Probe Diagnosis Of Low Temperature Magnetized Helicon Wave Plasma

The interaction between plasma and materials is a very complex process,involving the interaction of many elements?molecules,atoms,ions?with materials.In this process,the difference of plasma microparticles?such as different transport characteristics,chemical activity,etc.?will affect the surface modification effect of plasma.There are many factors affecting these differences,such as discharge power,gas type,working pressure and so on.These factors often need to be comprehensively discussed in different plasma devices.Only by the diagnosis of plasma parameters,the qualitative relationship between plasma parameters and their treatment effects can be found,and the mechanism of interaction between plasma and materials can be better analyzed.In magnetized plasma,the external magnetic field can often realize the fine tuning,confinement and optimization of the plasma.However,because of the existence of magnetic field,there will be some new phenomena in the plasma,such as the helical wave plasma?HWP?discharge device,The spatial magnetic field fluctuation caused by the nonlinear coupling of RF wave and magnetized plasma near the helical wave antenna.Therefore,in addition to the discharge power and other factors,it is necessary to study the magnetic field signal in magnetized plasma,including amplitude and phase.In this paper,Langmuir probe and electrostatic quadrupole plasma?EQP?were used to diagnose the discharge parameters of Ar helical wave plasma discharge.The results of steady state helical wave discharge at high magnetic field and magnetic field?up to 0.5 T?are introduced.The influence of RF power(P_rf)and the magnetic field on the discharge of HWP are studied.The variation of HWP parameters in different magnetic fields was studied.The results show that the electron density near the source region is higher,the electron temperature increases linearly with the increase of RF power.The effective impedance of antenna(R_eff)increases abruptly with the P_rfincreasing.This means that the coupling efficiency of HWP is higher than that of pure inductively coupled plasma?ICP?discharge.The curve of n_e is approximately linear at low fields.However,the ne decreases abruptly and then reaches saturation at high fields.The Te decreases slightly in low fields,and has a similar way to the n_e in high fields.A full width at half maximum?FWHM?of the ne peak is observed to increase with increasing B₀ indicative of increased radial confinement of plasma.The ion energy of Ar HWP was further analyzed by EQP.This result strongly suggests that a double layer?DL?is created in Ar HWP discharge,which accelerates the atomic Ar+ions and forms a beam downstream of the DL.In addition,magnetic probe and emission probes have been designed and developed,The diagnosis of emission probe has been tested on the helicon wave experiment platform in the laboratory.It is preliminarily concluded that with the increase of heating current,the number of electrons emitted from tungsten wire increases and the intersection of I-V characteristic curve and transverse axis moves to the right side,and the transition region of I-V characteristic curve becomes steeper.It shows that the inflection point of the I-V characteristic curve can be obtained more easily with higher heating current.