Conveners
TS-3 Plasma Physics Symposium (DPP) / Symposium de physique des plasmas (DPP)
- Lenaic Couedel (University of Saskatchewan)
The inertial confinement fusion scheme relies on the implosion of a Deuterium-Tritium pellet by the means of tens of laser beams. At maximum of compression, extreme thermodynamic conditions must be reached in order to trigger a thermonuclear wave. Laser-plasma interaction, for such large spatial and temporal scales, may only be described numerically with specific hydrodynamic codes. In the...
At relativistic intensities, electrons can be driven close to the speed of light, facilitating exploration of a new regime of laser-plasma interactions and high-field science. These intense pulses can drive matter into extreme states of temperature and pressure, mimicking those typically found in astrophysical environments, and leading to the observation of new states of high-energy-density...
Tajima and Dawson proposed the idea of laser-wakefield accelerators (LWFAs) during the late 1970s. LWFAs produce low transverse emittance, ultrashort electron bunches of few femtoseconds duration with the potential to drive free electron lasers and compact X-ray and gamma-ray sources. Through the implementation of high-gradient quadrupole magnets, it is possible to focus and transport LWFA...
The nonlinear behavior of absolute stimulated Raman scattering (SRS) near the quarter-critical density is investigated using one-dimensional (1D) Vlasov simulations with parameters relevant to ignition-scale direct-drive coronal plasmas. Numerical Vlasov simulations show that a strong and stable Airy pattern is formed by the Raman light as it is generated near its cutoff density. This...
Experiments performed at the National Ignition Facility (NIF) have provided evidence that stimulated Raman scattering (SRS) occurs at a level that poses a preheat risk for directly-driven inertial confinement fusion implosions [1]. To help investigate the mechanisms responsible for the generation of this SRS, recent experiments on the OMEGA EP laser (in which similar SRS signatures were...
The suppression of turbulence in fusion plasmas, crucial to the success of next-generation tokamaks such as ITER, depends on a variety of physical mechanisms including the shearing of turbulent eddies via zonal flow and possibly the generation of intrinsic rotation. The turbulence exhibits interesting features such as avalanche structures and self-organisation, and its absence is associated...
Study of high-confinement mode (H- mode) of tokamak operation plays an important role to optimize conditions for fusion reactors. Many experimental techniques, including electrode biasing and resonant magnetic perturbations (RMP), have been developed to improve the plasma confinement, facilitating transition from low to high confinement mode (L-H transition) and to study the transition...
There exists an unconventional class of waves known as thermal diffusion waves, or simply thermal waves, that are produced using sinusoidally, time-varying heat sources and they can be used to determine the thermal conductivity in the medium. Recent advancements have resulted in the construction of thermal wave resonator cavities (TWRCs) capable of sustaining quasi-standing thermal waves which...
The effects of the modification of the electron distribution function in the nonlinear regime of the Buneman instability and statistical noise effects have been investigated, using high-resolution Vlasov and Particle-in-Cell simulations. It is shown that this modification is a result of electron trapping. In nonlinear regimes, electron trapping and associated modification of the electron...
Engineering of defects located in-grain or at grain boundary is central to the development of functional materials and nanomaterials. While there is a recent surge of interest in the formation, migration, and annihilation of defects during ion and plasma irradiation of bulk (3D) materials, the detailed behavior in low-dimensional materials remains most unexplored and especially difficult to...
Polycrystalline monolayer graphene films grown by chemical vapor deposition were exposed to a low-pressure inductively-coupled plasma operated in a gaseous mixture of argon and diborane. Optical emission spectroscopy and plasma sampling mass spectrometry reveal high B2H6 fragmentation leading to significant populations of both boron and hydrogen species in the gas phase. X-ray photoelectron...
: Plasma Immersion Ion Implantation (PIII) is a versatile material processing technique [1,2] with many applications in semiconductor doping, micro- and nanofabrication [3], as well as the surface modification of metals for improved resistance against wear and corrosion. In PIII a solid target is immersed in plasma, and negative polarity high-voltage (typically 1-20 kV) are applied the...
Plasma immersion ion implantation (PIII) is a versatile tool in the field of materials processing, surface modification, and semiconductor manufacturing[1]. By immersing the target directly in the plasma, PIII boasts many advantages over its predecessor, conventional ion implantation, including a simpler design, faster throughput and more uniform implantation over irregular objects[4]. When a...
The vast majority of dusty/complex plasma experiments have involved the suspension of charged, micron-sized particles in plasmas. The particles are suspended due to a delicate balance between gravitational and electrostatic forces. The addition of a magnetic field to these systems has a profound influence on both the surrounding plasma and the dusty plasma as the dynamics of first the...
The dependence of the mode-coupling instability threshold in two-dimensional complex plasma crystals is studied. It is shown that for a given microparticle suspension at a given discharge power there exist two thresholds in pressure. Above a specific pressure $p_\mathrm{max}$, the monolayer is always in the crystal phase. Below a specific pressure $p_\mathrm{min}$, the crystalline monolayer...
Fixed-bias multi-needle Langmuir probes consisting of several cylindrical probes biased to different potentials can be used to measure plasma parameters on satellite without the need of sweeping bias voltages. Compared to a single Langmuir probe for which voltage is varied periodically in time, fixed bias probes enable measurement with a significantly higher sampling rate and, owing to the...
Affiliation: University of Saskatchewan
Fusion and related plasma physics research enables the development of a new, safe and reliable, high-output fusion energy source. There are however multiple problems to address with fusion devices. One such problem is that of contaminating dust, produced by plasma wall interactions within the reactor.
Dust generation from Plasma Facing Components...
For nearly a century, Langmuir probes have been used to infer plasma densities and temperatures from current characteristics. In practically all cases, these inferences are based on analytic expressions obtained theoretically. Despite their limitations, analytic expressions continue to be used because of their relative simplicity, and the fact that they can be used to construct fast inference...
This work considers the use of spherical segmented Langmuir probes as a means to measure ionospheric plasma flow velocities. This is done by carrying out three-dimensional kinetic self-consistent Particle in Cell (PIC) simulations to compute the response of a probe to space plasma under a range of space environment conditions of relevance to satellites in low Earth orbit (LEO) at low and mid...
Flow-through Z-pinches were first discovered over 50 years ago, manifesting themselves as a stable, pinch-like structure that persisted for 100 us in the Newton-Marshal gun experiments at LANL in the late 1960’s. Linear stability analysis performed by Uri Shumlak in the 1990’s showed that when dV_z/dr > 0.1 k V_A the kink mode could be stabilized in a Z-pinch plasma. Experimental work over the...
Energy loss in magnetic confinement fusion is dominated by plasma turbulence --- turbulent transport can surpass all other mechanisms by several orders of magnitude. Instability, driven by the Ion Temperature Gradient (ITG) mode is a key contributor to such turbulence, and is the topic of this work. Simulating such small-scale, $\mathcal{O}(\mathrm{mm})$, turbulence over an...
Steep thermal gradients in a magnetized plasma can induce a variety of spontaneous low frequency excitations such as drift-Alfven waves and vortices. We present results from basic experiments on heat transport in magnetized plasmas with multiple heat sources in close proximity [1]. The experiments were carried out at the upgraded Large Plasma Device (LAPD) operated by the Basic Plasma Science...
