Science.gov

Sample records for plasma microinstabilities

  1. Microinstabilities in plasmas

    SciTech Connect

    El Nadi, A.M.

    1995-09-01

    In this work we review some of the progress made in the area of plasma microinstabilities. The use of the microscopic approach allows the investigation of various features related to velocity-dependent effects such as particle trapping, wave-particle resonance, and short wavelength effects. The work presented will deal mainly with those instabilities generally considered to be important in fusion devices. These include the trapped electron mode, the ion-temperature-gradient-driven mode and instabilities due to the presence of an energetic particle component. Results obtained using both slab and toroidal models will be presented. {copyright} {ital 1995 American Institute of Physics.}

  2. Plasma heating from alpha particle micro-instabilities

    SciTech Connect

    Miley, G.H.; Sutton, W.R.; Choi, C.K.

    1981-01-01

    Potential use of thermonuclear (i.e., fusion product) driven kinetic instabilities to heat the background plasma has long been recognized. Considerable research on velocity space micro-instabilities exists. Most work to date has focused upon the basic physics criteria for and characteristics of particular micro-instabilities. Kinetic instabilities resulting in spatial transport of fusion products have also received some attention, but the effects on reactor concepts and performance remain uncertain. We have developed an engineering model which scopes the effect of a velocity space relaxation of fast alphas on a quasi-linear time scale. This model includes the additional heating to background plasma ions under the assumptions of: ion damping of the plasma wave; heating to background plasma results predominantly from fusion products; and periodic hiccups of the instability.

  3. Structure of micro-instabilities in tokamak plasmas: Stiff transport or plasma eruptions?

    SciTech Connect

    Dickinson, D.

    2014-01-15

    Solutions to a model 2D eigenmode equation describing micro-instabilities in tokamak plasmas are presented that demonstrate a sensitivity of the mode structure and stability to plasma profiles. In narrow regions of parameter space, with special plasma profiles, a maximally unstable mode is found that balloons on the outboard side of the tokamak. This corresponds to the conventional picture of a ballooning mode. However, for most profiles, this mode cannot exist, and instead, a more stable mode is found that balloons closer to the top or bottom of the plasma. Good quantitative agreement with a 1D ballooning analysis is found, provided the constraints associated with higher order profile effects, often neglected, are taken into account. A sudden transition from this general mode to the more unstable ballooning mode can occur for a critical flow shear, providing a candidate model for why some experiments observe small plasma eruptions (Edge Localised Modes, or ELMs) in place of large Type I ELMs.

  4. Global approach to the spectral problem of microinstabilities in tokamak plasmas using a gyrokinetic model

    NASA Astrophysics Data System (ADS)

    Brunner, S.; Fivaz, M.; Tran, T. M.; Vaclavik, J.

    1998-11-01

    A solution to the full two-dimensional eigenvalue problem of electrostatic microinstabilities in a tokamak plasma is presented in the framework of gyrokinetic theory. The approach is the generalization of methods previously developed for a cylindrical system [S. Brunner and J. Vaclavik, Phys. Plasmas 5, 365 (1998)]. By solving the spectral problem in a special Fourier space adapted to the curved geometry, orbit width as well as Larmor radius can be kept to all orders. For a first numerical implementation, a large aspect ratio plasma with circular concentric magnetic surfaces is considered. A root finding algorithm for identifying the eigenfrequencies, based on a higher order Nyquist method, enables straightforward implementation on a parallel computer. Illustrative results for ion temperature gradient-related instabilities are presented. These include scaling studies of the radial width, and toroidicity and magnetic shear scans, as well as the effects of nonadiabatic trapped electron dynamics.

  5. Global, Gyrokinetic Eigenvalue Calculations of ITG-Related Microinstabilities in Tokamak Plasmas

    NASA Astrophysics Data System (ADS)

    Brunner, S.; Fivaz, M.; Tran, T. M.; Vaclavik, J.

    1998-11-01

    Methods previously developed for a cylindrical system(S.Brunner and J.Vaclavik, Phys.Plasmas 5), 365 (1998) have been generalized to a tokamak plasma for solving the full 2-dimensional eigenvalue problem of electrostatic microinstabilities using a gyrokinetik model(S.Brunner, Ph.D thesis, Ecole Polytechnique Fédérale de Lausanne, Switzerland, thesis 1701 (1978)). By solving the spectral problem in a special Fourier space adapted to the curved geometry, orbit width as well as Larmor radius can be kept to all orders. For a first numerical implementation, a large aspect ratio plasma with circular concentric magnetic surfaces has been considered. A higher order Nyquist method(B.Davies, Jour.Comp.Phys. 66), 36 (1986), applied for identifying the eigenfrequencies in the complex plane, has been improved and enables straightforward implementation on a parallel computer. Illustrative results of ITG (ion temperature gradient) -related instabilities are presented. These include scaling studies of the radial width, toroidicity and magnetic shear scans, as well as the effects of non-adiabatic trapped electron dynamics.

  6. Unified fluid/kinetic description of plasma microinstabilities. Part I: Basic equations in a sheared slab geometry

    SciTech Connect

    Chang, Z.; Callen, J.D. )

    1992-05-01

    Unified fluid/kinetic equations for the plasma perturbed density ({ital {tilde n}}), parallel flow velocity ({ital {tilde u}}{sub {parallel}}) and temperature ({ital {tilde T}}) are developed in a sheared slab geometry by calculating the fluid moment closure relations kinetically. At first, a set of (unclosed) nonlinear perturbed fluid equations for {ital {tilde n}}, {ital {tilde u}}{sub {parallel}} and {ital {tilde T}} is developed using a drift ordering analysis and a new gyroviscous force ((spec. char. missing){center dot}{Pi}{sub {ital g}}). Thereafter, to develop linear closure relations for {bold b}{center dot}{del}{center dot}{tilde {Pi}}{sub {parallel}} and {ital {tilde q}}{sub {parallel}}, a drift-kinetic version of a new Chapman--Enskog-like (CEL) equation is developed and solved by using a moment approach and a physically realistic collision operator (Lorentz scattering operator plus the momentum restoring terms). The resultant closure relations for {bold b}{center dot}(spec. char. missing){center dot}{tilde {Pi}}{sub {parallel}} and {ital {tilde q}}{sub {parallel}} unify the fluid and kinetic approaches. In the collisional fluid limit the equations reduce to the well-known Braginskii equations. In the adiabatic limit they reproduce the usual kinetic results, including Landau damping. It is shown that this new CEL approach is more compatible with a fluidlike description of plasmas than the usual drift/gyrokinetic approach. Remarkably simplified forms of the closure relations are presented. The results are compared with other Landau damping models and shown to be more accurate, complete, and physically realistic. Applications of this set of equations to various microinstabilities in tokamak plasmas are presented in a separate paper (Part II) (Phys. Fluids B {bold 4}, 1182 (1992)).

  7. Microinstabilities in weak density gradient tokamak systems

    SciTech Connect

    Tang, W.M.; Rewoldt, G.; Chen, L.

    1986-04-01

    A prominent characteristic of auxiliary-heated tokamak discharges which exhibit improved (''H-mode type'') confinement properties is that their density profiles tend to be much flatter over most of the plasma radius. Depsite this favorable trend, it is emphasized here that, even in the limit of zero density gradient, low-frequency microinstabilities can persist due to the nonzero temperature gradient.

  8. Microinstabilities in the Gasdynamic Mirror Propulsion System

    NASA Technical Reports Server (NTRS)

    Emrich, William

    2005-01-01

    The gasdynamic mirror has been proposed as a concept which could form the basis of a highly efficient fusion rocket engine. Gasdynamic mirrors differ from most other mirror type plasma confinement schemes in that they have much larger aspect ratios and operate at somewhat higher plasma densities. There are several types of instabilities which are known to plague mirror type confinement schemes. These instabilities fall into two general classes. One class of instability is the Magnetohydrodynamic or MHD instability which induces gross distortions in the plasma geometry. The other class of instability is the "loss cone" microinstability which leads to general plasma turbulence. The "loss cone" microinstability is caused by velocity space asymmetries resulting from the loss of plasma having constituent particle velocities within the angle of the magnetic mirror "loss cone." These instabilities generally manifest themselves in high temperature, moderately dense plasmas. The present study indicates that a GDM configured as a rocket engine might operate in a plasma regime where microinstabilities could potentially be significant.

  9. Microinstabilities in the Gasdynamic Mirror Propulsion System

    NASA Technical Reports Server (NTRS)

    Emrich, William

    2005-01-01

    The gasdynamic mirror has been proposed as a concept which could form the basis of a highly efficient fusion rocket engine. Gasdynamic mirrors differ from most other mirror type plasma confinement schemes in that they have much larger aspect ratios and operate at somewhat higher plasma densities. There are several types of instabilities which are known to plague mirror type confinement schemes. These instabilities fall into two general classes. One class of instability is the Magnetohdrodynamic or MHD instability which induces gross distortions in the plasma geometry. The other class of instability is the "loss cone" microinstability which leads to general plasma turbulence. The "loss cone" microinstability is caused by velocity space asymmetries resulting from the loss of plasma having constituent particle velocities within the angle of the magnetic mirror "loss cone." These instabilities generally manifest themselves in high temperature, moderately dense plasmas. The present study indicates that a GDM configured as a rocket engine might operate in a plasma regine where microinstabilities could potentially be significant.

  10. Microinstabilities and anomalous transport

    NASA Technical Reports Server (NTRS)

    Papadopoulos, K.

    1985-01-01

    The role of microinstabilities in producing dissipation and anomalous transport in collisionless shock waves is reviewed. Particular emphasis is placed on quasiturbulent magnetosonic shocks. The review follows the historical development of anomalous transport and the incorporation of the coefficients into multifluid and hybrid models. A general formalism is presented which describes in a self-consistent manner, the macroscopic transport produced by short wavelength microinstabilities. Similarities and differences with models incorporating classical transport are emphasized. The important instabilities and their transport properties are summarized. It is shown that multifluid simulations with anomalous transport explain many features of the experimental observations. The relevance of ion reflection and the necessity for kinetic ion description for supercritical shocks along with state of the art numerical studies are also discussed. The review concludes with a brief discussion of the piston shock problem and of quasi-parallel turbulent shocks.

  11. Toroidal microinstability studies of high temperature tokamaks

    SciTech Connect

    Rewoldt, G.; Tang, W.M.

    1989-07-01

    Results from comprehensive kinetic microinstability calculations are presented showing the effects of toroidicity on the ion temperature gradient mode and its relationship to the trapped-electron mode in high-temperature tokamak plasmas. The corresponding particle and energy fluxes have also been computed. It is found that, although drift-type microinstabilities persist over a wide range of values of the ion temperature gradient parameter /eta//sub i/ /equivalent to/ (dlnT/sub i//dr)/(dlnn/sub i//dr), the characteristic features of the dominant mode are those of the /eta//sub i/-type instability when /eta//sub i/ > /eta//sub ic/ /approximately/1.2 to 1.4 and of the trapped-electron mode when /eta//sub i/ < /eta//sub ic/. 16 refs., 7 figs.

  12. Microinstability-based model for anomalous thermal confinement in tokamaks

    SciTech Connect

    Tang, W.M.

    1986-03-01

    This paper deals with the formulation of microinstability-based thermal transport coefficients (chi/sub j/) for the purpose of modelling anomalous energy confinement properties in tokamak plasmas. Attention is primarily focused on ohmically heated discharges and the associated anomalous electron thermal transport. An appropriate expression for chi/sub e/ is developed which is consistent with reasonable global constraints on the current and electron temperature profiles as well as with the key properties of the kinetic instabilities most likely to be present. Comparisons of confinement scaling trends predicted by this model with the empirical ohmic data base indicate quite favorable agreement. The subject of anomalous ion thermal transport and its implications for high density ohmic discharges and for auxiliary-heated plasmas is also addressed.

  13. Kinetic Modeling of Electron Conduction-Driven Microinstabilities and Their Relevance for AGN Feedback

    NASA Astrophysics Data System (ADS)

    Roberg-Clark, Gareth; Swisdak, M.; Reynolds, Christopher S.; Drake, James

    2016-04-01

    Since the Intracluster Medium (ICM) is a weakly collisional plasma, the standard Spitzer conduction rate (which relies on collisionality) does not necessarily describe the transport of heat in clusters. In addition, many plasma microinstabilities become unstable at high beta since the magnetic field is easily pliable in the presence of induced pressure anisotropies. These properties imply that the true rate of conduction in an ICM-like plasma could be highly dependent on small-scale effects. We perform 2D kinetic Particle-In-Cell simulations and derive an analytic theory of a conduction-driven electron microinstability present in high-beta collisionless plasmas. We find that scattering by electromagnetic waves significantly reduces the conductive heat flux of electrons in our model. Our results have implications for 1) cool-core clusters in which AGN feedback may play a crucial role in maintaing overall thermodynamic stability, 2) heat flux suppression and scattering by other microinstabilities and 3) basic plasma physics questions that up until this point have not been explored fully.

  14. Microinstability and internal impingement in overhead athletes.

    PubMed

    Chambers, Lauchlan; Altchek, David W

    2013-10-01

    A complex interplay exists between the static and dynamic stabilizers in the glenohumeral joint, especially in overheard athletes who need a shoulder hypermobile enough to perform overhead activity yet stable enough to prevent joint subluxation. Concomitant shoulder pathologies commonly occur in the setting of microinstability and internal impingement. Before any surgical intervention, a 3- to 6-month course of conservative measures should first be attempted, with exercises focused on rotator cuff and scapular stabilizer strengthening combined with posterior capsule stretching. If surgery is needed, arthroscopic suture plication with treatment of concomitant lesions has been shown to provide the best clinical outcomes. PMID:24079429

  15. Microinstabilities in the pedestal region

    NASA Astrophysics Data System (ADS)

    Dickinson, David; Dudson, Benjamin; Wilson, Howard; Roach, Colin

    2014-10-01

    The regulation of transport at the pedestal top is important for the inter-ELM pedestal dynamics. Linear gyrokinetic analysis of the pedestal region during an ELM cycle on MAST has shown kinetic ballooning modes to be unstable at the knee of the pressure profile and in the steep pedestal region whilst microtearing modes (MTMs) dominate in the shallow gradient region inboard of the pedestal top. The transition between these instabilities at the pedestal knee has been observed in low and high collisionality MAST pedestals, and is likely to play an important role in the broadening of the pedestal. Nonlinear simulations are needed in this region to understand the microturbulence, the corresponding transport fluxes, and to gain further insight into the processes underlying the pedestal evolution. Such gyrokinetic simulations are numerically challenging and recent upgrades to the GS2 gyrokinetic code help improve their feasibility. We are also exploring reduced models that capture the relevant physics using the plasma simulation framework BOUT + + . An electromagnetic gyrofluid model has recently been implemented with BOUT + + that has significantly reduced computational cost compared to the gyrokinetic simulations against which it will be benchmarked. This work was funded by the RCUK Energy programme, EURATOM and a EUROFusion fellowship WP14-FRF-CCFE/Dickinson and was carried out using: HELIOS at IFERC, Japan; ARCHER (EPSRC Grant No. EP/L000237/1); HECToR (EPSRC Grant No. EP/H002081/1).

  16. Core micro-instability analysis of JET hybrid and baseline discharges with carbon wall

    NASA Astrophysics Data System (ADS)

    Moradi, S.; Pusztai, I.; Voitsekhovitch, I.; Garzotti, L.; Bourdelle, C.; Pueschel, M. J.; Lupelli, I.; Romanelli, M.; JET-EFDA Contributors, the

    2014-12-01

    The core micro-instability characteristics of hybrid and baseline plasmas in a selected set of JET plasmas with carbon wall are investigated through local linear and non-linear and global linear gyro-kinetic simulations with the GYRO code (Candy and Belli 2011 General Atomics Report GA-A26818). In particular, we study the role of plasma pressure on the micro-instabilities, and scan the parameter space for the important plasma parameters responsible for the onset and stabilization of the modes under experimental conditions. We find that a good core confinement due to strong stabilization of the micro-turbulence driven transport can be expected in the hybrid plasmas due to the stabilizing effect of the fast ion pressure that is more effective at the low magnetic shear of the hybrid discharges. While parallel velocity gradient destabilization is important for the inner core, at outer radii the hybrid plasmas may benefit from a strong quench of the turbulence transport by E × B rotation shear.

  17. Simulations of global electrostatic microinstabilities in ASDEX Upgrade discharges

    NASA Astrophysics Data System (ADS)

    Bottino, A.; Peeters, A. G.; Sauter, O.; Vaclavik, J.; Villard, L.

    2004-01-01

    Electrostatic microinstabilities in ion internal barrier (ITB) and H-mode discharges of the ASDEX Upgrade tokamak [O. Gruber, R. Arslanbekov, C. Atanasiu et al., Nucl. Fusion 41, 1369 (2001)] have been investigated with a full radius gyrokinetic code. The code models linear stability and includes the effect of an equilibrium radial electric field and trapped electrons. In order to simulate plasmas in experimental conditions [k⊥ρL˜O(1)], the long wavelength approximation in the quasineutrality equation has been replaced by a Padé expansion of the modified Bessel function. Results show that the E×B flow, induced by the radial electric field, changes the linear stability of the dominant ion temperature gradient modes. The electrostatic potential eddies are tilted by the sheared flow thus reducing the radial extent and the growth rate of modes. However, the finite value of the flow has a stabilizing effect too; the most unstable modes are shifted away from the unfavorable curvature region leading to lower linear growth rates. In addition to this at least two other mechanisms give an important contribution to the stabilization in the ITB region; the reverse shear profile itself and, to a lesser degree, the local value of the temperature ratio, τ=Te/Ti.

  18. Collisionless microinstabilities in stellarators. II. Numerical simulations

    SciTech Connect

    Proll, J. H. E.; Xanthopoulos, P.; Helander, P.

    2013-12-15

    Microinstabilities exhibit a rich variety of behavior in stellarators due to the many degrees of freedom in the magnetic geometry. It has recently been found that certain stellarators (quasi-isodynamic ones with maximum-J geometry) are partly resilient to trapped-particle instabilities, because fast-bouncing particles tend to extract energy from these modes near marginal stability. In reality, stellarators are never perfectly quasi-isodynamic, and the question thus arises whether they still benefit from enhanced stability. Here, the stability properties of Wendelstein 7-X and a more quasi-isodynamic configuration, QIPC, are investigated numerically and compared with the National Compact Stellarator Experiment and the DIII-D tokamak. In gyrokinetic simulations, performed with the gyrokinetic code GENE in the electrostatic and collisionless approximation, ion-temperature-gradient modes, trapped-electron modes, and mixed-type instabilities are studied. Wendelstein 7-X and QIPC exhibit significantly reduced growth rates for all simulations that include kinetic electrons, and the latter are indeed found to be stabilizing in the energy budget. These results suggest that imperfectly optimized stellarators can retain most of the stabilizing properties predicted for perfect maximum-J configurations.

  19. Collisionless microinstabilities in stellarators. II. Numerical simulations

    NASA Astrophysics Data System (ADS)

    Proll, J. H. E.; Xanthopoulos, P.; Helander, P.

    2013-12-01

    Microinstabilities exhibit a rich variety of behavior in stellarators due to the many degrees of freedom in the magnetic geometry. It has recently been found that certain stellarators (quasi-isodynamic ones with maximum-J geometry) are partly resilient to trapped-particle instabilities, because fast-bouncing particles tend to extract energy from these modes near marginal stability. In reality, stellarators are never perfectly quasi-isodynamic, and the question thus arises whether they still benefit from enhanced stability. Here, the stability properties of Wendelstein 7-X and a more quasi-isodynamic configuration, QIPC, are investigated numerically and compared with the National Compact Stellarator Experiment and the DIII-D tokamak. In gyrokinetic simulations, performed with the gyrokinetic code GENE in the electrostatic and collisionless approximation, ion-temperature-gradient modes, trapped-electron modes, and mixed-type instabilities are studied. Wendelstein 7-X and QIPC exhibit significantly reduced growth rates for all simulations that include kinetic electrons, and the latter are indeed found to be stabilizing in the energy budget. These results suggest that imperfectly optimized stellarators can retain most of the stabilizing properties predicted for perfect maximum-J configurations.

  20. Microinstability of the Hip and the Splits Radiograph.

    PubMed

    Harris, Joshua D; Gerrie, Brayden J; Lintner, David M; Varner, Kevin E; McCulloch, Patrick C

    2016-01-01

    A normal hip has a natural tendency toward stability because of both osseous and soft tissue structures. Hip motion is primarily rotational around a center of rotation. When the femoral head and its center of rotation translate, with or without rotation, the inherent stability of the femoroacetabular articulation may be lost. The spectrum of hip instability ranges from subtle microinstability to traumatic dislocation. Microinstability may be the cause or the effect of several other hip pathologies. Soft tissue contributions to stability include the static capsule, dynamic musculotendinous units, and underlying generalized connective tissue (eg, Ehlers-Danlos). Osseous contributions include multiple femoral and acetabular radiographic coverage parameters. Iatrogenic contributions include an unrepaired capsulotomy, overresection of the acetabular rim (iatrogenic dysplasia), overresection of cam osteochondroplasty, iliopsoas tenotomy, labral debridement, and ligamentum teres debridement. Patients with hip microinstability often have deep groin pain, exhibited by a C sign. These patients frequently participate in flexibility sports and activities, such as ballet, gymnastics, figure skating, and martial arts. On physical examination, generalized hypermobility syndromes should be assessed, as should loss of log-roll external rotation recoil, excessive abduction, trochanteric-pelvic impingement, and abductor fatigue. Standard imaging, including plain radiographs, magnetic resonance imaging, and computed tomography, should be analyzed for all causes of hip pain. A new plain radiograph, the splits radiograph is introduced here, consistently showing lateral femoral head translation and creation of a vacuum sign, showing hip microinstability. The splits radiograph is illustrated in a 22-year-old female dancer who presented with bilateral deep anterolateral groin pain. [Orthopedics. 2016; 39(1):e169-e175.]. PMID:26730687

  1. Finite-β simulation of microinstabilities

    SciTech Connect

    Startsev, Edward A.; Lee, W. W.

    2014-02-15

    A new split-weight perturbative particle simulation scheme for finite-β plasmas in the presence of background inhomogeneities is presented. The scheme is an improvement over the original split-weight scheme, which splits the perturbed particle response into adiabatic and non-adiabatic parts to improve numerical properties. In the new scheme, by further separating out the adiabatic response of the particles associated with the quasi-static bending of the magnetic field lines in the presence of background inhomogeneities of the plasma, we are able to demonstrate the finite-β stabilization of drift waves and ion temperature gradient modes using a simple gyrokinetic particle code based on realistic fusion plasma parameters. However, for βm{sub i}/m{sub e} ≫ 1, it becomes necessary to use the electron skin-depth as the grid size of the simulation to achieve accuracy in solving the resulting equations, unless special numerical arrangement is made for the cancelling of the two large terms on the either side of the governing equation. The proposed scheme is most suitable for studying shear-Alfvén physics in general geometry using straight field line coordinates for microturbulence and magnetic reconnection problems.

  2. Characteristics of microinstabilities in electron cyclotron and ohmic heated discharges

    NASA Astrophysics Data System (ADS)

    Pusztai, I.; Moradi, S.; Fülöp, T.; Timchenko, N.

    2011-08-01

    Characteristics of microinstabilities in electron cyclotron (EC) and ohmic heated (OH) discharges in the T10 tokamak have been analyzed by linear electrostatic gyrokinetic simulations with gyro [J. Candy and R. E. Waltz, J. Comput. Phys. 186, 545 (2003)] aiming to find insights into the effect of auxiliary heating on the transport. Trapped electron modes are found to be unstable in both OH and the EC heated scenarios. In the OH case the main drive is from the density gradient and in the EC case from the electron temperature gradient. The growth rates and particle fluxes exhibit qualitatively different scaling with the electron-to-ion temperature ratios in the two cases. This is mainly due to the fact that the dominant drives and the collisionalities are different. The inward flow velocity of impurities and the impurity diffusion coefficient decreases when applying EC heating, which leads to lower impurity peaking, consistently with experimental observations.

  3. Characteristics of microinstabilities in electron cyclotron and ohmic heated discharges

    SciTech Connect

    Pusztai, I.; Moradi, S.; Fueloep, T.; Timchenko, N.

    2011-08-15

    Characteristics of microinstabilities in electron cyclotron (EC) and ohmic heated (OH) discharges in the T10 tokamak have been analyzed by linear electrostatic gyrokinetic simulations with gyro[J. Candy and R. E. Waltz, J. Comput. Phys. 186, 545 (2003)] aiming to find insights into the effect of auxiliary heating on the transport. Trapped electron modes are found to be unstable in both OH and the EC heated scenarios. In the OH case the main drive is from the density gradient and in the EC case from the electron temperature gradient. The growth rates and particle fluxes exhibit qualitatively different scaling with the electron-to-ion temperature ratios in the two cases. This is mainly due to the fact that the dominant drives and the collisionalities are different. The inward flow velocity of impurities and the impurity diffusion coefficient decreases when applying EC heating, which leads to lower impurity peaking, consistently with experimental observations.

  4. MICROINSTABILITY OF THE SHOULDER IN THE OVERHEAD ATHLETE

    PubMed Central

    Curtis, Alan S.

    2013-01-01

    The overhead throwing athlete is an extremely challenging patient in sports medicine. The repetitive microtraumatic stresses and extreme ranges of motion observed within the athlete’s shoulder joint complex during the throwing motion constantly place the athlete at risk for injury. While gross instability of the shoulder is possible, microinstability is seen far more frequently and is associated with a variety of different pathologies, including rotator cuff tendonitis, internal impingement, and labral lesions. Treatment of the overhead athlete requires the understanding of several principles based on the unique physical characteristics of this type of athlete and the demands placed upon the static stabilizing structures during the act of throwing. The purpose of this paper is to describe these principles and incorporate them into in a multi‐phase progressive rehabilitation program designed to prevent injuries and rehabilitate the injured athlete, both non‐operatively and postoperatively. PMID:24175140

  5. Dynamics and microinstabilities at perpendicular collisionless shock: A comparison of large-scale two-dimensional full particle simulations with different ion to electron mass ratio

    SciTech Connect

    Umeda, Takayuki Kidani, Yoshitaka; Matsukiyo, Shuichi; Yamazaki, Ryo

    2014-02-15

    Large-scale two-dimensional (2D) full particle-in-cell (PIC) simulations are carried out for studying the relationship between the dynamics of a perpendicular shock and microinstabilities generated at the shock foot. The structure and dynamics of collisionless shocks are generally determined by Alfven Mach number and plasma beta, while microinstabilities at the shock foot are controlled by the ratio of the upstream bulk velocity to the electron thermal velocity and the ratio of the plasma-to-cyclotron frequency. With a fixed Alfven Mach number and plasma beta, the ratio of the upstream bulk velocity to the electron thermal velocity is given as a function of the ion-to-electron mass ratio. The present 2D full PIC simulations with a relatively low Alfven Mach number (M{sub A} ∼ 6) show that the modified two-stream instability is dominant with higher ion-to-electron mass ratios. It is also confirmed that waves propagating downstream are more enhanced at the shock foot near the shock ramp as the mass ratio becomes higher. The result suggests that these waves play a role in the modification of the dynamics of collisionless shocks through the interaction with shock front ripples.

  6. Transport simulations of ohmic TFTR experiments with profile-consistent microinstability-based models for chi/sub e/ and chi/sub i/. [BALDUR

    SciTech Connect

    Redi, M.H.; Tang, W.M.; Efthimion, P.C.; Mikkelsen, D.R.; Schmidt, G.L.

    1987-03-01

    Transport simulations of ohmically heated TFTR experiments with recently developed profile-consistent microinstability models for the anomalous thermal diffusivities, chi/sub e/ and chi/sub i/, give good agreement with experimental data. The steady-state temperature profiles and the total energy confinement times, tau/sub e/, were found to agree for each of the ohmic TFTR experiments simulated, including three high radiation cases and two plasmas fueled by pellet injection. Both collisional and collisionless models are tested. The trapped-electron drift wave microinstability model results are consistent with the thermal confinement of large plasma ohmic experiments on TFTR. We also find that transport due to the toroidal ion temperature gradient (eta/sub i/) modes can cause saturation in tau/sub E/ at the highest densities comparable to that observed on TFTR and equivalent to a neoclassical anomaly factor of 3. Predictions based on stabilized eta/sub i/-mode-driven ion transport are found to be in agreement with the enhanced global energy confinement times for pellet-fueled plasmas. 33 refs., 26 figs., 4 tabs.

  7. Microinstability of the hip—it does exist: etiology, diagnosis and treatment

    PubMed Central

    Kalisvaart, Michael M.; Safran, Marc R.

    2015-01-01

    Symptomatic hip microinstability is now recognized as a potential cause of pain and disability in young patients. Causes of hip microinstability include underlying bony or soft tissue abnormalities and iatrogenic injuries of the hip capsule; however, many patients lack a clear underlying etiology. Treatment usually begins with an extensive course of non-operative management with an emphasis on activity modification and physical therapy. Surgical intervention should focus on treatment of the underlying cause as well as any associated intra-articular pathology. In many cases, arthroscopic suture plication can be considered when bony deficiency is not the cause. In this article, we will review the spectrum of symptomatic hip microinstability with a focus on the relevant anatomy, etiology, diagnosis and various treatment options. PMID:27011829

  8. Microinstability properties of negative magnetic shear discharges in the Tokamak Fusion Test Reactor and DIII-D

    NASA Astrophysics Data System (ADS)

    Rewoldt, G.; Lao, L. L.; Tang, W. M.

    1997-09-01

    The microinstability properties of discharges with negative (reversed) magnetic shear in the Tokamak Fusion Test Reactor (TFTR) [R. J. Hawryluk et al., Plasma Physics and Controlled Nuclear Fusion Research, 1994 (International Atomic Energy Agency, Vienna, 1995), Vol. 1, p. 11] and DIII-D [R. D. Stambaugh for the DIII-D Team, Plasma Physics and Controlled Nuclear Fusion Research, 1994 (International Atomic Energy Agency, Vienna, 1995), Vol. 1, p. 83] experiments with and without confinement transitions are investigated. A comprehensive kinetic linear eigenmode calculation employing the ballooning representation is employed with experimentally measured profile data, and using the corresponding numerically computed magnetohydrodynamic (MHD) equilibria. The instability considered is the toroidal drift mode (trapped-electron-ηi mode). A variety of physical effects associated with differing q-profiles are explained. In addition, different negative magnetic shear discharges at different times in the discharge for TFTR and DIII-D are analyzed. The effects of sheared toroidal rotation, using data from direct spectroscopic measurements for carbon, are analyzed using comparisons with results from a two-dimensional calculation. Comparisons are also made for nonlinear stabilization associated with shear in Er/RBθ. The relative importance of changes in different profiles (density, temperature, q, rotation, etc.) on the linear growth rates is considered.

  9. Experimental investigation of collisionless electron-electron microinstabilities. Final technical report for the period August 1, 1997-October 31, 2000

    SciTech Connect

    Scime, Earl E.

    2000-12-11

    This is the final report for the Office of Fusion Energy sponsored project entitled, "Experimental Investigation of Collisionless Electron-Electron Microinstabilities." The report summarizes the scientific and human resource development accomplishments supported through this project.

  10. Microinstabilities associated with a high Mach number, perpendicular bow shock

    NASA Technical Reports Server (NTRS)

    Wu, C. S.; Winske, D.; Tanaka, M.; Papadopoulos, K.; Akimoto, K.; Goodrich, C. C.; Zhou, Y. M.; Tsai, S. T.; Rodriguez, P.; Lin, C. S.

    1984-01-01

    Instability analyses incorporating insights gained through ISEE observations and hybrid simulations are used in an examination of the instabilities associated with a high Mach number perpendicular shock akin to the earth's bow shock. In the regions in front of, and at, the shock transition the cross-field instabilities are subdivided into the ion-ion streaming, kinetic cross-field streaming, and drift lower hybrid instability low frequency modes, as well as the electron cyclotron drift, ion sound, and electron whisker instability high frequency modes. Further downstream, ion ring-like and anisotropy-driven instabilities are considered. The implications of these results for wave signatures, plasma heating and acceleration are noted.

  11. A comprehensive gyrokinetic description of global electrostatic microinstabilities in a tokamak

    SciTech Connect

    Chowdhury, J.; Ganesh, R.; Brunner, S.; Vaclavik, J.; Villard, L.; Angelino, P.

    2009-05-15

    It is believed that low frequency microinstabilities such as ion temperature gradient (ITG) driven modes and trapped electron modes (TEMs) are largely responsible for the experimentally observed anomalous transport via the ion and electron channels in a tokamak. In the present work, a comprehensive global linear gyrokinetic model incorporating fully kinetic (trapped and passing) electrons and ions, actual ion to electron mass ratio, radial coupling, and profile variation is used to investigate the ITG driven modes and pure TEMs. These modes are found to exhibit multiscale structures in the presence of nonadiabatic passing electrons. The multiscale structure is related to the large nonadiabaticity of electrons in the vicinity of mode rational magnetic surfaces and leads to reduced mixing length estimates of transport compared to those obtained from adiabatic electron models.

  12. The effect of small 3D magnetic perturbations on linear micro-instability properties

    NASA Astrophysics Data System (ADS)

    Hegna, C. C.

    2014-10-01

    Small externally applied non-axisymmetric magnetic perturbations can significantly alter the edge properties of tokamaks. In this work, we model the effect of the applied 3D fields on the flux surface deformation and show that these can alter key geometric properties of interest to microinstabilities. Shielding physics is assumed to be operative so that flux surface integrity is retained. Local 3D equilibrium theory is employed using a perturbative approach to calculate flux surface deformations consistent with magnetostatic force balance. Prior work has shown applied 3D fields can significantly alter ideal ballooning stability boundaries due to order unity 3D field induced changes to the local shear. The impact of 3D fields on ion temperature gradient and trapped electron mode growth rates are quantified using analytically derived proxy functions. Research supported by U.S. DoE Grant No. DE-FG02-86ER53218.

  13. Collisionless microinstabilities in stellarators. I. Analytical theory of trapped-particle modes

    SciTech Connect

    Helander, P.; Proll, J. H. E.; Plunk, G. G.; Max-Planck/Princeton Research Center for Plasma Physics, 17491 Greifswald

    2013-12-15

    This is the first in a series of papers about collisionless, electrostatic micro-instabilities in stellarators, with an emphasis on trapped-particle modes. It is found that, in so-called maximum-J configurations, trapped-particle instabilities are absent in large regions of parameter space. Quasi-isodynamic stellarators have this property (approximately), and the theory predicts that trapped electrons are stabilizing to all eigenmodes with frequencies below the electron bounce frequency. The physical reason is that the bounce-averaged curvature is favorable for all orbits, and that trapped electrons precess in the direction opposite to that in which drift waves propagate, thus precluding wave-particle resonance. These considerations only depend on the electrostatic energy balance and are independent of all geometric properties of the magnetic field other than the maximum-J condition. However, if the aspect ratio is large and the instability phase velocity differs greatly from the electron and ion thermal speeds, it is possible to derive a variational form for the frequency showing that stability prevails in a yet larger part of parameter space than what follows from the energy argument. Collisionless trapped-electron modes should therefore be more stable in quasi-isodynamic stellarators than in tokamaks.

  14. Development of dike fragility curves for piping and micro-instability breach mechanisms

    NASA Astrophysics Data System (ADS)

    Vorogushyn, S.; Merz, B.; Apel, H.

    2009-08-01

    The paper analyses the prevailing breach mechanisms of fluvial dikes. Piping in the dike foundation and slope failure as a consequence of seepage flow through a dike core (micro-instability) were identified as two of the dominant breach mechanisms for historically-grown dikes along with overtopping and slope macro-instability. For the former two mechanisms the physically-based and empirical process descriptions were reviewed and led to the formulation of the reliability functions. Evaluation of these functions in the Monte Carlo framework for the time dependent load led to the development of fragility functions. These functions indicate the probability of failure of a dike section upon loading and can be computed for each spatially discretised dike section. The probability of breaching is conditioned by the uncertainty in geometrical and geotechnical dike parameters. This uncertainty is explicitly taken into account during computation of the fragility functions in a Monte Carlo simulation. Sensitivity analysis was carried out in order to identify the sensitive geotechnical parameters influencing the distribution of failure probability. The identification of sensitive parameters indicates the priorities in geotechnical measurement campaigns aimed at the assessment of dike stability. The newly developed fragility functions can be applied in flood hazard and risk assessment studies for modelling of dike failures in a probabilistic framework.

  15. Non-Linear Dynamics and Emergence in Laboratory Fusion Plasmas

    SciTech Connect

    Hnat, B.

    2011-09-22

    Turbulent behaviour of laboratory fusion plasma system is modelled using extended Hasegawa-Wakatani equations. The model is solved numerically using finite difference techniques. We discuss non-linear effects in such a system in the presence of the micro-instabilities, specifically a drift wave instability. We explore particle dynamics in different range of parameters and show that the transport changes from diffusive to non-diffusive when large directional flows are developed.

  16. Bump-on-tail instability in space plasmas

    NASA Astrophysics Data System (ADS)

    Sarkar, Susmita; Paul, Samit; Denra, Raicharan

    2015-10-01

    Bump-on-tail instability of Langmuir waves propagating in unmagnetized Lorentzian plasma modeled by a Kappa velocity distribution with spectral index ? has been investigated in this paper. Growth rate of this microinstability has been determined analytically from the Langmuir wave dispersion relation. Change in the maximum growth rate with increasing ? has been numerically estimated for different number density and temperature ratios using solar wind data.

  17. Effects of the magnetic equilibrium on gyrokinetic simulations of tokamak microinstabilities

    SciTech Connect

    Wan, Weigang; Chen, Yang; Parker, Scott E.; Groebner, Richard J.

    2015-06-15

    The general geometry of the experimental tokamak magnetic equilibrium is implemented in the global gyrokinetic simulation code GEM. Compared to the general geometry, the well used Miller parameterization of the magnetic equilibrium is a good approximation in the core region and up to the top of the pedestal. Linear simulations indicate that results with the two geometries agree for r/a ≤ 0.9. However, in the edge region, the instabilities are sensitive to the magnetic equilibrium in both the L-mode and the H-mode plasmas. A small variation of the plasma shaping parameters leads to large changes to the edge instability.

  18. Gyrokinetic Calculations of Microinstabilities and Transport During RF H-Modes on Alcator C-Mod

    SciTech Connect

    M.H. Redi; C. Fiore; P. Bonoli; C. Bourdelle; R. Budny; W.D. Dorland; D. Ernst; G. Hammett; D. Mikkelsen; J. Rice; S. Wukitch

    2002-06-18

    Physics understanding for the experimental improvement of particle and energy confinement is being advanced through massively parallel calculations of microturbulence for simulated plasma conditions. The ultimate goal, an experimentally validated, global, non-local, fully nonlinear calculation of plasma microturbulence is still not within reach, but extraordinary progress has been achieved in understanding microturbulence, driving forces and the plasma response in recent years. In this paper we discuss gyrokinetic simulations of plasma turbulence being carried out to examine a reproducible, H-mode, RF heated experiment on the Alcator CMOD tokamak3, which exhibits an internal transport barrier (ITB). This off axis RF case represents the early phase of a very interesting dual frequency RF experiment, which shows density control with central RF heating later in the discharge. The ITB exhibits steep, spontaneous density peaking: a reduction in particle transport occurring without a central particle source. Since the central temperature is maintained while the central density is increasing, this also suggests a thermal transport barrier exists. TRANSP analysis shows that ceff drops inside the ITB. Sawtooth heat pulse analysis also shows a localized thermal transport barrier. For this ICRF EDA H-mode, the minority resonance is at r/a * 0.5 on the high field side. There is a normal shear profile, with q monotonic.

  19. Effect of alpha drift and instabilities on tokamak plasma edge conditions

    SciTech Connect

    Miley, G H; Choi, C K

    1983-01-01

    As suprathermal fusion products slow down in a Tokamak, their average drift is inward. The effect of this drift on the alpha heating and thermalization profiles is examined. In smaller TFTR-type devices, heating in the outer region can be cut in half. Also, the fusion-product energy-distribution near the plasma edge has a positive slope with increasing energy, representing a possible driving mechanism for micro-instabilities. Another instability that can seriously affect outer plasma conditions and shear Alfven transport of alphas is also considered.

  20. plasmas

    NASA Astrophysics Data System (ADS)

    Zhang, H. Y.; Jin, C. G.; Yang, Y.; Ye, C.; Zhuge, L. J.; Wu, X. M.

    2014-12-01

    As-deposited HfO2 films were modified by CHF3, C4F8, and mixed C4F8/O2 plasmas in a dual-frequency capacitively coupled plasma chamber driven by radio frequency generators of 60 MHz as the high frequency (HF) source and 2 MHz as the low frequency source (60/2 MHz). The influences of various surface plasma treatments under CHF3, C4F8, and C4F8/O2 were investigated in order to understand the chemical and structural changes in thin-film systems, as well as their influence on the electrical properties. Fluorine atoms were incorporated into the HfO2 films by either CHF3 or C4F8 plasma treatment; meanwhile, the C/F films were formed on the surface of the HfO2 films. The formation of C/F layers decreased the k value of the gate stacks because of its low dielectric constant. However, the addition of O2 gas in the discharge gases suppressed the formation of C/F layers. After thermal annealing, tetragonal HfO2 phase was investigated in both samples treated with CHF3 and C4F8 plasmas. However, the samples treated with O-rich plasmas showed monoclinic phase, which indicated that the addition of O plasmas could influence the Hf/O ratio of the HfO2 films. The mechanism of the t-HfO2 formation was attributed to oxygen insufficiency generated by the incorporation of F atoms. The capacitors treated with C4F8/O2 plasmas displayed the highest k value, which ascribed that the C/F layers were suppressed and the tetragonal phase of HfO2 was formed. Good electrical properties, especially on the hysteresis voltage and frequency dispersion, were obtained because the bulk traps were passivated by the incorporation of F atoms. However, the H-related traps were generated during the CHF3 plasma treatments, which caused the performance degradation. All the treated samples showed lower leakage current density than the as-deposited HfO2 films at negative bias due to the reduced trap-assisted tunneling by the incorporation of F to block the electrons transferring from metal electrode to the trap level.

  1. Plasma stability studies of the gasdynamic mirror fusion propulsion experiment

    NASA Astrophysics Data System (ADS)

    Emrich, William Julius, Jr.

