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The production of ammonia (NH 3 ) with low-pressure, radiofrequency plasmas is studied in this paper in a wide range of experimental conditions using tungsten as a catalyst. The relative position of the tungsten foil in the pyrex tube was observed to dramatically impact ammonia formation. By positioning the catalyst in the middle of the tube, the concentration of NH 3 peaked at 120 W with ≈20 mol %, while it decreased by more than a factor of 2 at 300 W. When the foil was placed close to the end of the tube, the production of NH 3 was rather stable beyond 120 W. These results provide clear evidence of the surface's role in the local enhancement of the NH 3 formation rates. In the plasma volume, at some distance from the foil, the decomposition of NH 3 is the major occurring process and the decomposition rate increases with the power primarily due to a higher electron density. The optimum production of NH 3 was found to be at 45 mol % N 2 and 120 W, and the position of the maximum was observed to slightly decrease to

Energy-based facelifting techniques are a relatively new genre of surgery. In this approach, the energy-based device—whether laser, radiofrequency plasma, or ultrasound—can be used in the superficial plane to elevate skin flaps before performing more traditional facelift techniques involving the superficial musculoaponeurotic system (SMAS) or platysma. The initial reports of utilizing fiber lasers as surgical tools date back to approximately 2007 and initial lipolasers were used to elevate facial skin flaps. The other energy-based devices were also tested. The author has probably the largest series of energy-based facial rejuvenation procedures, having performed over 3,000 of these procedures. The advantages of laser-assisted rhytidectomy include hemostasis, facilitated dissection in areas hard to elevate conventionally such as nasolabial folds or distal neck and the remodeling and tightening of tissue that results from the activation of the wound healing cascade of neocollagenesis and wound contraction. The author currently has a preference for energy device used during rhytidectomy and it is a high frequency ultrasound energy delivered by a five-ring 2.9- and 3.7-mm probe. The use of the ultrasound dissector in both superficial and deep procedures is highlighted in this article with emphasis on its use for deep cervicoplasty and subplatysmal procedures as well as sub-SMAS elevations of the facial deep plane.

Microwave (MW) and radio-frequency (RF) plasma are emerging as attractive non-thermal technologies to ensure the safety and microbiological quality of food. Microwave plasma, at low or atmospheric pressure, can be used for microbial inactivation. Radiofrequency-driven plasma also possesses an antimicrobial potential against a broad range of microorganisms. Both microwave and radiofrequency plasma have the potential to inactivate heat-resistant spores. The two technologies are described in this chapter besides the potential applications for each one. The mechanisms of inactivation by both types of plasma are also discussed.

This study attempts to explore Batch-type Microwave (B-MW) plasma cleaning as a potential alternative to the conventional Strip-type Radiofrequency (S-RF) plasma; for application prior molding to improve adhesion along the mold-lead frame interface. Performance of B-MW was evaluated in terms of improvement in surface wettability, quantified via Contact Angle (CA) measurements. Mix of typical industrial plasma gases (Ar, H2 and O2) were assessed. Constant flow pattern was observed to significantly improve surface wettability and uniformity compared to its pulsed counterpart; and also affect the effect of other factors on the over-all cleaning performance of B-MW. Proceeding with constant flow pattern, surface wetting was found to improve with increasing power and cleaning time. The combination of O2 and H2 plasma was found to be more effective compared to utilizing them separately. Both cleaning time and flow rate increased the amount of reactive species that come in contact with the contaminants. With optimized parameters, B-MW was confirmed to be a more effective plasma method than S-RF i.e. 12% more effective in removing contamination and improving surface wettability, up to 20% better uniformity and can boost throughput to at least 34%.

Polysulfonamide membranes with a molecular weight cutoff of 20 kDa (pore size of 0.01 μm) have been treated with a flow of a radiofrequency (RF) capacitively coupled low-pressure glow discharge plasma in an argon and nitrogen atmosphere at an anode voltage of Ua = 1.5 kV and τ = 1.5 min. Instrumental methods of analysis have revealed the following changes in the structure of the membrane surface as a consequence of plasma treatment at the above parameters: a decrease in roughness, a decrease in the contact angle from 59.6° to 47.9°, and the formation of oxygen-containing functional groups. Experiments on the membrane separation of a 3% oil-in-water emulsion have been conducted; the results have shown that the use of plasmatreated polysulfonamide membranes leads to an intensification of the process.

