Plasma Parameter Diagnosis Based On Nonextensive Single Electric Probe

In the field of plasma parameter diagnosis,much of plasma parameter informa-tion is obtained by electric probe diagnosis.Presupposition distribution of components in plasma is very important for single probe measurement,which requires the presup-position of which statistical mechanics can be used to describe the plasma to be mea-sured.Statistical hypothesis of plasma includes Boltzmann-Gibbs statistical mechan-ics,in which the components of plasma obey the Maxwellian distribution.However,theoretical analysis and a large number of experiments have proved that plasma compo-nents do not satisfy Boltzmann-Gibbs statistics and can be well described by nonexten-sive statistical mechanics,while new plasma parameters,electron and ion nonextensive parameters,which are introduced to describe the nonextensive properties of plasma,cannot be diagnosed yet.Here we show the measurements of electron and ion nonextensive parameters of plasma with nonextensive single electric probe.We assume that the plasma to be mea-sured can be described by nonextensive statistical mechanics and then establish nonex-tensive single electric probe theory and nonextensive geodesic acoustic mode theory.Using nonextensive single electric probe,we measured an electron nonextensive pa-rameter_e=0.775 that cannot be measured by a traditional single probe and obtained more accurate electron temperature,plasma potential,electron density,and floating po-tential than a traditional single probe?utilizing the nonextensive single electric probe combined with the nonextensive geodesic acoustic mode theory,we measured the ion nonextensive parameters_i=1.565 which cannot be diagnosed even by a nonex-tensive single electric probe directly.The ion sheath formed around the nonextensive single electric probe is studied.It is found that the sheath potential coefficient is related to the electron nonextensive parameter,besides the extensive limit the results return to the case of the Boltzmann-Gibbs statistical framework.The sheath potential coeffi-cient presents different dependences on electron nonextensive parameters in different regions.We also have calculated the corresponding method error and evaluated with a set of real experiment data,and found that the error is as high as 83.91%indicating that the effect of nonextensive parameters should be considered in the actual measurement.We show the measurement of the plasma distribution function with a nonextensive sin-gle electric probe.We analyze the experimental data points of the-（1 curve,measure the plasma electron distribution function1）(),and display the distribution curve（fig-ure1）-).The diagnostic range of nonextensive single electric probe is extended from{_e,_e,Φ_P,9)_e,Φ_f,_e}to{_e,_e,Φ_P,9)_e,Φ_f,_e,1)}.The research shows that the nonextensive electric probe may play a role in plasma diagnosis,measuring the nonextensivity of plasma,and improving diagnostic accuracy of other plasma parameters.We expect that the proposed nonextensive single electric probe can be the starting point of more complex nonextensive electric probes.For ex-ample,it is possible to develop nonextensive single electric probes including effects of magnetic field,collision,secondary electron emission,rf field,etc.,as well as nonexten-sive double,triple,four,five,or N electric probes and an array of nonextensive electric probes.In addition,nonextensive electric probe is an important means to study various plasma waves and instability,turbulence,and anomalous transport,and a definite and quantitative test of nonextensive geodetic acoustic models theory will be relevant to such development.