    The gasdynamic mirror has been proposed as a concept which could form the basis of a highly efficient fusion rocket engine. Gasdynamic mirrors differ from most other mirror type plasma confinement schemes in that they have much larger aspect ratios and operate at somewhat higher plasma densities. These differences are postulated to permit gasdynamic mirrors to confine plasmas in a stable manner without the additional complicated equipment required by low aspect ratio, low plasma density mirror machines. To verify that a gasdynamic mirror could indeed confine plasmas in a stable manner for long periods of time, a small scale experimental gasdynamic mirror was built and tested. The gasdynamic mirror which was constructed is 2.5 meters long and can accommodate plasmas up to 20 centimeters in diameter. The device is able to support mirror magnetic fields of up to two tesla and central cell magnetic fields of up to a third of a tesla. A reciprocating Langmuir probe was used to determine the radial plasma density and electron temperature profiles upon which the experimental results of this study are based. The objective of this experiment was to determine ranges of mirror ratios and plasma densities over which gasdynamic mirror could maintain stable plasmas. Theoretical analyses indicated that plasma magnetohydrodynamic instabilities were likely to occur during subsonic to supersonic flow transitions in the mirror throat region of the gasdynamic mirror. The experimental evidence based upon data derived from the Langmuir probe measurements seems to confirm this analysis. These instabilities result in a loss of plasma confinement and would almost certainly prevent the initiation of fusion reactions. The assumption that a gasdynamic mirror using a simple mirror geometry could be used as a propulsion system, therefore, appears questionable. Fairly simple modifications to the simple mirror concept are presented, however, which if incorporated into the simple mirror configuration could mitigate these MHD instabilities. Theoretical analyses of plasma "loss cone" microinstabilities were also performed and judged likely not to be a major problem under the expected operating conditions of a gasdynamic mirror propulsion system. No plasma microinstabilities were observed during the experimental investigations.

  2. Updating Plasma Scattering of Electromagnetic Radiation

    NASA Astrophysics Data System (ADS)

    Sheffield, J.

    2010-05-01

    The monograph Plasma Scattering of Electromagnetic Radiation was published by Academic Press in 1975. A Russian edition, Atomidzat, came out in 1978. An updated version is being prepared by D. Froula, S. Glenzer. N Luhmann, and J. Sheffield for publication in 2010 by Elsevier. The new version will discuss the broader applications of Thomson scattering, which include the full range of plasmas used in research and industry. The expansion of the field has been made possible by the growing number of powerful radiation sources (from X-rays to microwaves), detectors, and innovative techniques. When the book was published, the highest temperatures in laboratory plasmas were around 2 keV for the electrons. Compare this to today's 25 keV where the relativistic effects are dramatic. The application to low temperature plasmas with Te in the range of 1 - 30+ eV, important in industry, has grown. Important capabilities have been developed in the areas of energetic particle, micro-instability, and high energy density plasma measurements. For the future, we look forward to the use of scattering as a diagnostic on the large new fusion facilities-NIF, LMJ, and ITER.

  3. Plasma instabilities and transport in the MPD thruster

    NASA Astrophysics Data System (ADS)

    Choueiri, Edgar Y.; Kelly, Arnold J.; Jahn, Robert G.

    1993-06-01

    This study deals with the development and testing of anomalous (turbulent) transport coefficient models that include the effects of plasma turbulence and that can be used in plasma fluid codes for more realistic numerical simulations. The anomalous transport models were derived using a kinetic description of microinstabilities in the MPD thruster plasma. Nonlinear plasma theory was used under the valid approximation of weak turbulence and the resulting transport models were studied in detail. A strong dependence of anomalous transport on the electron Hall parameter was found. The models were then reduced to a set of compact polynomials ideally suited for inclusion in fluid codes. The usefulness and importance of these models were demonstrated by including them in an advanced plasma fluid code and carrying numerical simulations of realistic MPD thruster flows. The results show the impact of turbulence on various aspects of dissipation in the thruster as well as on the overall propulsive efficiency. Fluid codes that include these models are more accurate engineering tools for the design and study of high efficiency plasma thrusters.

  4. Contributions to the Theory of Plasma Turbulence by Marshall N. Rosenbluth

    NASA Astrophysics Data System (ADS)

    Diamond, P. H.

    2004-11-01

    In this talk, I will review the many contributions of Marshall Rosenbluth to the theory of turbulence, fluctuations and anomalous transport in plasmas. This review will span Rosenbluth's career, starting from his early work on resistive instabilities and fluctuation theory, through his achievements in defining the theory of stochastic magnetic fields and tokamak microinstabilities, and conclude with a discussion of his final work which focused on zonal flow and L-H bifurcation physics. I shall attempt to integrate this story into a coherent whole which highlights Rosenbluth's seminal contributions to our understanding of anomalous transport, in fusion plasmas as it stands today. I shall also try to give some `flavor' of Rosenbluth's style and approach to these difficult problems.

  5. Adiabatic electron response and solitary wave generation by trapped particle nonlinearity in a hydrogen plasma

    SciTech Connect

    Mandal, Debraj; Sharma, Devendra

    2014-10-15

    The finite amplitude ion acoustic waves that trap electrons modify the structure of the evolving nonlinear soliton solutions. In the numerical simulations, self-consistently generated solitary waves are studied that emerge as a result of a current driven microinstability growing the ion acoustic mode in a collisionless Vlasov plasma. The growth saturates as a result of nonlinear effects governed by a combination of nonlinearities originating from the hydrodynamic model and kinetic particle trapping effects. The resulting solitary waves also coexist with a finite current and an electron plasma wave capable of perturbing the trapping potential. The results of multiscale simulation are analyzed and characterized following the kinetic prescription of undamped trapped particle mode in the form of phase space vortex solutions that are generalized form of Sagdeev's solitons and obey the solutions of a modified Korteweg-de Vries equation, accounting for a stronger nonlinearity originating from the electron trapping.

  6. Trapped ion mode in toroidally rotating plasmas

    SciTech Connect

    Artun, M.; Tang, W.M.; Rewoldt, G.

    1995-04-01

    The influence of radially sheared toroidal flows on the Trapped Ion Mode (TIM) is investigated using a two-dimensional eigenmode code. These radially extended toroidal microinstabilities could significantly influence the interpretation of confinement scaling trends and associated fluctuation properties observed in recent tokamak experiments. In the present analysis, the electrostatic drift kinetic equation is obtained from the general nonlinear gyrokinetic equation in rotating plasmas. In the long perpendicular wavelength limit k{sub {tau}}{rho}{sub bi} {much_lt} 1, where {rho}{sub bi} is the average trapped-ion banana width, the resulting eigenmode equation becomes a coupled system of second order differential equations nmo for the poloidal harmonics. These equations are solved using finite element methods. Numerical results from the analysis of low and medium toroidal mode number instabilities are presented using representative TFTR L-mode input parameters. To illustrate the effects of mode coupling, a case is presented where the poloidal mode coupling is suppressed. The influence of toroidal rotation on a TFTR L-mode shot is also analyzed by including a beam species with considerable larger temperature. A discussion of the numerical results is presented.

  7. Quasilinear Carbon Transport In An Impurity Hole Plasma In LHD

    SciTech Connect

    Mikkelsen, David R.; Tanaka, K.; Nunami, M.; Watanabe, T-H.; Sugama, H.; Yoshinuma, M.; Suzuki, Y.; Goto, M.; Morita, S.; Wieland, B.; Yamada, I.; Yashura, R.; Akiyama, T.; Pablant, Novimir A.

    2014-04-01

    Comprehensive electrostatic gyrokinetic linear stability calculations for ion-scale microinstabilities in an LHD plasma with an ion-ITB and carbon "impurity hole" are used to make quasilinear estimates of particle flux to explore whether microturbulence can explain the observed outward carbon fluxes that flow "up" the impurity density gradient. The ion temperature is not stationary in the ion-ITB phase of the simulated discharge, during which the core carbon density decreases continuously. To fully sample these varying conditions the calculations are carried out at three radial locations and four times. The plasma parameter inputs are based on experimentally measured profiles of electron and ion temperature, as well as electron and carbon density. The spectroscopic line-average ratio of hydrogen and helium densities is used to set the density of these species. Three ion species (H,He,C) and the electrons are treated kinetically, including collisions. Electron instability drive does enhance the growth rate significantly, but the most unstable modes have characteristics of ion temperature gradient (ITG) modes in all cases. As the carbon density gradient is scanned between the measured value and zero, the quasilinear carbon flux is invariably inward when the carbon density profile is hollow, so turbulent transport due to the instabilities considered here does not explain the observed outward flux of impurities in impurity hole plasmas. The stiffness of the quasilinear ion heat flux is found to be 1.7-2.3, which is lower than several estimates in tokamaks.

  8. Currents between tethered electrodes in a magnetized laboratory plasma

    NASA Technical Reports Server (NTRS)

    Stenzel, R. L.; Urrutia, J. M.

    1989-01-01

    Laboratory experiments on important plasma physics issues of electrodynamic tethers were performed. These included current propagation, formation of wave wings, limits of current collection, nonlinear effects and instabilities, charging phenomena, and characteristics of transmission lines in plasmas. The experiments were conducted in a large afterglow plasma. The current system was established with a small electron-emitting hot cathode tethered to an electron-collecting anode, both movable across the magnetic field and energized by potential difference up to V approx.=100 T(sub e). The total current density in space and time was obtained from complete measurements of the perturbed magnetic field. The fast spacecraft motion was reproduced in the laboratory by moving the tethered electrodes in small increments, applying delayed current pulses, and reconstructing the net field by a linear superposition of locally emitted wavelets. With this technique, the small-amplitude dc current pattern is shown to form whistler wings at each electrode instead of the generally accepted Alfven wings. For the beam electrode, the whistler wing separates from the field-aligned beam which carries no net current. Large amplitude return currents to a stationary anode generate current-driven microinstabilities, parallel electric fields, ion depletions, current disruptions and time-varying electrode charging. At appropriately high potentials and neutral densities, excess neutrals are ionized near the anode. The anode sheath emits high-frequency electron transit-time oscillations at the sheath-plasma resonance. The beam generates Langmuir turbulence, ion sound turbulence, electron heating, space charge fields, and Hall currents. An insulated, perfectly conducting transmission line embedded in the plasma becomes lossy due to excitation of whistler waves and magnetic field diffusion effects. The implications of the laboratory observations on electrodynamic tethers in space are discussed.

  9. Dynamics between the fishbone instability and nonlocal transient transport in HL-2A NBI plasmas

    NASA Astrophysics Data System (ADS)

    Chen, W.; Xu, Y.; Ding, X. T.; Shi, Z. B.; Jiang, M.; Zhong, W. L.; Ji, X. Q.; HL-2A Team

    2016-04-01

    Understanding of nonlocal electron heat transport is of key importance for current magnetic confinement fusion research. Global nonlocal response presents a fundamental challenge to the standard anomalous transport model based on local microinstabilities and turbulence. Here, we present for the first time a new nonlocal phenomenon triggered by the fishbone instability in HL-2A neutral beam injection plasmas. Rapid core heating leads to a simultaneous decrease in temperature at the plasma edge. The effect reveals fast anomalous transport of core heat pulses to the plasma edge, not compatible with diffusive time scales. More importantly, Δ {{T}\\text{e}}/< {{T}\\text{e}}> variations at different locations are restricted by the intensity of magnetic fluctuations. The Δ {{T}\\text{e}}/< {{T}\\text{e}}> and {{≤ft(δ {{B}θ}\\right)}\\text{rms}} form two types of hysteresis loops at two sides of the inversion radius. The ECEIs show that the 2D mode structure of the fishbone is intensive shearing/spiraling during the nonlocal transport. Experimental results suggest that magnetic perturbation, long-range correlation, mesoscale structure and E× B flow play crucial roles in the nonlocal response. The Hurst exponent and auto-correlation coefficient indicate that the nonlocal transport is potentially linked to the self-organized critical (SOC) dynamics. This work will be beneficial for understanding of the plasma dynamics in future fusion reactors.

  10. Evidence for density-gradient-driven trapped-electron modes in improved confinement RFP plasmas

    NASA Astrophysics Data System (ADS)

    Duff, James; Chapman, Brett; Sarff, John; Terry, Paul; Williams, Zach; Ding, Weixing; Brower, David; Parke, Eli

    2015-11-01

    Density fluctuations in the large-density-gradient region of improved-confinement MST RFP plasmas exhibit features characteristic of the trapped-electron-mode (TEM), strong evidence that drift wave turbulence emerges in RFP plasmas when magnetic transport is reduced. In standard RFP plasmas, core transport is governed by magnetic stochasticity stemming from current-driven tearing modes. Using inductive control, these tearing modes are reduced, improving confinement. The improved confinement is associated with substantial increases in the density and temperature gradients, and we present evidence for the onset of drift wave instability. Density fluctuations are measured with a multi-chord, laser-based interferometer. These fluctuations have wavenumbers kϕ *ρs <0.14, frequencies characteristic of drift waves (>50 kHz), and are clearly distinct from residual global tearing modes. Their amplitudes increase with the local density gradient, and require a critical density gradient. Gyrokinetic analysis provides supporting evidence of microinstability in these plasmas, in which the density-gradient-driven TEM is most unstable. The experimental threshold gradient is close to the predicted critical gradient for linear stability. Work supported by DOE.

  11. Unified fluid/kinetic description of magnetized plasmas

    SciTech Connect

    Chang, Zuoyang; Callen, J.D.

    1991-06-01

    Unified fluid/kinetic equations for the plasma perturbed density ({tilde n}), parallel flow velocity ({tilde u}{sub {parallel}}) and temperature ({tilde T}) are developed in a sheared slab geometry by calculating the fluid moment closure relations kinetically. At first, a set of (unclosed) nonlinear perturbed fluid equations for {tilde n}, {tilde u}{sub {parallel}} and {tilde T} is developed using a drift ordering analysis and a new gyroviscous force ({del} {center dot} {product}{sub g}). Thereafter, to develop linear closure relations for b {center dot} {del} {center dot} {tilde product}{sub {parallel}} and {tilde q}{sub {parallel}}, a drift-kinetic version of a Chapman-Enskog-like (CEL) equation is developed and solved by using a moment approach and a physically realistic collision operator (Lorentz scattering operator plus the momentum restoring terms.) The resultant closure relations for b {center dot} {del} {center dot} {tilde product}{sub {parallel}} and {tilde q}{sub {parallel}} unify both the fluid and kinetic approaches. In the collisional fluid limit the equations reduce to the well-known Braginskii equations. In the adiabatic limit they reproduce the usual kinetic results, including Landau damping. It is shown that the CEL approach is more compatible with a fluid-like description of plasmas than the usual drift/gyro kinetic approach. A remarkable simplification of these complicated closure relations is achieved by using single power of plasma dispersion functions with modified arguments. The results are compared with other recently developed Landau damping models and shown to be more accurate, complete and physically meaningful. The resultant set of nonlinear fluid/kinetic equations (with linear closure relations) will be applied to various microinstabilities in tokamak plasmas and drift type microturbulence in a separate paper. 19 refs., 7 refs., 1 tab.

  12. SciDAC - Center for Plasma Edge Simulation - Project Summary

    SciTech Connect

    Parker, Scott

    2014-11-03

    Final Technical Report: Center for Plasma Edge Simulation (CPES) Principal Investigator: Scott Parker, University of Colorado, Boulder Description/Abstract First-principle simulations of edge pedestal micro-turbulence are performed with the global gyrokinetic turbulence code GEM for both low and high confinement tokamak plasmas. The high confinement plasmas show a larger growth rate, but nonlinearly a lower particle and heat flux. Numerical profiles are obtained from the XGC0 neoclassical code. XGC0/GEM code coupling is implemented under the EFFIS (“End-to-end Framework for Fusion Integrated Simulation”) framework. Investigations are underway to clearly identify the micro-instabilities in the edge pedestal using global and flux-tube gyrokinetic simulation with realistic experimental high confinement profiles. We use both experimental profiles and those obtained using the EFFIS XGC0/GEM coupled code framework. We find there are three types of instabilities at the edge: a low-n, high frequency electron mode, a high-n, low frequency ion mode, and possibly an ion mode like kinetic ballooning mode (KBM). Investigations are under way for the effects of the radial electric field. Finally, we have been investigating how plasmas dominated by ion-temperature gradient (ITG) driven turbulence, how cold Deuterium and Tritium ions near the edge will naturally pinch radially inward towards the core. We call this mechanism “natural fueling.” It is due to the quasi-neutral heat flux dominated nature of the turbulence and still applies when trapped and passing kinetic electron effects are included. To understand this mechanism, examine the situation where the electrons are adiabatic, and there is an ion heat flux. In such a case, lower energy particles move inward and higher energy particles move outward. If a trace amount of cold particles are added, they will move inward.

  13. Pulsed power produced counter-propagating supersonic plasma jets

    NASA Astrophysics Data System (ADS)

    Krauland, Christine; Valenzuela, J.; Collins, G.; Mariscal, D.; Narkis, J.; Krasheninnikov, I.; Haque, S.; Hammel, B.; Wallace, M.; Covington, A.; Beg, F.

    2015-11-01

    High-Mach-number, ionized, flowing gases are ubiquitous in the universe, and in many astrophysical environments they take the shape of highly collimated and unidirectional jets. Pulsed power current drivers provide the opportunity to create plasma jets while achieving conditions required to explore radiative cooling, magnetic field advection, shock formation and microinstabilities, all of which are important in the astrophysical environment. We present results from an experimental campaign carried out with the ZEBRA driver (long pulse mode: 0.5 MA in 200 ns current rise) at the Nevada Terawatt Facility where we have performed a comprehensive study of the physics of conical wire array outflows. We have implemented a double conical array configuration in which two counter-propagating jets are produced. Characterization of the jets was done with Faraday rotation, interferometry and an optical streak camera. We will present available data comparing two wire materials (Al and Cu) and the shock formation in different parameter regimes. The work is funded by the Department of Energy Grant No. DE-SC0001063 and DE-NA0001995.

  14. Flute instability growth on a magnetized plasma column.

    SciTech Connect

    Genoni, Thomas C.; Welch, Dale Robert; Ditmire, T.; Rose, David Vincent; Mehlhorn, Thomas Alan; Porter, John Larry, Jr.

    2006-08-01

    The growth of the flute-type instability for a field-aligned plasma column immersed in a uniform magnetic field is studied. Particle-in-cell simulations are compared with a semi-analytic dispersion analysis of the drift cyclotron instability in cylindrical geometry with a Gaussian density profile in the radial direction. For the parameters considered here, the dispersion analysis gives a local maximum for the peak growth rates as a function of R/r{sub i}, where R is the Gaussian characteristic radius and r{sub i} is the ion gyroradius. The electrostatic and electromagnetic particle-in-cell simulation results give azimuthal and radial mode numbers that are in reasonable agreement with the dispersion analysis. The electrostatic simulations give linear growth rates that are in good agreement with the dispersion analysis results, while the electromagnetic simulations yield growth rate trends that are similar to the dispersion analysis but that are not in quantitative agreement. These differences are ascribed to higher initial field fluctuation levels in the electromagnetic field solver. Overall, the simulations allow the examination of both the linear and nonlinear evolution of the instability in this physical system up to and beyond the point of wave energy saturation. Keywords: Microinstabilities, Magnetic confinement and equilibrium, Particle-in-cell method.

  15. Sheared Rotation Effects on Kinetic Stability in Enhanced Confinement Tokamak Plasmas, and Nonlinear Dynamics of Fluctuations and Flows in Axisymmetric Plasmas

    SciTech Connect

    Rewoldt, G.; Beer, M.A.; Chance, M.S.; Hahm, T.S.; Lin, Z.; Tang, W.M.

    1997-12-01

    Sheared rotation dynamics are widely believed to have significant influence on experimentally observed confinement transitions in advanced operating modes in major tokamak experiments, such as the Tokamak Fusion Test Reactor (TFTR) with reversed magnetic shear regions in the plasma interior. The high-n toroidal drift modes destabilized by the combined effects of ion temperature gradients and trapped particles in toroidal geometry can be strongly affected by radially sheared toroidal and poloidal plasma rotation. In previous work with the FULL linear microinstability code, a simplified rotation model including only toroidal rotation was employed, and results were obtained. Here, a more complete rotation model, that includes contributions from toroidal and poloidal rotation and the ion pressure gradient to the total radial electric field, is used for a proper self-consistent treatment of this key problem. Relevant advanced operating mode cases for TFTR are presented. In addition, the complementary problem of the dynamics of fluctuation-driven E x B flow is investigated by an integrated program of gyrokinetic simulation in annulus geometry and gyrofluid simulation in flux tube geometry.

  16. Sheared Rotation Effects on Kinetic Stability in Enhanced Confinement Tokamak Plasmas, and Nonlinear Dynamics of Fluctuations and Flows in Axisymmetric Plasmas

    SciTech Connect

    Beer, M.A.; Chance, M.S.; Hahm, T.S.; Lin, Z.; Rewoldt, G.; Tang, W.M.

    1997-11-01

    Sheared rotation dynamics are widely believed to have signficant influence on experimentally observed confinement transitions in advanced operating modes in major tokamak experiments, such as the Tokamak Fusion Test Reactor (TFTR) [D.J. Grove and D.M. Meade, Nuclear Fusion 25, 1167 (1985)], with reversed magnetic shear regions in the plasma interior. The high-n toroidal drift modes destabilized by the combined effects of ion temperature gradients and trapped particles in toroidal geometry can be strongly affected by radially sheared toroidal and poloidal plasma rotation. In previous work with the FULL linear microinstability code, a simplified rotation model including only toroidal rotation was employed, and results were obtained. Here, a more complete rotation model, that includes contributions from toroidal and poloidal rotation and the ion pressure gradient to the total radial electric field, is used for a proper self-consistent treatment of this key problem. Relevant advanced operating mode cases for TFTR are presented. In addition, the complementary problem of the dynamics of fluctuation-driven E x B flow is investigated by an integrated program of gyrokinetic simulation in annulus geometry and gyrofluid simulation in flux tube geometry.

  17. Models of magnetic field evolution and effective viscosity in weakly collisional extragalactic plasmas

    NASA Astrophysics Data System (ADS)

    Mogavero, Federico; Schekochihin, Alexander A.

    2014-06-01

    In weakly collisional plasmas such as the intracluster medium (ICM), the viscous stress and the rate of change of the magnetic energy are proportional to the local pressure anisotropy, so subject to constraints imposed by the pressure-anisotropy-driven microinstabilities (mirror and firehose) and controlled by the local instantaneous plasma β. The dynamics of such plasmas can be dramatically different from a conventional magnetohydrodynamic fluid. The plasma is expected to stay locally marginal with respect to the instabilities, but how it does this remains an open question. Two models of magnetic field evolution are investigated. In the first, marginality is achieved via suppression of the rate of change of the field. In the second, the instabilities give rise to anomalous collisionality, reducing pressure anisotropy to marginal - at the same time decreasing viscosity and so increasing the turbulent rate of strain. Implications of these two models are studied in a simplified zero-dimensional setting. In the first model, the field grows explosively but on a time-scale that scales with the initial β, while in the second, dynamical field strength can be reached in one large-scale turbulence turnover time regardless of the initial seed. Both models produce very intermittent fields. Both also suffer from fairly strong constraints on their applicability: for typical cluster-core conditions, scale separation between the fluid motions (with account of suppressed viscous stress) and the miscoscale fluctuations break down at β ˜ 104-105. At larger β (weaker fields), a fully collisionless plasma dynamo theory is needed to justify field growth from a tiny primordial seed. However, the models discussed here are appropriate for studying the structure of the currently observed field as well as large-scale dynamics and thermodynamics of the magnetized ICM or similarly dilute astrophysical plasmas.

  18. Self-Organization in Turbulent Plasmas

    NASA Astrophysics Data System (ADS)

    Diamond, P. H.

    1997-11-01

    Self-Organization is a ubiquitous phenomenon in turbulent laboratory, space and astrophysical plasmas. In this review, we focus on the emergent behavior of large scale order in turbulent plasmas. Instances of such emergent behavior have the common elements of broken symmetry, criticality and auto-regulation, which collectively govern order parameter evolution. Here, we discuss three classic and illustrative paradigms of self-organization (s.-o.). Perhaps the simplest paradigm of s.-o. is that of criticality in one and two-dimensional cellular automata (CA). The goal is to understand the link between emergent macroscopic profile structure and microscopic automata rules, an end closely related to the calculation of tokamak confinement from gradient-driven micro-instabilities. Here, profile shape and stiffness may be calculated to good accuracy from Markov-chain algorithms, which agree well with direct implementation of the CA's with noise. For strongly-driven piles, hydrodynamic models reproduce ballistic propagation scaling and confirm the expectation that cross-gradient shear flows significantly alter avalanche statistics and scaling. A second paradigm of s.-o. is the magnetic dynamo, a classic realization of large scale s.-o. induced by small scale symmetry breaking. Here, it is the reflection symmetry of the small-scale turbulence which is broken, yielding a net helicity and alpha-effect. The structure of the self-organized state (i.e. scale of growth) is determined by alpha, which displays the footprint of small scale asymmetry. A novel element in the theory is the nonlinearity induced by rapid amplification of small scale magnetic fields. This, in turn, induces a nonlinear feedback which quenches the dynamo at finite amplitude. The quenching process is also manifested in passive scalar and magnetic flux transport. The third paradigm is the self-regulating shear flow. Here, small scale and large scale asymmetry are linked by a mechanism very similar to that operating in Langmuir turbulence. As a result, the asymmetry of the small scale drift or Rossby wave turbulence directly determines the spatial structure of the macroscopic sheared flow via Reynolds stress structure, which, in turn, re-enforces the initial turbulence asymmetry and changes its level. Limit-cycle states of bursting flow and fluctuations are predicted, and observed in simulations. Application of the self-regulating shear-flow paradigm to the dynamics of sheared flows in tokamak transport barriers and ionospheric plasmas will be discussed.

  19. Numerical simulations of anisotropic plasmas using a modified ZEUS-MP

    NASA Astrophysics Data System (ADS)

    Chandran, Benjamin; Tangri, Varun; Sarkar, Aveek; Perez, Jean; Sharma, Prateek

    2012-10-01

    Three dimensional linear and nonlinear simulations of collisionless one-fluid plasmas with pressure anisotropy are presented using the Chew- Goldberger-Low (CGL-MHD) and double-isothermal models. For this purpose, the code ZEUS-MP [J. C. Hayes et. al. The APJ Supplement Series 165 (2006) 188.] has been modified. Major modifications include a changed method of characteristics, new compressive and non-compressive forces, and a ``hard wall'' limit on pressure anisotropy that is intended to mimic the effects of plasma micro-instabilities that limit the temperature anisotropy. For purposes of validation, more than 100 test simulations of linear waves (Alfven, slow and fast), instabilities (firehose and mirror) and nonlinear vortices (Orszag-Tang) are presented for a number of initial conditions and parameters. Finally, this model is used to investigate the way that Alfven-wave turbulence leads to a spreading of the temperature-anisotropy probability distribution in the solar wind. Analysis is completed with a detailed analysis of the fluctuation data.

  20. Plasma turbulence

    SciTech Connect

    Horton, W.; Hu, G.

    1998-07-01

    The origin of plasma turbulence from currents and spatial gradients in plasmas is described and shown to lead to the dominant transport mechanism in many plasma regimes. A wide variety of turbulent transport mechanism exists in plasmas. In this survey the authors summarize some of the universally observed plasma transport rates.

  1. Numerical simulation of non-equilibrium plasma flow in a cylindrical MPD thruster using a high-order flux-difference splitting method

    NASA Astrophysics Data System (ADS)

    Ahangar, Mahdy; Ebrahimi, Reza; Shams, Mehrzad

    2014-10-01

    A two-dimensional axisymmetric computational algorithm is developed to simulate the plasma flow field in a self-field MPD thruster, in order to determine the flow behavior and the electromagnetic characteristics distribution. The convective flux vector is computed by using Roe's scheme in combination with Powell's eigensystem technique, and a new modified MUSCL technique called OMUSCL2 is employed to obtain the stable high-accuracy solution. Madrane-Tadmor entropy correction is used to prevent unrealistic expansion shocks near the electrodes tips. To accurately capture the physics of plasma in the system, different physical-chemical sub-models including multi-level non-equilibrium ionization model, generalized Ohm's law for partially ionized plasma, micro-instabilities effects, two-temperature model, and a real equation of state are considered. Numerical results of plasma flow simulation in a cylindrical lab-scale thruster, with mass flow rate of 6 g/s and total discharge current of 8 kA, are presented and comparison with experimental data shows good agreement between the predicted and measured contours of enclosed current and electric potential. The estimated thrust is 16.34 N which exhibits less than 5% difference compared with measured value. Furthermore, this simulation properly predicts the experimentally observed argon jet structure.

  2. PLASMA GENERATOR

    DOEpatents

    Foster, J.S. Jr.

    1958-03-11

    This patent describes apparatus for producing an electricity neutral ionized gas discharge, termed a plasma, substantially free from contamination with neutral gas particles. The plasma generator of the present invention comprises a plasma chamber wherein gas introduced into the chamber is ionized by a radiofrequency source. A magnetic field is used to focus the plasma in line with an exit. This magnetic field cooperates with a differential pressure created across the exit to draw a uniform and uncontaminated plasma from the plasma chamber.

  3. PIC Simulations of Hypersonic Plasma Instabilities

    NASA Astrophysics Data System (ADS)

    Niehoff, D.; Ashour-Abdalla, M.; Niemann, C.; Decyk, V.; Schriver, D.; Clark, E.

    2013-12-01

    The plasma sheaths formed around hypersonic aircraft (Mach number, M > 10) are relatively unexplored and of interest today to both further the development of new technologies and solve long-standing engineering problems. Both laboratory experiments and analytical/numerical modeling are required to advance the understanding of these systems; it is advantageous to perform these tasks in tandem. There has already been some work done to study these plasmas by experiments that create a rapidly expanding plasma through ablation of a target with a laser. In combination with a preformed magnetic field, this configuration leads to a magnetic "bubble" formed behind the front as particles travel at about Mach 30 away from the target. Furthermore, the experiment was able to show the generation of fast electrons which could be due to instabilities on electron scales. To explore this, future experiments will have more accurate diagnostics capable of observing time- and length-scales below typical ion scales, but simulations are a useful tool to explore these plasma conditions theoretically. Particle in Cell (PIC) simulations are necessary when phenomena are expected to be observed at these scales, and also have the advantage of being fully kinetic with no fluid approximations. However, if the scales of the problem are not significantly below the ion scales, then the initialization of the PIC simulation must be very carefully engineered to avoid unnecessary computation and to select the minimum window where structures of interest can be studied. One method of doing this is to seed the simulation with either experiment or ion-scale simulation results. Previous experiments suggest that a useful configuration for studying hypersonic plasma configurations is a ring of particles rapidly expanding transverse to an external magnetic field, which has been simulated on the ion scale with an ion-hybrid code. This suggests that the PIC simulation should have an equivalent configuration; however, modeling a plasma expanding radially in every direction is computationally expensive. In order to reduce the computational expense, we use a radial density profile from the hybrid simulation results to seed a self-consistent PIC simulation in one direction (x), while creating a current in the direction (y) transverse to both the drift velocity and the magnetic field (z) to create the magnetic bubble observed in experiment. The simulation will be run in two spatial dimensions but retain three velocity dimensions, and the results will be used to explore the growth of micro-instabilities present in hypersonic plasmas in the high-density region as it moves through the simulation box. This will still require a significantly large box in order to compare with experiment, as the experiments are being performed over distances of 104 λDe and durations of 105 ωpe-1.

  4. Plasma Medicine

    NASA Astrophysics Data System (ADS)

    Laroussi, M.; Kong, M. G.; Morfill, G.; Stolz, W.

    2012-05-01

    Foreword R. Satava and R. J. Barker; Part I. Introduction to Non-equilibrium Plasma, Cell Biology, and Contamination: 1. Introduction M. Laroussi; 2. Fundamentals of non-equilibrium plasmas M. Kushner and M. Kong; 3. Non-equilibrium plasma sources M. Laroussi and M. Kong; 4. Basic cell biology L. Greene and G. Shama; 5. Contamination G. Shama and B. Ahlfeld; Part II. Plasma Biology and Plasma Medicine: 6. Common healthcare challenges G. Isbary and W. Stolz; 7. Plasma decontamination of surfaces M. Kong and M. Laroussi; 8. Plasma decontamination of gases and liquids A. Fridman; 9. Plasma-cell interaction: prokaryotes M. Laroussi and M. Kong; 10. Plasma-cell interaction: eukaryotes G. Isbary, G. Morfill and W. Stolz; 11. Plasma based wound healing G. Isbary, G. Morfill and W. Stolz; 12. Plasma ablation, surgery, and dental applications K. Stalder, J. Woloszko, S. Kalghatgi, G. McCombs, M. Darby and M. Laroussi; Index.

  5. Cross-Scale Interactions between Electron and Ion Scale Turbulence in a Tokamak Plasma.

    PubMed

    Maeyama, S; Idomura, Y; Watanabe, T-H; Nakata, M; Yagi, M; Miyato, N; Ishizawa, A; Nunami, M

    2015-06-26

    Multiscale gyrokinetic turbulence simulations with the real ion-to-electron mass ratio and β value are realized for the first time, where the β value is given by the ratio of plasma pressure to magnetic pressure and characterizes electromagnetic effects on microinstabilities. Numerical analysis at both the electron scale and the ion scale is used to reveal the mechanism of their cross-scale interactions. Even with the real-mass scale separation, ion-scale turbulence eliminates electron-scale streamers and dominates heat transport, not only of ions but also of electrons. Suppression of electron-scale turbulence by ion-scale eddies, rather than by long-wavelength zonal flows, is also demonstrated by means of direct measurement of nonlinear mode-to-mode coupling. When the ion-scale modes are stabilized by finite-β effects, the contribution of the electron-scale dynamics to the turbulent transport becomes non-negligible and turns out to enhance ion-scale turbulent transport. Damping of the ion-scale zonal flows by electron-scale turbulence is responsible for the enhancement of ion-scale transport. PMID:26197130

  6. Cross-Scale Interactions between Electron and Ion Scale Turbulence in a Tokamak Plasma

    NASA Astrophysics Data System (ADS)

    Maeyama, S.; Idomura, Y.; Watanabe, T.-H.; Nakata, M.; Yagi, M.; Miyato, N.; Ishizawa, A.; Nunami, M.

    2015-06-01

    Multiscale gyrokinetic turbulence simulations with the real ion-to-electron mass ratio and ? value are realized for the first time, where the ? value is given by the ratio of plasma pressure to magnetic pressure and characterizes electromagnetic effects on microinstabilities. Numerical analysis at both the electron scale and the ion scale is used to reveal the mechanism of their cross-scale interactions. Even with the real-mass scale separation, ion-scale turbulence eliminates electron-scale streamers and dominates heat transport, not only of ions but also of electrons. Suppression of electron-scale turbulence by ion-scale eddies, rather than by long-wavelength zonal flows, is also demonstrated by means of direct measurement of nonlinear mode-to-mode coupling. When the ion-scale modes are stabilized by finite-? effects, the contribution of the electron-scale dynamics to the turbulent transport becomes non-negligible and turns out to enhance ion-scale turbulent transport. Damping of the ion-scale zonal flows by electron-scale turbulence is responsible for the enhancement of ion-scale transport.

  7. Dusty plasmas

    SciTech Connect

    Jones, M.E.; Winske, D.; Keinigs, R.; Lemons, D.

    1996-05-01

    This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The objective of this project has been to develop a fundamental understanding of dusty plasmas at the Laboratory. While dusty plasmas are found in space in galactic clouds, planetary rings, and cometary tails, and as contaminants in plasma enhanced fabrication of microelectronics, many of their properties are only partially understood. Our work has involved both theoretical analysis and self-consistent plasma simulations to understand basic properties of dusty plasmas related to equilibrium, stability, and transport. Such an understanding can improve the control and elimination of plasma dust in industrial applications and may be important in the study of planetary rings and comet dust tails. We have applied our techniques to the study of charging, dynamics, and coagulation of contaminants in plasma processing reactors for industrial etching and deposition processes and to instabilities in planetary rings and other space plasma environments. The work performed in this project has application to plasma kinetics, transport, and other classical elementary processes in plasmas as well as to plasma waves, oscillations, and instabilities.

  8. Plasma accelerators

    SciTech Connect

    Ruth, R.D.; Chen, P.

    1986-03-01

    In this paper we discuss plasma accelerators which might provide high gradient accelerating fields suitable for TeV linear colliders. In particular we discuss two types of plasma accelerators which have been proposed, the Plasma Beat Wave Accelerator and the Plasma Wake Field Accelerator. We show that the electric fields in the plasma for both schemes are very similar, and thus the dynamics of the driven beams are very similar. The differences appear in the parameters associated with the driving beams. In particular to obtain a given accelerating gradient, the Plasma Wake Field Accelerator has a higher efficiency and a lower total energy for the driving beam. Finally, we show for the Plasma Wake Field Accelerator that one can accelerate high quality low emittance beams and, in principle, obtain efficiencies and energy spreads comparable to those obtained with conventional techniques.

  9. Linear gyrokinetic calculations of toroidal momentum transport in the presence of trapped electron modes in tokamak plasmas

    SciTech Connect

    Kluy, N.; Angioni, C.; Camenen, Y.; Peeters, A. G.

    2009-12-15

    The toroidal momentum transport in the presence of trapped electron mode microinstabilities in tokamak plasmas is studied by means of quasilinear gyrokinetic calculations. In particular, the role of the Coriolis drift in producing an inward convection of toroidal momentum is investigated. The Coriolis drift term has been implemented in the gyrokinetic code GS2 [W. Dorland et al., Phys. Rev. Lett. 85, 5579 (2000)] specifically for the completion of this work. A benchmark between the GS2 implementation of the Coriolis drift and the implementations included in two other gyrokinetic codes is presented. The numerical calculations show that in the presence of trapped electron modes, despite of a weaker symmetry breaking of the eigenfunctions with respect to the case of ion temperature gradient modes, a pinch of toroidal momentum is produced in most conditions. The toroidal momentum viscosity is also computed, and found to be small as compared with the electron heat conductivity, but significantly larger than the ion heat conductivity. In addition, interesting differences are found in the dependence of the toroidal momentum pinch as a function of collisionality between trapped electron modes and ion temperature gradient modes. The results identify also parameter domains in which the pinch is predicted to be small, which are also of interest for comparisons with the experiments.

  10. Reduced model prediction of electron temperature profiles in microtearing-dominated NSTX plasmas

    NASA Astrophysics Data System (ADS)

    Kaye, S. M.; Guttenfelder, W.; Bell, R.; Gerhardt, S.; Leblanc, B.; Maingi, R.

    2014-10-01

    A representative H-mode discharge from the National Spherical Torus Experiment (NSTX) is studied in detail as a basis for a time-evolving prediction of the electron temperature profile using an appropriate reduced transport model. The time evolution of characteristic plasma variables such as βe, νe*, the MHD α parameter and the gradient scale lengths of Te, Ti and ne were examined prior to performing linear gyrokinetic calculations to determine the fastest growing microinstability at various times and locations throughout the discharge. The inferences from the parameter evolutions and the linear stability calculations were consistent. Early in the discharge, when βe and νe* were relatively low, ballooning parity modes were dominant. As both βe and νe* increased with time, microtearing became the dominant low-kθmode, especially in the outer half of the plasma. There are instances in time and radius where other modes, at higher-kθ, may be important for driving electron transport. The Rebut-Lallia-Watkins (RLW) electron thermal diffusivity model, which is based on microtearing-induced transport, was used to predict the time-evolving electron temperature across most of the profile. The results indicate that RLW does a good job of predicting Te for times and locations where microtearing was determined to be important, but not as well when microtearing was predicted to be stable or subdominant. This work has been supported by U.S. Dept of Energy contracts DE-AC02-09CH11466.

  11. Plasma valve

    DOEpatents

    Hershcovitch, Ady; Sharma, Sushil; Noonan, John; Rotela, Elbio; Khounsary, Ali

    2003-01-01

    A plasma valve includes a confinement channel and primary anode and cathode disposed therein. An ignition cathode is disposed adjacent the primary cathode. Power supplies are joined to the cathodes and anode for rapidly igniting and maintaining a plasma in the channel for preventing leakage of atmospheric pressure through the channel.

  12. Plasma accelerator

    DOEpatents

    Wang, Zhehui; Barnes, Cris W.

    2002-01-01

    There has been invented an apparatus for acceleration of a plasma having coaxially positioned, constant diameter, cylindrical electrodes which are modified to converge (for a positive polarity inner electrode and a negatively charged outer electrode) at the plasma output end of the annulus between the electrodes to achieve improved particle flux per unit of power.

  13. Unmatter Plasma

    NASA Astrophysics Data System (ADS)

    Smarandache, Florentin

    2015-11-01

    ``Unmatter Plasma'' is a novel form of plasma, exclusively made of matter and its antimatter counterpart. An experiment (2015) on matter-antimatter plasma [or unmatter plasma] was recently successful at the Astra Gemini laser facility at the Rutherford Appleton Laboratory, Oxford, United Kingdom. The experiment that was made has produced electron-positron plasma. The positron is the antimatter of the electron, having an opposite charge of the electron, but the other properties are the same. Unmatter is considered as a combination of matter and antimatter. For example electron-positron is a type of unmatter. We coined the word ``unmatter'' (2004) that means neither matter nor antimatter, but something in between. Besides matter and antimatter there may exist unmatter (as a new form of matter) in accordance with the neutrosophy theory that between an entity and its opposite there exist intermediate entities.

  14. PLASMA DEVICE

    DOEpatents

    Baker, W.R.

    1961-08-22

    A device is described for establishing and maintaining a high-energy, rotational plasma for use as a fast discharge capacitor. A disc-shaped, current- conducting plasma is formed in an axinl magnetic field and a crossed electric field, thereby creating rotational kinetic enengy in the plasma. Such energy stored in the rotation of the plasma disc is substantial and is convertible tc electrical energy by generator action in an output line electrically coupled to the plasma volume. Means are then provided for discharging the electrical energy into an external circuit coupled to the output line to produce a very large pulse having an extremely rapid rise time in the waveform thereof. (AE C)

  15. PLASMA ENERGIZATION

    DOEpatents

    Furth, H.P.; Chambers, E.S.

