What Is Plasma?

Plasma is the fourth state of matter (solids, liquids, and gases being the first three). Gases turn into plasma as they reach a thermal heat and ionize. Plasma makes up most of the Universe (the sun, lightning, stars etc.) Over 150 years ago, scientists discovered plasma in a laboratory. Ever since, they have been studying and researching it. They have even been coming up with many inventions like plasma TVs and metal cutting torches. The core of plasma ranges in temperature from 11,000° – 14,500° Fahrenheit thus limiting it’s applicable uses. Non-Thermal Plasma (NTP), on the other hand, can range from room temperature to over 4,500° Fahrenheit. NTP can be used as a catalyst for chemical reactions and as “controlled” heat value within milliseconds. NTP applications are focused in the fields of Energy, Medicine, Environmental Control, 3D Printing, Industrial, and Agriculture.

four states of matter

As an ionized gas, plasma's electron density is balanced by that of positive ions and contains a sufficient amount of electrically charged particles to affect its electrical properties and behavior.  Plasma discharges exist in a wide range of conditions. Their particular properties depend on a variety of parameters including pressure, temperature, and density. Plasma gas temperature is largely dependent upon average energies of particles and their degrees of freedom (translational, rotational, vibrational, and electronic).  Such energies are achieved via electron-electron collisions and electron collisions with heavy particles, which result in ionization of the heavy particles.  Depending on the frequency of collisions, the energy (and hence temperature) of plasma components (electrons and heavy particles) can be different.  As a result, the plasma can exist in a non-equilibrium state.

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 Non-thermal Plasma vs. Conventional Thermal Plasma

In NTP, electron temperature is highest (usually 10,000K or 1 eV); however, rotational excitation temperature, ion temperature, and heavy particle temperature are all quite low (room temperature).  Under such conditions, high energy electrons lead to the formation of active chemical species and radicals, such as atomic oxygen (O) and hydroxyl (OH), and electronically excited oxygen (OiAG).  These plasma-generated radicals and ions behave like catalysts and participate in chain reactions that promote or accelerate reaction pathways.  Conversely, Thermal plasma is often characterized by temperature equilibrium. Therefore, the temperature of all energy levels and components are nearly equal.  In thermal plasma, the joule heating effect results in high gas temperature. In thermal plasmas, energy is used to heat the entire gas, and temperatures often range from 10,000- 100,000K (10-100 electron volts (eV)).