大気圧プラズマジェットによる粒子表面電荷の制御

Abstract

大気圧プラズマジェットから生成される正イオンや電子を利用して粒子表面の電荷を制御する方法を実験的に検討した．石英ガラス管の内側に円筒電極を取り付けて交流電圧および直流バイアス電圧を印加し，ヘリウムガスを供給して大気圧プラズマジェットを生成した．直流バイアス電圧の値を変えることにより，プラズマ中の正イオンや電子を選択的に抽出できた．粒子をプラズマジェット中で重力落下させる実験と静置した粒子にプラズマジェットを照射する実験を行い，相互に比較した結果，いずれも空間電荷に基づく電場によって正イオンや電子を粒子に付与できることがわかった．また，外部電場の印加によっても粒子の帯電を制御できた．これらの実験結果をもとに粒子の帯電機構を考察した．

A method for controlling electrostatic charge on particles with positive ions and/or electrons generated by an atmospheric pressure plasma jet was studied experimentally. The atmospheric pressure plasma jet was generated by applying AC voltage and DC bias voltage to a cylindrical electrode in a quartz glass tube with helium gas flow. By changing the value of the DC bias voltage, positive ions and/or electrons could be extracted from the plasma. Two experiments, one in which particles were allowed to fall in the plasma jet and the other in which particles were irradiated with the plasma jet, were performed, and comparison of their results showed that both methods allowed the particles to acquire positive ions and/or electrons because of the electric field caused by the space charge. In addition, particle charging could be controlled by applying an external electric field. Based on these experimental results, the particle charging mechanism involved was discussed.