A plasma arc operates on principles similar to an arc-welding machine, where an
electrical arc is struck between two electrodes set under under high voltage
where high current is allowed to pass to create an high energetic arc plasma
discharge under atmospheric conditions. The high-energy arc creates extremely
high temperatures ranging from 3,000 degrees to 7,000 degrees Celsius. The
plasma arc can be used for several applications including plasma oxidation,
treating organic and inorganic wastes, etc.
Hydrogen plasma is a special case of arc plasmas where the arc is generated in a
controlled vacuum atmosphere where hydrogen is used as the source of plasma.
During the hydrogen plasma reduction (HPR), a plasma arc zone is generated
between an electrode and the input ore. In this zone, the ore can be melted and
reduced by hydrogen in both molecular and plasma states. Hydrogen plasma
reduction allows the production of liquid iron in one single step, in which the input
fine ores are melted and reduced simultaneously without the need for
intermediate agglomeration or refinement processing.
Plasma spray is a thermal spray coating process, which uses plasma under
atmospheric pressure to subject particles under plasma in-flight and deposited as
a desired composition on the substrate. This technique is used to produce a high
quality coating by a combination of high temperature, high energy heat source, a
relatively inert spraying medium, usually argon, and high particle velocities. The
great advantage of the plasma spray coating technique is its ability to spray a
wide range of materials, from metals to refractory ceramics, on both small and
large components offering: corrosion protection, wear resistance, clearance
control – abrasives and abradables, heat and oxidation resistance, temperature
management and electrical resistivity and conductivity.
Sputtering is the process of material removal from a solid surface (called as
target) as a consequence of momentum transfer between an energetic particle
(usually an ion which comes from the plasma) and the surface of the target. The
plasma discharge is achieved in a low pressure environment to achieve sufficient
particle momentum to enable elastic collision.
Direct current (DC) Sputtering is a cost effective way of applying metal target
coatings that are electrical conductors. The target is subjected to high DC
cathodic voltage where the ionized particles from the plasma collide and
sputter/knock off the target atoms which will eventually get deposited on the
substrate (set as anode). Radio Frequency (RF) Sputtering uses alternating
current as a driving force for collision. At radio frequencies charge building up on
certain types of sputtering target materials can be avoided.
The term “microplasma” usually refers to low-temperature plasma discharges
with dimensions that range from a few micrometers up to a few millimetres,
which is generated by electrical breakdown of gases upon applying voltage. The
plasma discharges generate a highly reactive environment that comprises
charged particles, excited species, radicals, and photons, and the reduced
dimensions allow low-power sources with small footprints suitable for the
combination in microsystems and portable devices.
Dielectric barrier discharges (DBDs) are plasmas generated in configurations with
an insulating (dielectric) material placed between the electrodes, where
displacive current is generated due to pulsing action of DC or polarity change in
AC currents. DBDs are a typical example of non-thermal atmospheric or normal
pressure plasma discharges. It is used in a wide range of applications, such as
ozone & UV generation, air & wastewater treatment, sterilization of packaging and
food, as well as activation, cleaning, etching and coating of surfaces.
Site Designed & Maintained @ CNeM Division, CSIR-IMMT, Bhubaneswar