Physical Verification Test of Plasma Environment for Chang’E-7 Electric Field Probe

The lunar surface becomes charged under the influence of solar wind and sunlight, and the potential differences on the surface form an electric field environment of various scales, which is the main mechanism for material transfer on the lunar surface. The electric field probe of Chang’E-7 will, for the first time, conduct in-situ electric field detection on the lunar surface. This paper introduces the design and results of the physical verification test of the probe in plasma environment based on the qualification model of the electric field probe. The basic principle of the electric field probe is the plasma electric probe principle. By clamping the probe current at a specific value, the potential of the probe can be determined according to the plasma V-I characteristic curve. The potential difference between different probes is the potential difference formed by the electric field environment on the plasma environment. Whether the probe can measure the plasma V-I characteristic curve is the key to the success of the probe design. With the help of a ground low-energy plasma simulation device, this test was carried out, and fixed current drive and scanning current measurement were conducted. The test results show that the electric field probe of Chang’E -7 can correctly reflect the plasma environment inside the simulation device and obtain a stable V-I characteristic curve. This proves that the electric field probe can achieve the function of obtaining the plasma potential by driving the probe current when working on the lunar surface, and the physical characteristics of the probe have been fully verified through the test.