Experimental Investigation Of Plasma Sheath Structure In A Magnetized Small Testing Chamber

Plasma sheath was proposed by Langmuir in 1932,after that,studies on plasma sheath have attracted more and more attention.There were many theoretical works on both non-magnetized plasma sheath and mag-netized plasma sheath.Recently,with the development of the diagnos-tic technology,experimental studies have been progressing.These work-s mainly focus on non-magnetized plasma sheath,potential distribution when the magnetic field is parallel with plasma sheath,ion velocity dis-tribution function.However,experimental works on plasma sheath when magnetic field is perpendicular with plasma sheath or works on plasma sheath in different magnetic field configuration are rarely reported.In the laboratory plasma,plasma sheath can be formed near the met-al plate or metal mesh.When the metal plat(or mesh)is given a nega-tive or a positive voltage,ion sheath or electron sheath will be formed.Some researches indicated that the characteristics of plasma sheath can be influenced by air pressure?plasma intensity?electron temperature and magnetic field.The experiments were conducted in a magnetized small testing cham-ber,with 2 coils were placed at both ends,the magnetic field can be changed from 0 to 740G.A metal plate was placed in the device and plas-ma sheath will be formed near the plate.In the experiments,we studied the sheath characteristics under different conditions(magnetic field config-uration?voltage of the plate?magnetic field?air pressure)?The main conclusions are as follows:1.First,we established a magnetized small testing chamber,the char-acteristics of plasma will be influence by the magnetic field:In the magnetic mirror field,the density and the temperature of electron will decrease with the increase of the magnetic field;In the cusped magnetic field,with the increase of the coil current,the electron den-sity will increase and the electron temperature will decrease.2.Second,we measured plasma characteristics and the sheath struc-tures when the direction of sheath is parallel and normal to the mag-netic field in a magnetic mirror field,and the sheath width will de-crease at first and then increase with the increase of the magnetic field.3.Furthermore,we measured plasma characteristics and the sheath structures in a cusped magnetic field,the sheath width will decrease with the increase of the coil current.