Plasma Physics: Theory, Methods and Applications (Second Edition)

Dear Colleagues,

Since gaseous discharge plasma is complex, it is systematically studied using numerical simulation, experimental diagnostics, and analytical theory. With respect to numerical calculation, we can develop a simulation code, such as a fluid model or a particle model, using the Fortran or C++ computer language, or rely directly on commercial software such as Analysis, COMSOL, Pegasus, or Quantemol. Whether using self-written code or commercial software, discharge profiles are always the preliminary data produced. For interpreting the profiles of the different parameters of plasma, such as density, temperature, charge density, potential, electromagnetic field, flux of mass and energy, and velocity of species, the concept of discharge structure has been established. Usually, the discharge structure of electropositive discharge plasma, such as argon inductively coupled plasma (ICP), is characterized by the parabola and Bessel functions in the axial and radial directions, respectively, with the assumption of azimuthal symmetry. While the discharge structure of electropositive plasma is easy to determine and can be validated through simulation, theory, and experiments, the discharge structure of electronegative plasma is relatively unknown and has not received much research interest. Regarding the fact that industrial plasmas are almost electronegative, a systematic study of their discharge structure would enable researchers to better recognize their source and hence optimize present plasma techniques, potentially leading to new applications in the future.

Research on the structure of electronegative plasma actually began in the 1980s, but most of these studies are focused on the analytical theory of fluid models accepted at that time. The theory utilized many assumptions, such as a constant temperature profile, a lack of collisions, cold ions, and net positive chemical source for species. With these approximations, the ambi-polar diffusion of electronegative plasma; the stratification of discharge; the double-layer dynamics; and the parabola, ellipse, and flat-top ionic density profiles were determined. However, today, a self-consistent fluid simulation technique with fewer approximations has been fully developed, and the COMSOL-generated plasma model of fluid simulation related to the Ar/SF₆ ICP perfectly reflects the above discharge structure. Moreover, since it is a self-consistent simulation, the self-coagulation dynamic prevails, which consists of free diffusion and a net-negative chemical source and is centered in the structure. Together with the above structures, the discharge of electronegative plasma is hierarchical. Furthermore, with the assistance of compressible heating and discharge hierarchy, self-coagulation has been found to be correlated with quantum wave–particle duality, the nuclear fusion of astrophysical plasma, particle physics with respect to Yukawa’s potential, and geophysical structural morphology. It is believed that plasma varies between cold (i.e., glow discharge), thermal (i.e., arc discharge), and fusion (i.e., nuclear reaction) states by means of self-coagulation and compressible heating. In addition, self-coagulation has been found to be universal, existing in the chemical dynamics of ions, electrons, and neutrons, and even in thermal energy dynamics (i.e., not mass transport, but energy transport).

The previous edition of this Special Issue focused on the connection between the different branches of plasma physics, and included articles in the fields of low- and high-temperature plasmas. As far as we know, it was the first paper in an academic journal to formally address the interaction of the two plasma sources, since they are usually reported separately. The second edition of this Special Issue addresses the physical reason for the connection between the two plasma sources, and aims to encourage the publication of inter-disciplinary research connecting the field of plasma to fields such as quantum physics, particle physics, nuclear physics, astrophysics, and geophysics. In addition, the discharge hierarchy of ICP led by self-coagulation is a self-organization behavior. Therefore, we also welcome papers addressing other self-organization behaviors, such as the stratified direct-current (DC), drift and ambi-polar (DA-), and striation discharging modes of capacitively coupled plasma.

Dr. Shuxia Zhao
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 250 words) can be sent to the Editorial Office for assessment.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Applied Sciences is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

• low-temperature plasma
• thermal nuclear fusion plasma
• discharge structure hierarchy
• self-coagulation
• inter-disciplinary research
• self-organization

• Plasma Physics: Theory, Methods and Applications in Applied Sciences (7 articles)