Strongly-Coupled Dusty Plasmas

对强耦合尘埃等离子体中的非平衡动力学、粘弹性行为和波动进行了基本的实验研究。强耦合等离子体是粒子间势能大于粒子动能的电离气体。在这些条件下，等离子体的行为像晶体或液体，不像更常见的弱耦合等离子体，后者的行为像气体。尘埃等离子体由悬浮在由电子和离子组成的等离子体中的微米级固体颗粒组成。由于从等离子体中收集电子和离子，粒子变得高度带电。通常，对于直径为10微米的球体，Q=-10,000 e。这种大电荷会产生很大的粒间斥力。这种巨大的排斥力，再加上用气体阻力冷却粒子，提供了强烈的耦合。颗粒的大小允许使用视频缩微术进行直接成像和颗粒跟踪。用微球的2D和3D悬浮液进行了实验。对于2D，等离子体鞘的电场在重力存在的情况下使粒子悬浮，产生单层粒子。利用这个2D系统所取得的发现也将有助于理解其他物理领域的2D物理学。对于3D，气体温度梯度所产生的力被用来抵消重力，产生了被称为“库伦球”的3D悬浮物。激光束可以以不同的方式推动和操纵粒子，以加热它们、驱动剪切流和激发波。这种操纵和气体摩擦的组合提供了一个驱动型耗散系统。这使得非平衡系统可以在通常只有在理论上才可能的基本水平上进行实验研究。提出了一个基本物理问题的实验方案：*2D中的非平衡涨落*3D膨胀等离子体的平衡*粘弹性2D物理*极端剪切下3D中的界面。*2D晶体中的孤立波。研究活动的其他影响包括：*“鹰眼看科学”系列中的K12外展介绍。*非颁授博士学位院校的教员参与。*将研究课题纳入教学课程本提案已提交给NSF-美国能源部等离子体科学与工程伙伴关系联合征集08-589。该奖项由物理系等离子体物理项目资助。

A fundamental experimental study is proposed for nonequilibrium dynamics, viscoelastic behavior, and waves in strongly-coupled dusty plasma. Strongly-coupled plasma is ionized gas in which the interparticle potential energy is greater than the particle kinetic energy. Under these conditions, plasma behaves like a crystal or liquid, unlike more familiar weakly-coupled plasmas which behave like a gas. Dusty plasma consists of micron-size particles of solid matter suspended in a plasma consisting of electrons and ions. Due to collecting electrons and ions from the plasma, particles become highly charged. Typically, Q = -10,000 e for a 10 micron diameter sphere. This large charge produces a large interparticle repulsion. This large repulsion, combined with cooling the particles with gas drag, provides strong coupling. The size of the particles allows direct imaging and particle tracking using video micrography. Experiments are done with both 2D and 3D suspensions of microspheres. For 2D, the electric field of a plasma sheath levitates particles in the presence of gravity, yielding a single layer of particles. Discoveries made with this 2D system will help in understanding 2D physics in other areas of physics as well. For 3D, forces due to gas temperature gradients are applied to offset gravity, yielding a 3D suspension called a "Coulomb ball." Laser beams can push and manipulate particles in different ways to heat them, drive shear flows, and excite waves. A combination of this manipulation and gas friction provides a driven-dissipative system. This allows nonequilibrium systems to be studied experimentally at a fundamental level that is usually possible only in theory. An experimental program is proposed for these fundamental physics topics: * Nonequilibrium fluctuations in 2D * Equilibration of 3D expanding plasma* Viscoelastic 2D physics* Interfaces in 3D under extreme shear. * Solitary waves in 2D crystal. Other impacts of the research activity include:* K12 outreach presentations in the "Hawk-Eyes on Science" series. * Participation of faculty of a non-PhD-granting institution. * Incorporating research topics in the teaching curriculumThis proposal was submitted to the NSF-DoE Partnership in Plasma Science and Engineering joint solicitation 08-589. This award is being funded by the Plasma Physics Program in the Division of Physics.