properties for potential medical applications of electron acceleration. In the near-critical density regime, electrons are accelerated by the ponderomotive force followed by the electron sheath formation, resulting in a flow of bulk electrons. This behavior represents a qualitatively distinct regime from that of low-density LWFA. A quantitative entropy index for differentiating these regimes is proposed. The dependence of accelerated electron energy on laser amplitude is also examined. For the majority of this study, the laser propagates along the axis of the target of carbon nanotubes in a 1D geometry. After the fundamental high-density physics is established, an alternative, 2D scheme of laser acceleration of electrons using carbon nanotubes is considered

Laser–Solid Interaction Studies Enabled by the New Capabilities of the iP2 BELLA PW Beamline

The new capabilities of the short focal length, high intensity beamline, named iP2, at the BELLA Center will extend the reach of research in high energy density science, including accessing new regimes of high gradient ion acceleration and their applications. This 1 Hz system will provide an on-target peak intensity beyond 1021 W/cm2 with a temporal contrast ratio of <10−14 that will be enabled by the addition of an on-demand double plasma mirror setup. An overview of the beamline design and the main available diagnostics are presented in this paper as well as a selection of accessible research areas. As a demonstration of the iP2 beamline's capabilities, we present 3D particle-in-cell simulations of ion acceleration in the magnetic vortex acceleration regime. The simulations were performed with pure hydrogen targets and multi-species targets. Proton beams with energy up to 125 MeV and an approximately 12° full angle emission are observed as preplasma scale length and target tilt are varied. The number of accelerated protons is on the order of 109/MeV/sr for energies above 60 MeV