Yonemori Seiya, Ono Ryo
Department of Advanced Energy, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 227-8568, Japan.
Biointerphases. 2015 Jun 1;10(2):029514. doi: 10.1116/1.4919709.
The atmospheric-pressure helium plasma jet is an emerging technology for plasma biomedical applications. In this paper, the authors focus on the effect of discharge polarity on propagation of the discharge and the densities of OH, NO, and O radicals. The plasma jet is applied to a glass surface placed on a grounded metal plate. Positive or negative voltage pulses with 25 μs duration, 8 kV amplitude, and 10 kpps repetition rate are used for the plasma jet. The plasma propagation is measured using a short-gated ICCD camera. The light emission intensity of the discharge generated at the rising phase of the voltage pulse is approximately equivalent for both polarities, while that generated during the falling phase is much higher for the negative discharge than the positive one. The shape of the discharge changes with the discharge polarity. The OH, NO, and O densities in the plasma jet are also measured for both polarities. It is found that the OH density is almost the same regardless the discharge polarity. Conversely, the negative discharge produces more O atoms and the positive discharge produces more NO molecules. These results indicate that the polarity of the discharge affects the densities of some reactive species produced in the plasma jet.
大气压氦等离子体射流是一种用于等离子体生物医学应用的新兴技术。在本文中，作者着重研究了放电极性对放电传播以及OH、NO和O自由基密度的影响。将等离子体射流施加到放置在接地金属板上的玻璃表面。使用持续时间为25 μs、幅度为8 kV、重复频率为10 kpps的正电压或负电压脉冲来产生等离子体射流。使用短门控ICCD相机测量等离子体的传播。在电压脉冲上升阶段产生的放电发光强度对于两种极性大致相当，而在下降阶段产生的放电发光强度对于负放电而言比正放电要高得多。放电的形状随放电极性而变化。还针对两种极性测量了等离子体射流中的OH、NO和O密度。结果发现，无论放电极性如何，OH密度几乎相同。相反，负放电产生更多的O原子，而正放电产生更多的NO分子。这些结果表明，放电极性会影响等离子体射流中产生的一些活性物种的密度。