    1962-03-01

    BS>A method is given for ion cyclotron resonance heatthg of a magnetically confined plasma by an applied radio-frequency field. In accordance with the invention, the radiofrequency energy is transferred to the plasma without the usual attendent self-shielding effect of plasma polarlzatlon, whereby the energy transfer is accomplished with superior efficiency. More explicitly, the invention includes means for applying a radio-frequency electric field radially to an end of a plasma column confined in a magnetic mirror field configuration. The radio-frequency field propagates hydromagnetic waves axially through the column with the waves diminishing in an intermediate region of the column at ion cyclotron resonance with the fleld frequency. In such region the wave energy is converted by viscous damping to rotational energy of the plasma ions. (AEC)

  16. Plasma universe

    NASA Technical Reports Server (NTRS)

    Alfven, H.

    1986-01-01

    Traditionally the views on the cosmic environent have been based on observations in the visual octave of the electromagnetic spectrum, during the last half-century supplemented by infrared and radio observations. Space research has opened the full spectrum. Of special importance are the X-ray-gamma-ray regions, in which a number of unexpected phenomena have been discovered. Radiations in these regions are likely to originate mainly from magnetised cosmic plasmas. Such a medium may also emit synchrotron radiation which is observable in the radio region. If a model of the universe is based on the plasma phenomena mentioned it is found that the plasma universe is drastically different from the traditional visual universe. Information about the plasma universe can also be obtained by extrapolation of laboratory experiments and magnetospheric in situ measurements of plasmas. This approach is possible because it is likely that the basic properties of plasmas are the same everywhere. In order to test the usefulness of the plasma universe model it is applied to cosmogony. Such an approach seems to be rather successful. For example, the complicated structure of the Saturnian C ring can be accounted for. It is possible to reconstruct certain phenomena 4 to 5 billions of years ago with an accuracy of better than 1%.

  17. Plasma Cleaning

    NASA Technical Reports Server (NTRS)

    Hintze, Paul E.

    2016-01-01

    NASA's Kennedy Space Center has developed two solvent-free precision cleaning techniques: plasma cleaning and supercritical carbon dioxide (SCCO2), that has equal performance, cost parity, and no environmental liability, as compared to existing solvent cleaning methods.

  18. PLASMA DEVICE

    DOEpatents

    Baker, W.R.; Brathenahl, A.; Furth, H.P.

    1962-04-10

    A device for producing a confined high temperature plasma is described. In the device the concave inner surface of an outer annular electrode is disposed concentrically about and facing the convex outer face of an inner annular electrode across which electrodes a high potential is applied to produce an electric field there between. Means is provided to create a magnetic field perpendicular to the electric field and a gas is supplied at reduced pressure in the area therebetween. Upon application of the high potential, the gas between the electrodes is ionized, heated, and under the influence of the electric and magnetic fields there is produced a rotating annular plasma disk. The ionized plasma has high dielectric constant properties. The device is useful as a fast discharge rate capacitor, in controlled thermonuclear research, and other high temperature gas applications. (AEC)

  19. Plasma separation

    NASA Technical Reports Server (NTRS)

    Steurer, Wolfgang

    1992-01-01

    This process employs a thermal plasma for the separation and production of oxygen and metals. It is a continuous process that requires no consumables and relies entirely on space resources. The almost complete absence of waste renders it relatively clean. It can be turned on or off without any undesirable side effects or residues. The prime disadvantage is its high power consumption.

  20. Plasma Shield

    NASA Astrophysics Data System (ADS)

    Hershcovitch, Ady

    2005-10-01

    The Plasma Shield is a vortex-stabilized arc that is employed to shield beams and workpiece area of interaction from atmospheric or liquid environment. A vortex-stabilized arc is established between a beam generating device (laser, ion or electron gun) and the target object. The arc, which is composed of a pure noble gas (chemically inert), engulfs the interaction region and generates an outward flow, thus, shielding it from any surrounding liquids (water) or atmospheric gases. The vortex is composed of a sacrificial gas or liquid that swirls around and stabilizes the arc. In current art, many industrial processes that involve ion and electron beams like, dry etching, micro-fabrication, machining, welding and melting are performed exclusively in vacuum, since guns, and accelerators must be kept at a reasonably high vacuum, and since chemical interactions with atmospheric gases adversely affect various processes. Various processes involving electron ion and laser beams can, with the Plasma Shield be performed in practically any environment (under water). It should allow for in situ repair of ship and nuclear reactor components, as well as in-air ion implantation of semiconductors. The plasma shield results in both thermal (since the plasma is hotter than the environment) and chemical shielding. The latter feature brings about in-vacuum process purity out of vacuum, and the thermal shielding aspect results in higher production rates. Experimental results will be presented. *Plasma Shield/Work supported by Acceleron, Inc., Connecticut Light & Power Co., US DOE funding under a NICE3 grant DE-FG41-01R110925, and Connecticut DEP.

  1. Properties of large scale plasma flow during the early stage of the plasmaspheric refilling

    NASA Technical Reports Server (NTRS)

    Singh, Nagendra; Craven, P.; Torr, D. G.; Richards, P. G.

    1990-01-01

    The objective is to better characterize the macroscopic properties of the interhemisphere plasma flow by solving a more complete set of hydrodynamic equations than that solved previously. Specifically, the ion continuity, momentum and energy equations were solved for the plasma flow along the closed magnetic field lines. During the initial stage of the supersonic outflow in the equatorial region, the ions cool substantially. Using the hydrodynamic model for the large-scale plasma flow, the dynamics of shocks was examined which form in the geomagnetic flux tubes during the early stages of refilling. These shocks are more like those forming in neutral gases than the electrostatic shocks driven by microinstabilities involving ion-ion interaction. Therefore, the shocks seen in the hydrodynamic model are termed as hydrodynamic shocks. Such shocks are generally unsteady and therefore the usual shock jump conditions given by Rankine-Hugoniot relations are not strictly applicable to them. The density, flow velocity and temperature structures associated with the shocks are examined for both asymmetrical and symmetrical flows. In the asymmetrical flow the outflow from one of two conjugate ionospheres is dominant. On the other hand, in the symmetrical case outflows from the two ionospheric sources are identical. Both cases are treated by a two-stream model. In the late type of flow, the early-time refilling shows a relaxation type of oscillation, which is driven by the large-scale interactions between the two identical streams. After this early stage, the resulting temperature structure shows some interesting features. In the equatorial region the streams are isothermal, but in the off-equatorial regions the streams have quite different temperatures, and also densities and flow velocities. The dense and slow stream is found to be warmer than the low-density fast stream. In the late stage of refilling, the temperature is found to steadily increase from the conjugate ionospheres towards the equator; the equatorial temperature is found to be as high as about 8000 K compared to the ionospheric temperature of 3600 K.

  2. Improved plasma accelerator

    NASA Technical Reports Server (NTRS)

    Cheng, D. Y.

    1971-01-01

    Converging, coaxial accelerator electrode configuration operates in vacuum as plasma gun. Plasma forms by periodic injections of high pressure gas that is ionized by electrical discharges. Deflagration mode of discharge provides acceleration, and converging contours of plasma gun provide focusing.

  3. Plasma Free Metanephrines

    MedlinePlus

    ... limited. Home Visit Global Sites Search Help? Plasma Free Metanephrines Share this page: Was this page helpful? ... known as: Plasma Metanephrines Formal name: Fractionated Plasma Free Metanephrines (Metanephrine and Normetanephrine) Related tests: Catecholamines ; Urine ...

  4. Applications of atmospheric plasmas

    NASA Astrophysics Data System (ADS)

    Oldham, Christopher John

    Surface modification techniques using plasmas have historically been completed in a low pressure environment due to Pd (pressure x gap distance) considerations influencing the behavior of plasma generation. Generally, plasmas produced in a low pressure environment are of a non-thermal or cold nature. The basic feature of non-thermal plasmas is the majority of electrical energy used to generate the plasma is primarily used to produce energetic electrons for generating chemical species. Low pressure plasmas serve many purposes for materials processing. Since the plasma environment is contained within a closed vessel, the plasma can be controlled very easily. Low pressure plasmas have been used in many industries but the complexity associated with the large pumping stations and limitation to batch processing has motivated new work in the area of atmospheric plasmas. Atmospheric plasmas offer both economic and technical justification for use over low pressure plasmas. Since atmospheric plasmas can be operated at ambient conditions, lower costs associated with continuous processing and a decrease in the complexity of equipment validate atmospheric plasma processing as a next generation plasma-aided manufacturing process. In an effort to advance acceptance of atmospheric plasma processing into industry, a process was developed, the dielectric barrier discharge (DBD), in order to generate a homogeneous and non-thermal plasma discharge at ambient conditions. The discharge was applied to the reduction of known food borne pathogens, deposition of thin film materials, and modification of lignocellulosic biomass.

  5. Magnetization of plasmas

    SciTech Connect

    Shukla, P. K.; Eliasson, B.; Stenflo, L.

    2010-12-14

    We critically examine and evaluate several physical mechanisms that are responsible for the seed magnetic fields in plasmas. The plasma magnetization is attributed to sources that foster motion of the background plasma electrons against the ions. The resulting space charge electric field and currents, in turn, are detrimental for the plasma magnetization.

  6. Progress on plasma accelerators

    SciTech Connect

    Chen, P.

    1986-05-01

    Several plasma accelerator concepts are reviewed, with emphasis on the Plasma Beat Wave Accelerator (PBWA) and the Plasma Wake Field Accelerator (PWFA). Various accelerator physics issues regarding these schemes are discussed, and numerical examples on laboratory scale experiments are given. The efficiency of plasma accelerators is then revealed with suggestions on improvements. Sources that cause emittance growth are discussed briefly.

  7. Communication through plasma sheaths

    SciTech Connect

    Korotkevich, A. O.; Newell, A. C.; Zakharov, V. E.

    2007-10-15

    We wish to transmit messages to and from a hypersonic vehicle around which a plasma sheath has formed. For long distance transmission, the signal carrying these messages must be necessarily low frequency, typically 2 GHz, to which the plasma sheath is opaque. The idea is to use the plasma properties to make the plasma sheath appear transparent.

  8. Plasma sweeper. [Patents

    DOEpatents

    Motley, R.W.; Glanz, J.

    1982-10-25

    A device is described for coupling RF power (a plasma sweeper) from RF power introducing means to a plasma having a magnetic field associated therewith comprises at least one electrode positioned near the plasma and near the RF power introducing means. Means are described for generating a static electric field at the electrode directed into the plasma and having a component substantially perpendicular to the plasma magnetic field such that a non-zero vector cross-product of the electric and magnetic fields exerts a force on the plasma causing the plasma to drift.

  9. Plasmas for space propulsion

    NASA Astrophysics Data System (ADS)

    Ahedo, Eduardo

    2011-12-01

    Plasma thrusters are challenging the monopoly of chemical thrusters in space propulsion. The specific energy that can be deposited into a plasma beam is orders of magnitude larger than the specific chemical energy of known fuels. Plasma thrusters constitute a vast family of devices ranging from already commercial thrusters to incipient laboratory prototypes. Figures of merit in plasma propulsion are discussed. Plasma processes and conditions differ widely from one thruster to another, with the pre-eminence of magnetized, weakly collisional plasmas. Energy is imparted to the plasma via either energetic electron injection, biased electrodes or electromagnetic irradiation. Plasma acceleration can be electrothermal, electrostatic or electromagnetic. Plasma-wall interaction affects energy deposition and erosion of thruster elements, and thus is central for thruster efficiency and lifetime. Magnetic confinement and magnetic nozzles are present in several devices. Oscillations and turbulent transport are intrinsic to the performances of some thrusters. Several thrusters are selected in order to discuss these relevant plasma phenomena.

  10. Industrial plasmas in academia

    NASA Astrophysics Data System (ADS)

    Hollenstein, Ch; Howling, AA; Guittienne, Ph; Furno, I.

    2015-01-01

    The present review, written at the occasion of the 2014 EPS Innovation award, will give a short overview of the research and development of industrial plasmas within the last 30 years and will also provide a first glimpse into future developments of this important topic of plasma physics and plasma chemistry. In the present contribution, some of the industrial plasmas studied at the CRPP/EPFL at Lausanne are highlighted and their influence on modern plasma physics and also discharge physics is discussed. One of the most important problems is the treatment of large surfaces, such as that used in solar cells, but also in more daily applications, such as the packaging industry. In this contribution, the advantages and disadvantages of some of the most prominent plasmas such as capacitively- and inductively-coupled plasmas are discussed. Electromagnetic problems due to the related radio frequency and its consequences on the plasma reactor performance, and also dust formation due to chemical reactions in plasma, are highlighted. Arcing and parasitic discharges occurring in plasma reactors can lead to plasma reactor damages. Some specific problems, such as the gas supply of a large area reactor, are discussed in more detail. Other topics of interest have been dc discharges such as those used in plasma spraying where thermal plasmas are applied for advanced material processing. Modern plasma diagnostics make it possible to investigate sparks in electrical discharge machining, which surprisingly show properties of weakly-coupled plasmas. Nanosecond dielectric barrier discharge plasmas have been applied to more speculative topics such as applications in aerodynamics and will surely be important in the future for ignition and combustion. Most of the commonly-used plasma sources have been shown to be limited in their performance. Therefore new, more effective plasma sources are urgently required. With the recent development of novel resonant network antennas for new advanced large area or large volume plasma sources, an important step towards high performance plasmas and new fast processes is made.

  11. Experiments with nonneutral plasmas

    NASA Astrophysics Data System (ADS)

    O'Neil, T. M.

    2016-03-01

    Selected experiments with nonneutral plasmas are discussed. These include the laser cooling of a pure ion plasma to a crystalline state, a measurement of the Salpeter enhancement factor for fusion in a strongly correlated plasma and the measurement of thermally excited plasma waves. Also, discussed are experiments that demonstrate Landau damping, trapping and plasma wave echoes in the 2D ExB drift flow of a pure electron plasma, which is isomorphic to the 2D ideal flow (incompressible and inviscid flow) of a neutral fluid.

  12. Basics of Dusty Plasma

    SciTech Connect

    Ignatov, A.M.

    2005-01-15

    The paper presents an introductory review of the basic physical processes in dusty plasmas. The topics to be addressed are dust charging, forces acting on dust grains, interaction between dust grains, and dust-plasma structures.

  13. Plasma in astrophysics

    SciTech Connect

    Kulsrud, R.M.

    1982-10-01

    Two examples of plasma phenomena of importance to astrophysics are reviewed. These are examples where astrophysical understanding hinges on further progress in plasma physics understanding. The two examples are magnetic reconnection and the collisionless interaction between a population of energetic particles and a cooler gas or plasma, in particular the interaction between galactic cosmic rays and the interstellar medium.

  14. A reconfigurable plasma antenna

    SciTech Connect

    Kumar, Rajneesh; Bora, Dhiraj

    2010-03-15

    An experiment aimed at investigating the antenna properties of different plasma structures of a plasma column as a reconfigurable plasma antenna, is reported. A 30 cm long plasma column is excited by surface wave, which acts as a plasma antenna. By changing the operating parameters, e.g., working pressure, drive frequency, input power, radius of glass tube, length of plasma column, and argon gas, single plasma antenna (plasma column) can be transformed to multiple small antenna elements (plasma blobs). It is also reported that number, length, and separation between two antenna elements can be controlled by operating parameters. Moreover, experiments are also carried out to study current profile, potential profile, conductivity profile, phase relations, radiation power patterns, etc. of the antenna elements. The effect on directivity with the number of antenna elements is also studied. Findings of the study indicate that entire structure of antenna elements can be treated as a phased array broadside vertical plasma antenna, which produces more directive radiation pattern than the single plasma antenna as well as physical properties and directivity of such antenna can be controlled by operating parameters. The study reveals the advantages of a plasma antenna over the conventional antenna in the sense that different antennas can be formed by tuning the operating parameters.

  15. Power Exhaust in Fusion Plasmas

    NASA Astrophysics Data System (ADS)

    Fundamenski, Wojciech

    2014-07-01

    Preface; 1. Introduction; 2. Magnetized plasma physics; 3. Magnetized plasma equilibrium; 4. Magnetized plasma stability; 5. Collisional transport in magnetized plasmas; 6. Turbulent transport in magnetized plasmas; 7. Tokamak plasma boundary and power exhaust; 8. Outlook: power exhaust in fusion reactors; Appendix A. Maxwellian distribution; Appendix B. Curvilinear co-ordinates; References; Index.

  16. Afterglow Complex Plasma

    SciTech Connect

    Samarian, A. A.; Boufendi, L.; Mikikian, M.

    2008-09-07

    The review of the first detailed experimental and theoretical studies of complex plasma in RF discharge afterglow is presented. The studies have been done in a frame of FAST collaborative research project between Complex Plasma Laboratory of the University of Sydney and the GREMI laboratory of Universite d'Orleans. We examined the existing models of plasma decay, presents experimental observations of dust dynamics under different afterglow complex plasma conditions, presents the experimental data obtained (in particular the presence of positively charged particles in discharge afterglow), discusses the use of dust particles as a probe to study the diffusion losses in afterglow plasmas.

  17. Mirror plasma apparatus

    DOEpatents

    Moir, Ralph W.

    1981-01-01

    A mirror plasma apparatus which utilizes shielding by arc discharge to form a blanket plasma and lithium walls to reduce neutron damage to the wall of the apparatus. An embodiment involves a rotating liquid lithium blanket for a tandem mirror plasma apparatus wherein the first wall of the central mirror cell is made of liquid lithium which is spun with angular velocity great enough to keep the liquid lithium against the first material wall, a blanket plasma preventing the lithium vapor from contaminating the plasma.

  18. Ultracold neutral plasmas

    NASA Astrophysics Data System (ADS)

    Rolston, Steven L.

    2008-07-01

    Plasmas are normally thought of as high temperature ionized gases or fluids, such as those in the sun's corona or those found in controlled nuclear fusion experiments. Many interesting plasma phenomena can occur, however, in plasmas at low temperature. With the help of laser trapping and cooling, atoms can be photoionized to form neutral plasmas at extremely low temperatures. These plasmas may exist in the so-called strong coupling regime, where the energy of the Coulomb interactions between particles is larger than their thermal energy. In addition to providing a test bed for studying the strongly coupled plasmas such as those found in Jovian planets and white dwarfs, ultracold plasmas play a critical role in understanding the formation of antihydrogen.

  19. Plasma contactor research, 1989

    NASA Technical Reports Server (NTRS)

    Williams, John D.

    1990-01-01

    The characteristics of double layers observed by researchers investigating magnetospheric phenomena are contrasted to those observed in plasma contacting experiments. Experiments in the electron collection mode of the plasma contacting process were performed and the results confirm a simple model of this process for current levels ranging to 3 A. Experimental results were also obtained in a study of the process of electron emission from a hollow cathode plasma contactor. High energy ions are observed coming from the cathode in addition to the electrons and a phenomenological model that suggests a mechanism by which this could occur is presented. Experimental results showing the effects of the design parameters of the ambient plasma simulator on the plasma potential, electron temperature, electron density and plasma noise levels induced in plasma contacting experiments are presented. A preferred simulator design is selected on the basis of these results.

  20. Plasmas for medicine

    NASA Astrophysics Data System (ADS)

    von Woedtke, Th.; Reuter, S.; Masur, K.; Weltmann, K.-D.

    2013-09-01

    Plasma medicine is an innovative and emerging field combining plasma physics, life science and clinical medicine. In a more general perspective, medical application of physical plasma can be subdivided into two principal approaches. (i) “Indirect” use of plasma-based or plasma-supplemented techniques to treat surfaces, materials or devices to realize specific qualities for subsequent special medical applications, and (ii) application of physical plasma on or in the human (or animal) body to realize therapeutic effects based on direct interaction of plasma with living tissue. The field of plasma applications for the treatment of medical materials or devices is intensively researched and partially well established for several years. However, plasma medicine in the sense of its actual definition as a new field of research focuses on the use of plasma technology in the treatment of living cells, tissues, and organs. Therefore, the aim of the new research field of plasma medicine is the exploitation of a much more differentiated interaction of specific plasma components with specific structural as well as functional elements or functionalities of living cells. This interaction can possibly lead either to stimulation or inhibition of cellular function and be finally used for therapeutic purposes. During recent years a broad spectrum of different plasma sources with various names dedicated for biomedical applications has been reported. So far, research activities were mainly focused on barrier discharges and plasma jets working at atmospheric pressure. Most efforts to realize plasma application directly on or in the human (or animal) body for medical purposes is concentrated on the broad field of dermatology including wound healing, but also includes cancer treatment, endoscopy, or dentistry. Despite the fact that the field of plasma medicine is very young and until now mostly in an empirical stage of development yet, there are first indicators of its enormous economic potential. This ambivalent situation fundamentally requires a responsible use of plasma sources, which are specifically designated for biomedical applications. To enable physicians as well as life scientists to decide whether a given plasma source is really suitable for medical applications or biological experiments, a meaningful and mandatory spectrum of indicators has to be compiled to allow for a basic estimation of the potential of this plasma source.

  1. Electronegative Plasma Instabilities in Pulsed Plasmas

    NASA Astrophysics Data System (ADS)

    Pribyl, Patrick; Gekelman, Walter

    2015-09-01

    Modern inductively coupled plasma reactors can all be operated in unstable configurations, although in many cases normal precautions result in quiescent stable operation. However, electronegative gases that are important for etch processes have a series of instabilities that occur at process relevant conditions. These have been studied since the 1990s, but are becoming a much more important today as plasma reactors are being pushed to produce ever finer features, and tight control of the etch process is becoming crucial. A device at UCLA was designed to simulate industrial reactors used in semiconductor processing. Various gas mixtures are programmable (Ar, SF6, O2). ICP coils in different configurations are driven by pulsed RF generators operating separately from 400 kHz to 40 MHz. A stainless steel ``chuck'' assembly can be positioned at a variable height, either with a wafer and RF bias, or with direct DC bias to directly program sheath voltage. A computer controlled automated probe drive can access the entire volume above the substrate. The probe can be a Langmuir probe, a ``Bdot'' probe, or an emissive probe the latter used for more accurate determination of plasma potential. A microwave interferometer is available to measure line-averaged electron density. Optical emission can be diagnosed using a half or 1 meter spectrometer. We describe work with electronegative gases to characterize and potentially stabilize the plasma against ionization instabilities using pulsed plasmas. Work supported by NSF and done at the Basic Plasma Science Facility.

  2. Plasma Biomedicine in Orthopedics

    NASA Astrophysics Data System (ADS)

    Hamaguchi, Satsohi

    2012-10-01

    Various effects of plasmas irradiation on cells, tissues, and biomaterials relevant for orthopedic applications have been examined. For direct application of plasmas to living cells or tissues, dielectric barrier discharges (DBDs) with helium flows into ambient air were used. For biomaterial processing, on the other hand, either helium DBDs mentioned above or low-pressure discharges generated in a chamber were used. In this presentation, plasma effects on cell proliferation and plasma treatment for artificial bones will be discussed. First, the conditions for enhanced cell proliferation in vitro by plasma applications have been examined. The discharge conditions for cell proliferation depend sensitively on cell types. Since cell proliferation can be enhanced even when the cells are cultured in a plasma pre-treated medium, long-life reactive species generated in the medium by plasma application or large molecules (such as proteins) in the medium modified by the plasma are likely to be the cause of cell proliferation. It has been found that there is strong correlation between (organic) hydroperoxide generation and cell proliferation. Second, effects of plasma-treated artificial bones made of porous hydroxyapatite (HA) have been examined in vitro and vivo. It has been found that plasma treatment increases hydrophilicity of the surfaces of microscopic inner pores, which directly or indirectly promotes differentiation of mesenchymal stem cells introduced into the pores and therefore causes faster bone growth. The work has been performed in collaboration with Prof. H. Yoshikawa and his group members at the School of Medicine, Osaka University.

  3. Flowing Magnetized Plasma experiment

    NASA Astrophysics Data System (ADS)

    Wang, Zhehui; Si, Jiahe

    2006-10-01

    Results from the Flowing Magnetized Plasma experiment at Los Alamos are summarized. Plasmas are produced using a modified coaxial plasma gun with a center electrode extending into a cylindrical vacuum tank with 0.75 m in radius and 4.5 m long. The basic diagnostics are Bdot probes for edge and internal magnetic field, Mach probes and Doppler spectroscopy for plasma flow in the axial and azimuthal directions, and Langmuir probes for plasma floating potential, electron density and temperature. We have found two different plasma flow patterns associated with distinct IV characteristics of the coaxial plasma gun, indicating axial flow is strongly correlated with the plasma ejection from the plasma gun. Global electromagnetic oscillations at frequencies below ion cyclotron frequency are observed, indicating that familiar waves at these frequencies, e.g. Alfven wave or drift wave, are strongly modified by the finite plasma beta. We eliminate the possibility of ion sound waves since the ion and electron temperatures are comparable, and therefore, ion sound waves are strongly Landau damped.

  4. What is a plasma?

    SciTech Connect

    Intrator, Thomas P.

    2012-08-30

    This introduction will define the plasma fourth state of matter, where we find plasmas on earth and beyond, and why they are useful. There are applications to many consumer items, fusion energy, scientific devices, satellite communications, semiconductor processing, spacecraft propulsion, and more. Since 99% of our observable universe is ionized gas, plasma physics determines many important features of astrophysics, space physics, and magnetosphere physics in our solar system. We describe some plasma characteristics, examples in nature, some useful applications, how to create plasmas. A brief introduction to the theoretical framework includes the connection between kinetic and fluid descriptions, quasi neutrality, Debye shielding, ambipolar electric fields, some plasma waves. Hands-on demonstrations follow. More complete explanations will follow next week.

  5. Plasma in dentistry

    PubMed Central

    Cha, Seunghee; Park, Young-Seok

    2016-01-01

    This review describes the contemporary aspects of plasma application in dentistry. Previous studies on plasma applications were classified into two categories, surface treatment and direct applications, and were reviewed, respectively according to the approach. The current review discussed modification of dental implant surface, enhancing of adhesive qualities, enhancing of polymerization, surface coating and plasma cleaning under the topics of surface treatment. Microbicidal activities, decontamination, root canal disinfection and tooth bleaching were reviewed as direct applications with other miscellaneous ones. Non-thermal atmospheric pressure plasma was of particular focus since it is gaining considerable attention due to the possibility for its use in living tissues. Future perspectives have also been discussed briefly. Although it is still not popular among dentists, plasma has shown promises in several areas of dentistry and is now opening a new era of plasma dentistry. PMID:27030818

  6. Divertor plasma detachment

    NASA Astrophysics Data System (ADS)

    Krasheninnikov, S. I.; Kukushkin, A. S.; Pshenov, A. A.

    2016-05-01

    Regime with the plasma detached from the divertor targets (detached divertor regime) is a natural continuation of the high recycling conditions to higher density and stronger impurity radiation loss. Both the theoretical considerations and experimental data show clearly that the increase of the impurity radiation loss and volumetric plasma recombination causes the rollover of the plasma flux to the target when the density increases, which is the manifestation of detachment. Plasma-neutral friction (neutral viscosity effects), although important for the sustainment of high density/pressure plasma upstream and providing the conditions for efficient recombination and power loss, is not directly involved in the reduction of the plasma flux to the targets. The stability of detachment is also discussed.

  7. Plasma cell cheilitis.

    PubMed

    Rocha, N; Mota, F; Horta, M; Lima, O; Massa, A; Sanches, M

    2004-01-01

    Plasma cell cheilitis is a rare inflammatory disorder of the lip with a characteristic band-like infiltrate of plasma cells in the upper dermis. Differential diagnosis should consider allergic/irritant contact cheilitis, candidiasis, syphilis, Queyrat's erythroplasia, granulomatous cheilitis, plasmoacanthoma, plasmacytoma, squamous cell carcinoma and exfoliative or factitious cheilitis. We observed plasma cell cheilitis in a 60-year-old Caucasian female who had a partial response to topical steroids and oral griseofulvin. PMID:14678543

  8. Space plasma physics research

    NASA Technical Reports Server (NTRS)

    Comfort, Richard H.; Horwitz, James L.

    1993-01-01

    During the course of this grant, work was performed on a variety of topics and there were a number of significant accomplishments. A summary of these accomplishments is included. The topics studied include empirical model data base, data reduction for archiving, semikinetic modeling of low energy plasma in the inner terrestrial magnetosphere and ionosphere, O(+) outflows, equatorial plasma trough, and plasma wave ray-tracing studies. A list of publications and presentations which have resulted from this research is also included.

  9. Plasma Processing Of Hydrocarbon

    SciTech Connect

    Grandy, Jon D; Peter C. Kong; Brent A. Detering; Larry D. Zuck

    2007-05-01

    The Idaho National Laboratory (INL) developed several patented plasma technologies for hydrocarbon processing. The INL patents include nonthermal and thermal plasma technologies for direct natural gas to liquid conversion, upgrading low value heavy oil to synthetic light crude, and to convert refinery bottom heavy streams directly to transportation fuel products. Proof of concepts has been demonstrated with bench scale plasma processes and systems to convert heavy and light hydrocarbons to higher market value products. This paper provides an overview of three selected INL patented plasma technologies for hydrocarbon conversion or upgrade.

  10. Planetary plasma waves

    NASA Technical Reports Server (NTRS)

    Gurnett, Donald A.

    1993-01-01

    The primary types of plasma waves observed in the vicinity of the planets Venus, Mars, Earth, Jupiter, Saturn, Uranus, and Neptune are described. The observations are organized according to the various types of plasma waves observed, ordered according to decreasing distance from the planet, starting from the sunward side of the planet, and ending in the region near the closest approach. The plasma waves observed include: electron plasma oscillations and ion acoustic waves; trapped continuum radiation; electron cyclotron and upper hybrid waves; whistler-mode emissions; electrostatic ion cyclotron waves; and electromagnetic ion cyclotron waves.

  11. Solid expellant plasma generator

    NASA Technical Reports Server (NTRS)

    Stone, Nobie H. (Inventor); Poe, Garrett D. (Inventor); Rood, Robert (Inventor)

    2010-01-01

    An improved solid expellant plasma generator has been developed. The plasma generator includes a support housing, an electrode rod located in the central portion of the housing, and a mass of solid expellant material that surrounds the electrode rod within the support housing. The electrode rod and the solid expellant material are made of separate materials that are selected so that the electrode and the solid expellant material decompose at the same rate when the plasma generator is ignited. This maintains a point of discharge of the plasma at the interface between the electrode and the solid expellant material.

  12. Princeton Plasma Physics Laboratory

    SciTech Connect

    Not Available

    1990-01-01

    This report discusses the following topics: principal parameters achieved in experimental devices fiscal year 1990; tokamak fusion test reactor; compact ignition tokamak; Princeton beta experiment- modification; current drive experiment-upgrade; international collaboration; x-ray laser studies; spacecraft glow experiment; plasma processing: deposition and etching of thin films; theoretical studies; tokamak modeling; international thermonuclear experimental reactor; engineering department; project planning and safety office; quality assurance and reliability; technology transfer; administrative operations; PPPL patent invention disclosures for fiscal year 1990; graduate education; plasma physics; graduate education: plasma science and technology; science education program; and Princeton Plasma Physics Laboratory reports fiscal year 1990.

  13. [Therapeutic plasmas available worldwide].

    PubMed

    Martinaud, C; Cauet, A; Sailliol, A

    2013-05-01

    Therapeutic plasma is a current product; French guidelines were reviewed in 2012. Connections between more or less closed countries are frequent, during relief disasters as well as in war settings. This is associated with the increasing use of plasma in the management of casualties. Additionally, The real possibility of lack of plasma supply in some countries provides a fundamental interest of the knowledge of foreign blood supply organizations. We present here the main divergences and mutual point between plasmas available worldwide. We present the main characteristics of each product. PMID:23522688

  14. Laser plasma diagnostics of dense plasmas

    SciTech Connect

    Glendinning, S.G.; Amendt, P.; Budil, K.S.; Hammel, B.A.; Kalantar, D.H.; Key, M.H.; Landen, O.L.; Remington, B.A.; Desenne, D.E.

    1995-07-12

    The authors describe several experiments on Nova that use laser-produced plasmas to generate x-rays capable of backlighting dense, cold plasmas (p {approximately} 1--3 gm/cm{sup 3}, kT {approximately} 5--10 eV, and areal density {rho}{ell}{approximately} 0.01--0.05 g/cm{sup 2}). The x-rays used vary over a wide range of h{nu}, from 80 eV (X-ray laser) to 9 keV. This allows probing of plasmas relevant to many hydrodynamic experiments. Typical diagnostics are 100 ps pinhole framing cameras for a long pulse backlighter and a time-integrated CCD camera for a short pulse backlighter.

  15. Laboratory Dipole Plasma Physics

    NASA Astrophysics Data System (ADS)

    Kesner, Jay

    2011-10-01

    Modern laboratory studies of plasma confined by a strong dipole magnet originated twenty years ago when it was learned that planetary magnetospheres have centrally-peaked plasma pressure profiles that form naturally when solar wind drives plasma circulation and heating. Unlike other internal rings devices, like spherators and octupoles, the magnetic flux tubes of the dipole field expand rapidly with radius. Unlike plasma confinement devices that obtain stability from magnetic shear and average good curvature, like tokamaks and levitrons, the dipole-confined plasma obtains stability from plasma compressibility. These two geometric characteristics of the dipole field have profound consequences: (i) plasma can be stable with local beta exceeding unity, (ii) fluctuations can drive either heat or particles inward to create stationary profiles that are strongly peaked, and (iii) the confinement of particles and energy can decouple. During the past decade, several laboratory dipole experiments and modeling efforts have lead to new understanding of interchange, centrifugal and entropy modes, nonlinear gyrokinetics, and plasma transport. Two devices, the LDX experiment at MIT and RT-1 at the University of Tokyo, operate with levitated superconducting dipole magnets. With a levitated dipole, not only is very high-beta plasma confined in steady state but, also, levitation produces high-temperature at low input power and demonstrates that toroidal magnetic confinement of plasma does not require a toroidal field. Modeling has explained many of the processes operative in these experiments, including the observation of a strong inward particle pinch. Turbulent low-frequency fluctuations in dipole confined plasma cause adiabatic transport and form a fundamental linkage between the radial variation of flux-tube volume and the centrally peaked density and pressure profiles. In collaboration with M.E. Mauel and D.T. Garnier; supported by DoE FG02-98ER54458.

  16. Self-energized plasma compressor. [for compressing plasma discharged from coaxial plasma generator

    NASA Technical Reports Server (NTRS)

    Shriver, E. L.; Igenbergs, E. B. (Inventor)

    1974-01-01

    The self-energized plasma compressor is described which compresses plasma discharged from a coaxial plasma generator. The device includes a helically shaped coil which is coaxially aligned with the center axis of the coaxial plasma generator. The plasma generator creates a current through the helical coil which, in turn, generates a time varying magnetic field that creates a force which acts radially upon the plasma. The coaxial plasma generator and helical coil move the plasma under high pressure and temperature to the narrow end of the coil. Positioned adjacent to the narrow end of the coil are beads which are engaged by the plasma to be accelerated to hypervelocities for simulating meteoroids.

  17. EDITORIAL: Plasma jets and plasma bullets Plasma jets and plasma bullets

    NASA Astrophysics Data System (ADS)

    Kong, M. G.; Ganguly, B. N.; Hicks, R. F.

    2012-06-01

    Plasma plumes, or plasma jets, belong to a large family of gas discharges whereby the discharge plasma is extended beyond the plasma generation region into the surrounding ambience, either by a field (e.g. electromagnetic, convective gas flow, or shock wave) or a gradient of a directionless physical quantity (e.g. particle density, pressure, or temperature). This physical extension of a plasma plume gives rise to a strong interaction with its surrounding environment, and the interaction alters the properties of both the plasma and the environment, often in a nonlinear and dynamic fashion. The plasma is therefore not confined by defined physical walls, thus extending opportunities for material treatment applications as well as bringing in new challenges in science and technology associated with complex open-boundary problems. Some of the most common examples may be found in dense plasmas with very high dissipation of externally supplied energy (e.g. in electrical, optical or thermal forms) and often in or close to thermal equilibrium. For these dense plasmas, their characteristics are determined predominantly by strong physical forces of different fields, such as electrical, magnetic, thermal, shock wave, and their nonlinear interactions [1]. Common to these dense plasma plumes are significant macroscopic plasma movement and considerable decomposition of solid materials (e.g. vaporization). Their applications are numerous and include detection of elemental traces, synthesis of high-temperature materials and welding, laser--plasma interactions, and relativistic jets in particle accelerators and in space [2]-[4]. Scientific challenges in the understanding of plasma jets are exciting and multidisciplinary, involving interweaving transitions of all four states of matter, and their technological applications are wide-ranging and growing rapidly. Using the Web of Science database, a search for journal papers on non-fusion plasma jets reveals that a long initial phase up to 1990 with only 31 papers per year on average, and a total of some 1300 papers, precedes a considerable growth of some 35-50% in research activity every five years, over the last 20 years or so. As shown in the table, the annual dissemination of the field is more than 1600 papers and the total number of papers is in excess of 20000. This upwards trajectory is typical of a strong and growing subject area in physical science, with considerable capacity in both fundamental science and applications. PeriodNumber of papersPapers per annum 1948-1990130031 1991-19952279456 1996-20003447689 2001-20054571914 2006-201066401328 2011 1658 In many of the dense plasma jets discussed above, strong physical forces generated by the plasma are often desired and this favours plasma generation at elevated gas pressure, including atmospheric pressure, which favours a high level of gas ionization. Historically it has been challenging to reduce and control the strong physical forces in high-pressure plasmas for applications where these are unwanted, for example, surface modification of polymeric sheets [5]. Indeed, there is a real need for a vast range of material processing applications at temperatures below 100oC (or below 400 K) and this favours atmospheric-pressure plasma jets sustained far from thermal equilibrium with the dissipated electrical energy largely used not in heat generation but in unleashing non-equilibrium chemical reactions. The long-standing difficulty of effectively controlling the level of gas ionization at atmospheric pressure was overcome by the technological breakthrough of achieving atmospheric-pressure glow discharges in the late 1980s [6]. A related challenge stemming from high collisionality of atmospheric-pressure plasmas (v >> ω0) means that large-area plasmas sustained between parallel-plate electrodes are very susceptible to strong plasma instabilities when molecular gases are introduced for processing applications. This led to an effective technological solution in the early to late 1990s of confining atmospheric plasmas in a small volume of plasma generation (i.e. with a small volume-to-surface ratio) and then extending it towards a downstream sample [7]-[9]. These are among the first low-temperature atmospheric plasmas aimed particularly at the exploitation of their ability to invoke the active and rich reactive chemistry close to ambient temperature. The main applications of these early devices are precision surface modification of low-temperature dielectric materials, for example thin film deposition and etching [7]-[9]. Variations of the early plasma jets include atmospheric plasma sheet jets [10] for the treatment of largely planar objects (e.g. polymeric sheets) as well as large arrays of many plasma jets for the treatment of complex-structured objects (e.g. surgical tools and open human wounds) [11]. As a material processing technology, the sub-100oC atmospheric-pressure plasma jet has benefited over the years from many innovations. Whilst a detailed account and analysis of these is clearly outside the scope of this Editorial, it is worth stating that there are different avenues with which to maintain a moderate electron density at the plasma core so as to keep the gas temperature at the sample point below a ceiling level. Most of the early studies employed excitation at radio frequencies above 10 MHz, at which electrons are largely confined in the plasma generation region, and this limits the current flow to and gas heating in the plume region of the plasma jet. Other techniques of current limitation have since been shown to be effective, including the use of dielectric barriers across a very large frequency range of 1 kHz--50 MHz, sub-microsecond pulses sustained at kHz frequencies, pulse-modulated radio frequencies and dual-frequency excitation [12]-[15]. These and other techniques have considerably advanced the atmospheric-pressure plasma jet technology. The period of some 15 years since the above-mentioned early studies has witnessed a considerable and exciting growth in terms of new phenomena observed, new physics and chemistry uncovered, new plasma jet sources conceived, and new applications developed. Examples include the observations of plasma bullets on a nanosecond scale [16], the similarity of plasma bullets to streamers [17], arrays of plasma jets as metamaterials [18], and a rapid increase of applications in biomedicine [19]. However the considerable growth in the research of plasma jets has not been adequately supported, so far, by a sound fundamental underpinning, partly resulting from a somewhat underdevelopment of effective diagnostics and modelling tools. Recognizing the critical importance of basic science for future growth of low-temperature plasma jet technology, this special issue on plasma jets and bullets aims to address some of the most important fundamental questions. Many of the special issue papers continue the established line of investigation to characterize the formation of plasma bullets, using typically ultrafast imaging, electrical detection including electric field and plasma conductivity measurement, and optical emission spectrometry [20]-[26]. These offer strong experimental evidence for the well-known hypothesis that a plasma jet is a form of streamer, and that the ionization wave plays a critical role in their formation. The interaction of two parallel plasma jets [27] and manipulation of plasma jet characteristics [28, 29] are also reported using a similar combination of experimental techniques. Some of the common characteristics of plasma jets are summarized in a review paper in this special issue [30]. A somewhat different line of investigation is employed in a detailed experimental characterization of deterministic chaos in atmospheric plasma jets [31], one of the few non-bullet modes of plasma jets. Although chaos in ionized gases have been observed in other types of discharge plasmas, their applications have not so far been linked to material processing applications, possibly because chaotic patterns of reaction chemistry could be undesirable for sample-sample reproducibility of application efficacy. Nevertheless, the lack of reproducibility in the presence of chaos may actually offer an advantage in tackling drug resistance in the new field of plasma medicine. As a material processing tool, it is important to characterize the reaction chemistry of plasma jets at a downstream point. Four special issue papers report measurement of argon and helium metastable atoms, ozone, oxygen atoms and UV irradiation using a variety of diagnostic tools including laser absorption spectroscopy, molecular beam mass spectrometry, optical emission and UV absorption spectrometry [32]-[35]. There is, however, a gap in these measurements of key reactive plasma species and characterization of plasma bullet formation [20]-[26], both in this special issue and elsewhere in the literature. Whilst atmospheric plasma modes are known to operate in bullet and non-bullet modes, it is unclear whether electron excitation of helium and/or argon metastables is different in the bullet mode from the non-bullet mode. Similarly, it remains little known whether the bullet mode facilitates a particularly efficient production of reactive plasma species [36]. An encouraging sign of our ability to address this and other knowledge gaps is evident from three excellent modelling investigations, looking into the behaviours of ionization waves [37], interaction of two counter-propagating streamers [38], and the two-dimensional structure of streamers [39]. Considerable detail unravelled from these and similar simulation studies is likely to not only uncover the physics of plasma bullet formation, but also link it to the design and manipulation of downstream reaction chemistry. In fact, very recent studies have combined experimental characterization of plasma jets with their numerical modelling [40].