Ion source development plays an important role for improving and advancing the neutron generator technology used for active interrogation techniques employed by the Department of Homeland Security. Active neutron interrogation using compact neutron generators has been around since the late 1950's for use in oil well logging. However, since the September 11th, 2001 terrorists attack, much attention has been paid to the field of active neutron interrogation for detecting hidden explosives and special nuclear materials (SNM) in cargo and luggage containers through the development of effective and efficient radioactive sources and detectors. In particular, the Associated Particle Imaging (API) method for detecting and imaging explosives is of great interest New compact neutron generators will help to enhance the capabilities of existing threat detection systems and promote the development of cutting-edge detection technologies. The work performed in this thesis includes the testing of various ion source configurations and the development and characterization of an inductively coupled radio frequency (RF) ion source for use in compact neutron generators. These ion source designs have been investigated for the purpose of D-T neutron generation for explosive detection via the Associated Particle Imaging (API) technique. API makes use of the 3.5 MeV alpha particles that are produced simultaneously with the 14 MeV neutrons in the deuterium-tritium (2D(3T,n)4α) fusion reaction to determine the direction of the neutrons and to reduce background noise. The Associated Particle Imaging neutron generator required a beam spot of 1-mm or less in diameter at the target in order to achieve the necessary spatial image resolution. For portable neutron generators used in API, the ion source and target cannot be water-cooled and the power deposited on the target must be low. By increasing the atomic ion fraction, the ion beam can be used more efficiently to generate neutrons, resulting in a lower beam power requirement and an increased lifetime of the alpha detector inside the acceleration column. Various source configurations, antenna design, and permanent magnet placement have been investigated so as to develop an ion source which could provide high monatomic deuterium species and high current density at relatively low RF powers (less than 200 W). In this work, an RF ion source was developed that uses an external, planar, spiral antenna at 13.56 MHz with a quartz source body and side multi-cusp magnets to generate hydrogen isotope plasmas with high mono-atomic ion species (> 80%) while consuming only 150 watts of power and operating under 10 mTorr of gas pressure. A single acceleration gap with a secondary electron suppression electrode are used in the tube. Experimental measurements of the ion source plasma parameters including ion current density, atomic ion fraction, ignition and operating pressures, electron temperature, and electron density are presented along with a discussion on the ion optics and engineering challenges. It is shown that the measured neutron yield for the developed D-D neutron generator was 2 × 105 n/s, which scales to 8 × 107 n/s for D-T operation. In addition, initial measurements of the neutron generator performance including the beam spot size, associated particle detection, and neutron tube (without pumping) operation will be discussed. Some suggestions for future improvement are also presented in this dissertation.

Suprastomal granulomas pose a persistent challenge for tracheostomy-dependent children. They can limit phonation, cause difficulty with tracheostomy tube changes and prevent decannulation. We describe the use of the coblator for radiofrequency plasma ablation of suprastomal granulomas in five consecutive children from September 2012 to January 2016.Retrospective case series at a tertiary medical center.The suprastomal granuloma could be removed with the coblator in all 5 cases. Three were removed entirely endoscopically and 2 required additional external approach through the tracheal stoma for complete removal. There were no intraoperative or postoperative complications. One patient was subsequently decannulated and 2 patients have improved tolerance of their speaking valves. Two patients remain ventilator dependent, but their bleeding and difficulty with tracheostomy tube changes resolved. Three of the patients have had subsequent re-evaluation with bronchoscopy, demonstrating resolution or markedly decreased size of the granuloma. This technique is time efficient, simple and minimizes risks associated with other techniques. The relatively low temperature and use of continuous saline irrigation with the coblator device minimizes the risk of airway fires. Additionally, the risk of hypoxia from keeping a low fractional inspiratory oxygen level (FIOCoblation can be used safely and effectively with an endoscopic or external approach to remove suprastomal granulomas in tracheostomy-dependent children. More studies that are larger and have longer follow-up are needed to evaluate the use of this technique.

