Charalambos Anastassiou

• Doctor of Philosophy
• University of Cyprus

Trichel pulses for negative direct current corona discharge in a pin plate configuration under open dry air conditions are investigated using two numerical models. The first well known general model takes electrons and positive and negative ions into consideration. The second model, a more detailed one, takes electrons and other 16 nitrogen and oxy...

We developed an in silico approach to model B16F10 melanoma cell response to a helium atmospheric pressure plasma jet (APPJ) or/and doxorubicin drug (DOX). The in silico model is informed by relevant data from previously published in vitro experiments (cancer cell viability), providing detailed information on (i) cell population number (Ncell) deve...

The use of cold atmospheric-pressure plasma jets (APPJs) and/or plasma-treated liquids is one of the most promising, rapidly growing, and challenging research fields in plasma (cancer) medicine. Different experimental and numerical studies have shown that APPJs have unique positive effects on the permeabilization and apoptosis of cancer cells [1,2]...

Micro-Tube Plasmas (μTP) have been gaining attention for applications ranging from medicine to material science and analytical chemistry due to their small size, low cost of operation and flexibility. In the present work a specific μTP, known as the Flexible Micro Tube Plasma (FμTP) is investigated experimentally and, for the first time, numericall...

25 In the present report, an atmospheric pressure plasma jet is sustained in a helium channel by square wave unipolar 26 high voltage. The gas flow rate and the square wave features (amplitude, frequency, and duty cycle) are varied over 27 a wide range, while the plasma ultraviolet-visible (UV-Visible) to near infrared (NIR) emission is recorded. T...

Battery energy storage systems (BESS) have started to be part of photovoltaic (PV) system design to allow the further penetration of PV into the grid. This paper deals with the sizing (power and energy capacity) of a BESS for residential households which are represented by a typical load consumption profile, they have electrical air conditioning (A...

In this study, a 1D plasma fluid model is used to shed light into the evolution of a He/dry air (500 ppm, 79% N 2 and 21% O 2 ) dielectric barrier discharge (DBD) under different levels of water admixtures (20 to 2000 ppm). The model considers the analytical chemistry between helium, nitrogen, oxygen and water species and it is verified with experi...

Atmospheric pressure plasma jets (APPJs) can be generated in capillary tubes flowing with pure helium and with admixtures of oxygen into the pure helium. The jet exiting the tube can be used for a variety of applications through surface interaction. In this study, a two-dimensional axi-symmetric model has been developed to provide insight into the...

Numerical simulations for DBD plasma that includes water admixtures

Numerical and experimental data showing the interaction of atmospheric plasma with biological cells.

This paper describes a methodology and guidelines to design a battery storage system at both residential (distributed) and community (centralized) level, where a common AC low voltage (LV) distribution feeder is used under a high PV penetration scenario in Cyprus. For this purpose, the methodology considers the load profile of typical residential h...

Microgrids (μG) are an emerging and promising concept for the integration of distributed Renewable Energy Sources (RES) into the power grid by introducing local coordination of controllable distributed energy sources. The University of Cyprus (UCY) plans to evolve the whole campus into a μG with a 10 MWp PV and respective Battery Energy Storage Sys...

With the existing energy systems and electricity grids worldwide being developed as smart systems and grids with increased renewable energy in general, there are critical needs in smart grid knowledge, development, testing, demonstration, evaluation, education and training. The University of Cyprus (UCY) is presently establishing a complete new gre...

In recent years, increasing concerns about climate change and the liberalisation of the energy market have provided the necessary impetus for a revolutionary restructuring of the electricity network. Traditional power networks are designed to operate in a passive and unidirectional way as their main functionality encompasses the transfer of energy...

The trend towards high penetration of renewable energy sources (RES) in the energy mix and particularly grid-connected photovoltaic (PV) systems in the low voltage (LV) network, offers the benefits of green decentralized generation, at the cost of the development of energy management tools to alleviate potential problems. More specifically, the fac...

The installed capacity of grid-tied photovoltaic (PV) systems around the globe is increasing rapidly due to the need for clean, sustainable and fuel independent energy. The PV technology is already a major part of the energy mix in many developed and developing countries. The electricity generated from these systems heavily depends on the prevailin...

In general, in one aspect, the disclosure features a system that includes a flexible waveguide having a hollow core extending along a waveguide axis and a region surrounding the core, the region being configured to guide radiation from the CO2 laser along the waveguide axis from an input end to an output end of the waveguide. The system also includ...

Carbon dioxide (CO2) lasers have become one of the most common surgical lasers due to excellent tissue interaction properties that offer precise control of cutting and ablation depth, minimal thermal damage to surrounding tissue, and good hemostasis. However, realization of the benefits offered by using surgical CO2 lasers in many endoscopic, minim...

We investigate heating from field propagation, coupling, and bending, which are the potential failure mechanisms for an emerging new type of high-power radiation guides-hollow photonic Bragg fibers. Continuous wave (CW) and pulsed radiation sources are considered, assuming continuous operation of the laser source.

The CO2 laser is the most widely used laser in laryngology, offering very precise cutting, predictable depth of penetration, and minimal collateral damage due to the efficient absorption of CO2 laser by water. Surgical applications of CO2 laser in microlaryngoscopy include removal of benign lesions and early-stage laryngeal cancer. A Transoral Lase...