  18. Microwave interactions with plasmas

    NASA Astrophysics Data System (ADS)

    Eckstrom, D. J.; Vidmar, R. J.; Stalder, K. R.

    1992-04-01

    Microwave interactions with a cold, collisional plasma having gradual density gradients were studied. The plasma was created by the photoionization of tetrakisdimethylaminoethylene (TMAE) vapor seeded into atmospheric pressure helium. Photoionization was provided primarily by sparkboard Spatial scans of the absorption of a microwave probe beam along chords across the plasma, with subsequent Abel inversion. Three-dimensional plasma density profiles were obtained that showed a gradual decrease in the peak plasma density versus distance away from the sparkboard. When a 58cm-diameter reflector was illuminated with 10-GHz microwaves in an anechoic chamber, the plasma sorbed as much as 28 dB in direct reflection, with similar attenuation of the normally weak side-scattered and cross-polarized radiation. The attenuation was compared with model predictions. Detailed analysis of the temporal and spatial dependence of the electron density following ionization indicated that both recombination and attachment processes influenced the plasma decay. The recombination rate of TMAE was found to be (9.0 +/- 1.1) x 10(exp -6) cm3 s(exp -1) for 300 K electrons. This work confirms the effectiveness of a cold, collisional plasma as a broadband, switchable wave absorber.

  19. Atoms in dense plasmas

    SciTech Connect

    More, R.M.

    1986-01-01

    Recent experiments with high-power pulsed lasers have strongly encouraged the development of improved theoretical understanding of highly charged ions in a dense plasma environment. This work examines the theory of dense plasmas with emphasis on general rules which govern matter at extreme high temperature and density. 106 refs., 23 figs.

  20. Plasma technology directory

    SciTech Connect

    Ward, P.P.; Dybwad, G.L.

    1995-03-01

    The Plasma Technology Directory has two main goals: (1) promote, coordinate, and share plasma technology experience and equipment within the Department of Energy; and (2) facilitate technology transfer to the commercial sector where appropriate. Personnel are averaged first by Laboratory and next by technology area. The technology areas are accelerators, cleaning and etching deposition, diagnostics, and modeling.

  1. The origins of 'plasma'

    NASA Astrophysics Data System (ADS)

    Braithwaite, Nicholas

    2008-12-01

    I agree with Raoul Franklin (November p22) that although the quest for controlled thermonuclear fusion opened up a new branch of plasma physics, the field itself is considerably older, dating back at least as far as 1928 when Irving Langmuir coined the term "plasma" to describe a neutral, ionized gas.

  2. Diamagnetism of rotating plasma

    SciTech Connect

    Young, W. C.; Hassam, A. B.; Romero-Talamas, C. A.; Ellis, R. F.; Teodorescu, C.

    2011-11-15

    Diamagnetism and magnetic measurements of a supersonically rotating plasma in a shaped magnetic field demonstrate confinement of plasma pressure along the magnetic field resulting from centrifugal force. The Grad-Shafranov equation of ideal magnetohydrodynamic force balance, including supersonic rotation, is solved to confirm that the predicted angular velocity is in agreement with spectroscopic measurements of the Doppler shifts.

  3. Plasma treatment of wood

    NASA Astrophysics Data System (ADS)

    Volokitin, G. G.; Skripnikova, N. K.; Sinitsyn, V. A.; Volokitin, O. G.; Shekhovtsov, V. V.; Vaschenko, S. P.; Kuz'min, V. I.

    2016-01-01

    Plasma technology was developed to create protective-decorative coatings on the wood surfaces. Experimental investigation on applying the protective coating using the low-temperature plasma energy as well as studies of the distribution of temperature fields over the section of the treated workpiece have been carried out, and the calculated results have been compared with the experimental data.

  4. Madison Plasma Dynamo Experiment

    NASA Astrophysics Data System (ADS)

    Kostadinova, Evdokiya; Forest, C.; Cooper, C.; Coquerel, M.

    2014-01-01

    The Madison Plasma Dynamo Experiment (MPDX) is investigating the self-generation of magnetic fields and related processes in a large, weakly magnetized, fast flowing, and hot (conducting) plasma. The dynamo re-creates conditions highly similar to many astrophysical plasmas. Stars and other planets have dynamos, and so do galaxies and clusters of galaxies, which makes it extremely crucial for researchers in the field to carry out experiments in this previously uninvestigated plasma regime, which will help for the development of a comprehensive theory of how magnetic fields are generated in planets, the Sun and other stars. MPDX is a laboratory astrophysical experiment where 200,000-degree Fahrenheit plasma is confined within a three-meter diameter spherical aluminum vacuum chamber with the help of multiple tracks of cusp magnets covering the inside shell. The dynamo utilizes six robotic insertion sweep probes that are programmed to find any point inside the sphere by given radial and angular coordinates. This innovative mechanical system allows us to take measurements of the state variables in key points in the plasma flow and to better investigate its cosmic-like plasma behavior. The probes are able to autonomously calculate coordinate transformations, move in a two dimensional plane, and return information about their relative position. This makes them an extremely useful, highly accurate, and easily controlled tool for plasma analysis.

  5. Plasma engineering for MARS

    SciTech Connect

    Carlson, G.A.; Baldwin, D.E.; Barr, W.L.

    1983-03-24

    The two-year Mirror Advanced Reactor Study (MARS) has resulted in the conceptual design of a commercial, electricity-producing fusion reactor based on tandem mirror confinement. The physics basis for the MARS reactor was developed through work in two highly coupled areas of plasma engineering: magnetics and plasma performance.

  6. Plasma thrusters from Russia

    SciTech Connect

    Lerner, E.J.

    1992-09-01

    A report on the Russian stationary plasma thrusters having plasma accelerated to high velocities by electrical and magnetic forces is described. For specific impulses of 15-20 km/sec, optimal for such applications as satellite station keeping and orbital transfer, a unit supplying 0.05 N from a 2-kW input has a 30-cm-diameter nozzle.

  7. Triggered plasma opening switch

    DOEpatents

    Mendel, Clifford W.

    1988-01-01

    A triggerable opening switch for a very high voltage and current pulse includes a transmission line extending from a source to a load and having an intermediate switch section including a plasma for conducting electrons between transmission line conductors and a magnetic field for breaking the plasma conduction path and magnetically insulating the electrons when it is desired to open the switch.

  8. Introduction to Quantum Plasmas

    NASA Astrophysics Data System (ADS)

    Bonitz, Michael; Filinov, Alexei; Böning, Jens; Dufty, James W.

    Plasmas are generally associated with a hot gas of charged particles which behave classically. However, when the temperature is lowered and/or the density is increased sufficiently, the plasma particles (most importantly, electrons) become quantum degenerate, that is, the extension of their wave functions becomes comparable to the distance between neighboring particles. This is the case in many astrophysical plasmas, such as those occurring in the interior of giant planets or dwarf and neutron stars, but also in various modern laboratory setups where charged particles are compressed by very intense ion or laser beams to multi-megabar pressures. Furthermore, quantum plasmas exist in solids - examples are the electron gas in metals and the electron-hole plasma in semiconductors. Finally, the exotic state of the Universe immediately after the Big Bang is believed to have been a quantum plasma consisting of electrons, quarks, photons, and gluons. In all these situations, a description in terms of classical mechanics, thermodynamics, or classical kinetic theory fails. In this chapter, an overview of quantum plasma features and their occurrence is given. The conditions for the relevance of quantum effects are formulated and discussed. The key concepts for a theoretical description of quantum plasmas are developed and illustrated by simple examples.

  9. Partially ionized plasmas, including the Third Symposium on Uranium Plasmas

    NASA Technical Reports Server (NTRS)

    Krishnan, M.

    1976-01-01

    Fundamentals of both electrically and fission generated plasmas are discussed. Research in gaseous fuel reactors using uranium hexafluoride is described and other partially ionized plasma applications are discussed.

  10. Diagnostics of Nanodusty Plasma

    NASA Astrophysics Data System (ADS)

    Greiner, Franko; Groth, Sebastian; Tadsen, Bejamin; Piel, Alexander

    2015-11-01

    The diagnostic of nanodusty plasmas, i.e. plasmas including nano-sized dust particles, is a challenging task. For both, the diagnostic of the nanodusty plasma itself, and the in-situ diagnostic of the nanoparticles, no standard diagnostic exist. Nanodust particle size and density can be estimated using light scattering techniques, namely kinetic Mie ellipsometry and extinction measurements. The charge of the nanoparticles can be estimated from the analysis of dust density waves (DDW). Parameters like the electron density, which give information about the plasma itself, may be deduced from the DDW analysis. We present detailed investigations on nanodust in a reactive Argon-Acetylene plasma created in an rf-driven parallel plate reactor at low pressure using the above mentioned portfolio of diagnostic. Funded by DFG under contract SFB TR-24/A2.

  11. Innovations in plasma sensors

    NASA Astrophysics Data System (ADS)

    Zurbuchen, Thomas H.; Gershman, Daniel J.

    2016-04-01

    During the history of space exploration, ever improving instruments have continued to enable new measurements and discoveries. Focusing on plasma sensors, we examine the processes by which such new instrument innovations have occurred over the past decades. Due to risk intolerance prevalent in many NASA space missions, innovations in plasma instrumentation occur primarily when heritage systems fail to meet science requirements, functional requirements as part of its space platform, or design constraints. We will review such innovation triggers in the context of the design literature and with the help of two case studies, the Fast Imaging Plasma Spectrometer on MErcury Surface, Space ENvironment, GEochemistry, and Ranging and the Fast Plasma Investigation on Magnetosphere Multiscale. We will then discuss the anticipated needs for new plasma instrument innovations to enable the science program of the next decade.

  12. Weakly relativistic plasma expansion

    SciTech Connect

    Fermous, Rachid Djebli, Mourad

    2015-04-15

    Plasma expansion is an important physical process that takes place in laser interactions with solid targets. Within a self-similar model for the hydrodynamical multi-fluid equations, we investigated the expansion of both dense and under-dense plasmas. The weakly relativistic electrons are produced by ultra-intense laser pulses, while ions are supposed to be in a non-relativistic regime. Numerical investigations have shown that relativistic effects are important for under-dense plasma and are characterized by a finite ion front velocity. Dense plasma expansion is found to be governed mainly by quantum contributions in the fluid equations that originate from the degenerate pressure in addition to the nonlinear contributions from exchange and correlation potentials. The quantum degeneracy parameter profile provides clues to set the limit between under-dense and dense relativistic plasma expansions at a given density and temperature.

  13. Plasma Astrophysics, second edition

    NASA Astrophysics Data System (ADS)

    Benz, Arnold

    2002-06-01

    This thoroughly revised textbook is a basic introduction to plasma phenomena in solar and stellar coronae emphasizing non-MHD aspects. The natural way in which the author unifies observations and theory gives a wide perspective to the subject. An important feature is the lucidly written presentation of the fundamentals of plasma physics. The basic theory thus developed is then extended to some exemplary and important observations of coronal dynamics, such as coronal currents, particle acceleration, propagation of particle beams, and shocks. The book has grown from teaching introductory courses on plasma astrophysics at the Swiss Federal Institute of Technology (ETH). It addresses advanced undergraduates and first-year graduate students without a background in plasma physics. It will also be of interest to more senior research workers involved in coronal physics of the Sun and other stars, solar/stellar winds, and various other fields of plasma astrophysics.

  14. Solar system plasma waves

    NASA Technical Reports Server (NTRS)

    Gurnett, Donald A.

    1995-01-01

    An overview is given of spacecraft observations of plasma waves in the solar system. In situ measurements of plasma phenomena have now been obtained at all of the planets except Mercury and Pluto, and in the interplanetary medium at heliocentric radial distances ranging from 0.29 to 58 AU. To illustrate the range of phenomena involved, we discuss plasma waves in three regions of physical interest: (1) planetary radiation belts, (2) planetary auroral acceleration regions and (3) the solar wind. In each region we describe examples of plasma waves that are of some importance, either due to the role they play in determining the physical properties of the plasma, or to the unique mechanism involved in their generation.

  15. Effective plasma inductance computation

    SciTech Connect

    Maslovsky, Dmitry A.; Boozer, Allen H.

    2005-04-15

    The calculation of the resistive wall modes and their feedback stabilization is greatly simplified by splitting the plasma response from that of the external conductors. Existing calculations either consider highly simplified models of the external conductors or assume the plasma response can be approximated by a single rigid mode. The full response of an ideal, nonrotating plasma to perturbations that evolve slowly compared to the Alfven time is contained in the matrix for the effective plasma inductance {lambda}<=>. This matrix can be used in a code that accurately calculates the effects of the external conductors to obtain an essentially complete description of both plasma and the conducting structures. Calculations of {lambda}<=> for a number of tokamak equilibria are given together with an explanation of how the calculations are made and why they are important.

  16. Helical plasma thruster

    NASA Astrophysics Data System (ADS)

    Beklemishev, A. D.

    2015-10-01

    A new scheme of plasma thruster is proposed. It is based on axial acceleration of rotating magnetized plasmas in magnetic field with helical corrugation. The idea is that the propellant ionization zone can be placed into the local magnetic well, so that initially the ions are trapped. The E × B rotation is provided by an applied radial electric field that makes the setup similar to a magnetron discharge. Then, from the rotating plasma viewpoint, the magnetic wells of the helically corrugated field look like axially moving mirror traps. Specific shaping of the corrugation can allow continuous acceleration of trapped plasma ions along the magnetic field by diamagnetic forces. The accelerated propellant is expelled through the expanding field of magnetic nozzle. By features of the acceleration principle, the helical plasma thruster may operate at high energy densities but requires a rather high axial magnetic field, which places it in the same class as the VASIMR® rocket engine.

  17. Plasma opening switch

    DOEpatents

    Savage, Mark E.; Mendel, Jr., Clifford W.

    2001-01-01

    A command triggered plasma opening switch assembly using an amplification stage. The assembly surrounds a coaxial transmission line and has a main plasma opening switch (POS) close to the load and a trigger POS upstream from the main POS. The trigger POS establishes two different current pathways through the assembly depended on whether it has received a trigger current pulse. The initial pathway has both POS's with plasma between their anodes and cathodes to form a short across the transmission line and isolating the load. The final current pathway is formed when the trigger POS receives a trigger current pulse which energizes its fast coil to push the conductive plasma out from between its anode and cathode, allowing the main transmission line current to pass to the fast coil of the main POS, thus pushing its plasma out the way so as to establish a direct current pathway to the load.

  18. SHEET PLASMA DEVICE

    DOEpatents

    Henderson, O.A.

    1962-07-17

    An ion-electron plasma heating apparatus of the pinch tube class was developed wherein a plasma is formed by an intense arc discharge through a gas and is radially constricted by the magnetic field of the discharge. To avoid kink and interchange instabilities which can disrupt a conventional arc shortiy after it is formed, the apparatus is a pinch tube with a flat configuration for forming a sheet of plasma between two conductive plates disposed parallel and adjacent to the plasma sheet. Kink instabilities are suppressed by image currents induced in the conductive plates while the interchange instabilities are neutrally stable because of the flat plasma configuration wherein such instabilities may occur but do not dynamically increase in amplitude. (AEC)

  19. SUPERFAST THERMALIZATION OF PLASMA

    DOEpatents

    Chang, C.C.

    1962-06-12

    A method is given for the superfast thermalization of plasma by shock conversion of the kinetic energy stored in rotating plasma rings or plasmoids colliding at near supersonic speeds in a containment field to heat energy in the resultant confined plasma mass. The method includes means for generating rotating plasmoids at the opposite ends of a Pyrotron or Astron containment field. The plasmoids are magnetically accelerated towards each other into the opposite ends of time containment field. During acceleration of the plasmoids toward the center of the containment field, the intensity of the field is sequentially increased to adiabatically compress the plasmoids and increase the plasma energy. The plasmoids hence collide with a violent shock at the eenter of the containment field, causing the substantial kinetic energy stored in the plasmoids to be converted to heat in the resultant plasma mass. (AEC)

  20. Plasma sheath criterion in thermal electronegative plasmas

    SciTech Connect

    Ghomi, Hamid; Khoramabadi, Mansour; Ghorannevis, Mahmod; Shukla, Padma Kant

    2010-09-15

    The sheath formation criterion in electronegative plasma is examined. By using a multifluid model, it is shown that in a collisional sheath there will be upper as well as lower limits for the sheath velocity criterion. However, the parameters of the negative ions only affect the lower limit.

  1. Waves in Space Plasmas Program

    NASA Technical Reports Server (NTRS)

    Fredricks, R. W.; Taylor, W. W. L.

    1981-01-01

    The Waves in Space Plasmas (WISP) program is a joint international effort involving instrumentation to be designed and fabricated by funding from NASA and the National Research Council of Canada. The instrumentation, with a tentatively planned payload for 1986, can be used to perturb the plasma with radio waves to solve problems in ionospheric, atmospheric, magnetospheric, and plasma physics. Among the ionospheric and plasma phenomena to be investigated using WISP instrumentation are VLF wave-particle interactions; ELF/VLF propagation; traveling ionospheric disturbances and gravity wave coupling; equatorial plasma bubble phenomena; plasma wave physics such as mode-coupling, dispersion, and instabilities; and plasma physics of the antenna-plasma interactions.

  2. Origins of magnetospheric plasma

    SciTech Connect

    Moore, T.E. )

    1991-01-01

    A review is given of recent (1987-1990) progress in understanding of the origins of plasmas in the earth's magnetosphere. In counterpoint to the early supposition that geomagnetic phenomena are produced by energetic plasmas of solar origin, 1987 saw the publication of a provocative argument that accelerated ionospheric plasma could supply all magnetospheric auroral and ring current particles. Significant new developments of existing data sets, as well as the establishment of entirely new data sets, have improved the ability to identify plasma source regions and to track plasma through the magnetospheric system of boundary layers and reservoirs. These developments suggest that the boundary between ionospheric and solar plasmas, once taken to lie at the plasmapause, actually lies much nearer to the magnetopause. Defining this boundary as the surface where solar wind and ionosphere contribute equally to the plasma, it is referred to herein as the 'geopause'. It is now well established that the infusion of ionospheric O(+) plays a major role in the storm-time distention of the magnetotail and inflation of the inner magnetosphere. After more than two decades of observation and debate, the question remains whether magnetosheric are protons of solar or terrestrial origin. 161 refs.

  3. Origins of magnetospheric plasma

    NASA Technical Reports Server (NTRS)

    Moore, Thomas E.

    1991-01-01

    A review is given of recent (1987-1990) progress in understanding of the origins of plasmas in the earth's magnetosphere. In counterpoint to the early supposition that geomagnetic phenomena are produced by energetic plasmas of solar origin, 1987 saw the publication of a provocative argument that accelerated ionospheric plasma could supply all magnetospheric auroral and ring current particles. Significant new developments of existing data sets, as well as the establishment of entirely new data sets, have improved the ability to identify plasma source regions and to track plasma through the magnetospheric system of boundary layers and reservoirs. These developments suggest that the boundary between ionospheric and solar plasmas, once taken to lie at the plasmapause, actually lies much nearer to the magnetopause. Defining this boundary as the surface where solar wind and ionosphere contribute equally to the plasma, it is referred to herein as the 'geopause'. It is now well established that the infusion of ionospheric O(+) plays a major role in the storm-time distention of the magnetotail and inflation of the inner magnetosphere. After more than two decades of observation and debate, the question remains whether magnetosheric are protons of solar or terrestrial origin.

  4. High energy plasma accelerators

    SciTech Connect

    Tajima, T.

    1985-05-01

    Colinear intense laser beams ..omega../sub 0/, kappa/sub 0/ and ..omega../sub 1/, kappa/sub 1/ shone on a plasma with frequency separation equal to the electron plasma frequency ..omega../sub pe/ are capable of creating a coherent large longitudinal electric field E/sub L/ = mc ..omega../sub pe//e of the order of 1GeV/cm for a plasma density of 10/sup 18/ cm/sup -3/ through the laser beat excitation of plasma oscillations. Accompanying favorable and deleterious physical effects using this process for a high energy beat-wave accelerator are discussed: the longitudinal dephasing, pump depletion, the transverse laser diffraction, plasma turbulence effects, self-steepening, self-focusing, etc. The basic equation, the driven nonlinear Schroedinger equation, is derived to describe this system. Advanced accelerator concepts to overcome some of these problems are proposed, including the plasma fiber accelerator of various variations. An advanced laser architecture suitable for the beat-wave accelerator is suggested. Accelerator physics issues such as the luminosity are discussed. Applications of the present process to the current drive in a plasma and to the excitation of collective oscillations within nuclei are also discussed.

  5. Plasma stabilization experiment

    NASA Astrophysics Data System (ADS)

    Sziklas, E. A.; Fader, W. J.; Jong, R. A.; Stufflebeam, J. H.

    1980-07-01

    The plasma stabilization experiment is an effort to enhance stability in a mirror-confined plasma by trapping cold ions with rf fields applied near the mirror throats. Nagoya Type 3 antennas, coupled to a 60 kW rf power supply are mounted in the throats of the UTRC baseball magnet. An external washer gun provides a source of plasma for both streaming and confined plasma tests. Results show a strong stoppering effect on streaming plasmas and a marginal effect on confined plasmas. Theoretical calculations provide an explanation for the experimental observations. The field generates a ponderomotive force acting on the electrons. The resultant improvement in electron confinement changes the ambipolar potential and inhibits the flow of ions through the mirror throat. Criteria are derived for the validity of this trapping concept. The requisite field strengths are significantly lower than those required to trap ions directly. Scaling laws are developed for application of cold ion trapping to large mirror devices containing dense plasmas. The use of slow-wave antenna structures operated at frequencies above the lower hybrid frequency is recommended for these applications.

  6. Stirring unmagnetized plasma.

    PubMed

    Collins, C; Katz, N; Wallace, J; Jara-Almonte, J; Reese, I; Zweibel, E; Forest, C B

    2012-03-16

    A new concept for spinning unmagnetized plasma is demonstrated experimentally. Plasma is confined by an axisymmetric multicusp magnetic field and biased cathodes are used to drive currents and impart a torque in the magnetized edge. Measurements show that flow viscously couples momentum from the magnetized edge (where the plasma viscosity is small) into the unmagnetized core (where the viscosity is large) and that the core rotates as a solid body. To be effective, collisional viscosity must overcome the ion-neutral drag due to charge-exchange collisions. PMID:22540478

  7. Plasma for cancer treatment

    NASA Astrophysics Data System (ADS)

    Keidar, Michael

    2015-06-01

    Plasma medicine is a relatively new field that grew from research in application of low-temperature (or cold) atmospheric plasmas in bioengineering. One of the most promising applications of cold atmospheric plasma (CAP) is cancer therapy. Convincing evidence of CAP selectivity towards the cancer cells has been accumulated. This review summarizes the state of the art of this emerging field, presenting various aspects of CAP application in cancer such as the role of reactive species (reactive oxygen and nitrogen), cell cycle modification, in vivo application, CAP interaction with cancer cells in conjunction with nanoparticles, and computational oncology applied to CAP.

  8. Ultracold neutral plasmas.

    PubMed

    Killian, Thomas C

    2007-05-01

    Ultracold neutral plasmas occupy an exotic regime of plasma physics in which electrons form a swarming, neutralizing background for ions that sluggishly move in a correlated manner. Strong interactions between the charged particles give rise to surprising dynamics such as oscillations of the average kinetic energy during equilibration and extremely fast recombination. Such phenomena offer stimulating and challenging problems for computational scientists, and the physics can be applied to other environments, such as the interior of gas giant planets and plasmas created by short-pulse laser irradiation of solid, liquid, and cluster targets. PMID:17478712

  9. Plasma control and utilization

    DOEpatents

    Ensley, Donald L.

    1976-12-28

    A plasma is confined and heated by a microwave field resonant in a cavity excited in a combination of the TE and TM modes while responding to the resonant frequency of the cavity as the plasma dimensions change to maintain operation at resonance. The microwave field is elliptically or circularly polarized as to prevent the electromagnetic confining field from going to zero. A high Q chamber having superconductive walls is employed to minimize wall losses while providing for extraction of thermonuclear energy produced by fusion of nuclei in the plasma.

  10. The auroral plasma cavity

    NASA Technical Reports Server (NTRS)

    Calvert, W.

    1981-01-01

    A region of diminished plasma density has been found to occur at the source of auroral kilometric radiation (AKR). The density within this auroral plasma cavity, determined from limited Hawkeye wave data, was less than 1/cu cm from 1.8 to 3 earth radii geocentric, at 70 deg + or - 3 deg invariant magnetic latitude. The altitude variation of the magnetic field produces a minimum in the ratio of plasma frequency to cyclotron frequency within the cavity which accounts for the observed spectrum of AKR.

  11. Ultracold neutral plasmas

    SciTech Connect

    Killian, Thomas C.; Rolston, Steven L.

    2010-03-15

    Plasmas are collections of charged particles that can exhibit an impressively diverse set of collective phenomena. They exist in an extraordinary variety of environments and span a great range of densities and temperatures, from 15 million kelvin in the core of the Sun to 200 K in the ionosphere and from 10{sup 30} particles per cubic centimeter in a white dwarf to 1 particle per cm{sup 3} in interstellar space. They can find application in lighting sources, manufacturing of computer chips, and fusion energy research. Plasmas created in the laboratory are used to replicate and study those that occur naturally and to probe the fundamental and complex behavior of plasmas.

  12. Plasmas in Saturn's magnetosphere

    NASA Technical Reports Server (NTRS)

    Frank, L. A.; Burek, B. G.; Ackerson, K. L.; Wolfe, J. H.; Mihalov, J. D.

    1980-01-01

    Passage of Pioneer 11 through Saturn's magnetosphere revealed a third magnetosphere with a high plasma abundance. The dominant ion species appears to be oxygen. The plasma is located in a large torus about Saturn, including the orbits of Dione and Tethys. The plasma are rigidly corotating with the planet to distances of at least 10 Saturn radii. Bulk flows appear to move in the corotation direction, but at speeds lower than those expected from rigid corotation. The ions appear to be the ionization products of water frost on the surface of the ring material.

  13. Plasma Chemical Aspects Of Dust Formation In Hydrocarbon Plasmas

    SciTech Connect

    Berndt, J.; Kovacevic, E.; Stepanovic, O.; Stefanovic, I.; Winter, J.

    2008-09-07

    This contribution deals with some plasma chemical aspects of dust formation in hydrocarbon plasmas. The interplay between dust formation and plasma chemistry will be discussed by means of different experimental results. One specific example concerns the formation of benzene and the role of atomic hydrogen for plasma chemical processes and dust formation in hydrocarbon discharges.

  14. Arc plasma jets of a nontransferred plasma torch

    SciTech Connect

    Kang, K.D.; Hong, S.H.

    1996-02-01

    The dc plasma torches have been widely used as clean plasma sources for plasma processings such as plasma spraying and synthesis. The plasma flow of a nontransferred plasma torch used for thermal plasma processings is produced by the arc-gas interactions between a cathode tip and an anode nozzle and expands as a jet through the nozzle. In this work, numerically calculated images of the arc plasma characteristics are found over the entire plasma region, including both an arc-gas interacting region inside the torch and a jet expanding region outside the torch. A numerical model used assumes a local thermodynamic equilibrium (LTE) with near-electrode phenomena and compressible flow effects. The computational system is described by a two-dimensional (2-D) axisymmetric model which is solved for plasma temperature and velocity by a control volume approach with the modified SIMPLER algorithm in a real torch geometry.

  15. Measuring the Plasma Density of a Ferroelectric Plasma Source in an Expanding Plasma

    SciTech Connect

    A. Dunaevsky; N.J. Fisch

    2003-10-02

    The initial density and electron temperature at the surface of a ferroelectric plasma source were deduced from floating probe measurements in an expanding plasma. The method exploits negative charging of the floating probe capacitance by fast flows before the expanding plasma reaches the probe. The temporal profiles of the plasma density can be obtained from the voltage traces of the discharge of the charged probe capacitance by the ion current from the expanding plasma. The temporal profiles of the plasma density, at two different distances from the surface of the ferroelectric plasma source, could be further fitted by using the density profiles for the expanding plasma. This gives the initial values of the plasma density and electron temperature at the surface. The method could be useful for any pulsed discharge, which is accompanied by considerable electromagnetic noise, if the initial plasma parameters might be deduced from measurements in expanding plasma.

  16. Physics of Plasmas

    NASA Astrophysics Data System (ADS)

    Woods, Leslie Colin

    2004-01-01

    A short, self-sufficient introduction to the physics of plasma for beginners as well as researchers in a number of fields. The author looks at the dynamics and stability of magnetoplasma and discusses wave and transport in this medium. He also looks at such applications as fusion research using magnetic confinement of Deuterium plasma, solar physics with its plasma loops reaching high into the corona, sunspots and solar wind, engineering applications to metallurgy, MHD direct generation of electricity, and railguns, finally touching on the relatively new and difficult subject of dusty plasmas. The book includes mathematical notes and 99 exercises that supplement the theory presented and thus offers the beginner an easy introduction to this exciting field. It is an equally good textbook for final year undergraduates and first year research students.

  17. Accelerating Particles with Plasma

    SciTech Connect

    Litos, Michael; Hogan, Mark

    2014-11-05

    Researchers at SLAC explain how they use plasma wakefields to accelerate bunches of electrons to very high energies over only a short distance. Their experiments offer a possible path for the future of particle accelerators.

  18. Simulation of Fusion Plasmas

    ScienceCinema

    Holland, Chris [UC San Diego, San Diego, California, United States

    2010-01-08

    The upcoming ITER experiment (www.iter.org) represents the next major milestone in realizing the promise of using nuclear fusion as a commercial energy source, by moving into the ?burning plasma? regime where the dominant heat source is the internal fusion reactions. As part of its support for the ITER mission, the US fusion community is actively developing validated predictive models of the behavior of magnetically confined plasmas. In this talk, I will describe how the plasma community is using the latest high performance computing facilities to develop and refine our models of the nonlinear, multiscale plasma dynamics, and how recent advances in experimental diagnostics are allowing us to directly test and validate these models at an unprecedented level.

  19. Fizeau plasma interferometer

    SciTech Connect

    Frank, A.M.

    1980-01-01

    This paper describes a technique by which the sensitivity of plasma interferometers can be increased. Stabilization and fractional fringe measurement techniques have improved to the point where additional optical sensitivity could be useful. (MOW)

  20. Wakes in inhomogeneous plasmas.

    PubMed

    Kompaneets, Roman; Ivlev, Alexei V; Nosenko, Vladimir; Morfill, Gregor E

    2014-04-01

    The Debye shielding of a charge immersed in a flowing plasma is an old classic problem. It has been given renewed attention in the last two decades in view of experiments with complex plasmas, where charged dust particles are often levitated in a region with strong ion flow. Efforts to describe the shielding of the dust particles in such conditions have been focused on the homogeneous plasma approximation, which ignores the substantial inhomogeneity of the levitation region. We address the role of the plasma inhomogeneity by rigorously calculating the point charge potential in the collisionless Bohm sheath. We demonstrate that the inhomogeneity can dramatically modify the wake, making it nonoscillatory and weaker. PMID:24827356

  1. Magnetospheric Plasma Physics

    NASA Astrophysics Data System (ADS)

    Mauk, Barry H.

    Magnetospheric Plasma Physics is volume 4 of an ongoing series of review books entitled Developments in Earth and Planetary Sciences organized by the Center for Academic Publications Japan. The series is intended to stress Japanese work; however, the present volume was written by seven internationally selected authors who have reviewed works from a broad range of sources. This volume is composed of articles drawn from five lecture series presented at the Autumn College o f Plasma Physics, International Center for Theoretical Physics, Trieste, Italy, October-November 1979. The audiences for these lecture series were plasma and/or space plasma physicists, or students of the same, and the level and tone of this volume clearly reflect that condition.

  2. Plasma Cell Disorders

    MedlinePlus

    ... of Undetermined Significance (MGUS) Multiple Myeloma Macroglobulinemia Heavy Chain Diseases Plasma cell disorders are uncommon. They begin ... antibody produced is incomplete, consisting of only light chains or heavy chains (functional antibodies normally consist of ...

  3. Induction plasma tube

    DOEpatents

    Hull, Donald E.

    1984-01-01

    An induction plasma tube having a segmented, fluid-cooled internal radiation shield is disclosed. The individual segments are thick in cross-section such that the shield occupies a substantial fraction of the internal volume of the plasma enclosure, resulting in improved performance and higher sustainable plasma temperatures. The individual segments of the shield are preferably cooled by means of a counterflow fluid cooling system wherein each segment includes a central bore and a fluid supply tube extending into the bore. The counterflow cooling system results in improved cooling of the individual segments and also permits use of relatively larger shield segments which permit improved electromagnetic coupling between the induction coil and a plasma located inside the shield. Four embodiments of the invention, each having particular advantages, are disclosed.

  4. Induction plasma tube

    DOEpatents

    Hull, D.E.

    1982-07-02

    An induction plasma tube having a segmented, fluid-cooled internal radiation shield is disclosed. The individual segments are thick in cross-section such that the shield occupies a substantial fraction of the internal volume of the plasma enclosure, resulting in improved performance and higher sustainable plasma temperatures. The individual segments of the shield are preferably cooled by means of a counterflow fluid cooling system wherein each segment includes a central bore and a fluid supply tube extending into the bore. The counterflow cooling system results in improved cooling of the individual segments and also permits use of relatively larger shield segments which permit improved electromagnetic coupling between the induction coil and a plasma located inside the shield. Four embodiments of the invention, each having particular advantages, are disclosed.

  5. Plasma Screen Floating Mount

    DOEpatents

    Eakle, Robert F.; Pak, Donald J.

    2004-10-26

    A mounting system for a flat display screen, particularly a plasma display screen, suspends the screen separately in each of the x-, y- and z-directions. A series of frames located by linear bearings and isolated by springs and dampers allows separate controlled movement in each axis. The system enables the use of relatively larger display screens in vehicles in which plasma screen are subject to damage from vibration.

  6. Plasmas in Saturn's magnetosphere

    NASA Technical Reports Server (NTRS)

    Frank, L. A.; Burek, B. G.; Ackerson, K. L.; Wolfe, J. H.; Mihalov, J. D.

    1980-01-01

    The solar wind plasma analyzer on board Pioneer 2 provides first observations of low-energy positive ions in the magnetosphere of Saturn. Measurable intensities of ions within the energy-per-unit charge (E/Q) range 100 eV to 8 keV are present over the planetocentric radial distance range about 4 to 16 R sub S in the dayside magnetosphere. The plasmas are found to be rigidly corotating with the planet out to distances of at least 10 R sub S. At radial distances beyond 10 R sub S, the bulk flows appear to be in the corotation direction but with lesser speeds than those expected from rigid corotation. At radial distances beyond the orbit of Rhea at 8.8 R sub S, the dominant ions are most likely protons and the corresponding typical densities and temperatures are 0.5/cu cm and 1,000,000 K, respectively, with substantial fluctuations. It is concluded that the most likely source of these plasmas in the photodissociation of water frost on the surface of the ring material with subsequent ionization of the products and radially outward diffusion. The presence of this plasma torus is expected to have a large influence on the dynamics of Saturn's magnetosphere since the pressure ratio beta of these plasmas approaches unity at radial distances as close to the planet as 6.5 R sub S. On the basis of these observational evidences it is anticipated that quasi-periodic outward flows of plasma, accompanied with a reconfiguration of the magnetosphere beyond about 6.5 R sub S, will occur in the local night sector in order to relieve the plasma pressure from accretion of plasma from the rings.

  7. Multicusp plasma containment apparatus

    SciTech Connect

    Limpaecher, R.

    1980-11-11

    It has been discovered that plasma containment by a chamber having multi-pole magnetic cusp reflecting walls in combination with electronic injection for electrostatic containment provides the means for generating magnetic field free quiescent plasmas for practical application in ion-pumps, electronic switches, and the like. 1250 ''alnico v'' magnets 1/2 '' X 1/2 '' X 1 1/2 '' provide containment in one embodiment. Electromagnets embodying toroidal funneling extend the principle to fusion apparatus.

  8. Plasma surface modification of polymers

    NASA Technical Reports Server (NTRS)

    Hirotsu, T.

    1980-01-01

    Thin plasma polymerization films are discussed from the viewpoint of simplicity in production stages. The application of selective, absorbent films and films used in selective permeability was tested. The types of surface modification of polymers discussed are: (1) plasma etching, (2) surface coating by plasma polymerized thin films, and (3) plasma activation surface graft polymerization.

  9. Plasma-based accelerator structures

    SciTech Connect

    Schroeder, Carl B.

    1999-12-01

    Plasma-based accelerators have the ability to sustain extremely large accelerating gradients, with possible high-energy physics applications. This dissertation further develops the theory of plasma-based accelerators by addressing three topics: the performance of a hollow plasma channel as an accelerating structure, the generation of ultrashort electron bunches, and the propagation of laser pulses is underdense plasmas.

  10. Inductively coupled helium plasma torch

    DOEpatents

    Montaser, Akbar; Chan, Shi-Kit; Van Hoven, Raymond L.

    1989-01-01

    An inductively coupled plasma torch including a base member, a plasma tube and a threaded insert member within the plasma tube for directing the plasma gas in a tangential flow pattern. The design of the torch eliminates the need for a separate coolant gas tube. The torch can be readily assembled and disassembled with a high degree of alignment accuracy.

  11. Plasma electron analysis: Voyager plasma science experiment

    NASA Technical Reports Server (NTRS)

    Sittler, E. C., Jr.

    1983-01-01

    The Plasma Science Experiment (PLS) on the Voyager spacecraft provide data on the plasma ions and electrons in the interplanetary medium and the magnetospheres of the giant planets Jupiter and Saturn. A description of the analysis used to obtain electron parameters (density, temperature, etc.) from the plasma science experiment PLS electron measurements which cover the energy range from 10 eV to 5950 eV is presented. The electron sensor (D cup) and its transmission characteristics are described. A derivation of the fundamental analytical expression of the reduced distribution function F(e) is given. The electron distribution function F(e), used in the moment integrations, can be derived from F(e). Positive ions produce a correction current (ion feedthrough) to the measured electron current, which can be important to the measurements of the suprathermal electron component. In the case of Saturn, this correction current, which can either add to or subtract from the measured electron current, is less than 20% of the measured signal at all times. Comments about the corrections introduced by spacecraft charging to the Saturn encounter data, which can be important in regions of high density and shadow when the spacecraft can become negatively charged are introduced.

  12. TOPICAL REVIEW: Plasma-chemical reactions: low pressure acetylene plasmas

    NASA Astrophysics Data System (ADS)

    Benedikt, J.

    2010-02-01

    Reactive plasmas are a well-known tool for material synthesis and surface modification. They offer a unique combination of non-equilibrium electron and ion driven plasma chemistry, energetic ions accelerated in the plasma sheath at the plasma-surface interface, high fluxes of reactive species towards surfaces and a friendly environment for thermolabile objects. Additionally, small negatively charged clusters can be generated, because they are confined in the positive plasma potential. Plasmas in hydrocarbon gases, and especially in acetylene, are a good example for the discussion of different plasma-chemical processes. These plasmas are involved in a plethora of possible applications ranging from fuel conversion to formation of single wall carbon nanotubes. This paper provides a concise overview of plasma-chemical reactions (PCRs) in low pressure reactive plasmas and discusses possible experimental and theoretical methods for the investigation of their plasma chemistry. An up-to-date summary of the knowledge about low pressure acetylene plasmas is given and two particular examples are discussed in detail: (a) Ar/C2H2 expanding thermal plasmas with electron temperatures below 0.3 eV and with a plasma chemistry initiated by charge transfer reactions and (b) radio frequency C2H2 plasmas, in which the energetic electrons mainly control PCRs.

  13. Plasma contactor research - 1991

    NASA Astrophysics Data System (ADS)

    Buchholtz, Brett; Williams, John D.; Wilbur, Paul J.

    1992-04-01

    A report describing the operating principles of hollow-cathode-based plasma contactors emitting or collecting electrons from an ambient plasma is summarized. Preliminary experiments conducted to determine the noise generated by these plasma contactors in the emission-current return line and in the plasma near it are described. These noise data are measured as current fluctuations in the return line and to the Langmuir probe and then analyzed using a fast Fourier transform technique. The spectral compositions of the data are characterized using power spectral density plots which are examined to identify possible noise source(s) and production mechanism(s). The precautions taken in the construction and calibration of the instrumentation to assure adequate frequency response are described. Experimental results show that line-current noise levels are typically 2 percent of the electron current being emitted or collected. However, noise levels increase to as much as 20 percent of the electron current at a few electron-collection operating conditions. The frequencies associated with most of the noise were harmonics of the 60 Hz input to system power supplies. Plasma noise had characteristics similar in magnitude and frequency to those for the return-line noise, but they contained additional features at frequencies considered to be related to ion-acoustic instabilities. Also discussed is a new probe positioning system built to facilitate future plasma-contractor research.

  14. Plasma contactor research - 1991

    NASA Technical Reports Server (NTRS)

    Buchholtz, Brett; Williams, John D.; Wilbur, Paul J.

    1992-01-01

    A report describing the operating principles of hollow-cathode-based plasma contactors emitting or collecting electrons from an ambient plasma is summarized. Preliminary experiments conducted to determine the noise generated by these plasma contactors in the emission-current return line and in the plasma near it are described. These noise data are measured as current fluctuations in the return line and to the Langmuir probe and then analyzed using a fast Fourier transform technique. The spectral compositions of the data are characterized using power spectral density plots which are examined to identify possible noise source(s) and production mechanism(s). The precautions taken in the construction and calibration of the instrumentation to assure adequate frequency response are described. Experimental results show that line-current noise levels are typically 2 percent of the electron current being emitted or collected. However, noise levels increase to as much as 20 percent of the electron current at a few electron-collection operating conditions. The frequencies associated with most of the noise were harmonics of the 60 Hz input to system power supplies. Plasma noise had characteristics similar in magnitude and frequency to those for the return-line noise, but they contained additional features at frequencies considered to be related to ion-acoustic instabilities. Also discussed is a new probe positioning system built to facilitate future plasma-contractor research.

