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Abstract
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This study developed a stable transfer of He atmospheric pressure cold plasma bullets in a large dielectric tube with a length of 70 cm and an inner diameter of 0.4–1.6 cm. DC superimposed AC voltage was used for this purpose. The DC component of the applied voltage generated corona ionization through the tube, which helped in the ignition and transfer of the plasma as a preionization background. The bullets followed the frequency of the AC component; therefore, very high applied energy was not required to ignite this large-scale plasma. To our knowledge, this is the first time such a complex waveform has been reported for the transfer of a plasma bullet. The characteristics of the transferring plasma bullet, such as the power, charge, propagation speed, resistance, AC electrical field (EF) of the plasma, and electrostatic field on the tube surface, were measured. The influence of the tube diameter on these characteristics was investigated. The results showed that the power applied, charge, and power deposited on the target increased as the tube diameter increased. Less plasma resistance and radiation were observed using larger diameters. The root mean square (RMS) values of the axial AC EF of the bullet along the jet axis were higher for the larger diameters, but no special relation between the propagation speed, radial AC EF, and static surface field and tube diameter was observed
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