Detailed Global Models (DGMs) for diagnostics and optimization of industrial plasma reactors

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Technology abstract

An SME from Thessaloniki, Greece has developed Detailed Global Models (DGM) combined with optical emission spectroscopy (OES) diagnostics that can be used for the diagnosis and optimization of plasma reactors. This unique combination allows the evaluation of plasma reactor capabilities in the conception stage and the in situ optimization of existing devices. The SME is open for different kind of collaborations for co-development and pilot testing.

Technology Description

The technology offered includes DGMs that take into consideration all of the important components appearing in the environment of a device during functioning and using them as a support of the optical emission spectroscopy (OES) diagnostics. The DGMs technology is an extension of the Collisional – Radiative models used in the study of gases and plasmas that apart from statistical equations include an energy equation describing the mechanisms of the absorbed energy spending. By evaluating this data set we are able to get a detailed description of the atomic, molecular and ionic constituents present in the gas / plasma and on surfaces using plasma component and functioning diagrams of the prototype / industrial device modeling. This technology leads to a quantitative preview and evaluation of the expected components, to an efficient measurement of their effective contribution and also the evaluation of the electron density and temperature. As a result monitoring and optimization of the device functioning and efficiency becomes possible. The acquired data sets are necessary for the OES diagnostics (a non-intrusive method, which requires a simple spectrograph). DGMs and the OES diagnostics can be applied to various technological fields. This technology has been already applied successfully in space for studying, designing and optimizing various types of plasma electric thrusters used in space propulsion, fed by various propellants (including Ar, H, He, Ne, O, I2 , CO2 , N2O, N2/O2, air) and another promising field of application is the modeling and diagnosing of Plasma Reactors (PR). Several types of industrial and prototype PRs are nowadays available and extensively used for different applications (direct current Magnetron Sputtering (dcMS),  Ionized Physical Vapor Deposition (IPVD) devices, High Power Pulsed Magnetron Sputtering and High Power Impulse Magnetron Sputtering (HiPIMS) reactive discharges), which can benefit from the proposed technology. The most promising non-space industrial application identified is thin film area, such as optical coating, permeation barrier coatings and hard coatings. 

Innovations & Advantages

The proposed DGM technology combines a Global Model (GM) and Collisional-Radiative (C-R) type models, implemented by OES diagnostics. Both models have been often used separately, the first in the modeling of plasma reactors and gas discharges in general and the second in modeling of various experimental and industrial devices and of large dimension space plasma.
Their combination allows us to:
·         Acquire an extended description of the device, that includes all expected ionized species together with the reactions among them
·         Determine the population of each component and of all excited species and evaluate the electron density and temperature in any place of the device
·         Calculate the theoretical spectra, which, by comparison with the experimental ones, leads to OES diagnostics
·         Monitor the function of the device
The offered technology help us in obtaining the spectral signatures of the constituents, helping us define the present plasma structure, together with tracking of each species position. As a result, optimization of prototypes / industrial devices becomes easier.

Further Information

The DGMs offered are applicable to any form factor, to a large domain of pressure values (already used between 1 mTorr and 1000 mTorr) and of electron densities (already used up to 1015 cm-3), and electron temperatures (already used up to 100 eV), with possibility of extension of the provided values when necessary.
The Optical Emission Spectroscopy (OES) which is supported by application of DGMs is very handy and considered as more trustful than using of probes, which are easily destroyed, especially in high temperatures and in the chemical reactants environment, expected in modern industrial plasma reactors.  

Current and Potential Domains of Application

Apart from space applications, this technology aims to constitute a strong theoretical and diagnosing support of experimental and of industrial devices in the domains related to application of thin film coatings. The technology provider is currently examining to extend the application of the described DGM technology mainly to modelling and to optical diagnostics of Plasma Reactors (PR).
The offered technology can be applied to the analysis and diagnostics of various types of industrial and of prototype PRs (dcMS, IPVD and HiPIMS reactive discharges), which are nowadays available and extensively used.
In the case of HiPIMS reactive discharges, the technology provider has observed that plasma reactions and the fundamental aspects of ionization / recombination play a more important role and therefore DGM can be easily implemented into full industrial scale PRs. DGM is able to deal with the used buffer and reactive gases and sputtering of various targets by means of careful evaluation of the corresponding data.
In the domain of space applications the company has developed an argon-oxygen mixture DGM for the needs of electric thruster modelling. This DGM is extended now by adding the necessary titanium data, in order to make it capable to support industrial HiPIMS type reactors with sputtered Ti targets.
The non-space industrial applications the company is aiming for is in the thin film area and they include:
·         optical coating
·         permeation barrier coatings
·         hard coatings.
The technology provider can enlarge this DGM technology in order to address deposition of various reactive gas (oxygen, nitrogen) to be obtained with argon or other carrier gas, according to the industrial needs.