Zbog velike zastupljenosti radiofrekvencijskih (RF) plazmi u industriji javila se potreba za definisanjem osnovnih fizičkih principa koji određuju proboj u RF električnim poljima. Uslovi, u vidu probojnog napona i pritiska, mogu se prikazati naponskom probojnom krivom, predstavljenom u V-p ravni. Oblik i položaj krive definisani su kako prirodom pozadinskog gasa tako i karakteristikama spoljašnjeg RF električnog izvora. Ova disertacija ima za cilj da nedvosmisleno definiše fizičke procese koji su odgovorni za proboj pri RF električnim poljima. Za to je korišćena Monte Karlo tehnika. Odabirom slučajnih brojeva, uz poznavanje preseka za određene procese, moguće je verno (čak se može tvrditi egzaktno) opisati kretanje roja naelektrisanih čestica između dve elektrode koje su pobuđene RF generatorom. Izgradnja modela je započeta posmatranjem kretanja elektrona u argonu pri frekvenciji od 13,56 MHz. Na primeru argona objašnjeni su osnovni mehanizmi proboja koji definišu oblik naponske probojne krive. Nadogradnja modela, kao verodostojne predstave RF proboja, uključuje efekte na površinama elektroda (refleksiju i emisiju sekundarnih elektrona), uticaj promene frekvencije i dvofrekvencijskih izvora, kao i teških čestica. Model je primenjen na različite gasove: helijum, kiseonik, sintetički vazduh i atmosfera Marsa. The wide range of radiofrequency (RF) plasma applications in industry rely on research of fundamental physical processes responsible for the RF breakdown. Conditions, such as the breakdown voltage and pressure, can be presented by breakdown voltage curves in the V-p plane. The shape and coordinates of the curve are defined by the nature of the background gas and characteristics of the applied RF electric field. The goal of this dissertation is to define physical processes responsible for the RF breakdown. For that purpose a Monte Carlo computational code has been used. If one knows cross sections for different processes by employing a random number generator, the transport of electrons between two electrodes can be determined. The development of the RF breakdown model begun by observing the motion of electrons in argon at the field frequency of 13.56 MHz. Argon was used to explain the basic mechanisms that define the shape of the breakdown voltage curve. Further upgrade of the model involved inclusion of the surface effects on electrodes (reflection and secondary electron emission), the influence of frequency and dual frequency RF power supplies, as well as the influence of heavy particles on the breakdown. The model was applied to different gases: helium, oxygen, and synthetic air, as well as the atmosphere of Mars.

Radiofrequency plasma for biomedical applications generated in coaxial geometry at atmospheric pressure was investigated. The plasma was characterized by key parameters, including gas temperature and electron density. It was shown that OH rotational temperature is in agreement with the temperature estimated by Rayleigh and Raman scattering techniques. RF plasma was combined with an aerosol injection for better control of the treated skin temperature and topical drugs delivery.

Cold plasma treatment leads to the electrical charging of liquid organic (polydimethylsiloxane) surfaces. Water droplets placed on the surface of cold radiofrequency plasma treated polydimethylsiloxane oil were used as probes enabling the estimation of the specific surface charge supplied by plasma to polydimethylsiloxane. The specific surface charge was also established independently by the electrostatic pendulum. The surface charge density was estimated as σ ≅ 0.5 ÷ 3 μC/m 2 .

The Haber-Bosch process has been the commercial benchmark process for ammonia synthesis for more than a century. Plasma-catalytic synthesis for ammonia production is theorized to have a great potential for being a greener alternative to the Haber-Bosch process. However, the underlying reactions for ammonia synthesis still require some detailed study especially for radiofrequency plasmas. Herein, the use of inductively coupled radiofrequency plasma for the synthesis of ammonia when employing Ga, In and their alloys as catalysts is presented. The plasma is characterized using emission spectroscopy and the surface of catalysts using Scanning Electron Microscope. A maximum energy yield of 0.31 g-NH3/kWh and energy cost of 196 MJ/mol is achieved with Ga-In (0.6:0.4 and 0.2:0.8) alloy at 50 W plasma power. Granular nodes are observed on the surface of catalysts indicating the formation of the intermediate GaN.