We present two potentially interesting new venues in all-optical signal processing. First, we demonstrate experimentally that collisions between vector (Manakov-like) solitons involve energy exchange; this feature could be explored for all-optical signal processing. Second, our detailed theoretical studies show how inserting materials that support...

Laser cutting of human bone and tissue is one of the oldest and most widespread applications of biophotonics. Due to the unique absorption of different kinds of tissue, choosing an appropriate laser wavelength allows selective ablation of tissue. Consequently, a large variety of laser sources with different emission wavelengths have been successful...

Novel optical fibers based on photonic bandgap reflectors enable a new approach to beam delivery for medical CO 2 lasers. A combination of desirable mechanical and optical properties allows flexible endoscopes to guide the laser beam into a patient's body through a very small incision. For the first time, the advantageous high-precision tissue-cutt...

We present a rigorous analysis methodology of fundamental to higher order mode converters in step index few mode optical fibers. We demonstrate experimental conversion from a fundamental LP 01 mode to the higher order LP 11 mode utilizing a multiple mechanical bend mode converter.We perform a quantitative analysis of the measured light intensity, a...

We calculate the growth rate of the small-amplitude perturbations superimposed on a one-dimensional soliton that is fully coherent in the self-trapping dimension, yet uniform and partially incoherent in the other transverse dimension. Such solitons become transversely stable only if the correlation distance is below a specific threshold value. We s...

Thesis (Ph. D)--Princeton University, 2001. Includes bibliographical references (leaves 146-148).

We demonstrate experimentally the transport of information from one vector (Manakov-like) spatial soliton to another via collisions with a third, intermediate soliton.

We present experimental observations of self-trapped rings carrying zero topological charge, along with simulations that display the self-focusing dynamics of the rings and their stability features in materials with saturable nonlinearities.

We experimentally demonstrate image transmission through a noninstantaneous self-focusing medium. A partially spatially incoherent soliton is used to form a multimode waveguide in a photorefractive crystal, and the modes of that waveguide are used to transmit an incoherent image through this nonlinear medium.

We present the first experimental observation of cascading two collisions between vector (Manakov-like) solitons. This experiment shows that it is possible to use collisions between vector solitons as a means of transferring information.

We show analytically, numerically, and experimentally that a transversely stable one-dimensional [(1+1)D] bright Kerr soliton can exist in a 3D bulk medium. The transverse instability of the soliton is completely eliminated if it is made sufficiently incoherent along the transverse dimension. We derive a criterion for the threshold of transverse in...

We demonstrate experimentally wavelength tuning of second-harmonic generation in waveguides induced by photorefractive solitons in a KNbO3 crystal. By rotating the crystal, we can attain as large wavelength tunability as in bulk but with considerable improvement in conversion efficiency and elimination of walk-off.

We present the first experimental observation of 2 + 1 -dimensional multimode (composite) solitons. A single-hump component and a double-hump (dipole-type) component are jointly self-trapped as a composite soliton in a biased photorefractive crystal.

Summary form only given. We have shown how to control the collisions of vector solitons: from solitons going through, to solitons bouncing and developed a simple physical explanation based on gratings. We are currently investigating experimental implementations in saturable nonlinear media such as photorefractives.

Summary form only given. We believe we present for the first time two-dimensional (2D) interactions and dynamics of partially coherent beams with emphasis on incoherent solitons in saturable nonlinear media. This is done by employing the coherent density approach in 2D

Image transmission through thick self-focusing highly nonlinear media has been a challenging task for the late 20 th century. In fact, transmitting even a simple Gaussian-like beam through such media is very difficult, because the beam breaks up into filaments with a characteristic width close to that of a spatial soliton under the same intensity a...

We have demonstrated that photorefractive soliton-induced waveguides can improve the SHG conversion efficiency considerably while offering tuning angle range of ±7°, which translates into 4 nanometer tunability. We expect much higher improvement with a longer crystal and a narrower soliton

Citation Song Lan, Ming-feng Shih, Greg Mizell, J. A. Giordmaine, Zhigang Chen, Charalambos Anastassiou, John Martin, and Mordechai Segev, "Harmonic Generation in Soliton-Induced Waveguides," Optics & Photonics News 10(12), 27_1-28 (1999) http://www.opticsinfobase.org/opn/abstract.cfm?URI=opn-10-12-27_1

We demonstrate experimentally collisions between vector (Manakov-like) solitons that involve energy exchange at large collision angles, for which scalar solitons pass through one another practically unaffected.

© 1999 Optical Society of America

We demonstrate experimentally second-harmonic generation in waveguides induced by photorefractive solitons and show that the conversion efficiency is improved considerably. These induced waveguides are flexible and can be generated in any crystalline direction that allows soliton formation, and thus offer broad tunability (by rotation of the crysta...

We show theoretically and experimentally that the photovoltaic nonlinearity that gives rise to spatial solitons can be switched from self-defocusing to self-focusing (or vice versa) by use of background illumination. This raises the possibility of bright photovoltaic solitons in LiNbO 3 .

Quantum mechanical anharmonic oscillators and Hamiltonians for particles in external magnetic fields are related to representations of nilpotent groups. Using this connection the eigenfunctions of the quartic anharmonic oscillator with potential V-alpha(x)=(alpha+(x(2)/2))(2) can be used to determine the eigenfunctions of a charged particle in a no...