Bruneau Bastien, Gans Timo, O'Connell Deborah, Greb Arthur, Johnson Erik V, Booth Jean-Paul
LPICM-CNRS, Ecole Polytechnique, route de Saclay, 91120 Palaiseau, France.
York Plasma Institute, Department of Physics, University of York, Heslington, YO10 5DD York, United Kingdom.
Phys Rev Lett. 2015 Mar 27;114(12):125002. doi: 10.1103/PhysRevLett.114.125002. Epub 2015 Mar 26.
The ionization dynamics in geometrically symmetric parallel plate capacitively coupled plasmas driven by radio frequency tailored voltage waveforms is investigated using phase resolved optical emission spectroscopy (PROES) and particle-in-cell (PIC) simulations. Temporally asymmetric waveforms induce spatial asymmetries and offer control of the spatiotemporal dynamics of electron heating and associated ionization structures. Sawtooth waveforms with different rise and fall rates are employed using truncated Fourier series approximations of an ideal sawtooth. Experimental PROES results obtained in argon plasmas are compared with PIC simulations, showing excellent agreement. With waveforms comprising a fast voltage drop followed by a slower rise, the faster sheath expansion in front of the powered electrode causes strongly enhanced ionization in this region. The complementary waveform causes an analogous effect in front of the grounded electrode.
利用相分辨光发射光谱（PROES）和粒子模拟（PIC）研究了由射频定制电压波形驱动的几何对称平行板电容耦合等离子体中的电离动力学。时间上不对称的波形会引起空间不对称，并能控制电子加热和相关电离结构的时空动力学。使用理想锯齿波的截断傅里叶级数近似来采用具有不同上升和下降速率的锯齿波。将在氩等离子体中获得的实验PROES结果与PIC模拟进行比较，显示出极好的一致性。对于包含快速电压下降随后缓慢上升的波形，在有源电极前方更快的鞘层扩展会导致该区域的电离显著增强。互补波形在接地电极前方会产生类似的效果。
