Useful References

Plasma FAQ
  1. What is plasma?
  2. What is special about the plasma state?
  3. What are some examples of plasma applications?

  1. What is plasma?

    Solids, when heated to a sufficiently high temperature, change their phase and become liquid. Heating liquids sufficiently can transform them into gases. In an ordinary gas each atom or molecule is electrically neutral. The positively charged nucleus of an atom is surrounded by an equal number of negatively charged electrons. If a sufficient amount of energy is transferred to an atom, the electrons can become detached from it. This process is referred to as “ionisation”. In a plasma some significant fraction of neutral atoms are ionised. We can refer to matter in the “plasma state” if the number of charged particles is high enough to influence the electrical characteristics of the gas. The plasma state is also called the “Fourth State of Matter”, following solid, liquid and gaseous states. It is estimated that over 99.9% of the universe is in the plasma state; however, Earth is a unique exception. Most of the plasma sources on Earth are man-made.

  2. What is special about the plasma state?

    It is the interactions between the charged particles and the neutral atoms, and the ability to manipulate the plasma by externally applied electric and magnetic fields that make the plasma state special and useful. A substance in the plasma state may offer new paths for chemical reactions. These new possibilities are explored and exploited for the synthesis of new materials, which is one of the important applications of plasma.

    When the energy of the ions in a plasma is increased to an extent that they can overcome the repulsive forces of other ions a nuclear fusion reaction can take place, with a huge amount of energy released as a consequence. This is the Sun’s source of energy. Scientists are trying to find efficient ways to harness the energy released from the fusion process to create a clean and safe source of energy for future generations.

  3. What are some examples of plasma applications?

    The unique properties of plasma create a broad spectrum of potential and actual applications. One can group plasma applications in three categories:

    Plasma as a Processing Tool

    • Surface Treatment: surface cleaning, surface activation, etching
      Application examples: optical components, sterilisation, changing hydrophobic (hydrophilic) properties, promotion of metal-polymer and polymer-polymer adhesion
    • Material Synthesis
    • Material Deposition: PVD, PECVD, plasma torch
      Application examples: corrosion reduction, friction reduction, increasing hardness, improving biocompatibility, (anti)reflective coatings, decorative applications
    • Heat Source: Cutting, welding, incineration, annealing

    Plasma as a Radiation Source 

    • Lighting source
    • Flat Panel Display
    • X-ray Source
    • Lasers

    Plasma as an Energy Source

    • Fusion Energy
    • MHD Generators