  15. Magnetospheric space plasma investigations

    NASA Technical Reports Server (NTRS)

    Comfort, Richard H.; Horwitz, James L.

    1995-01-01

    Topics and investigations covering this period of this semiannual report period (August 1994 - January 1995) are as follows: (1) Generalized SemiKinetic (GSK) modeling of the synergistic interaction of transverse heating of ionospheric ions and magnetospheric plasma-driven electric potentials on the auroral plasma transport. Also, presentations of GSK modeling of auroral electron precipitation effects on ionospheric plasma outflows, of ExB effects on such outflow, and on warm plasma thermalization and other effects during refilling with pre-existing warm plasmas; (2) Referees' reports received on the statistical study of the latitudinal distributions of core plasmas along the L = 4.6 field line using DE-1/RIMS data. Other work is concerned in the same field, field-aligned flows and trapped ion distributions; and (3) A short study has been carried out on heating processes in low density flux tubes in the outer plasmasphere. The purpose was to determine whether the high ion temperatures observed in these flux tubes were due to heat sources operating through the thermal electrons or directly to the ions. Other investigations center along the same area of plasmasphere-ionosphere coupling. The empirical techniques and model, the listing of hardware calibrated, and/or tested, and a description of notable meetings attended is included in this report, along with a list of all present publication in submission or accepted and those reference papers that have resulted from this work thus far.

  16. A Decade of Plasma Camp

    NASA Astrophysics Data System (ADS)

    Nuzzolese, Doreen; Zwicker, Andrew; Guilbert, Nicholas; Morgan, James

    2008-11-01

    To engage high school physics teachers in plasma physics, The Princeton Plasma Physics Laboratory (PPPL), established The Plasma Science and Fusion Energy Institute, or Plasma Camp, in 1998. Plasma camp is an intensive summer professional development workshop aimed at introducing teachers and their students to physics topics relevant to fusion plasma research and developing ways to integrate plasma physics into existing curricula. Plasma Camp has been evaluated by several different measures. Results have shown that high percentages of alumni have intertwined plasma physics throughout science curriculum across all disciplines and demographics, including demonstrations, lessons, and activities. Evidence has also shown that plasma camp promotes high pedagogical value, as many alumni have gone on to present at conferences, publish articles, conduct research, obtain advanced degrees, and win prestigious awards.

  17. Isoxyl assays in plasma.

    PubMed

    Wang, Chenchen; Garcia-Contreras, Lucila; Muttil, Pavan; Hickey, Anthony J

    2012-02-23

    Isoxyl is an effective drug to treat multi-drug resistant (MDR) tuberculosis but was abandoned due to failure in some clinical outcomes. The aim of this study was to develop and validate a reverse-phase high-performance liquid chromatographic (HPLC) method for determination of isoxyl concentrations in plasma, a prerequisite for understanding poor in vivo behavior of the drug. In the method, isoxyl was extracted from guinea pig plasma with acetonitrile and quantified by a Hewlett Packard 1100 series HPLC coupled with a Spherisorb 5 μm ODS2 (2 × 100 mm) column and UV detection at 270 nm. The mobile phase was 70% ACN in 20 mM ammonium acetate buffer. The isoxyl peak was eluted at 4.8 min with no interference with the peaks of impurities from plasma and internal standard. Recovery of isoxyl from guinea pig plasma was >68%, and LOQ (Limit of Quantification) was 0.25 μg/ml which was 8 times lower than the reported minimal inhibitory concentration (MIC, 2 μg/ml). The HPLC method was sensitive, reproducible, and accurate for quantification of isoxyl in guinea pig plasma according to FDA guidance for bioanalytical method validation. The method was utilized to quantify isoxyl plasma concentrations following oral administration of the drug to guinea pigs. The results suggest that the poor clinical outcomes of the drug may have been caused by the extremely low isoxyl plasma concentrations which were far below the MIC for action on Mycobacterium tuberculosis. PMID:22119164

  18. Plasma plume propagation characteristics of pulsed radio frequency plasma jet

    SciTech Connect

    Liu, J. H.; Liu, X. Y.; Hu, K.; Liu, D. W.; Lu, X. P.; Iza, F.; Kong, M. G.

    2011-04-11

    A 4 cm long helium cold atmospheric pressure plasma jet with pulsed radio frequency (rf) excitation was obtained by a copper electrode inside a quartz tube. The plasma bullet propagation characteristics common to the microseconds direct current pulse and kilohertz plasma jet is not observed in this case. The space-, time-, and wavelength-resolved optical emission profiles suggest the pulsed rf plasma channel out of the tube was strengthened by ions and metastables with longer life time than the rf period, and the plasma propagation was actually an illumination of the plasma channel caused by energetic electrons accelerated along the channel.

  19. Optical plasma torch electron bunch generation in plasma wakefield accelerators

    NASA Astrophysics Data System (ADS)

    Wittig, G.; Karger, O.; Knetsch, A.; Xi, Y.; Deng, A.; Rosenzweig, J. B.; Bruhwiler, D. L.; Smith, J.; Manahan, G. G.; Sheng, Z.-M.; Jaroszynski, D. A.; Hidding, B.

    2015-08-01

    A novel, flexible method of witness electron bunch generation in plasma wakefield accelerators is described. A quasistationary plasma region is ignited by a focused laser pulse prior to the arrival of the plasma wave. This localized, shapeable optical plasma torch causes a strong distortion of the plasma blowout during passage of the electron driver bunch, leading to collective alteration of plasma electron trajectories and to controlled injection. This optically steered injection is more flexible and faster when compared to hydrodynamically controlled gas density transition injection methods.

  20. Plasma confinement at JET

    NASA Astrophysics Data System (ADS)

    Nunes, I.; ">the JET Contributors, plasma core and (2) the need to mitigate the divertor target temperature to avoid W sputtering by Be and other low Z impurities and (3) a decrease of plasma energy confinement. A major difference is observed on the pedestal pressure, namely a reduction of the pedestal temperature which, due to profile stiffness the plasma core temperature is also reduced leading to a degradation of the global confinement. This effect is more pronounced in low β N scenarios. At high β N, the impact of the wall on the plasma energy confinement is mitigated by the weaker plasma energy degradation with power relative to the IPB98(y, 2) scaling calculated empirically for a CFC first wall. The smaller tolerable impurity concentration for tungsten (<10‑5) compared to that of carbon requires the use of electron heating methods to prevent W accumulation in the plasma core region as well as gas puffing to avoid W entering the plasma core by ELM flushing and reduction of the W source by decreasing the target temperature. W source and the target temperature can also be controlled by impurity seeding. Nitrogen and Neon have been used and with both gases the reduction of the W source and the target temperature is observed. Whilst more experiments with Neon are necessary to assess its impact on energy confinement, a partial increase of plasma energy confinement is observed with Nitrogen, through the increase of edge temperature. The challenge for scenario development at JET is to extend the pulse length curtailed by its transient behavior (W accumulation or MHD), but more importantly by the divertor target temperature limits. Re-optimisation of the scenarios to mitigate the effect of the change of wall materials maintaining high global energy confinement similar to JET-C is underway and JET has successfully achieved H 98(y,2)  =  1 for plasma currents up to 2.5 MA at moderate β N.

  1. Low Temperature Plasma Medicine

    NASA Astrophysics Data System (ADS)

    Graves, David

    2013-10-01

    Ionized gas plasmas near room temperature are used in a remarkable number of technological applications mainly because they are extraordinarily efficient at exploiting electrical power for useful chemical and material transformations near room temperature. In this tutorial address, I will focus on the newest area of low temperature ionized gas plasmas (LTP), in this case operating under atmospheric pressure conditions, in which the temperature-sensitive material is living tissue. LTP research directed towards biomedical applications such as sterilization, surgery, wound healing and anti-cancer therapy has seen remarkable growth in the last 3-5 years, but the mechanisms responsible for the biomedical effects have remained mysterious. It is known that LTP readily create reactive oxygen species (ROS) and reactive nitrogen species (RNS). ROS and RNS (or RONS), in addition to a suite of other radical and non-radical reactive species, are essential actors in an important sub-field of aerobic biology termed ``redox'' (or oxidation-reduction) biology. I will review the evidence suggesting that RONS generated by plasmas are responsible for their observed therapeutic effects. Other possible bio-active mechanisms include electric fields, charges and photons. It is common in LTP applications that synergies between different mechanisms can play a role and I will review the evidence for synergies in plasma biomedicine. Finally, I will address the challenges and opportunities for plasma physicists to enter this novel, multidisciplinary field.

  2. DC Dusty Plasma Simulation

    NASA Astrophysics Data System (ADS)

    Blumenkopf, Joshua; Wissel, Stephanie; Zwicker, Andrew

    2011-10-01

    We describe the development of simulations of a complex plasma-composed of a low-temperature plasma and dust grains-to be used in comparing the electron, dust and ion interactions in the simulations to the Dusty Plasma eXperiments (DPX) being conducted at the Princeton Plasma Physics Laboratory (PPPL). There are two DPX experiments: a ground-based experiment used to investigate the spontaneous formation of dust acoustic waves and the flight-based experiment that has gone on three flights on NASA's ``Weightless Wonder.'' The latter experiment has recently been outfitted with a thermal heater used to generate a thermal gradient in the device. This thermal gradient produces a thermophoretic force on the charged dust grains that counteracts gravity, thereby simulating the flights on the ``Weightless Wonder.'' We have modified the XOOPIC code (J.P. Verboncoeur et al., Comp. Phys. Comm., 87, May 11, 1995, pp. 199-211) to simulate the DPX apparatuses by adding a new dielectric particle species and creating additional modules to handle dust by allowing variable charge and deposition currents during the collision phase of the code. Using these simulations, plasma dynamics and dust cloud characteristics are compared with experimental results (C. Udemgba, these proceedings).

  3. Plasma coal reprocessing

    NASA Astrophysics Data System (ADS)

    Messerle, V. E.; Ustimenko, A. B.

    2013-12-01

    Results of many years of investigations of plasma-chemical technologies for pyrolysis, hydrogenation, thermochemical preparation for combustion, gasification, and complex reprocessing of solid fuels and hydrocarbon gas cracking are represented. Application of these technologies for obtaining the desired products (hydrogen, industrial carbon, synthesis gas, valuable components of the mineral mass of coal) corresponds to modern ecological and economical requirements to the power engineering, metallurgy, and chemical industry. Plasma fuel utilization technologies are characterized by the short-term residence of reagents within a reactor and the high degree of the conversion of source substances into the desired products without catalyst application. The thermochemical preparation of the fuel to combustion is realized in a plasma-fuel system presenting a reaction chamber with a plasmatron; and the remaining plasma fuel utilization technologies, in a combined plasma-chemical reactor with a nominal power of 100 kW, whose zone of the heat release from an electric arc is joined with the chemical reaction zone.

  4. Mechanisms of Plasma Therapeutics

    NASA Astrophysics Data System (ADS)

    Graves, David

    2015-09-01

    In this talk, I address research directed towards biomedical applications of atmospheric pressure plasma such as sterilization, surgery, wound healing and anti-cancer therapy. The field has seen remarkable growth in the last 3-5 years, but the mechanisms responsible for the biomedical effects have remained mysterious. It is known that plasmas readily create reactive oxygen species (ROS) and reactive nitrogen species (RNS). ROS and RNS (or RONS), in addition to a suite of other radical and non-radical reactive species, are essential actors in an important sub-field of aerobic biology termed ``redox'' (or oxidation-reduction) biology. It is postulated that cold atmospheric plasma (CAP) can trigger a therapeutic shielding response in tissue in part by creating a time- and space-localized, burst-like form of oxy-nitrosative stress on near-surface exposed cells through the flux of plasma-generated RONS. RONS-exposed surface layers of cells communicate to the deeper levels of tissue via a form of the ``bystander effect,'' similar to responses to other forms of cell stress. In this proposed model of CAP therapeutics, the plasma stimulates a cellular survival mechanism through which aerobic organisms shield themselves from infection and other challenges.

  5. Plasma jet ignition device

    DOEpatents

    McIlwain, Michael E.; Grant, Jonathan F.; Golenko, Zsolt; Wittstein, Alan D.

    1985-01-15

    An ignition device of the plasma jet type is disclosed. The device has a cylindrical cavity formed in insulating material with an electrode at one end. The other end of the cylindrical cavity is closed by a metal plate with a small orifice in the center which plate serves as a second electrode. An arc jumping between the first electrode and the orifice plate causes the formation of a highly-ionized plasma in the cavity which is ejected through the orifice into the engine cylinder area to ignite the main fuel mixture. Two improvements are disclosed to enhance the operation of the device and the length of the plasma plume. One improvement is a metal hydride ring which is inserted in the cavity next to the first electrode. During operation, the high temperature in the cavity and the highly excited nature of the plasma breaks down the metal hydride, liberating hydrogen which acts as an additional fuel to help plasma formation. A second improvement consists of a cavity insert containing a plurality of spaced, metal rings. The rings act as secondary spark gap electrodes reducing the voltage needed to maintain the initial arc in the cavity.

  6. Anatomy of plasma turbulence

    NASA Astrophysics Data System (ADS)

    Yamada, Takuma; Itoh, Sanae-I.; Maruta, Takashi; Kasuya, Naohiro; Nagashima, Yoshihiko; Shinohara, Shunjiro; Terasaka, Kenichiro; Yagi, Masatoshi; Inagaki, Shigeru; Kawai, Yoshinobu; Fujisawa, Akihide; Itoh, Kimitaka

    2008-09-01

    Turbulence is a state of fluids and plasma where nonlinear interactions including cascades to finer scales take place to generate chaotic structure and dynamics. However, turbulence could generate global structures, such as dynamo magnetic field, zonal flows, transport barriers, enhanced transport and quenching transport. Therefore, in turbulence, multiscale phenomena coevolve in space and time, and the character of plasma turbulence has been investigated in the laboratory as a modern and historical scientific mystery. Here, we report anatomical features of the plasma turbulence in the wavenumber-frequency domain by using nonlinear spectral analysis including the bi-spectrum. First, the formation of the plasma turbulence can be regarded as a result of nonlinear interaction of a small number of irreducible parent modes that satisfy the linear dispersion relation. Second, the highlighted finding here, is the first identification of a streamer (state of bunching of drift waves) that should degrade the quality of plasmas for magnetic confinement fusion. The streamer is a poloidally localized, radially elongated global structure that lives longer than the characteristic turbulence correlation time, and our results reveal that the streamer is produced as the result of the nonlinear condensation, or nonlinear phase locking of the major triplet modes.

  7. Plasma treatment of onychomycosis

    NASA Astrophysics Data System (ADS)

    Xiong, Zilan; Roe, Jeff; Grammer, Tim; Him, Yeon-Ho; Graves, David B.

    2015-09-01

    Onychomycosis or fungal infection of the toenail or fingernail is a common affliction. Approximately 10% of the world's adult population is estimated to suffer from onychomycosis. Current treatment options such as topical creams, oral drugs, or laser treatments are generally limited by a variety of problems. We present results for an alternative onychomycosis treatment scheme using atmospheric pressure cold air plasmas. Using thinned cow hoof as a model nail material, we tested the ability of various plasma sources to act through the model nail to eradicate either bacteria or fungus deposited on the opposite side. Following 20 minute exposure to a surface microdischarge (SMD) device operating in room air, we observed a ~ 2 log reduction of E. coli. A similar result was obtained against T. rubrum after 45 min plasma treatment. NOx species concentration penetrating through the model nail as well as uptake into the nail were measured as a function of nail thickness. We propose that these plasma-generated species, or perhaps their reaction products, are responsible for at least part of the observed anti-microbial effect. We also explore the use of ultraviolet light acting in synergy with plasma-generated chemical species.

  8. The Wonders of Plasma

    NASA Astrophysics Data System (ADS)

    Reardon, Jim; Sprott, Clint

    2004-11-01

    The ongoing Wonders of Physics outreach program at the University of Wisconsin has teamed up with the new Center for Magnetic Self-Organization of Laboratory and Astrophysical Plasmas (CMSO), an NSF Physics Frontier Center, in a variety of outreach efforts intended to attract students to plasma physics. Chief among these efforts are a live-action calculus competition--the ``Integration Bee''--in which students compete for prizes by doing integrals at the blackboard, and a video, tentatively entitled the ``Wonders of Plasma,'' which introduces CMSO-related plasma physics to a high-school level audience. Meanwhile, the Wonders of Physics continues to ``win fans for physics'' by putting on entertaining and informative shows before live audiences at the University of Wisconsin and elsewhere. Approximately 10,000 people have seen a Wonders of Physics show since the last APS DPP conference. Several new fusion-related demonstrations have been added to the Wonders of Physics Traveling Show in the past year. Some of them can be seen at the conference at the Plasma Expo on Thursday and Friday. This work supported by US DOE and NSF.

  9. Plasma Colloquium Travel Grant Program

    SciTech Connect

    Hazeltine, R.D.

    1998-09-14

    OAK B188 Plasma Colloquium Travel Grant Program. The purpose of the Travel Grant Program is to increase the awareness of plasma research. The new results and techniques of plasma research in fusion plasmas, plasma processing space plasmas, basic plasma science, etc, have broad applicability throughout science. The benefits of these results are limited by the relatively low awareness and appreciation of plasma research in the larger scientific community. Whereas spontaneous interactions between plasma scientists and other scientists are useful, a focused effort in education and outreach to other scientists is efficient and is needed. The academic scientific community is the initial focus of this effort, since that permits access to a broad cross-section of scientists and future scientists including undergraduates, graduate students, faculty, and research staff.

  10. Pulsed Plasma Accelerator Modeling

    NASA Technical Reports Server (NTRS)

    Goodman, M.; Kazeminezhad, F.; Owens, T.

    2009-01-01

    This report presents the main results of the modeling task of the PPA project. The objective of this task is to make major progress towards developing a new computational tool with new capabilities for simulating cylindrically symmetric 2.5 dimensional (2.5 D) PPA's. This tool may be used for designing, optimizing, and understanding the operation of PPA s and other pulsed power devices. The foundation for this task is the 2-D, cylindrically symmetric, magnetohydrodynamic (MHD) code PCAPPS (Princeton Code for Advanced Plasma Propulsion Simulation). PCAPPS was originally developed by Sankaran (2001, 2005) to model Lithium Lorentz Force Accelerators (LLFA's), which are electrode based devices, and are typically operated in continuous magnetic field to the model, and implementing a first principles, self-consistent algorithm to couple the plasma and power circuit that drives the plasma dynamics.

  11. Relativistic plasma dispersion functions

    NASA Astrophysics Data System (ADS)

    Robinson, P. A.

    1986-05-01

    The known properties of plasma dispersion functions (PDF's) for waves in weakly relativistic, magnetized, thermal plasmas are reviewed and a large number of new results are presented. The PDF's required for the description of waves with small wave number perpendicular to the magnetic field (Dnestrovskii and Shkarofsky functions) are considered in detail; these functions also arise in certain quantum electrodynamical calculations involving strongly magnetized plasmas. Series, asymptotic series, recursion relations, integral forms, derivatives, differential equations, and approximations for these functions are discussed as are their analytic properties and connections with standard transcendental functions. In addition a more general class of PDF's relevant to waves of arbitrary perpendicular wave number is introduced and a range of properties of these functions are derived.

  12. Large area plasma source

    NASA Technical Reports Server (NTRS)

    Foster, John (Inventor); Patterson, Michael (Inventor)

    2008-01-01

    An all permanent magnet Electron Cyclotron Resonance, large diameter (e.g., 40 cm) plasma source suitable for ion/plasma processing or electric propulsion, is capable of producing uniform ion current densities at its exit plane at very low power (e.g., below 200 W), and is electrodeless to avoid sputtering or contamination issues. Microwave input power is efficiently coupled with an ionizing gas without using a dielectric microwave window and without developing a throat plasma by providing a ferromagnetic cylindrical chamber wall with a conical end narrowing to an axial entrance hole for microwaves supplied on-axis from an open-ended waveguide. Permanent magnet rings are attached inside the wall with alternating polarities against the wall. An entrance magnet ring surrounding the entrance hole has a ferromagnetic pole piece that extends into the chamber from the entrance hole to a continuing second face that extends radially across an inner pole of the entrance magnet ring.

  13. Fundamentals of plasma simulation

    SciTech Connect

    Forslund, D.W.

    1985-01-01

    With the increasing size and speed of modern computers, the incredibly complex nonlinear properties of plasmas in the laboratory and in space are being successfully explored in increasing depth. Of particular importance have been numerical simulation techniques involving finite size particles on a discrete mesh. After discussing the importance of this means of understanding a variety of nonlinear plasma phenomena, we describe the basic elements of particle-in-cell simulation and their limitations and advantages. The differencing techniques, stability and accuracy issues, data management and optimization issues are discussed by means of a simple example of a particle-in-cell code. Recent advances in simulation methods allowing large space and time scales to be treated with minimal sacrifice in physics are reviewed. Various examples of nonlinear processes successfully studied by plasma simulation will be given.

  14. Partial pressure analysis of plasmas

    SciTech Connect

    Dylla, H.F.

    1984-11-01

    The application of partial pressure analysis for plasma diagnostic measurements is reviewed. A comparison is made between the techniques of plasma flux analysis and partial pressure analysis for mass spectrometry of plasmas. Emphasis is given to the application of quadrupole mass spectrometers (QMS). The interface problems associated with the coupling of a QMS to a plasma device are discussed including: differential-pumping requirements, electromagnetic interferences from the plasma environment, the detection of surface-active species, ion source interactions, and calibration procedures. Example measurements are presented from process monitoring of glow discharge plasmas which are useful for cleaning and conditioning vacuum vessels.

  15. Plasma contactor research, 1990

    NASA Technical Reports Server (NTRS)

    Williams, John D.; Wilbur, Paul J.

    1991-01-01

    Emissive and Langmuir probes were used to measure plasma potential profiles, plasma densities, electron energy distributions, and plasma noise levels near a hollow cathode-based plasma contactor emitting electrons. The effects of electron emission current (100 to 1500 mA) and contactor flowrate (2 to 10 sccm (Xenon)) on these data are examined. Retarding potential analyzer (RPA) measurements showing that high energy ions generally stream from a contactor along with the electrons being emitted are also presented, and a mechanism by which this occurs is postulated. This mechanism, which involves a high rate of ionization induced between electrons and atoms flowing together from the hollow cathode orifice, results in a region of high positive space charge and high positive potential. Langmuir and RPA probe data suggests that both electrons and ions expand spherically from this potential hill region. In addition to experimental observations, a simple one-dimensional model which describes the electron emission process and predicts the phenomena just mentioned is presented and is shown to agree qualitatively with these observations. Experimental results of the first stage of bilateral cooperation with the Italian Institute of Interplanetary Space Physics (IFSI CNR) are presented. Sharp, well-defined double layers were observed downstream of a contactor collecting electrons from an ambient plasma created in the IFSI Facility. The voltage drop across these double layers was observed to increase with the current drawn from the ambient plasma. This observation, which was not as clear in previous IFSI tests conducted at higher neutral pressures, is in agreement with previous experimental observations made at both Colorado State University and NASA Lewis Research Center. Greater double layer voltage drops, multiple double layers, and higher noise levels in the region near the double layers were also observed when a magnetic field was imposed and oriented perpendicular to the line joining the contactor and simulator.

  16. Plasma Simulation Program

    SciTech Connect

    Greenwald, Martin

    2011-10-04

    Many others in the fusion energy and advanced scientific computing communities participated in the development of this plan. The core planning team is grateful for their important contributions. This summary is meant as a quick overview the Fusion Simulation Program's (FSP's) purpose and intentions. There are several additional documents referenced within this one and all are supplemental or flow down from this Program Plan. The overall science goal of the DOE Office of Fusion Energy Sciences (FES) Fusion Simulation Program (FSP) is to develop predictive simulation capability for magnetically confined fusion plasmas at an unprecedented level of integration and fidelity. This will directly support and enable effective U.S. participation in International Thermonuclear Experimental Reactor (ITER) research and the overall mission of delivering practical fusion energy. The FSP will address a rich set of scientific issues together with experimental programs, producing validated integrated physics results. This is very well aligned with the mission of the ITER Organization to coordinate with its members the integrated modeling and control of fusion plasmas, including benchmarking and validation activities. [1]. Initial FSP research will focus on two critical Integrated Science Application (ISA) areas: ISA1, the plasma edge; and ISA2, whole device modeling (WDM) including disruption avoidance. The first of these problems involves the narrow plasma boundary layer and its complex interactions with the plasma core and the surrounding material wall. The second requires development of a computationally tractable, but comprehensive model that describes all equilibrium and dynamic processes at a sufficient level of detail to provide useful prediction of the temporal evolution of fusion plasma experiments. The initial driver for the whole device model will be prediction and avoidance of discharge-terminating disruptions, especially at high performance, which are a critical impediment to successful operation of machines like ITER. If disruptions prove unable to be avoided, their associated dynamics and effects will be addressed in the next phase of the FSP.

  17. Plasma Spray System

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Computer aided, fully-automatic TRW system sprays very hot plasma onto a turbine blade. Composed of gas into which metallic and ceramic powders have been injected, the plasma forms a two-layer coating which insulates the blade. Critical part of operation is controlling the thickness of the deposit which is measured in thousandths of an inch. This is accomplished by an optical detector which illuminates spots at various locations on the blade and determines thickness by measuring the light reflections. Optical sensor monitors spraying process until precise thickness is attained, then computer halts the spraying.

  18. Why plasma harmonics?

    NASA Astrophysics Data System (ADS)

    Ganeev, R. A.

    2015-09-01

    We discuss the emergence of interest in the high-order harmonic generation (HHG) of ultrashort pulses propagated through laser-produced plasmas. It is shown that, during the last few years, substantial amendments of plasma HHG allowed in some cases the characteristics of gas HHG to be surpassed. The attractiveness of a new approach in coherent extreme ultraviolet radiation generation is demonstrated, which can also be used as a tool for laser-ablation-induced HHG spectroscopy of a giant class of solids. We present general ideas and prospects for this relatively new field of nonlinear optics.

  19. Plasma Facing Components

    NASA Astrophysics Data System (ADS)

    Ulrickson, Michael

    2005-10-01

    Energy escapes from a magnetically confined plasma by convection and diffusion from closed flux regions to open field lines where it is transported to solid surfaces on the device walls. Particle and energy transport along the field lines is much more rapid than transport perpendicular to the field. This means the flux of power and particles on surfaces is quite narrow. Extremely high heat flux can be mitigated by tilting the plasma facing surface, spreading the magnetic field, and adding radiating impurities. Even so the peak heat flux can be in the range of 10-30 MW/m^2. While this heat flux can be removed by structures having adequate thermal conductivity and aggressive cooling, the existence of severe intermittent heat flux 10 to 100 times higher limits the choice of materials and heat sink design. Future fusion devices will have to operate successfully with particle fluence hundreds of times greater than existing devices, and fusion reactor grade plasmas will add energetic neutron damage to the picture. Advances in either materials or design of plasma facing components (PFCs) have had a profound effect on core plasma performance. Early advances relied on selection of carbon based materials that had good thermal conductivity and no melting rather than refractory metals. Carbon fiber reinforced carbon composites provided further performance improvement. Divertor plasmas allowed exploration of plasma sweeping and more effective particle control, but concentrated the heat flux onto a smaller region. Hydrogen retention in carbon is one of the challenges facing the next generation of fusion devices. Impurity shielding in divertor plasmas allows all metal PFCs to be considered. Engineering of high Z refractory metal PFCs with active cooling has matured for use on long pulse devices. Exploratory studies have shown that liquid PFCs may be able to remove high heat flux with no erosion or nuclear damage issues. The major issue for liquid surfaces is control of the magneto-hydrodynamic interaction between the liquid and the spatially and temporally varying fields in a fusion device. This paper will review the advances that have enabled fusion devices and examine the paths that are likely to meet the needs of future devices.

  20. Solar flares. [plasma physics

    NASA Technical Reports Server (NTRS)

    Rust, D. M.

    1979-01-01

    The present paper deals with explosions in a magnetized solar plasma, known as flares, whose effects are seen throughout the electromagnetic spectrum, from gamma-rays through the visible and to the radio band. The diverse phenomena associated with flares are discussed, along with the physical mechanisms that have been advanced to explain them. The impact of solar flare research on the development of plasma physics and magnetohydrodynamics is noted. The rapid development of solar flare research during the past 20 years, owing to the availability of high-resolution images, detailed magnetic field measurements, and improved spectral data, is illustrated.

  1. Plasma diagnostic reflectometry

    SciTech Connect

    Cohen, B.I.; Afeyan, B.B.; Garrison, J.C.; Kaiser, T.B.; Luhmann, N.C. Jr.; Domier, C.W.; Chou, A.E.; Baang, S.

    1996-02-26

    Theoretical and experimental studies of plasma diagnostic reflectometry have been undertaken as a collaborative research project between the Lawrence Livermore National Laboratory (LLNL) and the University of California Department of Applied Science Plasma Diagnostics Group under the auspices of the Laboratory Directed Research and Development Program at LLNL. Theoretical analyses have explored the basic principles of reflectometry to understand its limitations, to address specific gaps in the understanding of reflectometry measurements in laboratory experiments, and to explore extensions of reflectometry such as ultra-short-pulse reflectometry. The theory has supported basic laboratory reflectometry experiments where reflectometry measurements can be corroborated by independent diagnostic measurements.

  2. PINCHED PLASMA REACTOR

    DOEpatents

    Phillips, J.A.; Suydam, R.; Tuck, J.L.

    1961-07-01

    BS>A plasma confining and heating reactor is described which has the form of a torus with a B/sub 2/ producing winding on the outside of the torus and a helical winding of insulated overlapping tunns on the inside of the torus. The inner helical winding performs the double function of shielding the plasma from the vitreous container and generating a second B/sub z/ field in the opposite direction to the first B/sub z/ field after the pinch is established.

  3. DUST-PLASMA INTERACTIONS

    SciTech Connect

    Dr. M. Rosenberg

    2010-01-05

    The objective of our theoretical research under this grant over the past 3 years was to develop new understanding in a range of topics in the physics of dust-plasma interactions, with application to space and the laboratory. We conducted studies related to the physical properties of dust, waves and instabilities in both weakly coupled and strongly coupled dusty plasmas, and innovative possible applications. A major consideration in our choice of topics was to compare theory with experiments or observations, and to motivate new experiments, which we believe is important for developing this relatively new field. Our research is summarized, with reference to our list of journal publications.

  4. QED plasma and magnetars

    NASA Astrophysics Data System (ADS)

    Freytsis, Marat; Gralla, Samuel E.

    2016-05-01

    Magnetars are surrounded by diffuse plasma in magnetic field strengths well above the quantum electrodynamic critical value. We derive equations of ``quantum force-free electrodynamics'' for this plasma using effective field theory arguments. We argue that quantum effects do not modify the large scale structure of the magnetosphere, and in particular that the spin-down rate does not deviate significantly from the classical result. We provide definite evolution equations that can be used to explore potentially important small-scale corrections, such as shock formation, which has been proposed as a mechanism for both burst and quiescent emission from magnetars.

  5. Condensed Plasmas under Microgravity

    NASA Technical Reports Server (NTRS)

    Morfill, G. E.; Thomas, H. M.; Konopka, U.; Rothermel, H.; Zuzic, M.; Ivlev, A.; Goree, J.; Rogers, Rick (Technical Monitor)

    1999-01-01

    Experiments under microgravity conditions were carried out to study 'condensed' (liquid and crystalline) states of a colloidal plasma (ions, electrons, and charged microspheres). Systems with approximately 10(exp 6) microspheres were produced. The observed systems represent new forms of matter--quasineutral, self-organized plasmas--the properties of which are largely unexplored. In contrast to laboratory measurements, the systems under microgravity are clearly three dimensional (as expected); they exhibit stable vortex flows, sometimes adjacent to crystalline regions, and a central 'void,' free of microspheres.

  6. Design of a Plasma Injector for a Pulsed Plasma Accelerator

    NASA Technical Reports Server (NTRS)

    Cassibry, J. T.; Thio, Y. C. F.; Markusic, T. E.; Sommers, J.; Rodgers, Stephen L. (Technical Monitor)

    2002-01-01

    In recent years, a pulsed plasma accelerator has been proposed as a candidate stand-off driver for the formation of an imploding liner in magnetized target fusion. For a near-term physics exploratory experiment to study the feasibility of this standoff approach, a plasma accelerator has been proposed that requires the controlled introduction and preparation of the initial plasma for acceleration. This includes uniform injection of the propellant downstream of the breech with a high degree of ionization. The design of a plasma feed is presented, which injects a high conductivity, highly collisional propellant transverse to the conductor. The plasma injector is designed to establish an initial plasma with a moderate Hall parameter at the trailing edge of the plasma slug, high Hall parameter behind the slug for magnetic insulation, and a short diffusion length in comparison with characteristic dimensions of the plasma slug to avoid propellant loss at the trailing edge.

  7. Plasma heating power dissipation in low temperature hydrogen plasmas

    SciTech Connect

    Komppula, J. Tarvainen, O.

    2015-10-15

    A theoretical framework for power dissipation in low temperature plasmas in corona equilibrium is developed. The framework is based on fundamental conservation laws and reaction cross sections and is only weakly sensitive to plasma parameters, e.g., electron temperature and density. The theory is applied to low temperature atomic and molecular hydrogen laboratory plasmas for which the plasma heating power dissipation to photon emission, ionization, and chemical potential is calculated. The calculated photon emission is compared to recent experimental results.

  8. Thermal plasma processing of materials

    SciTech Connect

    Pfender, E.; Heberlein, J.

    1992-02-01

    Emphasis has been on plasma synthesis of fine powders, plasma Chemical Vapor Deposition (CVD), on related diagnostics, and on modeling work. Since plasma synthesis as well as plasma CVD make frequent use of plasma jets, the beginning has been devoted of plasma jets and behavior of particulates injected into such plasma jets. Although most of the construction of the Triple-Torch Plasma Reactor (TTPR) has already been done, modifications have been made in particular modifications required for plasma CVD of diamond. A new reactor designed for Counter-Flow Liquid Injection Plasma Synthesis (CFLIPS) proved to be an excellent tool for synthesis of fine powders as well as for plasma CVD. An attempt was made to model flow and temperature fields in this reactor. Substantial efforts were made to single out those parameters which govern particle size, size distribution, and powder quality in our plasma synthesis experiments. This knowledge is crucial for controlling the process and for meaningful diagnostics and modeling work. Plasma CVD of diamond films using both reactors has been very successful and we have been approached by a number of companies interested in using this technology for coating of tools.

  9. Process Sprays Uniforms Plasma Coatings

    NASA Technical Reports Server (NTRS)

    Sliney, H. E.; Jacobson, T. P.; Walther, G. C.; Nakamura, H. H.

    1983-01-01

    Composite-powder processing procedure developed along with plasma-spray parameters to achieve homogeneous, well-bonded, low-porosity, self-lubricating coatings. Multicomponent plasma coatings are applied without segretation of components.

  10. Theory of the unmagnetized plasma.

    NASA Technical Reports Server (NTRS)

    Montgomery, D. C.

    1971-01-01

    The Vlasov mathematical model of a plasma, which has come to be thought more useful than any other in describing the dynamical behavior of the majority of plasmas of interest, is first examined. Macroscopic variables and moment equations; linear electrostatics solutions; plasma oscillations, ion acoustic waves, and linear instabilities are treated, as well as external fields, 'test' charges, and nonlinear Vlasov phenomena. Plasmas are statistically described, and attention is given to the kinetic theory of the stable, uniform plasma and the Balescu-Lenard equation; two-time ensemble averages and fluctuation spectra in stable plasmas; the kinetic theory of the unstable plasma; and ensembles of Vlasov plasmas. Some illustrative experiments are described. Four appendixes deal with the electrostatic approximation and transverse waves; solution of the linearized Vlasov equation in a magnetic field; estimates of correlation functions from thermal equilibrium; and equivalence of spatially uniform BBGKY and Klimontovich correlations.

  11. A microwave plasma cleaning apparatus

    NASA Technical Reports Server (NTRS)

    Tsai, C. C.; Nelson, W. D.; Schechter, D. E.; Thompson, L. M.; Glover, A. L.

    1995-01-01

    In a microwave electron cyclotron resonance plasma source, reactive plasmas of oxygen and its mixtures of argon have been used for evaluating plasma cleaning technologies. Small aluminum samples (0.95 x 1.9 cm) were coated with thin films (less than or equal to 20 micrometers in thickness) of Shell Vitrea oil and cleaned with reactive plasmas. The discharge parameters, such as gas pressure, magnetic field, substrate biasing, and microwave power, were varied to change cleaning conditions. A mass spectroscopy (or residual gas analyzer) was used to monitor the status of plasma cleaning. Mass loss of the samples after plasma cleaning was measured to estimate cleaning rates. Measured cleaning rates of low-pressure (0.5-m torr) argon/oxygen plasmas were as high as 2.7 micrometers/min. X-ray photoelectron spectroscopy was used to determine cleanliness of the sample surfaces. In this paper, significant results of the plasma cleaning are reported and discussed.

  12. Recent results for plasma antennas

    SciTech Connect

    Alexeff, Igor; Anderson, Ted; Farshi, Esmaeil; Karnam, Naresh; Pulasani, Nanditha Reddy

    2008-05-15

    Plasma antennas are just as effective as metal antennas. They can transmit, receive, and reflect radio waves just as well as metal antennas. In addition, plasma generated noise does not appear to be a problem.

  13. A microwave plasma cleaning apparatus

    SciTech Connect

    Tsai, C.C.; Nelson, W.D.; Schechter, D.E.; Thompson, L.M.; Glover, A.L.

    1994-12-31

    In a microwave electron cyclotron resonance plasma source, reactive plasmas of oxygen and its mixtures of argon have been used for evaluating plasma cleaning technologies. Small aluminum samples (0.95 x 1.9 cm) were coated with thin films ({le} 20 {micro}m in thickness) of Shell Vitrea oil and cleaned with reactive plasmas. The discharge parameters, such as gas pressure, magnetic field, substrate biasing, and microwave power, were varied to change cleaning conditions. A mass spectroscopy (or residual gas analyzer) was used to monitor the status of plasma cleaning. Mass loss of the samples after plasma cleaning was measured to estimate cleaning rates. Measured cleaning rates of low-pressure (0.5-mtorr) argon/oxygen plasmas were as high as 2.7 {micro}m/min. X-ray photoelectron spectroscopy was used to determine cleanliness of the sample surfaces. In this paper, significant results of the plasma cleaning are reported and discussed.

  14. A plasma receiving dipole antenna

    SciTech Connect

    Minaev, I. M.; Gusein-zade, N. G.; Rukhadze, K. Z.

    2010-10-15

    Results from experimental studies of a short-wave plasma dipole transceiver antenna are presented. The efficiency of the plasma receiving antenna is estimated, and the optimal frequency range for excitation and reception under the given experimental conditions is determined.

  15. Vacuum plasma spray coating

    NASA Technical Reports Server (NTRS)

    Holmes, Richard R.; Mckechnie, Timothy N.

    1989-01-01

    Currently, protective plasma spray coatings are applied to space shuttle main engine turbine blades of high-performance nickel alloys by an air plasma spray process. Originally, a ceramic coating of yttria-stabilized zirconia (ZrO2.12Y2O3) was applied for thermal protection, but was removed because of severe spalling. In vacuum plasma spray coating, plasma coatings of nickel-chromium-aluminum-yttrium (NiCrAlY) are applied in a reduced atmosphere of argon/helium. These enhanced coatings showed no spalling after 40 MSFC burner rig thermal shock cycles between 927 C (1700 F) and -253 C (-423 F), while current coatings spalled during 5 to 25 test cycles. Subsequently, a process was developed for applying a durable thermal barrier coating of ZrO2.8Y2O3 to the turbine blades of first-stage high-pressure fuel turbopumps utilizing the enhanced NiCrAlY bond-coating process. NiCrAlY bond coating is applied first, with ZrO2.8Y2O3 added sequentially in increasing amounts until a thermal barrier coating is obtained. The enchanced thermal barrier coating has successfully passed 40 burner rig thermal shock cycles.

  16. Laboratory plasma probe studies

    NASA Technical Reports Server (NTRS)

    Heikkila, W. J.

    1975-01-01

    Diagnostic experiments performed in a collisionless plasma using CO2 as the working gas are described. In particular, simultaneous measurements that have been performed by means of Langmuir- and RF-probes are presented. A resonance occurring above the parallel resonance in the frequency characteristic of a two electrode system is interpreted as being due to the resonant excitation of electroacoustic waves.

  17. Plasma cell gingivitis

    PubMed Central

    Joshi, Chandershekhar; Shukla, Pradeep

    2015-01-01

    The aim of the article is to present a report on the clinical presentation of plasma cell gingivitis with the use of herbal toothpowder. Plasma cell gingivitis [PCG] is a rare benign condition of the gingiva characterized by sharply demarcated erythematous and edematous gingivitis often extending to the mucogingival junction. As the name suggests it is diffuse and massive infiltration of plasma cells into the sub-epithelial gingival tissue. It is a hypersensitivity reaction to some antigen, often flavouring agents or spices found in chewing gums, toothpastes and lorenzes. A 27-yr old male with a chief complaint of painful, bleeding swollen mass in his lower front teeth region with prolong use of herbal toothpowder. The gingiva bled readily on probing. Patient was advised to refrain from the use of herbal toothpowder and along with periodontal treatment, no further reoccurrence was found. as more and more herbal products are gaining popularity, clinicians should be aware of effects of these products. Early diagnosis is essential as plasma cell gingivitis has similar pathologic changes seen clinically as in leukemia, HIV infection, discoid lupus erythematosis, atrophic lichen planus, desquamative gingivitis, or cicatrical pemphigoid which must be differentiated through hematologic and serologic testing. PMID:26015677

  18. Laser Plasma Accelerators

    NASA Astrophysics Data System (ADS)

    Malka, Victor

    The continuing development of powerful laser systems has permitted to extend the interaction of laser beams with matter far into the relativistic domain, and to demonstrate new approaches for producing energetic particle beams. The extremely large electric fields, with amplitudes exceeding the TV/m level, that are produced in plasma medium are of relevance particle acceleration. Since the value of this longitudinal electric field, 10,000 times larger than those produced in conventional radio-frequency cavities, plasma accelerators appear to be very promising for the development of compact accelerators. The incredible progresses in the understanding of laser plasma interaction physic, allows an excellent control of electron injection and acceleration. Thanks to these recent achievements, laser plasma accelerators deliver today high quality beams of energetic radiation and particles. These beams have a number of interesting properties such as shortness, brightness and spatial quality, and could lend themselves to applications in many fields, including medicine, radio-biology, chemistry, physics and material science,security (material inspection), and of course in accelerator science.

