Experiments to investigate parametric wave interaction in Helicon Plasma

研究 Helicon 等离子体中参数波相互作用的实验

• 批准号: 2278408
• 金额: --
• 依托单位: University of Strathclyde
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2019
• 资助国家: 英国
• 起止时间: 2019 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2278408
• 关键词: Experiments; investigate; parametric; wave; interaction

Plasma is a state of matter dominated by collective interactions between particles, dominated by long range electro magnetic forces. There are a minimum of two species (negative electrons and positive ions). The charge of both types of particle make them each respond to electromagnetic fields (such as light, microwave and radio waves), but in opposite directions, and at very different rates. They particularly respond to waves at frequencies close those of natural plasma oscillations, determined by complicated combinations of the magnitude and direction of any static magnetic field, the number density and mass of the particles. They can absorb wave energy at frequencies called 'resonances', and reflect wave energy at frequencies called 'cut-offs'. These effects are often used to heat or measure plasmas in important laboratory experiments and applications, such as new techniques for energy production through fusion reactions (magnetically confined) and industrial processing, and natural plasma is important through its impact on modern energy distribution, communication and navigation systems. In industrial processing, plasma physics underpins semiconductor processing and hence modern digital technology. In fusion energy the impact potential can be profound, enabling an almost unlimited supply of energy, addressing serious environmental concerns surrounding the use of fossil fuel, with no long term radioactive byproducts.Parametric coupling refers to a multi-wave interaction where two or more waves exchange energy when their frequencies are related by a natural plasma oscillation frequency. Such processes have recently been found to cause difficulties in laser-plasma interactions for inertial confinement fusion, whilst at the same time offering exciting potential for new and more flexible ways of delivering energy into both inertially and magnetically confined fusion plasmas. Such new techniques will be increasingly important as research in these fields moves from fundamental experiments to application scale equipment. This project will undertake fundamental research investigating these interactions in the microwave frequency range. The microwave range is attractive for such research since powerful sources and amplifiers, developed for a range of applications, are readily available, can be very precisely controlled, enhancing the ability to investigate the plasma physics dynamics, whilst groundbreaking research points towards microwave generators achieving very high levels of normalised power. Microwave-Plasma coupling is directly relevant to industrial processing and magnetic confinement fusion plasma physics, and in the latter case beat wave interaction may have a special role to play in heating next generation reactors, likely to be highly dependent on EM waves to introcude heat and current into the reactor.The coupling of two precisely controlled microwave beams (~10cm to 3cm wavelength) in a (weakly to strongly) magnetised helicon plasma by plasma (acoustic-like) oscillations in the electrons and ions, cyclotron oscillation of the electrons and ions and hybrid oscillations including both quasi-acoustic and cyclotron motion will be investigated, as will the effects of stochastic heating where 'quasi-random' motion of particles in high amplitude waves gives very rapid increase in effective temperature.

等离子体是一种由粒子之间的集体相互作用主导的物质状态，由远程电磁力主导。至少有两种物质(负电子和正离子)。这两种类型的粒子的电荷使它们各自对电磁场(如光、微波和无线电波)做出反应，但方向相反，速度也截然不同。它们尤其对频率接近自然等离子体振荡的波做出反应，这是由任何静态磁场的大小和方向、粒子的数密度和质量的复杂组合决定的。它们能以被称为“共振”的频率吸收波能，并以被称为“截止”的频率反射波能。在重要的实验室实验和应用中，这些效应经常被用来加热或测量等离子体，例如通过聚变反应(磁约束)和工业加工产生能量的新技术，而天然等离子体因其对现代能量分配、通信和导航系统的影响而变得重要。在工业加工中，等离子体物理是半导体加工的基础，因此也是现代数字技术的基础。在聚变能源中，影响潜力可能是深远的，使能源供应几乎无限，解决了围绕化石燃料使用的严重环境问题，没有长期的放射性副产品。参数耦合指的是多波相互作用，当两个或更多波的频率与自然等离子体振荡频率相关时，它们交换能量。最近发现，这种过程在惯性约束聚变的激光-等离子体相互作用中造成了困难，同时为向惯性约束和磁约束聚变等离子体输送能量的新的、更灵活的方法提供了令人兴奋的潜力。随着这些领域的研究从基础实验转向应用规模的设备，这种新技术将变得越来越重要。该项目将在微波频率范围内进行基础研究，研究这些相互作用。微波范围对这类研究很有吸引力，因为为各种应用开发的强大源和放大器随时可用，可以非常精确地控制，增强了研究等离子体物理动力学的能力，而开创性的研究指向实现非常高水平的归一化功率的微波发生器。微波-等离子体耦合直接关系到工业加工和磁约束聚变等离子体物理，在后一种情况下，拍波相互作用可能在加热下一代反应堆中发挥特殊的作用，很可能高度依赖于电磁波将热和电流引入反应堆。我们将研究在(弱到强)磁化的螺旋形等离子体中，两束精确控制的微波光束(~10 cm到3 cm)通过电子和离子中的等离子体(类声学)振荡、电子和离子的回旋振荡以及包括准声和回旋运动在内的混合振荡的耦合。随机加热的影响也是如此，在这种情况下，粒子在高振幅波中的“准随机”运动会使有效温度迅速上升。