Use of Plasmas
Use of Plasmas
Plasma is considered the 4th state of matter, an ionized gas consisting of electrons, ions, and neutral atoms and molecules.
A plasma is created by using an oscillating “RF” (Radio Frequency) electric field that ionizes the gas either through capacitive plates, the electrodes, or magnetic induction. At low pressures, the rapidly changing electric field accelerates the electrons of the gas so that they collide with other gas molecules, resulting in ionization. This continously cascading reaction in the excited state is known as a plasma.
Depending on the process gas used and other parameters, such as pressure, excitation energy (RF power), the rate at which new gas molecules are replenished in the plasma, temperature, and time, are all part of the process inside the reactor. A plasma can be used to activate surfaces, deposit materials, remove materials, or change the surfaces properties it interacts with. A plasma typically only affects the near surface of the material, a few atomic layers of atoms, and does not alter the bulk material properties of the items. Plasmas can interact with and modify surfaces through several mechanisms such as chemical reactions, physical sputtering, deposition, etching, cross-linking, ablation or activation. Also, since a plasma consists of charged species, electrical potentials can be used to preferentially direct the motion of the electrons and ions that impinge on the surface.
Plasmas can be used to sterilize medical instruments, selectively deposit various materials, remove contamination or alter the surface energy of materials for improved wetting or increased phobia.
Plasma uses continue to expand to new frontiers, including medical surgery, the restoration of artifacts and even bio-genetic engineering.
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