  19. Electrostatic Plasma Accelerator (EPA)

    NASA Technical Reports Server (NTRS)

    Brophy, John R.; Aston, Graeme

    1989-01-01

    The Electrostatic Plasma Accelerator (EPA) is a thruster concept which promises specific impulse levels between low power arcjets and those of the ion engine while retaining the relative simplicity of the arcjet. The EPA thruster produces thrust through the electrostatic acceleration of a moderately dense plasma. No accelerating electrodes are used and the specific impulse is a direct function of the applied discharge voltage and the propellant atomic mass. The goal of the present program is to demonstrate feasibility of the EPA thruster concept through experimental and theoretical investigations of the EPA acceleration mechanism and discharge chamber performance. Experimental investigations will include operating the test bed ion (TBI) engine as an EPA thruster and parametrically varying the thruster geometry and operating conditions to quantify the electrostatic plasma acceleration effect. The theoretical investigations will include the development of a discharge chamber model which describes the relationships between the engine size, plasma properties, and overall performance. For the EPA thruster to be a viable propulsion concept, overall thruster efficiencies approaching 30% with specific impulses approaching 1000 s must be achieved.

  20. Computations in Plasma Physics.

    ERIC Educational Resources Information Center

    Cohen, Bruce I.; Killeen, John

    1983-01-01

    Discusses contributions of computers to research in magnetic and inertial-confinement fusion, charged-particle-beam propogation, and space sciences. Considers use in design/control of laboratory and spacecraft experiments and in data acquisition; and reviews major plasma computational methods and some of the important physics problems they

  1. Flare Plasma Iron Abundance

    NASA Technical Reports Server (NTRS)

    Dennis, Brian R.; Dan, Chau; Jain, Rajmal; Schwartz, Richard A.; Tolbert, Anne K.

    2008-01-01

    The equivalent width of the iron-line complex at 6.7 keV seen in flare X-ray spectra suggests that the iron abundance of the hottest plasma at temperatures >approx.10 MK may sometimes be significantly lower than the nominal coronal abundance of four times the photospheric value that is commonly assumed. This conclusion is based on X-ray spectral observations of several flares seen in common with the Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and the Solar X-ray Spectrometer (SOXS) on the second Indian geostationary satellite, GSAT-2. The implications of this will be discussed as it relates to the origin of the hot flare plasma - either plasma already in the corona that is directly heated during the flare energy release process or chromospheric plasma that is heated by flare-accelerated particles and driven up into the corona. Other possible explanations of lower-than-expected equivalent widths of the iron-line complex will also be discussed.

  2. Magnetospheric space plasma investigations

    NASA Technical Reports Server (NTRS)

    Comfort, Richard H.; Horwitz, James L.

    1993-01-01

    The topics addressed are: (1) generalized semikinetic models; (2) collision-collisionless transition model; (3) observation of O+ outflows; (4) equatorial transitions; (5) inner plasmasphere-ionosphere coupling; (6) plasma wave physical processes; (7) ULF wave ray-tracing; and (8) nighttime anomalous electron heating events.

  3. Microscopic plasma Hamiltonian

    NASA Technical Reports Server (NTRS)

    Peng, Y.-K. M.

    1974-01-01

    A Hamiltonian for the microscopic plasma model is derived from the Low Lagrangian after the dual roles of the generalized variables are taken into account. The resulting Hamilton equations are shown to agree with the Euler-Lagrange equations of the Low Lagrangian.

  4. Computations in Plasma Physics.

    ERIC Educational Resources Information Center

    Cohen, Bruce I.; Killeen, John

    1983-01-01

    Discusses contributions of computers to research in magnetic and inertial-confinement fusion, charged-particle-beam propogation, and space sciences. Considers use in design/control of laboratory and spacecraft experiments and in data acquisition; and reviews major plasma computational methods and some of the important physics problems they…

  5. Plasma and magnetospheric research

    NASA Technical Reports Server (NTRS)

    Comfort, R. H.; Horwitz, J. L.

    1984-01-01

    Research developments in the following areas are discussed: (1) an ion trajectory computer code which plots the paths of ions ejected from the polar cusp ionosphere; (2) the response of plasmaspheric ion temperatures to geomagnetic activity; (3) spacecraft sheath effects; (4) plasma flow; (5) neutral gas temperatures; and (6) instrument fabrication, modification, and maintenance.

  6. Filamentary magnetohydrodynamic plasmas

    SciTech Connect

    Kinney, R.; Tajima, T.; Petviashvili, N.; McWilliams, J.C.

    1993-05-01

    A filamentary construct of magnetohydrodynamical plasma dynamics, based on the Elsasser variables was developed. This approach is modeled after discrete vortex models of hydrodynamical turbulence, which cannot be expected in general to produce results identical to ones based on a Fourier decomposition of the fields. In a highly intermittent plasma, the induction force is small compared to the convective motion, and when this force is neglected. the plasma vortex system is described by a Hamiltonian. For a system with many such vortices we present a statistical treatment of a collection of discrete current-vorticity concentrations. Canonical and microcanonical statistical calculations show that both the vorticity and the current spectra are peaked at long wavelengths, and the expected states revert to known hydrodynamical states as the magnetic field vanishes. These results differ from previous Fourier-based statistical theories. but it is found that when the filament calculation is expanded to include the inductive force, the results approach the Fourier equilibria in the low-temperature limit, and the previous Hamiltonian plasma vortex results in the high-temperature limit. Numerical simulations of a large number of filaments are carried out and support the theory. A three-dimensional vortex model is outlined as well, which is also Hamiltonian when the inductive force is neglected.

  7. Implicit plasma simulation

    SciTech Connect

    Langdon, A.B.

    1985-03-03

    Implicit time integration methods have been used extensively in numerical modelling of slowly varying phenomena in systems that also support rapid variation. Examples include diffusion, hydrodynamics and reaction kinetics. This article discussed implementation of implicit time integration in plasma codes of the ''particle-in-cell'' family, and the benefits to be gained.

  8. Experiments on Cryogenic Complex Plasma

    SciTech Connect

    Ishihara, O.; Sekine, W.; Kubota, J.; Uotani, N.; Chikasue, M.; Shindo, M.

    2009-11-10

    Experiments on a cryogenic complex plasma have been performed. Preliminary experiments include production of a plasma in a liquid helium or in a cryogenic helium gas by a pulsed discharge. The extended production of a plasma has been realized in a vapor of liquid helium or in a cryogenic helium gas by rf discharge. The charge of dust particles injected in such a plasma has been studied in detail.

  9. Millimeter Wave Communication through Plasma

    NASA Technical Reports Server (NTRS)

    Bastin, Gary L.

    2008-01-01

    Millimeter wave communication through plasma at frequencies of 35 GHz or higher shows promise in maintaining communications connectivity during rocket launch and re-entry, critical events which are typically plagued with communication dropouts. Extensive prior research into plasmas has characterized the plasma frequency at these events, and research at the Kennedy Space Center is investigating the feasibility of millimeter communication through these plasma frequencies.

  10. Plasma sources for spacecraft neutralization

    NASA Technical Reports Server (NTRS)

    Davis, V. A.; Katz, I.; Mandell, M. J.

    1990-01-01

    The principles of the operation of plasma sources for the neutralization of the surface of a spacecraft traveling in the presence of hot plasma are discussed with special attention given to the hollow-cathode-based plasma contactors. Techiques are developed that allow the calculation of the potentials and particle densities in the near environment of a hollow cathode plasma contactor in both the test tank and the LEO environment. The techniques and codes were validated by comparison of calculated and measured results.

  11. Plasma model for charging damage

    SciTech Connect

    Vella, M.C.; Lukaszek, W.; Current, M.I.; Tripsas, N.H.

    1994-07-01

    The mechanism responsible for charging damage is treated as beam/plasma driven differences in local floating potentials on the process surface. A cold plasma flood is shown to limit these potential differences. Beam/plasma J-V characteristics obtained with CHARM2 in a high current implanter are fit with the theory. With flood OFF, the fit corresponds to plasma buildup over the target surface.

  12. Controlled zone microwave plasma system

    SciTech Connect

    Ripley, Edward B.; Seals, Roland D.; Morrell, Jonathan S.

    2009-10-20

    An apparatus and method for initiating a process gas plasma. A conductive plate having a plurality of conductive fingers is positioned in a microwave applicator. An arc forms between the conductive fingers to initiate the formation of a plasma. A transport mechanism may convey process materials through the plasma. A spray port may be provided to expel processed materials.

  13. Numerical simulation of dusty plasmas

    SciTech Connect

    Winske, D.

    1995-09-01

    The numerical simulation of physical processes in dusty plasmas is reviewed, with emphasis on recent results and unresolved issues. Three areas of research are discussed: grain charging, weak dust-plasma interactions, and strong dust-plasma interactions. For each area, we review the basic concepts that are tested by simulations, present some appropriate examples, and examine numerical issues associated with extending present work.

  14. High-power radiating plasma

    NASA Technical Reports Server (NTRS)

    Rozanov, V. B.; Rukhadze, A. A.

    1984-01-01

    The physical principles underlying the use of radiating plasmas for the optical pumping of lasers are described. Particular consideration is given to the properties of radiating plasmas; radiation selectivity; the dynamics, equilibrium, and stability of radiating plasmas; the radiative Reynolds number; and experimental results on radiating discharges.

  15. Plasma pyrolysis of toxic waste

    NASA Astrophysics Data System (ADS)

    Rutberg, Ph G.

    2003-06-01

    The comparison of technical economic indexes of different waste treatment methods and plasma pyrolysis is presented in the paper. It testifies that plasma technologies are economically expedient for these purposes. Physical prerequisites allowing realizing plasma technologies are presented. Reliable and economical (70-120 Euro per ton of treated product) plasma generation is the basic condition of the technology realization. In this connection, various types of powerful generators of dense plasma (plasmatrons) in the range from 100 kW to 3 MW and temperature of plasma jets from 2000 to 10 000 K, and also physical processes taking place in electric-discharge chambers are examined. Differences between AC and DC electric arc plasma generators are analysed. Temperature in arcs of plasma generators varies from 6000 to 20 000 K, electron concentration is ne~(1014-1019 cm-3). Specific ware of electrodes in various types of plasma generators intended for long-time operation modes is (10-7-10-4) g C-1. Physicochemical processes in plasma reactors intended for waste treatment and pyrolysis are described. Different types of technological processes on plasma treatment and pyrolysis of waste are analysed. Estimation of present situation of physical investigations and technological developments in this area and predictions for nearest future are included. This article was scheduled to appear in issue 5 of Plasma Phys. Control. Fusion. To access this Special issue please follow this link: http://www.iop.org/EJ/toc/0741-3335/45/5

  16. Plasma chemistry and its applications

    NASA Technical Reports Server (NTRS)

    Hozumi, K.

    1980-01-01

    The relationship between discharge phenomena and plasma chemistry, as well as the equipment and mechanisms of plasma chemical reactions are described. Various areas in which plasma chemistry is applied are surveyed, such as: manufacturing of semiconductor integrated circuits; synthetic fibers; high polymer materials for medical uses; optical lenses; and membrane filters (reverse penetration films).

  17. Tomographic diagnostics of nonthermal plasmas

    NASA Astrophysics Data System (ADS)

    Denisova, Natalia

    2009-10-01

    In the previous work [1], we discussed a ``technology'' of tomographic method and relations between the tomographic diagnostics in thermal (equilibrium) and nonthermal (nonequilibrium) plasma sources. The conclusion has been made that tomographic reconstruction in thermal plasma sources is the standard procedure at present, which can provide much useful information on the plasma structure and its evolution in time, while the tomographic reconstruction of nonthermal plasma has a great potential at making a contribution to understanding the fundamental problem of substance behavior in strongly nonequilibrium conditions. Using medical terminology, one could say, that tomographic diagnostics of the equilibrium plasma sources studies their ``anatomic'' structure, while reconstruction of the nonequilibrium plasma is similar to the ``physiological'' examination: it is directed to study the physical mechanisms and processes. The present work is focused on nonthermal plasma research. The tomographic diagnostics is directed to study spatial structures formed in the gas discharge plasmas under the influence of electrical and gravitational fields. The ways of plasma ``self-organization'' in changing and extreme conditions are analyzed. The analysis has been made using some examples from our practical tomographic diagnostics of nonthermal plasma sources, such as low-pressure capacitive and inductive discharges. [0pt] [1] Denisova N. Plasma diagnostics using computed tomography method // IEEE Trans. Plasma Sci. 2009 37 4 502.

  18. High-temperature plasma physics

    SciTech Connect

    Furth, H.P.

    1988-03-01

    Both magnetic and inertial confinement research are entering the plasma parameter range of fusion reactor interest. This paper reviews the individual and common technical problems of these two approaches to the generation of thermonuclear plasmas, and describes some related applications of high-temperature plasma physics.

  19. Gas-discharge plasma sources for nonlocal plasma technology

    SciTech Connect

    Demidov, V. I.; DeJoseph, C. A. Jr.; Simonov, V. Ya.

    2007-11-12

    Nonlocal plasma technology is based on the effect of self-trapping of fast electrons in the plasma volume [V. I. Demidov, C. A. DeJoseph, Jr., and A. A. Kudryavtsev, Phys. Rev. Lett. 95, 215002 (2006)]. This effect can be achieved by changing the ratio of fast electron flux to ion flux incident on the plasma boundaries. This in turn leads to a significant change in plasma properties and therefore can be useful for technological applications. A gas-discharge device which demonstrates control of the plasma properties by this method is described.

  20. Modelling of Complex Plasmas

    NASA Astrophysics Data System (ADS)

    Akdim, Mohamed Reda

    2003-09-01

    Nowadays plasmas are used for various applications such as the fabrication of silicon solar cells, integrated circuits, coatings and dental cleaning. In the case of a processing plasma, e.g. for the fabrication of amorphous silicon solar cells, a mixture of silane and hydrogen gas is injected in a reactor. These gases are decomposed by making a plasma. A plasma with a low degree of ionization (typically 10_5) is usually made in a reactor containing two electrodes driven by a radio-frequency (RF) power source in the megahertz range. Under the right circumstances the radicals, neutrals and ions can react further to produce nanometer sized dust particles. The particles can stick to the surface and thereby contribute to a higher deposition rate. Another possibility is that the nanometer sized particles coagulate and form larger micron sized particles. These particles obtain a high negative charge, due to their large radius and are usually trapped in a radiofrequency plasma. The electric field present in the discharge sheaths causes the entrapment. Such plasmas are called dusty or complex plasmas. In this thesis numerical models are presented which describe dusty plasmas in reactive and nonreactive plasmas. We started first with the development of a simple one-dimensional silane fluid model where a dusty radio-frequency silane/hydrogen discharge is simulated. In the model, discharge quantities like the fluxes, densities and electric field are calculated self-consistently. A radius and an initial density profile for the spherical dust particles are given and the charge and the density of the dust are calculated with an iterative method. During the transport of the dust, its charge is kept constant in time. The dust influences the electric field distribution through its charge and the density of the plasma through recombination of positive ions and electrons at its surface. In the model this process gives an extra production of silane radicals, since the growth of dust is not included. Results are presented for situations in which the dust signi_cantly changes the discharge characteristics, both by a strong reduction of the electron density and by altering the electric field by its charge. Simulations for dust with a radius of 2 mu-m show that the stationary solution of the dust density and the average electric field depend on the total amount of the dust. The presence of dust enhances the deposition rate of amorphous silicon 2 at the electrodes because of the rise in the average electron energy associated with the decrease of the electron density and the constraint of a constant power input. This increase of deposition rate has also been observed in experiments by others. To study the behavior of dust in a less complicated environment, experiments in non-reactive plasmas have been carried out by a number of research groups. In these experiments the dust particles are injected through the electrodes in an argon discharge. These experiments have shown very interesting phenomena. Dust particles start to interact with each other in the discharge and form two-dimensional Coulomb clusters. These experiments often show an appearance of a void, a dustfree region in the discharge. Similar experiments have also been carried out under microgravity. These experiments have shown three-dimensional Coulomb clusters of dust particles also with the appearance of a void. Also rotating dust clouds (vortices) near the edges of the electrodes have been observed, that tend to rotate as long as the plasmas is on. To understand the behavior of the particles, we have developed a two-dimensional fluid model for a dusty argon plasma in which the plasma and dust parameters are solved self-consistently to study the behavior of dust particles. Simulations for dust with a radius of 7.5 mu-m show that a double space charge layer is created around the sharp boundary of the dust crystal. The inter-particle interaction is taken into account by means of an equation of state for the dust. A central dust-free region (void) is created by the ion drag force. The contribution of the thermophoretic force, driven by the temperature gradient induced by gas heating from ion-neutral collisions and heating of the dust particle material by the recombining ions and electrons, can be neglected in the quasi-neutral center of the plasma. Inside this void a strong increase of the production of argon meta-stables is found. This phenomenon is in agreement with experimental observations, where an enhanced light emission is seen inside the void.

  1. Depletion of Abundant Plasma Proteins and Limitations of Plasma Proteomics

    PubMed Central

    Tu, Chengjian; Rudnick, Paul A.; Martinez, Misti Y.; Cheek, Kristin L.; Stein, Stephen E.; Slebos, Robbert J. C.; Liebler, Daniel C.

    2010-01-01

    Immunoaffinity depletion with antibodies to the top 7 or top 14 high abundance plasma proteins is used to enhance detection of lower abundance proteins in both shotgun and targeted proteomic analyses. We evaluated the effects of top 7/top 14 immunodepletion on the shotgun proteomic analysis of human plasma. Our goal was to evaluate the impact of immunodepletion on detection of proteins across detectable ranges of abundance. The depletion columns afforded highly repeatable and efficient plasma protein fractionation. Relatively few nontargeted proteins were captured by the depletion columns. Analyses of unfractionated and immunodepleted plasma by peptide isoelectric focusing (IEF), followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) demonstrated enrichment of nontargeted plasma proteins by an average of 4-fold, as assessed by MS/MS spectral counting. Either top 7 or top 14 immunodepletion resulted in a 25% increase in identified proteins compared to unfractionated plasma. Although 23 low abundance (<10 ng mL−1) plasma proteins were detected, they accounted for only 5–6% of total protein identifications in immunodepleted plasma. In both unfractionated and immunodepleted plasma, the 50 most abundant plasma proteins accounted for 90% of cumulative spectral counts and precursor ion intensities, leaving little capacity to sample lower abundance proteins. Untargeted proteomic analyses using current LC-MS/MS platforms—even with immunodepletion—cannot be expected to efficiently discover low abundance, disease-specific biomarkers in plasma. PMID:20677825

  2. High beta plasma operation in a toroidal plasma producing device

    DOEpatents

    Clarke, John F.

    1978-01-01

    A high beta plasma is produced in a plasma producing device of toroidal configuration by ohmic heating and auxiliary heating. The plasma pressure is continuously monitored and used in a control system to program the current in the poloidal field windings. Throughout the heating process, magnetic flux is conserved inside the plasma and the distortion of the flux surfaces drives a current in the plasma. As a consequence, the total current increases and the poloidal field windings are driven with an equal and opposing increasing current. The spatial distribution of the current in the poloidal field windings is determined by the plasma pressure. Plasma equilibrium is maintained thereby, and high temperature, high beta operation results.

  3. Pulsed Electromagnetic Acceleration of Plasmas

    NASA Technical Reports Server (NTRS)

    Thio, Y. C. Francis; Cassibry, Jason T.; Markusic, Tom E.; Rodgers, Stephen L. (Technical Monitor)

    2002-01-01

    A major shift in paradigm in driving pulsed plasma thruster is necessary if the original goal of accelerating a plasma sheet efficiently to high velocities as a plasma "slug" is to be realized. Firstly, the plasma interior needs to be highly collisional so that it can be dammed by the plasma edge layer not (upstream) adjacent to the driving 'vacuum' magnetic field. Secondly, the plasma edge layer needs to be strongly magnetized so that its Hall parameter is of the order of unity in this region to ensure excellent coupling of the Lorentz force to the plasma. Thirdly, to prevent and/or suppress the occurrence of secondary arcs or restrike behind the plasma, the region behind the plasma needs to be collisionless and extremely magnetized with sufficiently large Hall parameter. This places a vacuum requirement on the bore conditions prior to the shot. These requirements are quantified in the paper and lead to the introduction of three new design parameters corresponding to these three plasma requirements. The first parameter, labeled in the paper as gamma (sub 1), pertains to the permissible ratio of the diffusive excursion of the plasma during the course of the acceleration to the plasma longitudinal dimension. The second parameter is the required Hall parameter of the edge plasma region, and the third parameter the required Hall parameter of the region behind the plasma. Experimental research is required to quantify the values of these design parameters. Based upon fundamental theory of the transport processes in plasma, some theoretical guidance on the choice of these parameters are provided to help designing the necessary experiments to acquire these data.

  4. Plasmas in the earth's magnetotail

    NASA Technical Reports Server (NTRS)

    Frank, L. A.

    1985-01-01

    An overview of the general charcteristics of plasmas within the earth's magnetotail and its environs is presented. Present knowledge of the plasma within these regions as gained via in situ measurements provides the general theme, although observations of magnetic fields, energetic particles and plasma waves are included in the discussion. Primary plasma regimes in the magnetotail are the plasma sheet, its boundary layer, the magnetotail lobes, the boundary layer at the magnetopause and the distant magnetotail. Although great progress in the understanding of these regions is evident in the literature of the past several years, many of their features remain as exciting enigmas to be resolved by future observational and theoretical investigation.

  5. Plasma chemistry for inorganic materials

    NASA Technical Reports Server (NTRS)

    Matsumoto, O.

    1980-01-01

    Practical application of plasma chemistry to the development of inorganic materials using both low temperature and warm plasmas are summarized. Topics cover: the surface nitrification and oxidation of metals; chemical vapor deposition; formation of minute oxide particles; the composition of oxides from chloride vapor; the composition of carbides and nitrides; freezing high temperature phases by plasma arc welding and plasma jet; use of plasma in the development of a substitute for petroleum; the production of silicon for use in solar cell batteries; and insulating the inner surface of nuclear fusion reactor walls.

  6. Experimental Plasma Research project summaries

    SciTech Connect

    1980-09-01

    This report contains descriptions of the activities supported by the Experimental Plasma Research Branch of APP. The individual project summaries were prepared by the principal investigators and include objectives and milestones for each project. The projects are arranged in six research categories: Plasma Properties; Plasma Heating; Plasma Diagnostics; Atomic, Molecular and Nuclear Physics; Advanced Superconducting Materials; and the Fusion Plasma Research Facility (FPRF). Each category is introduced with a statement of objectives and recent progress and followed by descriptions of individual projects. An overall budget summary is provided at the beginning of the report.

  7. Closed inductively coupled plasma cell

    DOEpatents

    Manning, Thomas J.; Palmer, Byron A.; Hof, Douglas E.

    1990-01-01

    A closed inductively coupled plasma cell generates a relatively high power, low noise plasma for use in spectroscopic studies. A variety of gases can be selected to form the plasma to minimize spectroscopic interference and to provide a electron density and temperature range for the sample to be analyzed. Grounded conductors are placed at the tube ends and axially displaced from the inductive coil, whereby the resulting electromagnetic field acts to elongate the plasma in the tube. Sample materials can be injected in the plasma to be excited for spectroscopy.

  8. Closed inductively coupled plasma cell

    DOEpatents

    Manning, T.J.; Palmer, B.A.; Hof, D.E.

    1990-11-06

    A closed inductively coupled plasma cell generates a relatively high power, low noise plasma for use in spectroscopic studies is disclosed. A variety of gases can be selected to form the plasma to minimize spectroscopic interference and to provide a electron density and temperature range for the sample to be analyzed. Grounded conductors are placed at the tube ends and axially displaced from the inductive coil, whereby the resulting electromagnetic field acts to elongate the plasma in the tube. Sample materials can be injected in the plasma to be excited for spectroscopy. 1 fig.

  9. Plasma afterburners and related issues

    NASA Astrophysics Data System (ADS)

    Huang, Chengkun

    2006-10-01

    In plasma wakefield acceleration experiments, the drive beam moves at the speed of light in the plasma and excites an accelerating plasma wakefield behind the driver. Therefore it is possible to use a trailing electron beam to extract energy from the plasma wave wake. Such a design, called the plasma afterburner, has been proposed to double the energy of the incoming beam train for a future linear collider. We investigate the nonlinear beam-plasma interaction in such scenario using a 3D computer modeling code, QuickPIC. We will report on the simulation results of a 1 TeV plasma afterburner design. Several issues such as efficient beam-loading and the stability of the beam in the plasma are also analyzed. The electron hosing instability in the blow-out regime of plasma wakefield acceleration is also investigated using linear perturbation theory upon the electron blow-out trajectory. The growth of the hosing instability is found to be affected by the plasma self-fields, the relativistic mass, the axial motion of plasma electrons and the position-dependent ion channel radius respectively. Therefore the hosing growth has dependence on the beam current, which is not found in the fluid theory. PIC simulations agree very well with this new theory.

  10. Transport processes in space plasmas

    SciTech Connect

    Birn, J.; Elphic, R.C.; Feldman, W.C.

    1997-08-01

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The project represents a comprehensive research effort to study plasma and field transport processes relevant for solar-terrestrial interaction, involving the solar wind and imbedded magnetic field and plasma structures, the bow shock of the Earth`s magnetosphere and associated waves, the Earth`s magnetopause with imbedded flux rope structures and their connection with the Earth, plasma flow in the Earth`s magnetotail, and ionospheric beam/wave interactions. The focus of the work was on the interaction between plasma and magnetic and electric fields in the regions where different plasma populations exist adjacent to or superposed on each other. These are the regions of particularly dynamic plasma behavior, important for plasma and energy transport and rapid energy releases. The research addressed questions about how this interaction takes place, what waves, instabilities, and particle/field interactions are involved, how the penetration of plasma and energy through characteristic boundaries takes place, and how the characteristic properties of the plasmas and fields of the different populations influence each other on different spatial and temporal scales. These topics were investigated through combining efforts in the analysis of plasma and field data obtained through space missions with theory and computer simulations of the plasma behavior.

  11. Main Features of Plasma Control

    SciTech Connect

    Crisanti, F.; Albanese, R.; Ambrosino, G.

    2008-03-12

    In the recent years Plasma Control has always increased his importance in any advanced experiment. It is now clear that ITER will not be able to operate without a quite advanced and sophisticated control apparatus. Necessarily this system will have to integrate several different aspects of the Plasma behavior. One of the most important parts of a closed loop control system is the quality of the measurement of the plasma parameters that should be controlled. Eventually, this aspect involves sophisticated and complex diagnostic apparatus. This paper presents an overview of the present status, and further studies and developments needed, in the next future, for the design and realization of an integrated plasma control system aimed at both stabilizing the plasma non-axisymmetric instabilities and controlling the most important internal plasma parameters. In particular the Edge Localized Modes (ELMs), the Neo-Classical Tearing Modes (NTM), the Resistive Wall Mode (RWM) and the Plasma Profiles control system necessities will be shortly illustrated.

  12. Space plasma contractor research, 1988

    NASA Technical Reports Server (NTRS)

    Williams, John D.; Wilbur, Paul J.

    1989-01-01

    Results of experiments conducted on hollow cathode-based plasma contractors are reported. Specific tests in which attempts were made to vary plasma conditions in the simulated ionospheric plasma are described. Experimental results showing the effects of contractor flowrate and ion collecting surface size on contactor performance and contactor plasma plume geometry are presented. In addition to this work, one-dimensional solutions to spherical and cylindircal space-charge limited double-sheath problems are developed. A technique is proposed that can be used to apply these solutions to the problem of current flow through elongated double-sheaths that separate two cold plasmas. Two conference papers which describe the essential features of the plasma contacting process and present data that should facilitate calibration of comprehensive numerical models of the plasma contacting process are also included.

  13. Main Features of Plasma Control

    NASA Astrophysics Data System (ADS)

    Crisanti, F.; Albanese, R.; Ambrosino, G.

    2008-03-01

    In the recent years Plasma Control has always increased his importance in any advanced experiment. It is now clear that ITER will not be able to operate without a quite advanced and sophisticated control apparatus. Necessarily this system will have to integrate several different aspects of the Plasma behavior. One of the most important parts of a closed loop control system is the quality of the measurement of the plasma parameters that should be controlled. Eventually, this aspect involves sophisticated and complex diagnostic apparatus. This paper presents an overview of the present status, and further studies and developments needed, in the next future, for the design and realization of an integrated plasma control system aimed at both stabilizing the plasma non-axisymmetric instabilities and controlling the most important internal plasma parameters. In particular the Edge Localized Modes (ELMs), the Neo-Classical Tearing Modes (NTM), the Resistive Wall Mode (RWM) and the Plasma Profiles control system necessities will be shortly illustrated.

  14. Potentials of fissioning plasmas

    NASA Technical Reports Server (NTRS)

    Thom, K.

    1979-01-01

    Successful experiments with the nuclear pumping of lasers have demonstrated that in a gaseous medium the kinetic energy of fission fragments can be converted directly into nonequilibrium optical radiation. This confirms the concept that the fissioning medium in a gas-phase nuclear reactor shows an internal structure such as a plasma in near thermal equilibrium varying up to a state of extreme nonequilibrium. During 20 years of research under NASA support major elements of the fissioning plasma reactor were demonstrated in theory and experiment, culminating in a proof-of-principle reactor test conducted at the Los Alamos Scientific Laboratory. It is concluded that the construction of a gaseous fuel reactor power plant is within the reach of present technology.

  15. Instabilities in uranium plasma.

    NASA Technical Reports Server (NTRS)

    Tidman, D. A.

    1971-01-01

    The nonlinear evolution of unstable sound waves in a uranium plasma has been calculated using a multiple time-scale asymptotic expansion scheme. The fluid equations used include the fission power density, radiation diffusion, and the effects of the changing degree of ionization of the uranium atoms. The nonlinear growth of unstable waves is shown to be limited by mode coupling to shorter wavelength waves which are damped by radiation diffusion. This mechanism limits the wave pressure fluctuations to values of order delta P/P equal to about .00001 in the plasma of a typical gas-core nuclear rocket engine. The instability is thus not expected to present a control problem for this engine.

  16. Plasma wave accelerator. II

    SciTech Connect

    Mori, W.; Joshi, C.; Dawson, J.M.

    1982-01-01

    It was shown that the insertion of a cross magnetic field prevents the particles from getting out of phase with the electric field of the plasma wave in the beat wave accelerator scheme. Thus, using a CO/sub 2/ laser, n/sub c//n/sub e/ = (..omega../sub 0//..omega../sub p/)/sup 2/ approx. 35, and a 300 kG magnetic field, electrons can be (in principle) accelerated to 100 GeV in 2 meters. For comparison without the magnetic field, the same energies may be obtained in a n/sub c//n/sub e/ approx. 10/sup 5/ plasma over a distance of 100 meters.

  17. Dust interferometers in plasmas

    NASA Astrophysics Data System (ADS)

    Chaudhuri, M.; Nosenko, V.; Thomas, H. M.

    2016-03-01

    An interferometric imaging technique has been proposed to instantly measure the diameter of individual spherical dust particles suspended in a gas discharge plasma. The technique is based on the defocused image analysis of both spherical particles and their binary agglomerates. Above a critical diameter, the defocused images of spherical particles contain stationary interference fringe patterns and the fringe number increases with particle diameters. Below this critical diameter, the particle size has been measured using the rotational interference fringe patterns which appear only on the defocused images of binary agglomerates. In this case, a lower cutoff limit of particle diameter has been predicted, below which no such rotational fringe patterns are observed for the binary agglomerates. The method can be useful as a diagnostics for complex plasma experiments on earth as well as under microgravity conditions.

  18. Equatorially trapped plasma populations

    NASA Technical Reports Server (NTRS)

    Olsen, R. C.

    1981-01-01

    The SCATHA observations of the equatorially trapped plasmas are presented in order to emphasize the importance of making measurements at the equator. The UCSD plasma detector and the GSFC electric field experiment are described, as are the pertinent characteristics of the magnetometer and mass spectrometers. The electron distribution reveals a width of 20 deg to 60 deg, narrowing with increasing energy. The 20- to 100-eV ion fluxes typically exhibit temperatures in the 20to 50-eV range and densities of 1-10 per cu cm. The electron population typically ranges from 50 to 500 eV, with temperatures of 100-200 eV and densities also in the 1-10 per cu cm range. Field-aligned populations of lower energy are occasionally found in both ions and electrons at the same location.

  19. Plasma and magnetospheric research

    NASA Technical Reports Server (NTRS)

    Comfort, R. H.; Horwitz, J. L.

    1985-01-01

    Several programs and variations have been developed to determine statistical means of different plasma parameters when binned in different variables. These parameters include temperature, densities and spacecraft potentials for any of the ion species, as well as ratios of these variables for any other ion species to the corresponding variable for H(+). The variables for binning include L, radial distance, and geomagnetic latitude; and separate statistics are automatically run for local morning and local evening data. These programs all run from output files from the plasma parameter thin sheath analysis program. A variant program also bins for magnetic activity, using either Kp or Dst, which requires an additional magnetic activity input file. These programs can be run either interactively or in batch mode, using file listings generated by a DIRECTORY command. In addition to printed output, these programs generate output files which can be used to plot the results. Programs to plot these averaged data are under development.

  20. Plasma Generated Spherules

    NASA Astrophysics Data System (ADS)

    Ransom, C. J.

    2005-04-01

    Z-pinch plasma simulations have been performed that indicate the production of spherules under certain experimental parameters. (A. L. Peratt, private communication) While performing experiments dealing with the impact of plasma discharges on various materials, we observed that spherules were created at the surface of some of the materials. For specific materials and conditions, spherules were always produced. Both individual spherules and joined spherules were created. The size and shapes were nearly identical to items found by the Mars rover, Opportunity, and called ``blueberries.'' Sky & Telescope, June 2004, p. 20, among other sources indicated the blueberries were gray spherules composed of hematite. The experiments produced hematite spherules identical in appearance to those found on Mars. These experiments suggest how the newly discovered blueberries were formed on Mars while providing an explanation that does not depend on the presence of water.

  1. The cathode plasma simulation

    NASA Astrophysics Data System (ADS)

    Suksila, Thada

    Since its invention at the University of Stuttgart, Germany in the mid-1960, scientists have been trying to understand and explain the mechanism of the plasma interaction inside the magnetoplasmadynamics (MPD) thruster. Because this thruster creates a larger level of efficiency than combustion thrusters, this MPD thruster is the primary cadidate thruster for a long duration (planetary) spacecraft. However, the complexity of this thruster make it difficult to fully understand the plasma interaction in an MPD thruster while operating the device. That is, there is a great deal of physics involved: the fluid dynamics, the electromagnetics, the plasma dynamics, and the thermodynamics. All of these physics must be included when an MPD thruster operates. In recent years, a computer simulation helped scientists to simulate the experiments by programing the physics theories and comparing the simulation results with the experimental data. Many MPD thruster simulations have been conducted: E. Niewood et al.[5], C. K. J. Hulston et al.[6], K. D. Goodfellow[3], J Rossignol et al.[7]. All of these MPD computer simulations helped the scientists to see how quickly the system responds to the new design parameters. For this work, a 1D MPD thruster simulation was developed to find the voltage drop between the cathode and the plasma regions. Also, the properties such as thermal conductivity, electrical conductivity and heat capacity are temperature and pressure dependent. These two conductivity and heat capacity are usually definded as constant values in many other models. However, this 1D and 2D cylindrical symmetry MPD thruster simulations include both temperature and pressure effects to the electrical, thermal conductivities and heat capacity values interpolated from W. F. Ahtye [4]. Eventhough, the pressure effect is also significant; however, in this study the pressure at 66 Pa was set as a baseline. The 1D MPD thruster simulation includes the sheath region, which is the interface between the plasma and the cathode regions. This sheath model [3] has been fully combined in the 1D simulation. That is, the sheath model calculates the heat flux and the sheath voltage by giving the temperature and the current density. This sheath model must be included in the simulation, as the sheath region is treated differently from the main plasma region. For our 2D cylindrical symmetry simulation, the dimensions of the cathode, the anode, the total current, the pressure, the type of gases, the work function can be changed in the input process as needed for particular interested. Also, the sheath model is still included and fully integrated in this 2D cylindrical symmetry simulation at the cathode surface grids. In addition, the focus of the 2D cylindrical symmetry simulation is to connect the properties on the plasma and the cathode regions on the cathode surface until the MPD thruster reach steady state and estimate the plasma arc attachement edge, electroarc edge, on the cathode surface. Finally, we can understand more about the behavior of an MPD thruster under many different conditions of 2D cylindrical symmetry MPD thruster simulations.

  2. Plasma jet takes off.

    PubMed

    Frazer, L

    1999-08-01

    Thanks to a series of joint research projects by Los Alamos National Laboratory, Beta Squared of Allen, Texas, and the University of California at Los Angeles, there is now a more environmentally sound method for cleaning semiconductor chips that may also be effective in cleaning up chemical, bacterial, and nuclear contaminants. The Atmospheric Pressure Plasma Jet uses a type of ionized gas called plasma to clean up contaminants by binding to them and lifting them away. In contrast to the corrosive acids and chemical solvents traditionally used to clean semiconductor chips, the jet oxidizes contaminants, producing only benign gaseous by-products such as oxygen and carbon dioxide. The new technology is also easy to transport, cleans thoroughly and quickly, and presents no hazards to its operators. PMID:10417375

  3. Axially Modulated Plasma Waveguides

    SciTech Connect

    Layer, B. D.; York, A. G.; Varma, S.; Chen, Y.-H.; Milchberg, H. M.

    2009-01-22

    We demonstrate two techniques for making periodically modulated plasma waveguides-one with sharp, stable voids as short as 50 {mu}m with a period as small as 200 {mu}m, and another which modulates the waveguide diameter with a corrugation period as short as 35 {mu}m[1]. These features persist as the plasma expands for the full lifetime of the waveguide (>6 ns). The waveguides were made using the hydrodynamic shock method in a cluster jet using hydrogen, nitrogen, and argon. We demonstrate guided propagation at intensities up to 2x10{sup 17} W/cm{sup 2}, limited by our laser energy currently available. This technique is useful for quasi-phase matching to allow efficient coupling of laser energy to acceleration of relativistic electrons or generation of coherent electromagnetic radiation at selected frequencies.

  4. Plasma dust crystallization

    NASA Technical Reports Server (NTRS)

    Goree, John; Thomas, H.; Morfill, G.

    1994-01-01

    In a ground-based definition study, a concept for a new type of microgravity experiment is developed. We formed a new state of matter: a crystalline lattice structure of charged micron-size spheres, suspended in a charge-neutral plasma. The plasma is formed by a low-pressure radio-frequency argon discharge. Solid microspheres are introduced, and they gain a negative electric charge. They are cooled by molecular drag on the ambient neutral gas. They are detected by laser light scattering and video photography. Laboratory experiments have demonstrated that a two-dimensional nonquantum lattice forms through the Coulomb interaction of these spheres. Microgravity is thought to be required to observe a three-dimensional structure.

  5. [Plasma cell leukemia].

    PubMed

    Ravinet, Aurlie; Bay, Jacques Olivier; Tournilhac, Olivier

    2014-11-01

    Plasma cell leukemia (PCL) is a rare disorder which develops spontaneously (primary PCL) or evolves in patients with multiple myeloma (secondary PCL). It is defined by the presence of 2 10(9)/L peripheral blood plasma cells or plasmacytosis accounting for more than 20 % of the differential white cell count. PCL presents more often extramedullary involvement, anemia, thrombocytopenia, hypercalcemia, as well as impaired renal function. Cytogenetic abnormalities and mutations observed in PCL lead to escape from immune surveillance and independence from the bone marrow microenvironment with changes in expression of adhesion molecules or chemokines receptors. The outcome of PCL has improved with combination approaches with novel agents (including bortezomib and immunomodulatory drugs, such as lenalidomide) and with autologous stem cell transplantation. Allogeneic hematopoietic stem cell transplantation is currently available for young patients. This article is an overview of this rare and severe disease and the different therapeutics options that are recommended. PMID:25418598

  6. Hybrid plasma modeling.

    SciTech Connect

    Hopkins, Matthew Morgan; DeChant, Lawrence Justin.; Piekos, Edward Stanley; Pointon, Timothy David

    2009-02-01

    This report summarizes the work completed during FY2007 and FY2008 for the LDRD project ''Hybrid Plasma Modeling''. The goal of this project was to develop hybrid methods to model plasmas across the non-continuum-to-continuum collisionality spectrum. The primary methodology to span these regimes was to couple a kinetic method (e.g., Particle-In-Cell) in the non-continuum regions to a continuum PDE-based method (e.g., finite differences) in continuum regions. The interface between the two would be adjusted dynamically ased on statistical sampling of the kinetic results. Although originally a three-year project, it became clear during the second year (FY2008) that there were not sufficient resources to complete the project and it was terminated mid-year.

  7. Io Plasma Torus: Nature of the Iogenic Plasma Source

    NASA Astrophysics Data System (ADS)

    Marconi, M. L.; Smyth, W. H.