Bipolar plasma kinetic vaporization of the prostate (BPKVP) is an endoscopic transurethral ablation technique used in the treatment of benign prostatic hyperplasia (BPH). Also known as the “button” procedure, BPKVP utilizes an axipolar electrode, shaped as a mushroom or “button” to apply radiofrequency plasma energy to prostatic tissue. Studies comparing BPKVP to monopolar transurethral resection of the prostate (mTURP) have found decreased operative, catheterization, and hospitalization times using the BPKVP approach, along with equivalent or better efficacy in short- to medium-term follow-up periods. In addition, BPKVP is associated with fewer perioperative and postoperative complications compared with mTURP. BPKVP is an effective and safe treatment option for BPH and provides an alternative to the traditional mTURP approach.

Experimental and computational diagnostics for radiofrequency plasma micro-thrusters are presented, based on the low power (10–100 W) electrothermal thruster prototype, Mini Pocket Rocket, developed for use on the Cubesat nanosatellite platform. Computer simulations include computer fluid dynamics simulations and particle in cell simulations while experimental results are obtained using a variety of electrostatic, optical and momentum probes. The output and limitations of each diagnostic are discussed within the context of device development for space use.

CO2, N2, and N2/H2 radiofrequency plasma exposure was used for functionalization of poly(vinylidene fluoride) surface aiming the fibrinogen immobilization. Fibrinogen was immobilized onto poly(vinylidene fluoride) surface using both simple plasma activation and covalent coupling. The modified surfaces have been characterized by X-ray photoelectron spectroscopy, attenuated total reflectance–Fourier transform infrared spectroscopy, near infrared–chemical imaging, atomic force microscopy, and wettability measurements, and the obtained materials were tested as supports for fibroblast cell cultures. The plasma type and the immobilization procedure have influenced the fibrinogen attachment onto the poly(vinylidene fluoride) surface, which was achieved mainly through amide bonds when using coupling agents. Covalent immobilization of fibrinogen onto poly(vinylidene fluoride) surface leads to a more stable protein-modified polymer surface. Non-cytotoxic plasma-based coating technology has the ability to covalently immobilize bioactive molecules for surface modification of some biomaterials that mainly could be achieved by the immobilization of proteins such as fibrinogen that triggers desirable cellular responses. The fibrinogen-modified poly(vinylidene fluoride) materials showed increased cell viability of fibroblasts. Cell viability was enhanced by plasma-activated fibrinogen coatings onto poly(vinylidene fluoride) surface, this being more significant if coating was linked further by a coupling reaction. Hence, they could be good candidates for biomedical applications.

Cold radiofrequency plasma treatment modified wetting and floating regimes of pepper seeds. The wetting regime of plasma-treated seeds was switched from the Wenzel-like partial wetting to the complete wetting. No hydrophobic recovery following the plasma treatment was registered. Environmental scanning electron microscopy of the fine structure of the (three-phase) triple line observed with virgin and plasma-treated seeds is reported. Plasma treatment promoted rapid sinking of pepper seeds placed on the water/air interface. Plasma treatment did not influence the surface topography of pepper seeds, while charged them electrically. Electrostatic repulsion of floating plasma-treated seeds was observed. The surface charge density was estimated from the data extracted from floating of charged seeds and independently with the electrostatic pendulum as σ≈1-2μC/m2.

We report the robust technique allowing manufacturing of superhydrophobic and oleophobic (omniphobic) surfaces with industrial grade low density polyethylene. The reported process includes two stages: (1) hot embossing of polyethylene with micro-scaled steel gauzes; (2) treatment of embossed surfaces with cold radiofrequency plasma of tetrafluoromethane. The reported surfaces demonstrate not only pronounced superhydrophobicity but also superoleophobicity. Superoleophobicity results from the hierarchical nano-scaled topography of fluorinated polyethylene surface. The observed superoleophobicity is strengthened by the hydrophobic recovery. The stability of the Cassie wetting regime was studied.

In this paper a method is described that allows mapping of the forces acting on dust particles in a GEC reference cell. Monodisperse particles are dropped into the plasma environment and their trajectories are tracked using a high-speed camera system to determine local accelerations and respective forces. Collecting data from a large number of particle drops allows the identification of three-dimensional vector fields for the acting forces. The procedure is described and multiple examples in which the method has been applied are given. These examples include a simple plasma sheath, plasmas perturbed by a horizontal and vertical dipole magnet, an array of multiple magnets mimicking the fields found at a lunar swirl, and the fields inside a glass box used for particle confinement. Further applicability in other plasma environments will be discussed shortly.

