Using the high frequency discharge phenomenon in the rarefied gas to ionize the gas, it is usually used to produce low charge positive ions, and sometimes lead to negative ions.
In the high frequency electric field, the free electrons collide with the atoms (or molecules) in the gas and ionize them. The results of charged particle multiplication, the formation of electrodeless discharge, resulting in a large number of plasma. General use of Pyrex or quartz tube production tube discharge RF ion source. The high frequency field generated by the solenoid coil tube, can also be produced by the ring electrode in the tube. The former is called inductive coupling, the latter is called a capacitively coupled high frequency oscillator with a frequency of 10 ~10 Hz and an output power of more than a few hundred watts.
There are two ways to extract ions from high frequency ion source. One is at the top of the discharge tube is inserted into a tungsten filament as cathode, the discharge tube hole is installed at the tail end of the negative electrode, and the hole is made of tube, lead ion flow from. Another way is to make the cap into a cap, near the electrode, and the discharge area on the other side. No matter what kind of lead out method, the metal electrode should be wrapped with quartz or glass, in order to reduce the ion on the metal surface composite.
When a constant magnetic field is added in the high frequency discharge region, the ion concentration in the discharge region can be increased due to the resonance phenomenon. Sometimes, still leads to regional non uniform magnetic field leads to improve.
Arc discharge ion source
In a uniform magnetic field, an ion source for maintaining a gas discharge by thermionic emission of electrons from a cathode. In order to reduce gas consumption, the discharge area is often closed. The anode is made into a cylinder, and the axis is parallel to the magnetic field. The magnetic field can restrain the electron flow emitted by the cathode, and the atoms (or molecules) of the gas can be ionized in the anode cavity to form an arc column with high plasma density. Ion beam can be perpendicular to the axis of the lateral direction, can also lead to the direction of the axis.