    1996-09-01

    The primary source of plasma for Jupiter's magnetosphere is supplied internally by Io, the innermost Galilean satellite. The Iogenic plasma source is created by gases (e.g., Na, K, O, S, and SO_2) lost from Io as they undergo electron impact and charge exchange reactions in the plasma torus. This Iogenic plasma source provides mass, momentum, pick-up electrical conductivity, and energy to the plasma torus. The three-dimensional nature of the Iogenic plasma source is an important input quantity (1) in local studies to understand the plasma torus properties (density, composition, subcorotational motion, electric currents, and temperature) and the plasma torus near-Io MHD flow and atmosphere interactions, and (2) in more global studies to understand the spacetime structure of the outward transport dynamics of the plasma torus, such as in RCM-J (Rice Convection Model for Jupiter) calculations. To elucidate and quantify the nature of the Iogenic plasma source for such studies, we have undertaken simulations of it using the AER neutral cloud models. Calculations will be presented to illustrate the spacetime nature of the Iogenic plasma source and to estimate the net-mass, momentum and energy input rates to the plasma torus and the height-integrated electrical conductivity near Io and in Jupiter's ionosphere. These calculations show that the instantaneous Iogenic plasma source is highly peaked at Io's position in the plasma torus and that its rates vary significantly with Io System III longitude and also with Io phase angle because of the east-west electric field. For the lower-velocity escape of gases by incomplete collisional cascade processes (i.e., plasma torus ion sputtering), contributions to the instantaneous Iogenic plasma source are primarily confined to a broader (but still limited) spatial region in L-shell and System III longitude angle near Io. For the higher-velocity loss of gases by charge exchange, contributions to the Iogenic plasma source are more spatially concentrated at Io and produce a large pick-up electrical conductivity with large associated field-aligned currents in the vicinity of the satellite. The Iogenic source should therefore locally reduce both the magnetic field and the plasma flow velocity.

  8. Collisionless microinstabilities in stellarators. III. The ion-temperature-gradient mode

    SciTech Connect

    Plunk, G. G. Helander, P.; Xanthopoulos, P.; Max-Planck Connor, J. W.

    2014-03-15

    We investigate the linear theory of the ion-temperature-gradient (ITG) mode, with the goal of developing a general understanding that may be applied to stellarators. We highlight the Wendelstein 7X (W7-X) device. Simple fluid and kinetic models that follow closely from existing literature are reviewed and two new first-principle models are presented and compared with results from direct numerical simulation. One model investigates the effect of regions of strong localized shear, which are generic to stellarator equilibria. These “shear spikes” are found to have a potentially significant stabilizing affect on the mode; however, the effect is strongest at short wavelengths perpendicular to the magnetic field, and it is found to be significant only for the fastest growing modes in W7-X. A second model investigates the long-wavelength limit for the case of negligible global magnetic shear. The analytic calculation reveals that the effect of the curvature drive enters at second order in the drift frequency, confirming conventional wisdom that the ITG mode is slab-like at long wavelengths. Using flux tube simulations of a zero-shear W7-X configuration, we observe a close relationship to an axisymmetric configuration at a similar parameter point. It is concluded that scale lengths of the equilibrium gradients constitute a good parameter space to characterize the ITG mode. Thus, to optimize the magnetic geometry for ITG mode stability, it may be fruitful to focus on local parameters, such as the magnitude of bad curvature, connection length, and local shear at locations of bad curvature (where the ITG mode amplitude peaks)

  9. How non-adiabatic passing electron layers of linear microinstabilities affect turbulent transport

    NASA Astrophysics Data System (ADS)

    Dominski, J.; Brunner, S.; Görler, T.; Jenko, F.; Told, D.; Villard, L.

    2015-06-01

    The response of passing electrons in ion temperature gradient and trapped electron mode microturbulence regimes is investigated in tokamak geometry making use of the flux-tube version of the gyrokinetic code GENE. Results are obtained using two different electron models, fully kinetic and hybrid in which passing particles are forced to respond adiabatically, while trapped are handled kinetically. Comparing linear eigenmodes obtained with these two models enables to systematically isolate fine radial structures located at corresponding mode rational surfaces, clearly resulting from the non-adiabatic passing-electron response. Non-linear simulations show that these fine structures on the non-axisymmetric modes survive in the turbulent phase. Furthermore, through non-linear coupling to axisymmetric modes, they induce radial modulations in the effective profiles of density, ion/electron temperature, and E × B shearing rate. Finally, the passing-electron channel is shown to significantly contribute to the transport levels, at least in our ion temperature gradient case. Also shown is that the passing electrons significantly influence the E × B saturation mechanism of turbulence fluxes.

  10. Dusty spin plasmas

    SciTech Connect

    Brodin, G.; Marklund, M.; Zamanian, J.

    2008-09-07

    A fluid model is derived, taking into account the effect of spin magnetization of electrons as well as of magnetized dust grains. The model is analyzed, and it is found that both the acoustic velocity and the Alfven velocity is decreased due to the magnetization effects. Furthermore, for low-temperature high density plasmas, it is found that the linear wave modes can be unstable, due to the magnetic attraction of individual fluid elements. The significance of our results are discussed.

  11. Future of plasma simulation

    SciTech Connect

    Forslund, D.W.

    1986-01-01

    The author briefly comments on factors essential to improving the capabilities of plasma modeling. These factors include high input/output performance, large solid state disk capacity, symbolic debugging tools, high speed graphics, high speed image generation and workstations for pre- and post-processing. Also important is the development of additional software to provide an enhanced interface between the work-stations and supercomputers. (DWL)

  12. Princeton Plasma Physics Laboratory:

    SciTech Connect

    Phillips, C.A.

    1986-01-01

    This paper discusses progress on experiments at the Princeton Plasma Physics Laboratory. The projects and areas discussed are: Principal Parameters Achieved in Experimental Devices, Tokamak Fusion Test Reactor, Princeton Large Torus, Princeton Beta Experiment, S-1 Spheromak, Current-Drive Experiment, X-ray Laser Studies, Theoretical Division, Tokamak Modeling, Spacecraft Glow Experiment, Compact Ignition Tokamak, Engineering Department, Project Planning and Safety Office, Quality Assurance and Reliability, and Administrative Operations.

  13. Spectroscopy of divertor plasmas

    SciTech Connect

    Isler, R.C.

    1995-12-31

    The requirements for divertor spectroscopy are treated with respect to instrumentation and observations on present machines. Emphasis is placed on quantitative measurements.of impurity concentrations from the interpretation of spectral line intensities. The possible influence of non-Maxwellian electron distributions on spectral line excitation in the divertor is discussed. Finally the use of spectroscopy for determining plasma temperature, density, and flows is examined.

  14. Linking plasma kinetics to plasma-bio interactions

    NASA Astrophysics Data System (ADS)

    Bruggeman, Peter

    2015-05-01

    Cold non-equilibrium atmospheric pressure plasmas have received a lot of attention in the last decade due to their huge potential for biomedical applications. In my group, we have characterized an RF driven APPJ in great detail. The characterization includes electrical measurements, imaging, optical emission spectroscopy, (two photon enhanced) laser induced fluorescence, Thomson scattering, Rayleigh scattering, Raman scattering and mass spectrometry. This led to a detailed knowledge of the electron density, electron temperature, gas temperature, NO, O, OH, O3 densities, ionic species and air concentrations in the plasma effluent. Living organisms for in vitro studies are typically kept in complex solutions or culture media. Plasma-bio interactions involves not only the production of reactive species in the plasma gas phase but also transport to the liquid phase and plasma induced liquid phase chemistry and its impact on the living organisms. Reactive nitrogen and oxygen species have been identified as the key reactive species. Recent results of my group show that controlling the gas phase plasma chemistry can lead to significant different biological responses of the living organisms corresponding to different chemical pathways. The effect of plasma jet interaction with liquids containing mammalian cells, bacteria and virus will be discussed. The outcomes of these studies allow unraveling chemical pathways responsible for plasma-bio interactions and linking plasma kinetics to plasma-bio interactions.

  15. Plasma Torch for Plasma Ignition and Combustion of Coal

    NASA Astrophysics Data System (ADS)

    Ustimenko, Alexandr; Messerle, Vladimir

    2015-09-01

    Plasma-fuel systems (PFS) have been developed to improve coal combustion efficiency. PFS is a pulverized coal burner equipped with arc plasma torch producing high temperature air stream of 4000 - 6000 K. Plasma activation of coal at the PFS increases the coal reactivity and provides more effective ignition and ecologically friendly incineration of low-rank coal. The main and crucial element of PFS is plasma torch. Simplicity and reliability of the industrial arc plasma torches using cylindrical copper cathode and air as plasma forming gas predestined their application at heat and power engineering for plasma aided coal combustion. Life time of these plasma torches electrodes is critical and usually limited to 200 hours. Considered in this report direct current arc plasma torch has the cathode life significantly exceeded 1000 hours. To ensure the electrodes long life the process of hydrocarbon gas dissociation in the electric arc discharge is used. In accordance to this method atoms and ions of carbon from near-electrode plasma deposit on the active surface of the electrodes and form electrode carbon condensate which operates as ``actual'' electrode. Complex physicochemical investigation showed that deposit consists of nanocarbon material.

  16. Momentum transfer to rotating magnetized plasma from gun plasma injection

    SciTech Connect

    Shamim, Imran; Hassam, A. B.; Ellis, R. F.; Witherspoon, F. D.; Phillips, M. W.

    2006-11-15

    Numerical simulations are carried out to investigate the penetration and momentum coupling of a gun-injected plasma slug into a rotating magnetized plasma. An experiment along these lines is envisioned for the Maryland Centrifugal Experiment (MCX) [R. F. Ellis et al., Phys. Plasmas 8, 2057 (2001)] using a coaxial plasma accelerator gun developed by HyperV Technologies Corp. [F. D. Witherspoon et al., Bull. Am. Phys. Soc. 50, LP1 87 (2005)]. The plasma gun would be located in the axial midplane and fired off-axis into the rotating MCX plasma annulus. The numerical simulation is set up so that the initial momentum in the injected plasma slug is of the order of the initial momentum of the target plasma. Several numerical firings are done into the cylindrical rotating plasma. Axial symmetry is assumed. The slug is seen to penetrate readily and deform into a mushroom, characteristic of interchange deformations. It is found that up to 25% of the momentum in the slug can be transferred to the background plasma in one pass across a cylindrical chord. For the same initial momentum, a high-speed low density slug gives more momentum transfer than a low-speed high density slug. Details of the numerical simulations and a scaling study are presented.

  17. Precise plasma process control based on combinatorial plasma etching

    NASA Astrophysics Data System (ADS)

    Sekine, Makoto; Suzuki, Toshiya; Takeda, Keigo; Kondo, Hiroki; Ishikawa, Kenji; Setsuhara, Yuichi; Shiratani, Masaharu; Hori, Masaru

    2012-10-01

    For the realization of super-fine plasma etching process, fluctuations of plasma parameters such as densities of radicals, ions and electrons is required to be minimized. In particular, conditions of inner surface of reactor wall can significantly influence on the radical density in subsequent plasma process owing to outgas consisting of deposited reaction products and adsorbed species from the previous process on the wall. To investigate variety of gaseous radical densities for H2/N2 plasma when inner wall condition was changed by the previous process, we analyzed the radical densities using vacuum ultraviolet absorption spectroscopy (VUVAS). It was clearly confirmed that the radical densities in 100-MHz capacitively coupled plasma (CCP) of H2/N2 were temporally changed subsequently after different kind of conditions for H2/N2 plasma, O2 plasma, and air exposure. We clarified how and what kind of etched products or process gases adsorbed on inner wall surface during the previous process and what species desorbed from the wall into bulk plasmas. Then we are trying to establish a precise process control systematically based on the plasma nano-science database that is constructing using the combinatorial plasma etching approach [1]. [4pt] [1] C. Moon, et al., Applied Physics Express 2 (2009) 096001.

  18. The Coalition for Plasma Science: Bringing Plasmas to the Public

    NASA Astrophysics Data System (ADS)

    Berry, Lee

    2003-10-01

    The Coalition for Plasma Science is a group of institutions, organizations, and companies that have joined forces to increase awareness and understanding of plasma science and its many applications and benefits for society. The CPS undertakes a range of activities to support this goal. Members include national laboratories, universities, industries, and individuals. The CPS maintains a web page (http://www.plasmacoalition.org), and has developed several types of plasma-related publications. The web page includes a compilation of evaluated plasma web sites. The evaluations were conducted by teachers and based on national teaching standards. The web site also contains copies of CPS publications including the brochure ''Plasmas are Everywhere.'' Thousands of these brochures are distributed each year, and a poster version is now available. Another publication is the ''About Plasmas'' series. Each of these two-page papers (which is written for a general audience) is about a specific plasma-related topic, such as lighting, fusion, space plasmas and plasma decontamination of biological hazards. Papers on other topics are under development. The CPS also organizes educational luncheon/seminars for Members of Congress and their staff. The most recent seminar was given by David Newman on January 28th of this year and was his ''state of the universe'' address. A second seminar is planned this year on the topic of semiconductor manufacturing. Activities under discussion include a topical science fair award for a project on plasmas and the development of a broad, history-based educational web site.

  19. Plasma Properties of Microwave Produced Plasma in a Toroidal Device

    NASA Astrophysics Data System (ADS)

    Singh, Ajay; Edwards, W. F.; Held, Eric

    2011-10-01

    We have modified a small tokamak, STOR-1M, on loan from University of Saskatchewan, to operate as a low-temperature (~5 eV) toroidal plasma machine with externally induced toroidal magnetic fields ranging from zero to ~50 G. The plasma is produced using microwave discharges at relatively high pressures. Microwaves are produced by a kitchen microwave-oven magnetron operating at 2.45 GHz in continuous operating mode, resulting in pulses ~0.5 s in duration. Initial measurements of plasma formation in this device with and without applied magnetic fields are presented. Plasma density and temperature profiles have been measured using Langmuir probes and the magnetic field profile inside the plasma has been obtained using Hall probes. When the discharge is created with no applied toroidal magnetic field, the plasma does not fill the entire torus due to high background pressure. However, when a toroidal magnetic field is applied, the plasma flows along the applied field, filling the torus. Increasing the applied magnetic field seems to aid plasma formation - the peak density increases and the density gradient becomes steeper. Above a threshold magnetic field, the plasma develops low-frequency density oscillations due to probable excitation of flute modes in the plasma.

  20. Screening Resonances In Plasmas

    SciTech Connect

    Winkler, P.

    1998-12-01

    When it was suggested that a new recombination mechanism (Resonant Radiative Recombination (RRR)) which, based on very general physical arguments, should happen in dense plasmas and promises to provide useful information for the local temperature and density diagnostics of plasmas, they assumed the existence of screening resonances. For model potentials the existence of screening resonances has been demonstrated beyond reasonable doubt in a number of calculations. The key question, how well those potentials describe the dominant effects of a real plasma remains open. The relation of theoretical predictions to experimentally measurable effects is an important issue at the present stage of their research. In particular, RRR is expected to account for enhanced recombination rates of low energetic electrons with their ions, since the first stage is the resonant capture of a slow electron by an atom or ion. The mechanism that traps an electron is a combination of complicated many-body interactions of the ions and electrons. For clarity they start here, however, with a discussion in terms of local potential traps the shapes of which are determined predominantly and in an average way by two factors: the degree of screening present at the ionic site and the degree of short-range order in the immediate neighborhood of this ion.

  1. Plasma Modeling of Electrosurgery

    NASA Astrophysics Data System (ADS)

    Jensen, Scott; Friedrichs, Daniel; Gilbert, James; Park, Wounjhang; Maksimovic, Dragan

    2014-10-01

    Electrosurgery is the use of high frequency alternating current (AC) to illicit a clinical response in tissue, such as cutting or cauterization. Power electronics converters have been demonstrated to generate the necessary output voltage and current for electrosurgery. The design goal of the converter is to regulate output power while supplying high frequency AC. The design is complicated by fast current and voltage transients that occur when the current travels through air in the form of an arc. To assist in designing a converter that maintains the desired output power during these transients, we have used the COMSOL Plasma Module to determine the output voltage and current characteristics during an arc. This plasma model, used in conjunction with linear circuit elements, allows the full electrosurgical system to be validated. Two models have been tested with the COMSOL Plasma Module. One is a four-species, four-reaction model based on the local field approximation technique. The second simulates the underlying air chemistry using 30 species, 151 chemical reactions, and a coupled electron energy distribution function. Experimental output voltage and current samples have been collected and compared to both models.

  2. PLASMA CELL LEUKEMIA

    PubMed Central

    de Larrea, Carlos Fernandez; Kyle, Robert A.; Durie, Brian GM; Ludwig, Heinz; Usmani, Saad; Vesole, David H.; Hajek, Roman; Miguel, Jésus San; Sezer, Orhan; Sonneveld, Pieter; Kumar, Shaji K.; Mahindra, Anuj; Comenzo, Ray; Palumbo, Antonio; Mazumber, Amitabha; Anderson, Kenneth C.; Richardson, Paul G.; Badros, Ashraf Z.; Caers, Jo; Cavo, Michele; LeLeu, Xavier; Dimopoulos, Meletios A.; Chim, CS; Schots, Rik; Noeul, Amara; Fantl, Dorotea; Mellqvist, Ulf-Henrik; Landgren, Ola; Chanan-Khan, Asher; Moreau, Philippe; Fonseca, Rafael; Merlini, Giampaolo; Lahuerta, JJ; Bladé, Joan; Orlowski, Robert Z.; Shah, Jatin J.

    2014-01-01

    Plasma cell leukemia (PCL) is a rare and aggressive variant of myeloma characterized by the presence of circulating plasma cells. It is classified as either primary PCL occurring at diagnosis or as secondary PCL in patients with relapsed/refractory myeloma. Primary PCL is a distinct clinic-pathologic entity with different cytogenetic and molecular findings. The clinical course is aggressive with short remissions and survival duration. The diagnosis is based upon the percentage (≥ 20%) and absolute number (≥ 2 × 10 9/L) of plasma cells in the peripheral blood. It is proposed that the thresholds for diagnosis be reexamined and consensus recommendations are made for diagnosis, as well as, response and progression criteria. Induction therapy needs to begin promptly and have high clinical activity leading to rapid disease control in an effort to minimize the risk of early death. Intensive chemotherapy regimens and bortezomib-based regimens are recommended followed by high-dose therapy with autologous stem-cell transplantation (HDT/ASCT) if feasible. Allogeneic transplantation can be considered in younger patients. Prospective multicenter studies are required to provide revised definitions and better understanding of the pathogenesis of PCL. PMID:23288300

  3. Microwave Argon Plasma Torch

    NASA Astrophysics Data System (ADS)

    Felizardo, Edgar; Pencheva, Mariana; Benova, Evgenia; Dias, Fransisco; Tatarova, Elena

    2009-10-01

    A theoretical and experimental investigation of a microwave (2.45 GHz) Argon plasma torch driven by a surface wave is presented. The theoretical model couples in a self-consistent way the wave electrodynamics and the electron and heavy particle kinetics. The set of coupled equations includes: Maxwell's equations, the electron Boltzmann equation, including electron-electron collisions, and the particle balance equations for electrons, excited atoms (4s, 4p, 3d, 5s, 5p, 4d, 6s), and atomic (Ar^+) and molecular ions (Ar2^+). The input parameters of the model are: gas pressure (760 Torr), plasma radius (R = 0.75 cm), dielectric permittivity (ɛd = 4.0) and tube thickness (d = 0.15 cm) as well as the measured axial profile of the gas temperature (3500 K - 1500 K). The latter was determined from measurements of the rotational temperature of the OH molecular band in the range 306 - 315 nm. Phase and amplitude sensitive recording provides the data for the axial wavenumber and wave attenuation coefficient. The wavenumber decreases along the generated plasma torch. The electron density (Ne) axial profile as determined from measurements of Hβ Stark broadening is in agreement with the theoretical one.

  4. Auroral Plasma Physics

    NASA Astrophysics Data System (ADS)

    Paschmann, G.; Haaland, S.; Treumann, R.

    2003-03-01

    This volume gives a broad synthesis of the current knowledge and understanding of the plasma physics behind the aurora. The aurora is not only one of the most spectacular natural phenomena on Earth, but the underlying physical processes are expected to be ubiquitous in the plasma universe. Recognizing the enormous progress made over the last decade, through in situ and groundbased measurements as well as theoretical modelling, it seemed timely to write the first comprehensive and integrated book on the subject. Recent advances concern the clarification of the nature of the acceleration process of the electrons that are responsible for the visible aurora, the recognition of the fundamental role of the large-scale current systems in organizing the auroral morphology, and of the interplay between particles and electromagnetic fields. Although written by a team of 32 leading scientists from 9 different countries, the book is characterized by consistency in style, nomenclature, notations and format. Extensive cross-referencing helps to integrate the various chapters. The book is intended to be used both as a learning tool for graduate students, and as a reference for space plasma physicists and auroral researchers. Link: http://www.wkap.nl/prod/b/1-4020-0963-1

  5. Plasma Sensor Suite

    NASA Astrophysics Data System (ADS)

    Matlis, Eric; Bowles, Patrick; Corke, Thomas

    2008-11-01

    Progress has been made towards the development of a new class of sensors which have the potential to overcome the temperature limitations found in conventional sensors, thus addressing an important measurement challenge faced in the measurement of high speed flows. The new approach is based on the a.c.-driven mass-flow laboratory plasma anemometer developed by Matlis et al. and uses a weakly ionized glow discharge encapsulated between two electrodes as the sensing element. These sensors will feature proven elements of the technology used in the plasma anemometer, but will be extended for high-temperature, multiparameter operation. The sensitivity to different parameters can be provided by the design and orientation of the electrodes. The objective is to replace conventional sensors which provide diagnostics in the laboratory but are known to fail in real-world applications with a suite of rugged sensors optimized to measure wall shear-stress, pressure, temperature, heat flux, mass-flow, strain, and gas species. The advantages of the plasma sensor are that it has no mechanical parts (like a pressure transducer diaphragm) to fatigue or break, its operation is insensitive to temperature, it has a very high frequency response (2MHz +), and its output can be received wirelessly. These advantages over other sensors makes it ideal for use in high speed flows.

  6. Nanomaterials induced plasma spectroscopy

    NASA Astrophysics Data System (ADS)

    El Sherbini, A. M.; Abdel Galil, A.; Allam, S. H.; El Sherbini, Th M.

    2014-11-01

    LIBS of nanosecond pulsed Nd: YAG laser (1064 nm) produced plasma from a set of nanomaterial and bulk targets (ZnO, Fe3O4, Ag2O, TiO2, SiO2 and Al2O3) is investigated at laser fluencies in the range 86 J/cm2 to 2.5 J/cm2. The optical emission spectra is recorded at the gate and time delay of 1 ps after the onset of the plasma in air having a constant spot size of 0.9 mm. Nanoparticle targets revealed salient enhanced spectral emission compared to their bulky counterparts. Atomic spectral lines average and integral radiance tend to decrease exponentially with laser fluence. Yet, plasma parameters measurements indicated unnoticeable variation of relative electron density and temperature. Therefore, self-absorption corrected enhanced spectral emission was plausibly attributed solely to variation in the inherent nanoparticle relative concentrations. Viable explanations were elaborated based on changes in the intrinsic physical properties of the nanomaterial under high power laser irradiation.

  7. Influence of Plasma Instabilities in Ceramic Suspension Plasma Spraying

    NASA Astrophysics Data System (ADS)

    Etchart-Salas, R.; Rat, V.; Coudert, J. F.; Fauchais, P.; Caron, N.; Wittman, K.; Alexandre, S.

    2007-12-01

    Direct current Suspension Plasma Spraying (SPS) allows depositing finely structured coatings. This article presents an analysis of the influence of plasma instabilities on the yttria-stabilized suspension drops fragmentation. A particular attention is paid to the treatment of suspension jet or drops according to the importance of voltage fluctuations (linked to those of the arc root) and depending on the different spray parameters such as the plasma forming gas mixture composition and mass flow rate and the suspension momentum. By observing the suspension drops injection with a fast shutter camera and a laser flash sheet triggered by a defined transient voltage level of the plasma torch, the influence of plasma fluctuations on jet or drops fragmentation is studied through the deviation and dispersion trajectories of droplets within the plasma jet.

  8. Plasma generating apparatus for large area plasma processing

    DOEpatents

    Tsai, Chin-Chi; Gorbatkin, Steven M.; Berry, Lee A.

    1991-01-01

    A plasma generating apparatus for plasma processing applications is based on a permanent magnet line-cusp plasma confinement chamber coupled to a compact single-coil microwave waveguide launcher. The device creates an electron cyclotron resonance (ECR) plasma in the launcher and a second ECR plasma is created in the line cusps due to a 0.0875 tesla magnetic field in that region. Additional special magnetic field configuring reduces the magnetic field at the substrate to below 0.001 tesla. The resulting plasma source is capable of producing large-area (20-cm diam), highly uniform (.+-.5%) ion beams with current densities above 5 mA/cm.sup.2. The source has been used to etch photoresist on 5-inch diam silicon wafers with good uniformity.

  9. Plasma generating apparatus for large area plasma processing

    DOEpatents

    Tsai, C.C.; Gorbatkin, S.M.; Berry, L.A.

    1991-07-16

    A plasma generating apparatus for plasma processing applications is based on a permanent magnet line-cusp plasma confinement chamber coupled to a compact single-coil microwave waveguide launcher. The device creates an electron cyclotron resonance (ECR) plasma in the launcher and a second ECR plasma is created in the line cusps due to a 0.0875 tesla magnetic field in that region. Additional special magnetic field configuring reduces the magnetic field at the substrate to below 0.001 tesla. The resulting plasma source is capable of producing large-area (20-cm diam), highly uniform (.+-.5%) ion beams with current densities above 5 mA/cm[sup 2]. The source has been used to etch photoresist on 5-inch diam silicon wafers with good uniformity. 3 figures.

  10. Systematic study of plasma flow during plasma sheet thinnings

    NASA Technical Reports Server (NTRS)

    Lui, A. T. Y.; Frank, L. A.; Ackerson, K. L.; Meng, C.-I.; Akasofu, S.-I.

    1977-01-01

    On the basis of a study of Imp 6 measurements of plasma flow, it is concluded that there is no clear indication of a predominance of tailward plasma flow beyond about X = -15 R sub E in the midnight sector of the plasma sheet during the expansive phase of a substorm. In fact, it is shown statistically that sunward plasma flow is more frequently observed in the midnight sector within about 30 R sub E from the earth than in any other direction during plasma sheet thinning at the substorm expansion. This result supports the conclusion that there is no definite evidence for the formation of a reconnection neutral line in the near-earth plasma sheet during most substorms.

  11. The diverse applications of plasma

    SciTech Connect

    Sharma, Mukul Darwhekar, Gajanan; Dubey, Shivani; Jain, Sudhir Kumar

    2015-07-31

    Plasma being the fourth state of matter has always been an attraction for Physicists and Chemists. With the advent of time, plasma energy has been recognized in having widening horizons in the field of Biomedical Sciences. Plasma medicine can be subdivided into three main fields; Non-thermal atmospheric-pressure direct plasma for medical therapy; Plasma-assisted modification of bio-relevant surfaces and Plasma-based bio-decontamination and sterilization. The basis of the research is that as it has free carrier molecules, it has the ability to target specific cells and regulate functions like wound healing. Plasma does not harm healthy human cells but can kill bacteria and possibly even cancer cells to help treat various diseases. Nosocomial infection control, prevention and containment of contagious diseases, disinfection of medical devices, surface treatment (heat and UV sensitive surfaces) are research of interest. Recent success in generating plasma at very low temperature ie. Cold plasma makes the therapy painless. It has the ability to activate cellular responses and important mechanisms in the body. They target specific molecules such as prothrombin for blood coagulation, cytokines for killing bacteria, and angiogenesis for tissue regeneration. Plasma has bactericidal, fungicidal and virucidal properties. Plasma technology has flourishing future in diverse fields like Textiles, Nanofabrication, Automotives, Waste management, Microbiology, Food Hygiene, Medical Science like Skin treatments, sterilisation of wounds, Hand disinfection, Dental treatments etc. Food hygiene using plasma can be achieved in disinfection of food containers, food surface disinfection, hygiene in food handling, preparation and packaging. Therefore Plasma is most promising field for budding Scientist for fluorishing research in Biological Sciences.

  12. The diverse applications of plasma

    NASA Astrophysics Data System (ADS)

    Sharma, Mukul; Dubey, Shivani; Darwhekar, Gajanan; Jain, Sudhir Kumar

    2015-07-01

    Plasma being the fourth state of matter has always been an attraction for Physicists and Chemists. With the advent of time, plasma energy has been recognized in having widening horizons in the field of Biomedical Sciences. Plasma medicine can be subdivided into three main fields; Non-thermal atmospheric-pressure direct plasma for medical therapy; Plasma-assisted modification of bio-relevant surfaces and Plasma-based bio-decontamination and sterilization. The basis of the research is that as it has free carrier molecules, it has the ability to target specific cells and regulate functions like wound healing. Plasma does not harm healthy human cells but can kill bacteria and possibly even cancer cells to help treat various diseases. Nosocomial infection control, prevention and containment of contagious diseases, disinfection of medical devices, surface treatment (heat and UV sensitive surfaces) are research of interest. Recent success in generating plasma at very low temperature ie. Cold plasma makes the therapy painless. It has the ability to activate cellular responses and important mechanisms in the body. They target specific molecules such as prothrombin for blood coagulation, cytokines for killing bacteria, and angiogenesis for tissue regeneration. Plasma has bactericidal, fungicidal and virucidal properties. Plasma technology has flourishing future in diverse fields like Textiles, Nanofabrication, Automotives, Waste management, Microbiology, Food Hygiene, Medical Science like Skin treatments, sterilisation of wounds, Hand disinfection, Dental treatments etc. Food hygiene using plasma can be achieved in disinfection of food containers, food surface disinfection, hygiene in food handling, preparation and packaging. Therefore Plasma is most promising field for budding Scientist for fluorishing research in Biological Sciences.

  13. Relativistic plasma and electron bunches in plasma synchrotrons of GYRAC

    NASA Astrophysics Data System (ADS)

    Andreev, V. V.; Umnov, A. M.

    1999-08-01

    A review of experimental research performed on installations of GYRAC-type based on the synchrotron gyromagnetic autoresonance (SGA) phenomenon is presented. It is shown that the SGA-regime can be used to obtain relativistic plasma as well as a controlled bunch of relativistic electrons. GYRAC-produced plasma is of interest for applied plasma physics as a source of particles and different kinds of radiation (synchrotron radiation and bremsstrahlung).

  14. Surface plasma wave excitation via laser irradiated overdense plasma foil

    SciTech Connect

    Kumar, Pawan; Tripathi, V. K.

    2012-04-09

    A laser irradiated overdense plasma foil is seen to be susceptible to parametric excitation of surface plasma wave (SPW) and ion acoustic wave (IAW) on the ion plasma period time scale. The SPW is localised near the front surface of the foil while IAW extends upto the rear. The evanescent laser field and the SPW exert a ponderomotive force on electrons driving the IAW. The density perturbation associated with the latter beats with the laser induced oscillatory electron velocity to drive the SPW. At relativistic laser intensity, the growth rate is of the order of ion plasma frequency.

  15. Towards Plasma Surgery: Plasma Treatment of Living Cells

    NASA Astrophysics Data System (ADS)

    Stoffels, E.; Kieft, I. E.; Sladek, R. E. J.; Slaaf, D. W.; van der Laan, E. P.; Jimenez-Moreno, P.; Steinbuch, M.

    2004-12-01

    The physical, biological and technical background for high-precision plasma surgery is prepared in a multi-disciplinary team. The aim of the research is to achieve controlled removal of diseased cells and bacteria without harming the healthy rest of the tissue. For this purpose, a small, cold, flexible and non-toxic plasma is developed (the plasma needle) and tested on cultured cells and bacterial samples. The needle is an atmospheric discharge induced by a radio-frequency voltage applied to a metal pin. This plasma operates at room temperature, in the milliwatt power regime; it poses no risk of thermal or electrical damage to living tissues. Several beneficial responses of living cells to plasma treatment have been already identified. Plasma does not cause accidental cell death (necrosis), which leads to inflammation and tissue damage. Instead, it allows to detach cells from each other and from the scaffold, and thus to remove them in a non-destructive way. Moreover, plasma is capable of bacterial inactivation. I parallel, we have determined the electrical and optical properties of the plasma and found a method of precise positioning of the plasma needle with respect to the treated tissue.

  16. Revisiting the plasma sheath—dust in plasma sheath

    NASA Astrophysics Data System (ADS)

    Das, G. C.; Deka, R.; Bora, M. P.

    2016-04-01

    In this work, we have considered the formation of warm plasma sheath in the vicinity of a wall in a plasma with considerable presence of dust particles. As an example, we have used the parameters relevant in case of plasma sheath formed around surfaces of various solid bodies in space, though the results obtained in this work can be applied to any other physical situation such as laboratory plasma. In the ion-acoustic time scale, we neglect the dust dynamics. The dust particles affect the sheath dynamics by affecting the Poisson equation which determines the plasma potential in the sheath region. It is important to note that our calculations are valid only when the amount of dust particles is not sufficient so as to affect the plasma dynamics in the dust-acoustic time scale, but enough to affect the plasma sheath. We have assumed the current to a dust particle to be balanced throughout the analysis. This makes the grain potential dependent on plasma potential, which is then incorporated into the Poisson equation. The resultant numerical model becomes an initial value problem, which is described by a 1-D integro-differential equation, which is then solved self-consistently by incorporating the change in plasma potential caused by inclusion of the dust potential in the Poisson equation.

  17. A contoured gap coaxial plasma gun with injected plasma armature

    NASA Astrophysics Data System (ADS)

    Witherspoon, F. Douglas; Case, Andrew; Messer, Sarah J.; Bomgardner, Richard; Phillips, Michael W.; Brockington, Samuel; Elton, Raymond

    2009-08-01

    A new coaxial plasma gun is described. The long term objective is to accelerate 100-200 μg of plasma with density above 1017 cm-3 to greater than 200 km/s with a Mach number above 10. Such high velocity dense plasma jets have a number of potential fusion applications, including plasma refueling, magnetized target fusion, injection of angular momentum into centrifugally confined mirrors, high energy density plasmas, and others. The approach uses symmetric injection of high density plasma into a coaxial electromagnetic accelerator having an annular gap geometry tailored to prevent formation of the blow-by instability. The injected plasma is generated by numerous (currently 32) radially oriented capillary discharges arranged uniformly around the circumference of the angled annular injection region of the accelerator. Magnetohydrodynamic modeling identified electrode profiles that can achieve the desired plasma jet parameters. The experimental hardware is described along with initial experimental results in which approximately 200 μg has been accelerated to 100 km/s in a half-scale prototype gun. Initial observations of 64 merging injector jets in a planar cylindrical testing array are presented. Density and velocity are presently limited by available peak current and injection sources. Steps to increase both the drive current and the injected plasma mass are described for next generation experiments.

  18. A contoured gap coaxial plasma gun with injected plasma armature.

    PubMed

    Witherspoon, F Douglas; Case, Andrew; Messer, Sarah J; Bomgardner, Richard; Phillips, Michael W; Brockington, Samuel; Elton, Raymond

    2009-08-01

    A new coaxial plasma gun is described. The long term objective is to accelerate 100-200 microg of plasma with density above 10(17) cm(-3) to greater than 200 km/s with a Mach number above 10. Such high velocity dense plasma jets have a number of potential fusion applications, including plasma refueling, magnetized target fusion, injection of angular momentum into centrifugally confined mirrors, high energy density plasmas, and others. The approach uses symmetric injection of high density plasma into a coaxial electromagnetic accelerator having an annular gap geometry tailored to prevent formation of the blow-by instability. The injected plasma is generated by numerous (currently 32) radially oriented capillary discharges arranged uniformly around the circumference of the angled annular injection region of the accelerator. Magnetohydrodynamic modeling identified electrode profiles that can achieve the desired plasma jet parameters. The experimental hardware is described along with initial experimental results in which approximately 200 microg has been accelerated to 100 km/s in a half-scale prototype gun. Initial observations of 64 merging injector jets in a planar cylindrical testing array are presented. Density and velocity are presently limited by available peak current and injection sources. Steps to increase both the drive current and the injected plasma mass are described for next generation experiments. PMID:19725654

  19. Plasma surface cleaning in a microwave plasma source

    SciTech Connect

    Tsai, C.C.; Nelson, W.D.; Haselton, H.H.; Schechter, D.E.; Thompson, L.M.; Campbell, V.B.; Glover, A.L.; Googin, J.M.

    1994-03-01

    A microwave electron cyclotron resonance (ECR) plasma source has been operated to produce reactive plasmas of oxygen and its mixture with argon. Aluminum samples (0.95 cm by 1.9 cm) were coated with thin films (<20 {mu}m in thickness) of Shell Vitrea oil and cleaned by using such reactive plasmas. The plasma cleaning was done in discharge conditions of microwave power up to 1300 W, radio frequency power up to 200 W, biased potential up to 400 V, gas pressures up to 5 mtorr, and operating time up to 35 min. The surface texture of the postcleaned samples has been examined visually. Mass loss of the samples after plasma cleaning was measured to estimate cleaning rates. Measured clean rates of low-pressure (0.5-mtorr) argon/oxygen plasmas were as high as 2.7 {mu}m/min. X-ray photoelectron spectroscopy (XPS) was used to determine cleanliness of the sample surfaces after plasma cleaning. The XPS study on polished samples confirmed the effectiveness of plasma cleaning in achieving atomic level of surface cleanliness. In this technical memorandum plasma properties, cleaning phenomena, and significant results are reported and discussed.

  20. A contoured gap coaxial plasma gun with injected plasma armature

    SciTech Connect

    Witherspoon, F. Douglas; Case, Andrew; Messer, Sarah J.; Bomgardner, Richard II; Phillips, Michael W.; Brockington, Samuel; Elton, Raymond

    2009-08-15

    A new coaxial plasma gun is described. The long term objective is to accelerate 100-200 {mu}g of plasma with density above 10{sup 17} cm{sup -3} to greater than 200 km/s with a Mach number above 10. Such high velocity dense plasma jets have a number of potential fusion applications, including plasma refueling, magnetized target fusion, injection of angular momentum into centrifugally confined mirrors, high energy density plasmas, and others. The approach uses symmetric injection of high density plasma into a coaxial electromagnetic accelerator having an annular gap geometry tailored to prevent formation of the blow-by instability. The injected plasma is generated by numerous (currently 32) radially oriented capillary discharges arranged uniformly around the circumference of the angled annular injection region of the accelerator. Magnetohydrodynamic modeling identified electrode profiles that can achieve the desired plasma jet parameters. The experimental hardware is described along with initial experimental results in which approximately 200 {mu}g has been accelerated to 100 km/s in a half-scale prototype gun. Initial observations of 64 merging injector jets in a planar cylindrical testing array are presented. Density and velocity are presently limited by available peak current and injection sources. Steps to increase both the drive current and the injected plasma mass are described for next generation experiments.

  1. Plasma Sterilization Technology for Spacecraft Applications

    NASA Technical Reports Server (NTRS)

    Fraser, S. J.; Olson, R. L.; Leavens, W. M.

    1975-01-01

    The application of plasma gas technology to sterilization and decontamination of spacecraft components is considered. Areas investigated include: effective sterilizing ranges of four separate gases; lethal constituents of a plasma environment; effectiveness of plasma against a diverse group of microorganisms; penetrating efficiency of plasmas for sterilization; and compatibility of spacecraft materials with plasma environments. Results demonstrated that plasma gas, specifically helium plasma, is a highly effective sterilant and is compatible with spacecraft materials.

  2. Slotted antenna waveguide plasma source

    NASA Technical Reports Server (NTRS)

    Foster, John (Inventor)

    2007-01-01

    A high density plasma generated by microwave injection using a windowless electrodeless rectangular slotted antenna waveguide plasma source has been demonstrated. Plasma probe measurements indicate that the source could be applicable for low power ion thruster applications, ion implantation, and related applications. This slotted antenna plasma source invention operates on the principle of electron cyclotron resonance (ECR). It employs no window and it is completely electrodeless and therefore its operation lifetime is long, being limited only by either the microwave generator itself or charged particle extraction grids if used. The high density plasma source can also be used to extract an electron beam that can be used as a plasma cathode neutralizer for ion source beam neutralization applications.

  3. Plasma Detachment Study in VASIMR

    NASA Astrophysics Data System (ADS)

    Ilin, A. V.; Daz, F. R. Chang; Squire, J. P.; Breizman, B. N.; Novakovski, S. V.; Sagdeev, R. Z.

    2000-10-01

    We present kinetic and MHD simulations of plasma detachment in the exhaust of the Variable Specific Impulse Magnetoplasma Rocket (VASIMR). The detachment is associated with a transition from subalfvenic to superalfvenic plasma flow in the magnetic nozzle. As a result, the kinetic energy of the outgoing plasma flow is greater than the magnetic field energy in the exhaust area, so that the plasma is no longer confined by the magnetic field. We model the outgoing plasma flow under the assumptions that the plasma is collisionless and has a constant electron temperature. Particle simulations show that the ion motion may become nonadiabatic in the exhaust area as the magnetic field decreases downstream. This effect should facilitate the detachment.

  4. Plasma flows in MPD thrusters

    NASA Astrophysics Data System (ADS)

    Giannelli, Sebastiano; Andreussi, Tommaso; Pegoraro, Francesco; Andrenucci, Mariano

    2011-10-01

    A fundamental description of the plasma acceleration process in magnetoplasmadynamic (MPD) thrusters is presented. The properties of plasma flows in self-field MPD thrusters are investigated by adopting a stationary, axisymmetric, resistive magnetohydrodynamic plasma model. First, the acceleration process in a cylindrical MPD channel is analyzed by neglecting the gasdynamic pressure term. A class of solutions is presented, which allows for a simple analytical treatment of the flow. The physical and mathematical nature of the flow is thus described in terms of two characteristic parameters: a dimensionless channel length, scaled with the plasma resistive length, and a dimensionless parameter which depends on the applied voltage. Then, the effect of gasdynamic pressure is investigated. The presented approach gives an effective description of the plasma acceleration process and defines a framework for the parametric analysis of plasma flows in MPD thrusters. Alta SpA: www.alta-space.com.

  5. MPD thruster plasma instability studies

    SciTech Connect

    Kelly, A.J.; Jahn, R.G.; Choueiri, E.Y.

    1987-05-01

    Results of an ongoing experimental/theoretical effort to understand the influence of plasma waves and instabilities upon coaxial plasma thruster performance and longevity are discussed. An experiment which permits measurement of the plasma dispersion relation plus a suite of plasma parameters for each one millisecond quasi-steady discharge is described. This investigation is guided by a linearized Boltzmann-Poisson kinetic numerical model which can accommodate the effects of collisions, inhomogeneities and the magnetic field. Preliminary tests reveal the presence of the low-frequency branch of an ion cyclotron wave. Although the stability of these waves still has to be established through spatial growth rate measurements, it is well known that they are prone to current-driven instabilities. Current-driven instabilities in the collisional tensor conducting plasma of the MPD thruster are analytically discussed and their relevance to the MPD plasma is illustrated by estimating a critical total current at which their onset occurs. 5 references.

