# Applications of Plasma Produced with Electrical Discharges in Gases for Agriculture and Biomedicine
## 2 Plasma as a Medium for Application in Agriculture and Biomedicine  
In the physical sciences, plasma-which is ubiquitous in the universe-refers to the fourth state of matter, in addition to solid, liquids and gas. It is an ionised gas containing positive and negative ions, as well as electrons and inert gas molecules, and it has a net electric charge that is equal to zero. In the biomedical sciences, intercellular plasma is known as the non-cellular fluid component of blood. The unique physicochemical properties of biological plasma and the coagulation factors it contains are the basis of the haemostasis process--stopping bleeding when one cuts themselves or breaks the continuity of their blood vessels in some other way. Due to the properties of physical plasma and its analogy to the ubiquity of ionic liquid in biology and medicine, [PERSON] [59] introduced the term \"plasma\" for ionised gas. As a technological medium, plasma can be produced in a wide range of temperatures and pressures. The moment of change in the physical properties of the gas, accompanied by the appearance of electrical conductivity and loss of insulating capacity, is considered as the most important. It is a state of matter with the broadest particle energy band. The electrons are partially or completely detached from the atoms and play a crucial role in initiating chemical reactions in the plasma. Other plasma particles may be weakly, partially or fully ionised including excited particles, positive and negative ions, neutral particles, and photons, the nature of which depends on the gas in which the electrical discharge occurs, have much lower energies than electrons. Their properties and interactions are used in a variety of technological processes. An important criterion for the classification of plasma is the thermodynamic equilibrium of the particles, which means that electrons, ions, and neutral particles have an approximately equal energy. When talking about the thermodynamic equilibrium of a plasma, we usually mean the so-called local balance. Discharges, which are the source of plasma in local thermodynamic equilibrium, are characterised by relatively high temperatures and are used where heat is required. It should be emphasised that although high pressure usually means thermal and equilibrium plasma, and low pressure means non-thermal and non-equilibrium plasma, the final criteria for determining the classification of plasma as thermal or non-thermal are the products of the gas pressure, \(p\), and the electrode gap, \(d\), of the plasma reactor [46]. In recent years, research has been conducted on the use of thermal plasma in the combustion of municipal waste (biomass, plastics, post-hospital, pharmaceutical, etc.) containing hazardous organic compounds, such as phenols, chlorinated biphenyl and dioxins [73; 74; 75; 76], which can contaminate the soil, making it barren and incapable for plants to breed. The sources of thermal plasma are arcs, plasma torches and microwave reactors. In biomedical applications, especially in the decontamination of heat-sensitive devices and the tissues of living organisms, thermal plasma is used in the so-called remote mode [56; 77; 78]. The plasma does not reach the contaminated object directly, but the radicals, chemical compounds and UV radiation produced in it enable the treatment of heat-sensitive objects. Non-equilibrium and non-thermal (cold) plasmas are used in agriculture and biomedicine where heat may adversely affect technological processes. The thermodynamic imbalance of cold plasma makes it suitable for organic syntheses due to the low power requirements and the possibility of conducting chemical reactions in the gas at relatively low and close to ambient temperatures. This type of plasma is used directly to carry out plasma-chemical processes in facilities, such as living tissues and medical instruments, that are made of materials non-resistant to high temperatures.