A space plasma facility has been operated with a back-diffusion-type plasma source installed in a mid-sized vacuum chamber with a diameter of ~1.5 m located in Satellite Technology Research Center (SaTReC), Korea Advanced Institute of Science and Technology (KAIST). To generate plasma with a temperature and density similar to the ionospheric plasma, nickel wires coated with carbonate solution were used as filaments that emit thermal electrons, and the accelerated thermal electrons emitted from the heated wires collide with the neutral gas to form plasma inside the chamber. By using a disk-type Langmuir probe installed inside the vacuum chamber, the generation of plasma similar to the space environment was validated. The characteristics of the plasma according to the grid and plate anode voltages were investigated. The grid voltage of the plasma source is realized as a suitable parameter for manipulating the electron density, while the plate voltage is suitable for adjusting the electron temperature. A simple physical model based on the collision cross-section of electron impact on nitrogen molecule was established to explain the plasma generation mechanism.

1. INTRODUCTION
 2. BACK-DIFFUSION-TYPE PLASMA SOURCE
 3. LANGMUIR PROBE FOR DIAGNOSINGPLASMA CONDITION
  3.1 Principle of Langmuir Probe
  3.2 Derivation of Ne and Te from the Langmuir Prove I-VCurve
 4. RESULTS AND DISCUSSIONS
 5. SUMMARY
 ACKNOWLEDGMENTS
 REFERENCES

• Kwangsun Ryu(Satellite Technology Research Center, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea) Corresponding Author
• Junchan Lee(Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea)
• Songoo Kim(Satellite Technology Research Center, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea)
• Taejin Chung(Satellite Technology Research Center, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea)
• Goo-Hwan Shin(Satellite Technology Research Center, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea)
• Wonho Cha(Satellite Technology Research Center, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea)
• Kyoungwook Min(Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea)
• Vitaly P. Kim(Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radiowave Propagation, Russian Academy of Sciences (IZMIRAN))