Comparative studies of the laser Thomson scattering and Langmuir probe methods for measurements of negative ion density in a glow discharge plasma

Abstract

The newly developed method of the negative ion density measurement in a plasma by laser Thomson scattering (LTS) was checked by comparing the obtained results against an independent technique, namely the Langmuir probe method. Both measurements were performed at the same position of the same inductively coupled plasma. The results agree quite well with each other and this has given confidence in the LTS method of negative ion density measurement. At the same time, both methods are complementary to each other, because the Langmuir probe measurement requires knowledge of the positive ion mass number.

Characteristics of VHF H2 Plasma Produced at High Pressure

“…Therefore, the observation of high negative ion density may come from the short gap VHF discharge. Direct measurements of both the negative ion density [15] and negative ion species will be necessary in the future. Furthermore, Fig.…”

Effects of oxygen addition on physical properties of ZnO thin film grown by radio frequency reactive magnetron sputtering

“…In brief summary, results indicated a reduction in plasma number density and thus the reduction of ion flux/energy in bombarding the target [21,25,26]. Accordingly, this also reduced the sputtering yield, which resulted in a lower deposition rate at a higher O 2 /(Ar + O 2 ) ratio [21,27].…”

Comparison of Two Methods of Interpretation of LangmuirProbe Data for an Inductively Coupled Oxygen Plasma

“…However, the negative ion temperature needs to be known accurately from other methods [22]. To determine the temperature ratio γ more accurately, one has to use a separate double probe along with the single probe [23] or a more sophisticated Thomson scattering technique [8]. Figure 1b) shows the comparison of the experimental I − V curve of the probe for P abs = 300 W, p = 26 mtorr with the theoretical I − V curve.…”

“…There is considerable scientific and technological interest in electronegative plasmas [2,3] and so in the determination of negative ion density [4][5][6]. Langmuir probes [7], photodetachment [4,5], and laser Thomson scattering [8] are diagnostic tools for investigating negative ions in plasma . Among these, Langmuir probe technique is simple, inexpensive and provides the spatial resolution of plasma parameters.…”