Plasma Generation
Plasma Novus is a start-up specializing in Non-thermal Plasmas generated in Luminescent Discharge Cells. In recent years, we have developed new and disruptive 'electrodes' generally known as gas discharge tubes. Our devices, called Luminescent Discharge Cells, are made of glass and quartz by the best blowers and specialists worldwide. Under certain conditions of pressure, voltage, and intensity, plasmas can be generated in their different regimes. In the case of our devices, the voltage has to be increased until the potential difference in the dielectric medium reaches the breakdown voltage value and the plasma sustains itself. Thus, it transitions from Townsend discharge to Normal Glow.
Plasma Novus specializes in the generation of non-thermal plasmas through innovative methods.
Different plasma regimes generated depending on the applied power difference (voltage) and the electric current flowing through them. The breakdown voltage is marked at points D and D’. [M.J. Druyvesteyn, F.M. Penning, The Mechanism of Electrical Discharges in Gases of Low Pressure, Rev. of Modern Physics, Vol. 12, April 1940, Nº2].
The use of luminescent discharge cells made of glass and quartz is a key feature of our technology.
Different plasma regimes generated depending on the applied power difference (voltage) and the electric current flowing through them. A normal glow is observed in the range of 10-5 to 10-3 mA, produced in a vacuum discharge tube containing Neon (Ne)
The breakdown voltage depends on the gas confined in the Cell, or rather, that flows through it. Following Paschen's Law, which considers the breakdown potential, different curves can be mathematically deduced and experimentally obtained for each of the gases.
Our technology operates under carefully controlled conditions of pressure, voltage, and intensity.
For each of them, the breakdown voltage (UB) is represented as a function of the pressure-distance product (pd).
We generate different plasma regimes based on the applied voltage and current.
Dependence of the breakdown voltage as a function of the pressure-distance product for each dielectric medium (different gases) according to Paschen's Law (Gas Tube Design, by H H Wittenberg, Electron Tube Design, RCA Electron Tube Division, 1962, pages 792 – 817).
We use Paschen's law to determine the breakdown voltage depending on the gas used in the discharge cells.
Simulation of Paschen's law for air (72%N2/21%O2) [Dr. Eduardo Alonso]
A non-thermal plasma is a partially ionized gas in which the temperatures of the positive and negative charges are not equal. Typically, the temperature of these plasmas is around 1.15·104 Kelvin (K), or approximately 1 electron Volt (1eV = 11,500 C). Figure 4 shows a graph with the types of plasmas based on their temperature.
Types of plasmas (and places/devices where they are produced) based on their internal temperature. ('Fundamentals of Plasma Physics' J.D. Callen)
There are many definitions of what plasma is. At Plasma Novus, we have opted for the one given by Boris M. Smirnov (Theory of Gas Discharge Plasma, Springer Series on Atomic, Optical and Plasma Physics, Volume 84, 2015), which we reproduce below:
“ According to its nature, gas discharge is the passage of electric current through a gas that is located under the action of external fields. The principal property of gas discharge, its self-maintenance, was formulated in the beginning of the twentieth century [1-5] and consists in the ionization balance inside gas discharge. This provided by formation of an ionized gas called a gas discharge plasma, and the ionization equilibrium is supported in this plasma ”
In Chapter 1 (Introduction) of his book, the most important keys are pointed out, which may be of greatest interest to understand the use of a Luminescent Discharge Cell concerning the multiple applications for which it has been conceived from Plasma Novus.
“…A gas discharge plasma as a physical object is a nonequilibrium system because of the character of energy transmission from an electric field to a gas through electrons. Indeed, electrons as more mobile charged atomic particles acquire energy from the electric field and then transfer it to gas atoms or molecules in collisions with them.
… the velocity or energy electron distribution function (EEDF) is one of the characteristics of a gas discharge plasma under consideration.
Then the first self-consistent scheme of a gas discharge plasma was represented by Townsend [ref. 1] and has the form
𝒆 + A → 2𝒆 + A+ 𝑎𝑛𝑑 A+ + 𝑀 →A + M + + 𝒆 “
Figure 5 shows a photograph courtesy of the DOE fusion laboratories (NASA) and Steve Albers. It shows the plasma temperature as a function of the particle (charged) density per cubic meter (m3). This is an essential parameter to characterize the type of plasma. The plasma generated by our Luminescent Discharge Cell is non-thermal and corresponds to a density of around 1015 particles/m3.
Types of plasma as a function of Temperature (K) and 'Number density' (Charged particles /m3). .
This plasma is similar to that produced by a gas, generally Neon (Ne), confined in a vacuum tube, which has been (and continues to be) used for over a century in signs and billboards, since George Claude presented his invention at the Paris Motor Show in 1910. However, it was the German glassblower Heinrich Geissler who invented in 1857 a discharge tube that bears his name: the Geissler Tube. This is a gas discharge tube used to demonstrate the principles of glow discharge. Geissler also invented a special vacuum pump (the mercury displacement vacuum pump) used to reduce the pressure in his tubes, achieving a 'record' level never before experienced: 10 Pascal (0.1 Torr). Thus, two sciences of vital importance for the development of Plasma Novus's inventions and their application in industrial processes were born from the same man. Interestingly, in the same year of 1857, W. Siemens published his research on ozone (O3) generation using a Dielectric Barrier Discharge (DBD) cell.
During the summer of 2011, the doctoral candidate Eduardo Alonso-Gil, after obtaining his Master's degree in Chemistry and Applications at UPV/EHU (Lejona, Spain), moved to Garching (Germany) to conduct his doctoral thesis. There, at the Chair of Physical Chemistry of the Technical University of Munich (TUM), he came into contact for the first time with a Luminescent Discharge Cell, which was the seed of what almost 10 years later (April 2021) materialized into the company: Plasma Novus (Clean Air Solutions) S.L., which we present on this website.
Non-thermal Plasma generated in Luminescent Discharge Cells
Luminescent Discharge Cells finished in the glassblowing workshop, with their high-voltage safety connectors (up to 20 kV), ready to be assembled.