This work reports a detailed experimental study of the plasma properties in low pressure RF discharges in hydrogen peroxide and a comparison with argon under the same operating conditions. H2O2 plasmas have been proposed for sterilization purposes. Electrical properties of the discharge were shown to be similar, as for the RF and DC voltages of the driving electrode. Bulk plasma volume remains stable, concentrated in an almost cylindrical region between the two facing electrodes. It was found that the electron temperature is almost uniform across the plasma and independent of the power level. This is higher than in argon discharges: T e = 4.6 ± 0.9 eV versus T e = 3.3 ± 1.1 eV. The plasma density increases almost linearly with the power level and a substantial negative ion component has been ruled out in hydrogen peroxide. Dissociation in the plasma gas phase was revealed by atomic hydrogen and hydroxyl radical emission in the discharge spectra. Emission from hydroxyl and atomic oxygen demonstrates that oxidizing radicals are produced by hydrogen peroxide discharges, revealing its usefulness for plasma processing other than sterilization, for instance to increase polymer film surface energy. On the other hand, argon could be considered as a candidate for the sterilization purposes due to the intense production of UV radiation.

Radio frequency plasma treatment of 96-well PCR polypropylene plate, using O2, decreased DNA adsorption relative to untreated plates. Furthermore, radio frequency plasma treatment with a N2/H2 gas mixture increased DNA adsorption. This technique provides a simple means of modifying DNA adsorption to PCR polypropylene plates for various applications.

Experimental evidence of the existence of an intermediate region between a capacitively coupled plasma and the collisional space-charge region at its borders is presented. This proof is generated by monitoring—in an airplane carrying out parabolic flights—the trajectory of plasma-confined microparticles. Based on only primary data and without the need for a sophisticated model, our analysis concludes a sharply marked transition from the sheath region into another region with a significantly lower—yet nonzero—space-charge density, i.e., a region which is often called the presheath.

Shaped “cubic” non-stick droplets are reported. Shaped composite droplets were manufactured via a two-stage process. In the first stage, cubic foamed-polystyrene particles were hydrophilized with cold radiofrequency plasma. Then particles were wetted with water. In the second stage, they were coated with solid, colloidal particles such as lycopodium, Teflon or carbon black. Thus, “liquid marble”-like non-stick shaped droplets were obtained. The shaped “cubic” droplets remained stable when supported by a NaCl water solution. Shaped Janus droplets coated on one side with dielectric Teflon and with semiconductor carbon black on the other side, were prepared. Janus marbles were actuated with an electric field.

Atomic emission from a 350-kHz helium plasma was evaluated for the calculation of C/Cl and C/Br ratios in compounds separated by capillary gas chromatography. When the plasma was sustained inside the end of a 0.32 mm I.D. fused-silica GC column in 2 ml/min of GC carrier gas + 18 ml/min of make-up gas (helium), 94% of the elemental ratios obtained deviated by less than 20% from the theoretical values. These results with the on-column r.f. discharge were comparable to data obtained with a commercial GC-atomic emission detection system based on a microwave-induced plasma.

Parallel plate field emission measurements using a-C:H and a-C:H:N thin-film cathodes deposited at room temperature in a magnetically confined radiofrequency plasma enhanced chemical vapor deposition chamber reveal a low emission barrier of 0.05 eV. The onset fields for emission are in the 20 to 30 V/μm range. Currents which are two orders higher were measured from the a-C:H:N films compared to a-C:H films. A current density of 0.2 mA/cm 2 (taking the entire film surface as the emitting area) at 40 V/μm was obtained from an a-C:H:N film with 11 at.% of N. An a-C:H:N film with 15% N gave a space charge limited current density of 0.2 mA/cm 2 at 20 V/μm.

The effect of fluorination on the transport properties of three classes of materials is presented. The intercalation of fluorine in graphitized carbon fibres drastically modifies their electrical behaviour. A wide range of conductivities is observed from sigma(300K) similar to 1.5 X 10(5) S cm(-1) for Csimilar to 14F to sigma(300K) similar to 10(2) S cm(-1) for C