In the second week experiment,we calculated the exact value of each components in the current source which is represented the ion current. We calculate the ion current using the equation Ii=neA(kTe/M.40)^1/2. Finally, the ion current is nearly equal to 0.38 to 0.40mA. In the current source, the zener diode is about 6.2V to 6.8V. The resistance is about 1Kohm. The DC voltage is about 9V. Therefore, we connected the current source on the breadboard. The technician told us the battery which we need in the electron current will be arrive in the third week, so we just complete the current source part in this week.