尘埃粒子在直流辉光放电阴极鞘层中的运动及悬浮

DYNAMICS AND SUSPENSION OF DUST PARTICLES IN CATHODE SHEATHS OF DC GLOW DISCHARGES 

研究尘埃粒子在直流辉光放电阴极鞘层中的运动特性 ,并讨论了尘埃粒子携带的电荷、受到的各种力及悬浮位置等 .尘埃粒子在鞘层中的运动特性及悬浮位置主要由它的尺寸大小和它所受到的各种力 (重力、电场力、离子拖拽力、中性粒子拖拽力 )决定 .比较无碰撞鞘层和碰撞鞘层发现 ,尘埃粒子在碰撞鞘层中的悬浮位置更加靠近极板 ;比较下鞘 (阴极板放在下方时的鞘层 )和上鞘 (阴极板放在上方时的鞘层 )发现 ,在下鞘中只有同一半径的尘埃粒子悬浮在鞘层中的同一位置 ,而在上鞘中两种不同半径的尘埃粒子可以悬浮在鞘层中的同一位置 .悬浮在鞘层中的尘埃粒子只可能是携带负电荷的 ,并满足合力Fnet=0及dFnet/dx <0 ,但满足上述条件的尘埃粒子能否悬浮在鞘层中 。

We have investigated the dynamics of dust particles in electrode sheaths of dc glow discharges.The charge of dust particles,the various forces and the suspension position are also calculated.The dynamics and the suspension position of dust particles are determined by their size and the forces acting on them. We find that the suspension position in the collisional sheath is closer to the electrode than that in the collisionless sheath.It is also shown that in the lower sheath (above the lower electrode) only those particles of the same size can be suspended in the same position.In the upper sheath (under the upper electrode) grains with different sizes can be suspended in the same position.All the dust particles suspended in the sheath are charged negatively and satisfy F net =0 and d F net /d x <0.However,whether the dust particles that satisfy these conditions can be suspended in the sheath is also determined by their initial position and velocity.