Supersonic plasma flow

Solar wind Supersonic plasma flow from the sun. 

A decrease of energy efficiency at higher values of the specific energy input is due to overheating and as a result of acceleration of VT relaxatioa Serious restrictions of the specific energy input in supersonic plasma systems are also related to the critical heat release and choking of the flow. 

Limitations of Specific Energy Input and CO2 Conversion Degree in Supersonic Plasma Related to Critical Heat Release and Choking the Flow... 

The specific energy input and conversion degree are limited in supersonic plasma reactors by the critical heat release, which corresponds to a drop of the initial Mach number from M > 1 before the discharge to M = 1 afterward and leads to choking of the supersonic flow. The critical heat release for the supersonic reactor with constant cross section is equal to... 

Here Too is the initial gas temperature in the tank before the supersonic nozzle. If the initial Mach number is not very close to unity, the critical heat release can be estimated as g cr CpToo. Numerical values of the critical heat release at different initial Mach numbers for the supersonic CO2 flow can also be found in Fig. 5 1. Further increase of the heat release in plasma over the critical value leads to the formation of non-steady-state flow perturbations like shock waves, which do no good to a non-equilibrium plasma-chemical system. Even taking into account the high energy efficiency of chemical reactions in supersonic flows, the critical heat release seriously restricts the specific energy input ... 

A non-linear wall-stabilized non-transferred arc is shown in Fig. 4 8. It consists of a cylindrical hollow cathode and coaxial hollow anode located in a water-cooled chamber and separated by an insulator. Gas flow blows the arc column out of the anode opening to heat a downstream material, which is supposed to be treated. In contrast to transferred arcs, the treated material is not supposed to operate as an anode. Magnetic 7x5 forces cause the arc roots to rotate around electrodes (Fig. 4-48), which provides longer electrode lifetime. The generation of electrons on the cathode is provided in this case by field emission. An axisymmetric version of the non-transferred arc, usually referred to as the plasma torch or the arc jet, is illustrated in Fig. 4-49. The arc is generated in a conical gap in the anode and pushed out of this opening by gas flow. The heated gas flow forms a very-high-temperature arc jet, sometimes at supersonic velocities. 

Figure 5- 1. Gasdynamic characteristics of a plasma-chemical discharge in supersonic flow (1) discharge inlet temperature Ti, (2) initial tank pressure poii (3) exit pressure po3 in the conditions of critical heat release (4) critical heat release q. All the parameters (1 ) are shown as functions of Mach number Mi in front of the discharge. Initial gas tank temperature Too = 300 K static pressure infrontofdischarge Pi = 0.1 atm.

Kinetics and Energy Balance of Non-Equilibrium Plasma-Chemical CO2 Dissociation in Supersonic Flow... 

Figure 5-43. Energy efficiency of plasma-chemical CO2 dissociation in supersonic flow, taking into account energy cost of compression, as a function of specific energy input at different Mach numbers (1)M=2.5 (2)M = 3 (3) M=4 (4)M=5 (5)M=7 (6)M=8. Solid lines correspond to pressure restoration in a ditfuser, calculated based on Oswatieh theory dashed curves correspond to diffuser eonsidera-tion as a normal shock.

Gasdynamic Stimulation of CO2 Dissociation in Supersonic Flow Plasma Chemistry Without Electricity ... 

Primary products of the chain reaction are molecular hydrogen (H2) and hydrogen peroxide (H2O2), which is usually unstable at typical plasma conditions and decays quite fast into water (H2O) and oxygen (O2). H2O2 can be stabilized in the products of water dissociation at low temperatures, in particular if the process is carried out in a supersonic flow. Such a process is not only very fundamentally interesting, but also permits us to effectively separate the dissociation products and protect them from reverse reactions. The chain termination, finally, is related to different three-body recombination processes, and first of all to the following reaction ... 

Flow Velocity and Compressibility Effects on CO2 Vibrational Relaxation Kinetics. Analyze the characteristic VT -relaxation time (5-51) and the maximum linear preheating temperature (5-53) during CO2 dissociation in plasma stimulated by vibrational excitation, taking into account the gas compressibility. Describe the qualitative difference of the systems performed in subsonic flows (M 1), supersonic flows (M 1), and near the speed of sound. 

Supersonic Discharges. Explain why the critical vibrational temperature and, hence, the threshold in dependence rj Ey) are essentially lower and strongly depend on initial translational temperature To when the plasma-chemical CO2 dissociation is done in supersonic flow. Use relations (5-46) and (5-90) for estimations compare the results with those shown in Fig. 5-2. 

Figure 9-4. General sehematie of a mierowave plasma system of methane eonversion (1) plasma-ehemieal reaetor (2, 3, 6) vaeuum meters (4) reeeiver (5) flow rotameter (7) pump (8) eell for eharaeterization of ehemieal composition (9) liquid nitrogen trap (10) receiving cell (11) supersonic nozzle.

Experiments with Plasma Ignition of Supersonic Flows... 

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