Sheath and dust particle transport in plasmas

等离子体中的鞘层和尘埃粒子传输

• 批准号: RGPIN-2019-04333
• 负责人: Couedel, Lenaic
• 金额: $ 2.48万
• 依托单位: University of Saskatchewan
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=714109
• 关键词: Sheath; dust; particle; transport; plasmas

Plasmas are (weakly) ionised gases consisting of positive ions and free electrons. They can be found everywhere from astrophysical environment (stars, interstellar medium) to energy production and industrial applications (ion implantation, plasma etching, production of nanoparticles, Hall-effect thrusters, fusion devices, etc). In devices used for laboratory experiments or industrial applications, plasmas are confined and bound by the walls of the vessel. The plasma-wall interface (referred to as the plasma sheath) is a narrow region in which the quasi-neutrality condition applicable to bulk plasmas does not hold. The sheath plays a major role in determining the plasma discharge parameters and affects the flows of particles and the heat to the surface. Plasma-surface (or plasma-wall) interactions are thus common to all laboratory plasma systems. Plasmas containing large solid particles (dusts) are called dusty plasmas. Due to interactions with the plasma electrons and ions, dusts acquire net electric charges. In laboratory low-temperature plasmas, dusts are usually charged negatively due to high electron mobility. Sheaths form in the vicinity of dusts affecting plasma species fluxes on dust surfaces and dust transport. Understanding dust interactions with the surrounding plasma requires a good comprehension of sheath formation around small floating solid grains and an accurate knowledge of local plasma parameters (electric fields, ion velocity distribution function). Hence, the problem can be widened to a more general study of plasma-surface interactions (PSI), plasma-dust interactions being only one aspect of it. While sheath formation in front of conducting surface in non-magnetised collision-less low-temperature plasma is known, sheath formation in front of surfaces emitting particles or in magnetised plasma is still poorly understood. The long term objectives of the proposed research are to gain deep understanding on sheath formation and on the transport and dynamics of dust particles in plasmas. They can be formulated under two major themes: (i) Electric fields and Ion velocity distribution function in the sheath, (ii) Dynamics of dust particles in plasmas. Short term objectives include: (1) Studies of sheaths parameters in front of different surfaces using state-of-the-art laser based diagnostics; (2) Dynamics and transport of dusts in conventional gas discharges; (3) Dynamics, transport and lifetime of dust particles in tokamaks; (4) Theoretical and numerical studies on sheath formation in front of emissive surfaces in plasmas. HQPs will be involved in all steps of this research program which focus on a highly applicable area of plasma physics and technology.

等离子体是由正离子和自由电子组成的（弱）电离气体。从天体物理环境（恒星、星际介质）到能源生产和工业应用（离子注入、等离子体蚀刻、纳米颗粒生产、霍尔效应推进器、聚变装置等），它们无处不在。在用于实验室实验或工业应用的设备中，等离子体受到容器壁的限制和束缚。等离子体壁界面（称为等离子体鞘层）是一个狭窄的区域，在这个区域中，适用于大块等离子体的准中性条件不成立。鞘层在等离子体放电参数的确定中起着重要的作用，并影响着粒子的流动和表面的热量。因此，等离子体表面（或等离子体壁）相互作用在所有实验室等离子体系统中都是常见的。