Nanosecond Pulsed Electric Discharge Synthesis of Carbon Nanomaterials in Helium at Atmospheric Pressure from Adamantane

A self-consistent state-to-state model of pure hydrogen has been used to investigate the development of nanosecond repetitively pulsed discharges and dielectric barrier discharges, the latter coupling the kinetic model with an equation for the circuit, thus mimicking an insulated electrode with an external capacitance. Vibrationally excited states play a fundamental role, affecting the degrees of dissociation and ionization, as well as internal and free-electron distributions.

Section: Introductionmentioning

confidence: 99%

The role of molecular vibration in nanosecond repetitively pulsed discharges and in DBDs in hydrogen plasmas

Colonna

D’Ammando

Pietanza

2016

“…less favourable energetically, were obtained under flow conditions, whereas the same diamondoids could not be realised in the batch process. In addition to the ability of tuning the fluidic conditions, another main advantage of the approach for diamondoid synthesis is that owing to the high density of the SCF, the quantity of adamantane that can be dissolved in xenon is about three orders of magnitude higher than that of atmospheric pressure gas [148].…”

Section: Applicationsmentioning

confidence: 99%

Review on plasmas in extraordinary media: plasmas in cryogenic conditions and plasmas in supercritical fluids

Stauss

Muneoka

Terashima

2018

Self Cite

Plasma science and technology has enabled advances in very diverse fields: micro-and nanotechnology, chemical synthesis, materials fabrication and, more recently, biotechnology and medicine. While many of the currently employed plasma tools and technologies are very advanced, the types of plasmas used in micro-and nanofabrication pose certain limits, for example, in treating heat-sensitive materials in plasma biotechnology and plasma medicine. Moreover, many physical properties of plasmas encountered in nature, and especially outer space, i.e. very-low-temperature plasmas or plasmas that occur in high-density media, are not very well understood. The present review gives a short account of laboratory plasmas generated under 'extreme' conditions: at cryogenic temperatures and in supercritical fluids. The fundamental characteristics of these cryogenic plasmas and cryoplasmas, and plasmas in supercritical fluids, especially supercritical fluid plasmas, are presented with their main applications. The research on such exotic plasmas is expected to lead to further understanding of plasma physics and, at the same time, enable new applications in various technological fields.

“…Nanosecond pulse discharge in gases is characterized by a low gas temperature and a high electron temperature, showing promising advantages in many applications, such as sterilization [1], fuel conversion [2], acoustic modulation [3] and synthesis of carbon nanomaterials [4]. For this reason, the Due to the pulse breakdown delay, a gas gap usually breaks down at an overvoltage [11].…”

Section: Introductionmentioning

confidence: 99%

Observation of electron runaway in a tip-plane air gap under negative nanosecond pulse voltage by PIC/MCC simulation

Liu

et al. 2022

The initial stage of the gas breakdown with the generation of the runaway electrons was investigated by particle-in-cell/Monte Carlo collision simulations. The parameters of the solved problem are 1-mm long and atmospheric air gap between the tip-plane electrodes applied with the nanosecond pulse voltage. The pulse is 5.2 ns in rising time (10%-90%), 10 ns in pulse width (FWHM) and 40 kV in amplitude. The cathode is a cone-shaped electrode whose tip is defined by the elliptic equation (the major axis is 4 mm and the minor axis is 1 mm), and the minimum radius of curvature is 0.125 mm. Since it is found in the simulation that the development of discharge channel from the cathode to the anode only takes about tens to hundreds of picoseconds, especially at high over-voltages with runaway electrons, it was assumed that the gap voltage applied in such a short time is nearly constant. Depending on the voltage at the breakdown, the different behavior of the energetic electrons was observed. When the voltage is low, about 12 kV, energetic electrons are produced only in the tip cathode layer where the electric field is highest; No runaway electrons leading the discharge channel are observed. When the voltage is higher, about 15 kV, the energetic electrons begin to run away at the head of the discharge channel where the electric field is high enough. When the voltage is further higher, the energetic electrons run away even at the beginning of the discharge and from the cathode to the anode. The pre-ionization of the gas ahead of the discharge channel by the runaway electrons was observed, which may play an important role in the fast breakdown of the gas under the nanosecond short pulse.