Microwave Plasma Generator Research Articles

Production of Nitrogen Atoms in a Microwave Discharge*

ABSTRACTA “Large Volume Microwave Plasma Generator” (LMP) has been used to generate nitrogen atoms by microwave discharge in a flow of nitrogen gas. Experimental parameters investigated are N2 flow rate and pressure, microwave power absorbed by the plasma, and the effects of gaseous “catalysts” and treatment of the reactor walls.The optimum energy yield for N atoms attained in this study, 1.2 g atoms kWh, is a factor of 2 greater than the highest value so far reported in the literature.

Transverse-Flow Quasi-cw HF Chemical Laser: Design and Preliminary Performance

A small transverse-flow HF chemical laser has been constructed using a large volume microwave plasma generator for the production of F atoms. The F atoms react with hydrogen to form the lasing HF molecules. The active medium is about 5 cm long, and the maximum average laser power was found to be 560mW for all lines. Three laser lines with wavelengths 2.61 microm, 2.64 microm, and 2.73 microm were observed. The time-varying laser transition profile closely resembles the density profile of the excited fluorine atoms in the plasma. Both profiles are greatly affected by changes in flow conditions.

Experimental investigation of the transient formation of a microwave-generated ionized sheath in air

Microwave and photometric techniques are used to study the temporal and spatial behavior of a transient microwave-generated air plasma sheath in a coaxial transmission line. In particular, breakdown times, stabilization times, and thickness of the ionized sheath are investigated at different pressures and generating signal amplitudes.

Microwave plasma generation by end-on and side-on irradiation in the pressure range 0.1–10 mTorr of hydrogen

This paper describes investigations of hydrogen plasmas produced by mean of linearly polarized microwaves (f=2.45 GHz,P 0=2.2–5.0 kW). A superimposed uniform and stationary magnetic field $$\vec B_z $$ is tuned in most of the experiments to the electron cyclotron resonance. The RF is coupled to the plasma by different antennae. A conical horn is used for end-on irradiation (wave vector $$\vec k\parallel \vec B_z $$ ). With regard to toroidal discharge geometries the side-on irradiation $$\vec k \bot \vec B_z $$ is of particular interest. For this purpose two newT-shaped antennae were developed. In the pressure range investigated the plasma produced by the microwaves fills up the whole discharge vessel (l=200 cm,V≈104cm3). The electron densities are in the range between 2.5 · 1010 and 1.5 · 1011 cm−3 and the electron temperatures between 1.2 and 5.0 eV. The plasma produced by side-on RF irradiation $$(\vec k \bot \vec B_z ,\vec E\parallel \vec B_z )$$ is used as a pre-ionization plasma for aZ-pinch discharge. The degree of ionization obtained in this way is ≳5%. The optimum conditions for this type of preionization are evaluated from density measurements at higher cyclotron harmonics.

The Large Volume Microwave Plasma Generator (LMP™): A New Tool for Research and Industrial Processing*

ABSTRACTThe large volume microwave plasma generator (LMP™), a new technology for producing microwave plasmas is introduced. Microwave energy is coupled into the plasma by means of a slow wave structure, and plasma volumes well in excess of 1,000 cm3 can readily be achieved with 2.5 Kw of microwave power at 2.45 GHz. General operating characteristics, and some experimental data for the dissociation reaction of diatomic gases (oxygen and nitrogen) are presented. Some of the many promising applications are discussed.