In this week's experiment, the supervisor told us that we do not need to connect the circuit on the breadboard. What we need to do is to determine the type and the size of the components in our circuit. For instance, the capacitors,the radio frequency voltage, the diodes and the transistors. And then, we ought to calculate the value of the ion current and electron current by using the equation given in the reference book.At last, we should draw our circuit clearly on the paper which will be connected later.
   Through this project, we need to firstly know some basic knowledge of the plasma.A plasma is a collection of free charged particles moving in random directions. The plasma is electrically neutral. The plasma is usually called the fourth state of the matter. It has the following features. 1.The plasma is driven electrically. 2. Charged particle collisions with neutral gas molecules are important. 3. The boundaries at which surface losses are important. 4. Ionization of neutrals sustains the plasma in the steady state.5. The electrons are not on thermal equilibrium with the ions.

           Figure one: The equivalent circuit of the low pressure plasma

           Figure two: The circuit that can supply the constant current

 During the experiment, we should measure the voltage and the current in the plasma.Two parallel circuits are connected to the radio frequency voltage. The ideal diode represents the electron current. The current source is corresponding to the steady ion current.The capacitor is the sheath in the equivalent circuit. The experiment will be implemented in two situations. The first situation is that the parallel circuit with no capacitor which is the condition that there is no displacement current in the sheaths. The other situation is the circuit have the circuit with the capacitor which means take the displacement current into account.In the laboratory, the current source can be replaced by the circuit shown in the second figure