Freon destruction in the decaying plasma of nanosecond microwave discharge

Conference · Sun Dec 31 04:00:00 EST 1995

OSTI ID:226931

Vikharev, A L; Gorbachev, A M; Ivanov, O A ^[1]

---

1. Inst. of Applied Physics, Novgorod (Russian Federation); and others

The problem of freons acting destructively on the Earth ozone layer has been given much discussion recently, and various ways to purify the atmosphere have been suggested. One of such ways described is based on the use of a microwave discharge in the troposphere, which is produced with two short-pulse wave beams by ground-based antennas. Such a discharge produces in the atmosphere the plasma with electron density N{sub e} {approx} 10{sup 10} - 10{sup 12}cm{sup -3}. After the microwave pulse, at the stage of plasma decay, electrons destroy freon molecules selectively due to high rate (kd = 10{sup -7} - 10{sup -9} cm{sup 3}/s) of dissociate attachment. Efficiency of purification (the number of freon molecules destroyed) depends significantly on the velocity of decay of the discharge plasma. The processes of death of electrons, which are not associated with attachment to freons (electron-ion recombination and attachment of electrons to oxygen molecules) lead to lower efficiency of purification. It is very important to achieve slow plasma decay when freon composition is low and air pressure is high, since then the frequency of dissociate electron attachment to freon molecules, is much lower than the frequency of three-body attachment to oxygen. Earlier studies of the microsecond microwave discharge showed that slow recombination decay of plasma in air may be realized at the high level of specific energy contribution. Such decay is explained by the processes of electrons` detachment from the negative oxygen ions when they collide with active particles formed in the discharge. At the same time, in terms of energy saving, promising for the considered purification method is the nanosecond discharge with high values of the reduced electric field, E/N, when the main share of the microwave energy is spared on gas ionization. This presentation contains the results of studying decay of the nanosecond microwave discharge plasma.

• OSTI ID: 226931
• Report Number(s): CONF-950749--
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
54 ENVIRONMENTAL SCIENCES
66 PHYSICS
AIR
DISSOCIATION
ELECTRON ATTACHMENT
ELECTRON DENSITY
FREONS
HIGH-FREQUENCY DISCHARGES
OZONE LAYER