PLASMA TECHNOLOGY

What is PLASMA?

IRVING LANGMUIR first used the term plasma in 1926 to describe the inner region of an electrical discharge.

It is defined as a state of matter in which a significant number of atom and/or molecules are electrically charged or ionised.

Plasma is any substance (usually a gas) whose atoms have one or more electrons detached and therefore become ionised remains in gas. Thus,plasma is electrically neutral.

Plasma carries high energy and makes up over 90% of the entire universe.

COMPARISON PLASMA & GAS PHASESProperty Gas Plasma

Electrical

conductivity very low usually very

High

Independently acting species

one two or three

Velocity distribution

Maxwellian

velocity distribution

often non

Maxwellian

Interaction binary collective

ENERGY GRAPH Plasma is a form of matter that higher energy than

the corresponding solid,liquid and gases.In plasma the energy is also due presence of ions & free electrons.Inspite of high energy it is not very hot.

GENERATION OF PLASMAA gas becomes plasma when the kinetic energy of the gas particles rises to equal the ionisation energy of the gas. When this level is reached, collisions of the gas particles cause a rapid cascading ionisation, resulting in plasma.

A gas can be converted into plasma by passing high-energy electrons through the gas

Generation of Plasma can be created by applying an electric field to a low-pressure gas, as in neon or fluorescent tubes

Plasma can also be created by heating a neutral gas to very high temperatures by external source .

VARIOUS PLASMA TECHNIQUEGlow discharge

1) It is produced at reduced pressure (low-pressure plasma technique) and provides the highest possible uniformity and flexibility of any plasma treatment.

2) The plasma is formed by applying a DC, low frequency (50 Hz) or radio frequency (40 kHz, 13.56 MHz) voltage over a pair or a series of electrodes.

Corona discharge

1) It is formed at atmospheric pressure by applying a low frequency or pulsed high voltage over an electrode pair.

2) The corona consists of a series of small lightning-type discharges; their in homogeneity and the high local energy levels.

Dielectric Barrier Discharge

1) Dielectric barrier discharge is formed by applying a pulsed voltage over an electrode pair of which at least one is covered by a dielectric material.

2) Though also here lightning-type discharges are created, a major advantage over corona discharges is the improved textile treatment uniformity.  

Atmospheric pressure plasma technique

1) This technique provides the highest possible plasma density at low gas temperatures.

2) Thus treats fabric and other substrates without damaging them.

3) The discharge uses a high-flow feed-gas primarily an inert carrier gas, like He, and small amount of additive to be activated, such as O2, H2O or CF4.

FORMS OF PLASMA

Artificially produced plasma1) Those found in plasma display.

2) Inside fluorescent lamp,neon signs,etc.

3) Fusion energy research.

4) Plasma used for surface modification of textiles.

5) The electric arc in an arc lamp ,an arc welder, or plasma torch.

Terrestrial plasma

1) Lighting.

2) Sprites,elves,jets.

3) The ionosphere.

Space & astrophysical plasma1) The sun and the other stars.

2) The solar wind.

3) The interplanetary med

USES OF PLASMA

In cleaning surfaces The beam of plasma is created from the air by a

pulsed current that excites the molecules. The resulting ions and free electrons then remove static electricity and dust, as well as vaporize contaminants, including waxes and silicone residues.

In functionalizing surfaces1) The surfaces of plastics are chemically unreactive

due to long polymer low energy chains and have no functional groups.

2) A plasma beam can replace them with its functional groups that are more reactive like –OH and –NH.

In making material wettable

Many liquids are self-loving, so they do not spread out on a surface unless their energy is similarly high.Plasma promotes wettability by first cleaning the surface to remove contaminants, then it increases surface energy by changing its structure.

In welding

When the surfaces to be welded are treated with plasma, the contaminants are removed and the resulting weld can be achieved more quickly and is stronger.The plasma nozzle can be mounted ahead of the welding head, allowing the surfaces to be cleaned and welded in a single pass.

PRODUCTS

Plasma acceleration1) Plasma acceleration is a technique for

accelerating charged particles using an electric field associated with an electron plasma wave.

2) If an external electric field is applied, the plasma will separate, with the particles being attracted to the external field. A particle injected into such a plasma would be accelerated by the charge separation.

PROCESS:-

PLASMA DISPLAY

1) The plasma video display was co-invented in 1964 at the by Donald Bitzer,H. Gene Slottow, and graduate student Robert Willson for the PLATO Computer System.

2) A plasma display panel (PDP) is a type of flat panel display.Many tiny cells located between two panels of glass hold an inert mixture of noble gases (neon and xenon). The gas in the cells is electrically turned into a plasma which then excites phosphors to emit light.

APPLICATIONSPlastics

1) With plasma dissimilar materials can be combined in a two-shot injection molding process.

Metal-non metal combination1) Plasma can treat metal/non-metal combinations,

removing organic and silicone contaminants as well as activating the surfaces before printing, coating and bonding.

Fabrics1) Plasma makes textiles more hydrophilic or

absorptive .This improved wettability enables the use of adhesives over clothes.

Using plasma beam we can impart more efficient painting and coating of metal surfaces.This method use lower cost materials.Eliminate environmentally problematic solvents. Plasma can carry a lot of energy and is highly reactive, but it is not necessarily hot. Plasma treatments can be integrated into the manufacturing process,reducing pollution and energy consumption.there is no waste production.

SIGNIFICANCE

REFRENCES

1) www.wikipedia.com

2) www.plasmatreat.com

3) www.indiantextilejournal.com

Manmath Agarwal