Resonance hairpin and Langmuir probe-assisted laser photodetachment measurements of the negative ion density in a pulsed dc magnetron discharge
Resonance hairpin and Langmuir probe-assisted laser photodetachment measurements of the negative ion density in a pulsed dc magnetron discharge
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DOI：
10.1116/1.3580934
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发表时间：
2011-04
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影响因子：
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通讯作者：
J. Bradley;R. Dodd;S. You;N. Sirse;S. Karkari
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文献类型：
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作者：
J. Bradley;R. Dodd;S. You;N. Sirse;S. Karkari
首次用激光光解和共振发夹探测相结合的方法测量了反应脉冲直流磁控放电(10−，占空比50%)中线附近的时间分辨负氧离子密度n。放电功率为50W，工作气体为70%Ar和30%氧气，压力为1.3Pa.结果表明，在放电驱动阶段，O−密度基本保持不变，一般小于5×10 14m−3，而在关断时间，O−密度增加到通电时的数倍。这导致负离子分数(或电负性程度)α=n−/Ne在关闭阶段(最大值α∼1)高于在开启阶段(α=0.0 5-0.3)。作者还发现，在靠近磁零点的位置，α的值比在等离子体的磁化程度更高的区域更高。脱相过程中负离子密度的小幅增加归因于离解电子的增强。
The time-resolved negative oxygen ion density n− close to the center line in a reactive pulsed dc magnetron discharge (10 kHz and 50% duty cycle) has been determined for the first time using a combination of laser photodetachment and resonance hairpin probing. The discharge was operated at a power of 50 W in 70% argon and 30% oxygen gas mixtures at 1.3 Pa pressure. The results show that the O− density remains pretty constant during the driven phase of the discharge at values typically below 5×1014 m−3; however, in the off-time, the O− density grows reaching values several times those in the on-time. This leads to the negative ion fraction (or degree of electronegativity) α=n−/ne being higher in the off phase (maximum value α∼1) than in the on phase (α=0.05–0.3). The authors also see higher values of α at positions close to the magnetic null than in the more magnetized region of the plasma. This fractional increase in negative ion density during the off-phase is attributed to the enhanced dissociative elec...