  6. Plasma ignition for laser propulsion

    NASA Technical Reports Server (NTRS)

    Askew, R. F.

    1982-01-01

    For a specific optical system a pulsed carbon dioxide laser having an energy output of up to 15 joules was used to initiate a plasma in air at one atmosphere pressure. The spatial and temporal development of the plasma were measured using a multiframe image converter camera. In addition the time dependent velocity of the laser supported plasma front which moves opposite to the direction of the laser pulse was measured in order to characterize the type of wavefront developed. Reliable and reproducible spark initiation was achieved. The lifetime of the highly dense plasma at the initial focal spot was determined to be less than 100 nanoseconds. The plasma front propagates toward the laser at a variable speed ranging from zero to 1.6 x 1,000,000 m/sec. The plasma front propagates for a total distance of approximately five centimeters for the energy and laser pulse shape employed.

  7. MPD thruster plasma instability studies

    NASA Technical Reports Server (NTRS)

    Kelly, A. J.; Jahn, R. G.; Choueiri, E. Y.

    1987-01-01

    Results of an ongoing experimental/theoretical effort to understand the influence of plasma waves and instabilities upon coaxial plasma thruster performance and longevity are discussed. An experiment which permits measurement of the plasma dispersion relation plus a suite of plasma parameters for each one millisecond quasi-steady discharge is described. This investigation is guided by a linearized Boltzmann-Poisson kinetic numerical model which can accommodate the effects of collisions, inhomogeneities and the magnetic field. Preliminary tests reveal the presence of the low-frequency branch of an ion cyclotron wave. Although the stability of these waves still has to be established through spatial growth rate measurements, it is well known that they are prone to 'current-driven' instabilities. 'Current-driven' instabilities in the collisional tensor conducting plasma of the MPD thruster are analytically discussed and their relevance to the MPD plasma is illustrated by estimating a critical total current at which their onset occurs.

  8. SSX MHD plasma wind tunnel

    NASA Astrophysics Data System (ADS)

    Brown, Michael R.; Schaffner, David A.

    2015-06-01

    A new turbulent plasma source at the Swarthmore Spheromak Experiment (SSX) facility is described. The MHD wind tunnel configuration employs a magnetized plasma gun to inject high-beta plasma into a large, well-instrumented, vacuum drift region. This provides unique laboratory conditions approaching that in the solar wind: there is no applied background magnetic field in the drift region and has no net axial magnetic flux; the plasma flow speed is on the order of the local sound speed (M ~ 1), so flow energy density is comparable to thermal energy density; and the ratio of thermal to magnetic pressure is of order unity (plasma β ~ 1) so thermal energy density is also comparable to magnetic energy density. Results presented here and referenced within demonstrate the new capabilities and show how the new platform is proving useful for fundamental plasma turbulence studies.

  9. Electron cyclotron resonance plasma photos

    SciTech Connect

    Racz, R.; Palinkas, J.; Biri, S.

    2010-02-15

    In order to observe and study systematically the plasma of electron cyclotron resonance (ECR) ion sources (ECRIS) we made a high number of high-resolution visible light plasma photos and movies in the ATOMKI ECRIS Laboratory. This required building the ECR ion source into an open ECR plasma device, temporarily. An 8MP digital camera was used to record photos of plasmas made from Ne, Ar, and Kr gases and from their mixtures. We studied and recorded the effect of ion source setting parameters (gas pressure, gas composition, magnetic field, and microwave power) to the shape, color, and structure of the plasma. The analysis of the photo series gave us many qualitative and numerous valuable physical information on the nature of ECR plasmas.

  10. Plasma Sources for Medical Applications - A Comparison of Spot Like Plasmas and Large Area Plasmas

    NASA Astrophysics Data System (ADS)

    Weltmann, Klaus-Dieter

    2015-09-01

    Plasma applications in life science are currently emerging worldwide. Whereas today's commercially available plasma surgical technologies such as argon plasma coagulation (APC) or ablation are mainly based on lethal plasma effects on living systems, the newly emerging therapeutic applications will be based on selective, at least partially non-lethal, possibly stimulating plasma effects on living cells and tissue. Promising results could be obtained by different research groups worldwide revealing a huge potential for the application of low temperature atmospheric pressure plasma in fields such as tissue engineering, healing of chronic wounds, treatment of skin diseases, tumor treatment based on specific induction of apoptotic processes, inhibition of biofilm formation and direct action on biofilms or treatment of dental diseases. The development of suitable and reliable plasma sources for the different therapies requires an in-depth knowledge of their physics, chemistry and parameters. Therefore much basic research still needs to be conducted to minimize risk and to provide a scientific fundament for new plasma-based medical therapies. It is essential to perform a comprehensive assessment of physical and biological experiments to clarify minimum standards for plasma sources for applications in life science and for comparison of different sources. One result is the DIN-SPEC 91315, which is now open for further improvements. This contribution intends to give an overview on the status of commercial cold plasma sources as well as cold plasma sources still under development for medical use. It will discuss needs, prospects and approaches for the characterization of plasmas from different points of view. Regarding the manageability in everyday medical life, atmospheric pressure plasma jets (APPJ) and dielectric barrier discharges (DBD) are of special interest. A comprehensive risk-benefit assessment including the state of the art of commercial sources for medical use will be discussed.

  11. Plasma Sail Concept Fundamentals

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Delamere, P.; Kabin, K.; Linde, T. J.

    2004-01-01

    The mini-magnetospheric plasma propulsion (M2P2) device, originally proposed by Winglee et al., predicts that a 15-km standoff distance (or 20-km cross-sectional dimension) of the magnetic bubble will provide for sufficient momentum transfer from the solar wind to accelerate a spacecraft to unprecedented speeds of 50 C80 km/s after an acceleration period of 3 mo. Such velocities will enable travel out of the solar system in period of 7 yr almost an order of magnitude improvement over present chemical-based propulsion systems. However, for the parameters of the simulation of Winglee et al., a fluid model for the interaction of M2P2 with the solar wind is not valid. It is assumed in the magnetohydrodynamic (MHD) fluid model, normally applied to planetary magnetospheres, that the characteristic scale size is much greater than the Larmor radius and ion skin depth of the solar wind. In the case of M2P2, the size of the magnetic bubble is actually less than or comparable to the scale of these characteristic parameters. Therefore, a kinetic approach, which addresses the small-scale physical mechanisms, must be used. A two-component approach to determining a preliminary estimate of the momentum transfer to the plasma sail has been adopted. The first component is a self-consistent MHD simulation of the small-scale expansion phase of the magnetic bubble. The fluid treatment is valid to roughly 5 km from the source and the steady-state MHD solution at the 5 km boundary was then used as initial conditions for the hybrid simulation. The hybrid simulations showed that the forces delivered to the innermost regions of the plasma sail are considerably ( 10 times) smaller than the MHD counterpart, are dominated by the magnetic field pressure gradient, and are directed primarily in the transverse direction.

  12. The plasma environment of comets

    SciTech Connect

    Gombosi, T.I. )

    1991-01-01

    U.S. research activities in the area of cometary plasma physics during 1987-1990 are reviewed. Consideration is given to mass loading and its consequences in the upstream region, the cometary shock, the cometosheath, the diamagnetic cavity boundary and the inner shock, and the plasma tail. Special attention is given to models and observations that have modified the pre-encounter understanding of cometary plasma environments. 211 refs.

  13. Progress on laser plasma accelerators

    SciTech Connect

    Chen, P.

    1986-04-01

    Several laser plasma accelerator schemes are reviewed, with emphasis on the Plasma Beat Wave Accelerator (PBWA). Theory indicates that a very high acceleration gradient, of order 1 GeV/m, can exist in the plasma wave driven by the beating lasers. Experimental results obtained on the PBWA experiment at UCLA confirms this. Parameters related to the PBWA as an accelerator system are derived, among them issues concerning the efficiency and the laser power and energy requirements are discussed.

  14. Strongly magnetized classical plasma models

    NASA Technical Reports Server (NTRS)

    Montgomery, D.; Peyraud, J.; Dewitt, C.

    1974-01-01

    Discrete particle processes in the presence of a strong external magnetic field were investigated. These processes include equations of state and other equilibrium thermodynamic relations, thermal relaxation phenomena, transport properties, and microscopic statistical fluctuations in such quantities as the electric field and the charge density. Results from the equilibrium statistical mechanics of two-dimensional plasmas are discussed, along with nonequilibrium statistical mechanics of the electrostatic guiding-center plasma (a two-dimensional plasma model).

  15. Bumper wall for plasma device

    DOEpatents

    Coultas, Thomas A.

    1977-01-01

    Operation of a plasma device such as a reactor for controlled thermonuclear fusion is facilitated by an improved bumper wall enclosing the plasma to smooth the flow of energy from the plasma as the energy impinges upon the bumper wall. The bumper wall is flexible to withstand unequal and severe thermal shocks and it is readily replaced at less expense than the cost of replacing structural material in the first wall and blanket that surround it.

  16. Hot plasmas in interstellar space

    NASA Astrophysics Data System (ADS)

    Grewing, M.

    1983-06-01

    Observational evidence for hot plasmas in interstellar space is reviewed. A number of phases that differ in both their temperature and density from each other exist. While part of this multiphase structure can be explained qualitatively by a model for the interstellar medium which assumes cool clouds with evaporative interfaces embedded in a tenuous very hot plasma, quantitative comparisons show that the origin of the plasmas and the relation between the different phases is not understood.

  17. Compact Plasma Accelerator

    NASA Technical Reports Server (NTRS)

    Foster, John E.

    2004-01-01

    A plasma accelerator has been conceived for both material-processing and spacecraft-propulsion applications. This accelerator generates and accelerates ions within a very small volume. Because of its compactness, this accelerator could be nearly ideal for primary or station-keeping propulsion for spacecraft having masses between 1 and 20 kg. Because this accelerator is designed to generate beams of ions having energies between 50 and 200 eV, it could also be used for surface modification or activation of thin films.

  18. Laser plasma accelerators

    SciTech Connect

    Malka, V.

    2012-05-15

    This review article highlights the tremendous evolution of the research on laser plasma accelerators which has, in record time, led to the production of high quality electron beams at the GeV level, using compact laser systems. I will describe the path we followed to explore different injection schemes and I will present the most significant breakthrough which allowed us to generate stable, high peak current and high quality electron beams, with control of the charge, of the relative energy spread and of the electron energy.

  19. Renormalization and plasma physics

    SciTech Connect

    Krommes, J.A.

    1980-02-01

    A review is given of modern theories of statistical dynamics as applied to problems in plasma physics. The derivation of consistent renormalized kinetic equations is discussed, first heuristically, later in terms of powerful functional techniques. The equations are illustrated with models of various degrees of idealization, including the exactly soluble stochastic oscillator, a prototype for several important applications. The direct-interaction approximation is described in detail. Applications discussed include test particle diffusion and the justification of quasilinear theory, convective cells, E vector x B vector turbulence, the renormalized dielectric function, phase space granulation, and stochastic magnetic fields.

  20. Making a quark plasma

    NASA Astrophysics Data System (ADS)

    McLerran, Larry; Svetitsky, Benjamin

    1987-10-01

    If nuclear matter is compressed or heated so that the hadrons overlap, they may coalesce into a plasma of quarks and gluons. At still-higher densities, it is believed that all interactions among quarks and gluons will become unimportant, so that the quark matter will become an almost ideal gas of quarks and gluons. Attention is presently drawn to the natural quark matter and that which may be producible by means of nuclear collisions. The behavior or matter under these conditions has never been observed, and new phenomena are sure to appear, throwing light on the underlying theory of quantum chromodynamics.

  1. Auroral plasma waves

    NASA Technical Reports Server (NTRS)

    Gurnett, Donald A.

    1989-01-01

    A review is given of auroral plasma wave phenomena, starting with the earliest ground-based observations and ending with the most recent satellite observations. Two types of waves are considered, electromagnetic and electrostatic. Electromagnetic waves include auroral kilometric radiation, auroral hiss, ELF noise bands, and low-frequency electric and magnetic noise. Electrostatic waves include upper hybrid resonance emissions, electron cyclotron waves, lower hybrid waves, ion cyclotron waves and broadband electrostatic noise. In each case, a brief overview is given describing the observations, the origin of the instability, and the role of the waves in the physics of the auroral acceleration region.

  2. Fluorescence in Astrophysical Plasmas

    NASA Astrophysics Data System (ADS)

    Hartman, Henrik

    Following the initial detection by Bowen in 1934 of the strong O III lines being due to accidental resonance with strong He II radiation, many strong spectral emission lines are explained as produced by fluorescence. Many of these are Fe II lines pumped by H Lyα, as a consequence of strong radiation from hydrogen and a favorable energy level structure for Fe II. The lines are observed in many types of objects with low density plasma components. The Weigelt condensations in the vicinity of the massive star Eta Carinae is one location where these lines are observed and can be studied in detail, as well as been used for diagnostics.

  3. ROTATING PLASMA DEVICE

    DOEpatents

    Boyer, K.; Hammel, J.E.; Longmire, C.L.; Nagle, D.E.; Ribe, F.L.; Tuck, J.L.

    1961-10-24

    ABS>A method and device are described for obtaining fusion reactions. The basic concept is that of using crossed electric and magnetic fields to induce a plasma rotation in which the ionized particles follow a circumferential drift orbit on wldch a cyclotron mode of motion is superimposed, the net result being a cycloidal motion about the axis of symmetry. The discharge tube has a radial electric field and a longitudinal magnetic field. Mirror machine geometry is utilized. The device avoids reliance on the pinch effect and its associated instability problems. (AEC)

  4. Laser plasma acceleratorsa)

    NASA Astrophysics Data System (ADS)

    Malka, V.

    2012-05-01

    This review article highlights the tremendous evolution of the research on laser plasma accelerators which has, in record time, led to the production of high quality electron beams at the GeV level, using compact laser systems. I will describe the path we followed to explore different injection schemes and I will present the most significant breakthrough which allowed us to generate stable, high peak current and high quality electron beams, with control of the charge, of the relative energy spread and of the electron energy.

  5. Plasma Structure and Dynamics

    NASA Astrophysics Data System (ADS)

    Karpen, Judith T.

    Despite over a century of observations, the physical processes by which prominence plasma forms and evolves remain controversial. In this chapter we review the observational constraints on all mass formation models, review the four leading models—injection, levitation, evaporation-condensation, and magneto-thermal convection, describe the strengths and weaknesses of each model, and point out opportunities for future work. As needed, short tutorials are provided on fundamental physical mechanisms and concepts not covered in other chapters, including magnetic reconnection and energy balance in coronal loops.

  6. Pulsed Plasma Thruster Technology

    NASA Technical Reports Server (NTRS)

    1996-01-01

    The continuing emphasis on reducing costs and downsizing spacecraft is forcing increased emphasis on reducing the subsystem mass and integration costs. For many commercial, scientific, and Department of Defense space missions, onboard propulsion is either the predominant spacecraft mass or it limits the spacecraft lifetime. Electromagnetic-pulsed-plasma thrusters (PPT's) offer the combined benefits of extremely low average electric power requirements (1 to 150 W), high specific impulse (approx. 1000 sec), and system simplicity derived from the use of an inert solid propellant. Potential applications range from orbit insertion and maintenance of small satellites to attitude control for large geostationary communications satellites.

  7. Quark Gluon Plasma

    SciTech Connect

    Lincoln, Don

    2015-05-07

    Matter is malleable and can change its properties with temperature. This is most familiar when comparing ice, liquid water and steam, which are all different forms of the same thing. However beyond the usual states of matter, physicists can explore other states, both much colder and hotter. In this video, Fermilab’s Dr. Don Lincoln explains the hottest known state of matter – a state that is so hot that protons and neutrons from the center of atoms can literally melt. This form of matter is called a quark gluon plasma and it is an important research topic being pursued at the LHC.

  8. Modeling of Photoionized Plasmas

    NASA Technical Reports Server (NTRS)

    Kallman, Timothy R.

    2010-01-01

    In this paper I review the motivation and current status of modeling of plasmas exposed to strong radiation fields, as it applies to the study of cosmic X-ray sources. This includes some of the astrophysical issues which can be addressed, the ingredients for the models, the current computational tools, the limitations imposed by currently available atomic data, and the validity of some of the standard assumptions. I will also discuss ideas for the future: challenges associated with future missions, opportunities presented by improved computers, and goals for atomic data collection.

  9. Plasma wake field accelerator

    SciTech Connect

    Chen, P.; Dawson, J.M.

    1985-03-01

    A new scheme of electron acceleration, employing relativistic electron bunches in a cold plasma, is analyzed. The wake field of a leading bunch is derived in a single-particle model. We then extend the model to include finite bunch length effect. In particular, we discuss the relation between the charge distributions of the driving bunch and the energies transformable to the trailing electrons. It is shown that for symmetric charge distribution of the driving bunches, the maximum energy gain for a driven electron is 2..gamma../sub 0/mc/sup 2/. This limitation can be overcome by introducing asymmetric charge distributions. 13 refs., 5 figs.

  10. Autoresonant Excitation of Antiproton Plasmas

    SciTech Connect

    Andresen, G. B.; Bowe, P. D.; Hangst, J. S.; Ashkezari, M. D.; Hayden, M. E.; Baquero-Ruiz, M.; Chapman, S.; Fajans, J.; Povilus, A.; So, C.; Bertsche, W.; Butler, E.; Charlton, M.; Humphries, A. J.; Madsen, N.; Werf, D. P. van der; Carpenter, P. T.; Hurt, J. L.; Robicheaux, F.; Cesar, C. L.

    2011-01-14

    We demonstrate controllable excitation of the center-of-mass longitudinal motion of a thermal antiproton plasma using a swept-frequency autoresonant drive. When the plasma is cold, dense, and highly collective in nature, we observe that the entire system behaves as a single-particle nonlinear oscillator, as predicted by a recent theory. In contrast, only a fraction of the antiprotons in a warm plasma can be similarly excited. Antihydrogen was produced and trapped by using this technique to drive antiprotons into a positron plasma, thereby initiating atomic recombination.

  11. Autoresonant excitation of antiproton plasmas.

    PubMed

    Andresen, G B; Ashkezari, M D; Baquero-Ruiz, M; Bertsche, W; Bowe, P D; Butler, E; Carpenter, P T; Cesar, C L; Chapman, S; Charlton, M; Fajans, J; Friesen, T; Fujiwara, M C; Gill, D R; Hangst, J S; Hardy, W N; Hayden, M E; Humphries, A J; Hurt, J L; Hydomako, R; Jonsell, S; Madsen, N; Menary, S; Nolan, P; Olchanski, K; Olin, A; Povilus, A; Pusa, P; Robicheaux, F; Sarid, E; Silveira, D M; So, C; Storey, J W; Thompson, R I; van der Werf, D P; Wurtele, J S; Yamazaki, Y

    2011-01-14

    We demonstrate controllable excitation of the center-of-mass longitudinal motion of a thermal antiproton plasma using a swept-frequency autoresonant drive. When the plasma is cold, dense, and highly collective in nature, we observe that the entire system behaves as a single-particle nonlinear oscillator, as predicted by a recent theory. In contrast, only a fraction of the antiprotons in a warm plasma can be similarly excited. Antihydrogen was produced and trapped by using this technique to drive antiprotons into a positron plasma, thereby initiating atomic recombination. PMID:21405235

  12. Analysis of nuclear induced plasmas

    NASA Technical Reports Server (NTRS)

    Deese, J. E.; Hassan, H. A.

    1976-01-01

    A kinetic model is developed for a plasma generated by fission fragments and the results are employed to study He plasma generated in a tube coated with fissionable material. Because both the heavy particles and electrons play important roles in creating the plasma, their effects are considered simultaneously. The calculations are carried out for a range of neutron fluxes and pressures. In general, the predictions of the theory are in good agreement with available intensity measurements. Moreover, the theory predicts the experimentally measured inversions. However, the calculated gain coefficients are such that lasing is not expected to take place in a helium plasma generated by fission fragments.

  13. Vacuum Plasma Spraying Replaces Electrodeposition

    NASA Technical Reports Server (NTRS)

    Holmes, Richard R.; Power, Chris; Burns, David H.; Daniel, Ron; Mckechnie, Timothy N.

    1992-01-01

    Vacuum plasma spraying used to fabricate large parts with complicated contours and inner structures, without uninspectable welds. Reduces time, and expense of fabrication. Wall of combustion chamber built up inside of outer nickel-alloy jacket by plasma spraying. Particles of metal sprayed partially melted in plasma gun and thrown at supersonic speed toward deposition surface. Vacuum plasma-spray produces stronger bond between the grooves and covering layer completing channels and wall of combustion chamber. In tests, bond withstood pressure of 20 kpsi, three times allowable limit by old method.

  14. Method for generating surface plasma

    DOEpatents

    Miller, Paul A.; Aragon, Ben P.

    2003-05-27

    A method for generating a discharge plasma which covers a surface of a body in a gas at pressures from 0.01 Torr to atmospheric pressure, by applying a radio frequency power with frequencies between approximately 1 MHz and 10 GHz across a plurality of paired insulated conductors on the surface. At these frequencies, an arc-less, non-filamentary plasma can be generated to affect the drag characteristics of vehicles moving through the gas. The plasma can also be used as a source in plasma reactors for chemical reaction operations.

  15. Analysis of nuclear induced plasmas

    NASA Technical Reports Server (NTRS)

    Deese, J. E.; Hassan, H. A.

    1976-01-01

    A kinetic model is developed for a plasma generated by fission fragments, and the results are employed to study He plasma generated in a tube coated with fissionable material. Because both the heavy particles and electrons play important roles in creating the plasma, their effects are considered simultaneously. The calculations are carried out for a range of neutron fluxes and pressures. In general, the predictions of the theory are in good agreement with available intensity measurements. Moreover, the theory predicts the experimentally measured inversions. However, the calculated gain coefficients are such that lasing is not expected to take place in a helium plasma generated by fission fragments.

  16. Plasma technology: Preliminary studies 2

    NASA Astrophysics Data System (ADS)

    Bergring, C.; Sivusaari, T.; Jeskanen, R.; Halonen, A.; Saikkonen, J.

    The report includes four preliminary studies based on literature and one preliminary study based on tests: (1) raising and maintaining the temperature of the ladle and the melt using plasma; (2) the use of plasma technology in cupolas; (3) raising the temperature of the blast furnace blast using plasma; (4) the use of plasma technology in drying; and (5) cleaning up hazardous waste using plasma technology. Study 1, deals with the applicability of plasma technology to raising and maintaining the temperature of the ladle. This technique improves the earlier methods but the equipment is still expensive. Study 2, deals with the ways of cutting production costs in cupolas using plasma technology. The process is best suited for the smelting of fine raw material and for increasing the smelting capacity. Study 3, deals with the effects of raising the blast furnace blast temperature on the properties and economy of the process. The use of electricity to only replace energy received from coke is uneconomical but it also has other advantages. Study 4, considers the applicability of air and steam plasma to the drying of pulp, and its economy. At the present price of electricity the process is uneconomical. Study 5, describes tests on decomposing liquid organic substances using plasma. The process is still being developed, and seems promising.

  17. First Observation of Electrorheological Plasmas

    SciTech Connect

    Ivlev, A. V.; Morfill, G. E.; Thomas, H. M.; Raeth, C.; Huber, P.; Kompaneets, R.; Joyce, G.; Fortov, V. E.; Lipaev, A. M.; Molotkov, V. I.; Reiter, T.; Turin, M.; Vinogradov, P.

    2008-03-07

    We report the experimental discovery of ''electrorheological (ER) complex plasmas,'' where the control of the interparticle interaction by an externally applied electric field is due to distortion of the Debye spheres that surround microparticles (dust) in a plasma. We show that interactions in ER plasmas under weak ac fields are mathematically equivalent to those in conventional ER fluids. Microgravity experiments, as well as molecular dynamics simulations, show a phase transition from an isotropic to an anisotropic (string) plasma state as the electric field is increased.

  18. Electrical characterization of rf plasmas

    SciTech Connect

    Miller, P.A.

    1991-08-01

    Radio-frequency (rf) electrical sources are commonly used to generate plasmas for processing of industrial materials and for related experimental work. Published descriptions of such plasmas usually include generator-power measurements, and occasionally include plasma dc-bias measurements. One or both of these quantitites are also used in industrial feedback ccontrol systems for setpoint regulation. Recent work at Sandia an elsewhere with an experimental rf discharge device (the GEC RF Reference Cell'') has shown that power and dc-bias levels are often insufficient information for specifying the state of the plasma. The plasma can have nonlinear electrical characteristics that cause harmonic generation, and the harmonic levels can depend sensitively on the impedance of the external circuitry at harmonic frequencies. Even though the harmonics may be low in amplitude, they can be directly related to large changes in plasma power and to changes in optical emission from the plasma. Consequently, in order for a worker to truly master the plasma-generation process, it is necessary to understand, measure, and control electrical characteristics of the plamsa. In this paper we describe technique that have been developed from work with the Reference Cell for making electrical measurements on rf plasmas, and we describe surprising observations of harmonic behavior. 10 refs., 4 figs.

  19. Ternary gas plasma welding torch

    NASA Technical Reports Server (NTRS)

    Rybicki, Daniel J. (Inventor); Mcgee, William F. (Inventor); Waldron, Douglas J. (Inventor)

    1995-01-01

    A plasma arc welding torch is discussed. A first plasma gas is directed through the body of the welding torch and out of the body across the tip of a welding electrode disposed at the forward end of the body. A second plasma gas is disposed for flow through a longitudinal bore in the electrode. The second plasma gas enters one end of the electrode and exits the electrode at the tip thereof for co-acting with the electric welding arc to produce the desired weld. A shield gas is directed through the torch body and circulates around the head of the torch adjacent to the electrode tip.

  20. Important plasma problems in astrophysics

    SciTech Connect

    Kulsrud, R.M.

    1995-01-01

    In astrophysics, plasmas occur under very extreme conditions. For example there are ultra strong magnetic fields in neutron stars) relativistic plasmas around black holes and in jets, extremely energetic particles such as cosmic rays in the interstellar medium, extremely dense plasmas in accretion disks, and extremely large magnetic Reynold`s numbers in the interstellar medium. These extreme limits for astrophysical plasmas make plasma phenomena much simpler to analyze in astrophysics than in the laboratory. An understanding of such phenomena often results in an interesting way, by simply taking the extreme limiting case of a known plasma theory. I will describe one of the more exciting examples. I will attempt to convey the excitement I felt when I was first exposed to it. However, not all plasma astrophysical phenomena are so simple. There are certain important plasma phenomena in astrophysics, which have not been so easily resolved. In fact a resolution of them is blocking significant progress in astrophysical research. They have not yet yielded to attacks by theoretical astrophysicists nor to extensive numerical simulation. I will attempt to describe one of the more important of these plasma-astrophysical problems, and discuss why its resolution is so important to astrophysics. This significant example is fast, magnetic reconnection. Another significant example is the large-magnetic-Reynold`s-number MHD dynamos.

  1. Particle simulations in magnetospheric plasmas

    NASA Technical Reports Server (NTRS)

    Nishikawa, Ken-Ichi

    1990-01-01

    In view of the recent remarkable advancement of computer technology and simulation software, simulation studies are one of the most powerful academic tools for establishment of quantitative space physics and modelling of our space environment. The complex nature encountered in space plasma physics has motivated considerable development in computer simulations, which have played an essential role in the development of space plasma theory. This report describes research undertaken to understand physical processes involved in plasma waves observed in the magnetospheric plasmas, and associated nonlinear phenomena such as heating, diffusion, and acceleration of particles due to excited waves. The research explains and clarifies the observational data both qualitatively and quantitatively.

  2. On the excess energy of nonequilibrium plasma

    SciTech Connect

    Timofeev, A. V.

    2012-01-15

    The energy that can be released in plasma due to the onset of instability (the excess plasma energy) is estimated. Three potentially unstable plasma states are considered, namely, plasma with an anisotropic Maxwellian velocity distribution of plasma particles, plasma with a two-beam velocity distribution, and an inhomogeneous plasma in a magnetic field with a local Maxwellian velocity distribution. The excess energy can serve as a measure of the degree to which plasma is nonequilibrium. In particular, this quantity can be used to compare plasmas in different nonequilibrium states.

  3. Plasma networking in magnetically confined plasmas and diagnostics of nonlocal heat transport in tokamak filamentary plasmas

    NASA Astrophysics Data System (ADS)

    Kukushkin, A. B.; Rantsev-Kartinov, V. A.

    1999-02-01

    The method of multilevel dynamical contrasting is applied to analyzing available data from tokamak plasmas. The results illustrate a possibility of extending the concept of the plasma percolating networks in dense Z pinches (and other inertially confined plasmas) to the case of magnetically confined plasmas. This extension suggests a necessity to append the conventional picture of the nonfilamentary plasma (which is nearly a fluid described by conventional magnetohydrodynamics) with a "network" component which is formed by the strongest long-living filaments of electric current and penetrate the "fluid" component. Signs of networking are found in visible light and soft x-ray images, and magnetic probing data. A diagnostic algorithm is formulated for identifying the role of plasma networking in observed phenomena of nonlocal (non-diffusive) heat transport in a tokamak.

  4. Plasma, The Fourth State of Matter

    ERIC Educational Resources Information Center

    Zandy, Hassan F.

    1970-01-01

    Discusses plasma as a source of energy through nuclear fission processes, as well as the difficulties encountered in such a process. States that 99 percent of the matter in the universe is plasma, and only 1 percent is the common three states of matter. Describes the fundamental properties of plasma, plasma "pinch, and plasma oscillations. (RR)

  5. Purification of tantalum by plasma arc melting

    DOEpatents

    Dunn, Paul S.; Korzekwa, Deniece R.

    1999-01-01

    Purification of tantalum by plasma arc melting. The level of oxygen and carbon impurities in tantalum was reduced by plasma arc melting the tantalum using a flowing plasma gas generated from a gas mixture of helium and hydrogen. The flowing plasma gases of the present invention were found to be superior to other known flowing plasma gases used for this purpose.

  6. Purification of tantalum by plasma arc melting

    SciTech Connect

    Dunn, P.S.; Korzekwa, D.R.

    1999-10-26

    Purification of tantalum by plasma arc melting is disclosed. The level of oxygen and carbon impurities in tantalum was reduced by plasma arc melting the tantalum using a flowing plasma gas generated from a gas mixture of helium and hydrogen. The flowing plasma gases of the present invention were found to be superior to other known flowing plasma gases used for this purpose.

  7. Experimental results from detached plasmas in TFTR

    SciTech Connect

    Strachan, J.D.; Boody, F.P.; Bush, C.E.; Cohen, S.A.; Grek, B.; Grisham, L.; Jobes, F.C.; Johnson, D.W.; Mansfield, D.K.; Medley, S.S.

    1986-10-01

    Detached plasmas are formed in TFTR which have the principal property of the boundary to the high temperature plasma core being defined by a radiating layer. This paper documents the properties of TFTR ohmic-detached plasmas with a range of plasma densities at two different plasma currents.

  8. Fission-induced plasmas

    NASA Technical Reports Server (NTRS)

    Harries, W. L.; Shiu, Y. J.

    1979-01-01

    The possibility of creating a plasma from fission fragments, and to utilize the energy of the particles to create population inversion that would lead to laser action is investigated. An investigation was made of various laser materials which could be used for nuclear-pumped lasing. The most likely candidate for a fissioning material in the gaseous form is uranium hexafluoride - UF6, and experiments were performed to investigate materials that would be compatible with it. One of the central problems in understanding a fission-induced plasma is to obtain a model of the electron behavior, and some preliminary calculations are presented. In particular, the rates of various processes are discussed. A simple intuitive model of the electron energy distribution function is also shown. The results were useful for considering a mathematical model of a nuclear-pumped laser. Next a theoretical model of a (3)He-Ar nuclear-pumped laser is presented. The theory showed good qualitative agreement with the experimental results.

  9. Undamped electrostatic plasma waves

    SciTech Connect

    Valentini, F.; Perrone, D.; Veltri, P.; Califano, F.; Pegoraro, F.; Morrison, P. J.; O'Neil, T. M.

    2012-09-15

    Electrostatic waves in a collision-free unmagnetized plasma of electrons with fixed ions are investigated for electron equilibrium velocity distribution functions that deviate slightly from Maxwellian. Of interest are undamped waves that are the small amplitude limit of nonlinear excitations, such as electron acoustic waves (EAWs). A deviation consisting of a small plateau, a region with zero velocity derivative over a width that is a very small fraction of the electron thermal speed, is shown to give rise to new undamped modes, which here are named corner modes. The presence of the plateau turns off Landau damping and allows oscillations with phase speeds within the plateau. These undamped waves are obtained in a wide region of the (k,{omega}{sub R}) plane ({omega}{sub R} being the real part of the wave frequency and k the wavenumber), away from the well-known 'thumb curve' for Langmuir waves and EAWs based on the Maxwellian. Results of nonlinear Vlasov-Poisson simulations that corroborate the existence of these modes are described. It is also shown that deviations caused by fattening the tail of the distribution shift roots off of the thumb curve toward lower k-values and chopping the tail shifts them toward higher k-values. In addition, a rule of thumb is obtained for assessing how the existence of a plateau shifts roots off of the thumb curve. Suggestions are made for interpreting experimental observations of electrostatic waves, such as recent ones in nonneutral plasmas.

  10. Modeling plasma loudspeakers.

    PubMed

    Béquin, Ph; Castor, K; Herzog, Ph; Montembault, V

    2007-04-01

    This paper deals with the acoustic modeling and measurement of a needle-to-grid plasma loudspeaker using a negative Corona discharge. In the first part, we summarize the model described in previous papers, where the electrode gap is divided into a charged particle production region near the needle and a drift region which occupies most of the inter-electrode gap. In each region, interactions between charged and neutral particles in the ionized gas lead to a perturbation of the surrounding air, and thus generate an acoustic field. In each region, viewed as a separate acoustic source, an acoustical model requiring only a few parameters is proposed. In the second part of the paper, an experimental setup is presented for measuring acoustic pressures and directivities. This setup was developed and used to study the evolution of the parameters with physical properties, such as the geometrical and electrical configuration and the needle material. In the last part of this paper, a study on the electroacoustic efficiency of the plasma loudspeaker is described, and differences with respect to the design parameters are analyzed. Although this work is mainly aimed at understanding transduction phenomena, it may be found useful for the development of an audio loudspeaker. PMID:17471712

  11. Electrostatic Plasma Accelerator (EPA)

    NASA Technical Reports Server (NTRS)

    Brophy, John R.; Aston, Graeme

    1995-01-01

    The application of electric propulsion to communications satellites, however, has been limited to the use of hydrazine thrusters with electric heaters for thrust and specific impulse augmentation. These electrothermal thrusters operate at specific impulse levels of approximately 300 s with heater powers of about 500 W. Low power arcjets (1-3 kW) are currently being investigated as a way to increase specific impulse levels to approximately 500 s. Ion propulsion systems can easily produce specific impulses of 3000 s or greater, but have yet to be applied to communications satellites. The reasons most often given for not using ion propulsion systems are their high level of overall complexity, low thrust with long burn times, and the difficulty of integrating the propulsion system into existing commercial spacecraft busses. The Electrostatic Plasma Accelerator (EPA) is a thruster concept which promises specific impulse levels between low power arcjets and those of the ion engine while retaining the relative simplicity of the arcjet. The EPA thruster produces thrust through the electrostatic acceleration of a moderately dense plasma. No accelerating electrodes are used and the specific impulse is a direct function of the applied discharge voltage and the propellant atomic mass.

  12. Pulsed Plasma Thruster Contamination

    NASA Technical Reports Server (NTRS)

    Myers, Roger M.; Arrington, Lynn A.; Pencil, Eric J.; Carter, Justin; Heminger, Jason; Gatsonis, Nicolas

    1996-01-01

    Pulsed Plasma Thrusters (PPT's) are currently baselined for the Air Force Mightysat II.1 flight in 1999 and are under consideration for a number of other missions for primary propulsion, precision positioning, and attitude control functions. In this work, PPT plumes were characterized to assess their contamination characteristics. Diagnostics included planar and cylindrical Langmuir probes and a large number of collimated quartz contamination sensors. Measurements were made using a LES 8/9 flight PPT at 0.24, 0.39, 0.55, and 1.2 m from the thruster, as well as in the backflow region behind the thruster. Plasma measurements revealed a peak centerline ion density and velocity of approx. 6 x 10(exp 12) cm(exp -3) and 42,000 m/s, respectively. Optical transmittance measurements of the quartz sensors after 2 x 10(exp 5) pulses showed a rapid decrease in plume contamination with increasing angle from the plume axis, with a barely measurable transmittance decrease in the ultraviolet at 90 deg. No change in optical properties was detected for sensors in the backflow region.

  13. Plasma motor generator system

    NASA Technical Reports Server (NTRS)

    Hite, Gerald E.

    1987-01-01

    The significant potential advantages of a plasma motor generator system over conventional systems for the generation of electrical power and propulsion for spacecraft in low Earth orbits warrants its further investigation. The two main components of such a system are a long insulated wire and the plasma generating hollow cathodes needed to maintain electrical contact with the ionosphere. Results of preliminary theoretical and experimental investigations of this system are presented. The theoretical work involved the equilibrium configurations of the wire and the nature of small oscillation about these equilibrium positions. A particularly interesting result was that two different configurations are allowed when the current is above a critical value. Experimental investigations were made of the optimal starting and running conditions for the proposed, low current hollow cathodes. Although optimal ranges of temperature, argon pressure and discharge voltage were identified, start up became progressively more difficult. This supposed depletion or contamination of the emissive surface could be countered by the addition of new emissive material.

  14. Effect of plasma motion on tearing modes in cylindrical plasmas

    NASA Astrophysics Data System (ADS)

    Xu, J. Q.; Peng, X. D.

    2015-10-01

    The effect of equilibrium plasma motion on the resistive m/n = 2/1 tearing mode (TM) in low β plasmas is investigated in cylindrical geometry (with m and n being poloidal and toroidal mode numbers). Without equilibrium plasma motion but with viscosity, the TM stability is mainly determined by the Reynolds number S and reaches maximum near S = 104, which is consistent with previous findings. The poloidal plasma rotation has stabilizing effect on TM; however, the rotation shear has destabilization effect in the low viscosity regime. The axial plasma motion has strong stabilizing effect on TM in the low viscosity regime for Prandtl number Pr < 1, while its shear has slight stabilizing effect with the decrease of growth rate less than 15%. When the axial velocity becomes large enough, the mode frequency tends to be independent of the Prandtl number. In the presence of parallel plasma motion, the growth rate is determined by the axial component at low parallel velocity, while determined by poloidal component at large parallel velocity. The parallel plasma motion drives the TM rotating in the opposite direction. It is shown that the equilibrium motion reduces the growth rate of TM by changing the phase difference and coupling coefficient between potential perturbation and magnetic flux perturbation (deviating from π/2 ), which results in a lower mode frequency. Compared to the role of velocity shear, the magnitude of plasma velocity itself at the m/n = 2/1 rational surface is dominant in determining the TM characteristics.

  15. Plasma-wall transition in weakly collisional plasmas

    SciTech Connect

    Manfredi, G.; Devaux, S.

    2008-10-15

    This paper reviews some theoretical and computational aspects of plasma-wall interactions, in particular the formation of sheaths. Some fundamental results are derived analytically using a simple fluid model, and are subsequently tested with kinetic simulations. The various regions composing the plasma-wall transition (Debye sheath, collisional and magnetic presheaths) are discussed in details.

  16. Plasma neutralization models for intense ion beam transport in plasma

    SciTech Connect

    Kaganovich, Igor D.; Startsev, Edward A.; Davidson, Ronald C.; O'Rourke, Sean; Lee, Edward P.

    2003-05-01

    Plasma neutralization of an intense ion pulse is of interest for many applications, including plasma lenses, heavy ion fusion, cosmic ray propagation, etc. An analytical electron fluid model has been developed based on the assumption of long charge bunches (l{sub b} >> r{sub b}). Theoretical predictions are compared with the results of calculations utilizing a particle-in-cell (PIC) code. The cold electron fluid results agree well with the PIC simulations for ion beam propagation through a background plasma. The analytical predictions for the degree of ion beam charge and current neutralization also agree well with the results of the numerical simulations. The model predicts very good charge neutralization (>99%) during quasi-steady-state propagation, provided the beam pulse duration {tau}{sub b} is much longer than the electron plasma period 2{pi}/{omega}{sub p}, where {omega}{sub p} = (4{pi}e{sup 2}n{sub p}/m){sup 1/2} is the electron plasma frequency, and n{sub p} is the background plasma density. In the opposite limit, the beam pulse excites large-amplitude plasma waves. The analytical formulas derived in this paper can provide an important benchmark for numerical codes, and provide scaling relations for different beam and plasma parameters.

  17. Cold plasma: overview of plasma technologies and applications

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cold plasma is a novel nonthermal food processing technology. It is based on energetic, reactive gases which inactivate contaminating microbes on meats, poultry and fruits and vegetables. The primary modes of action are due to UV light and reactive chemical products of the cold plasma ionization pro...

  18. Theoretical Plasma Physics

    SciTech Connect

    Vahala, George M.

    2013-12-31

    Lattice Boltzmann algorithms are a mesoscopic method to solve problems in nonlinear physics which are highly parallelized – unlike the direction solution of the original problem. These methods are applied to both fluid and magnetohydrodynamic turbulence. By introducing entropic constraints one can enforce the positive definiteness of the distribution functions and so be able to simulate fluids at high Reynolds numbers without numerical instabilities. By introducing a vector distribution function for the magnetic field one can enforce the divergence free condition on the magnetic field automatically, without the need of divergence cleaning as needed in most direct numerical solutions of the resistive magnetohydrodynamic equations. The principal reason for the high parallelization of lattice Boltzmann codes is that they consist of a kinetic collisional relaxation step (which is purely local) followed by a simple shift of the relaxed data to neighboring lattice sites. In large eddy simulations, the closure schemes are highly nonlocal – the most famous of these schemes is that due to Smagorinsky. Under a lattice Boltzmann representation the Smagorinsky closure is purely local – being simply a particular moment on the perturbed distribution fucntions. After nonlocal fluid moment models were discovered to represent Landau damping, it was found possible to model these fluid models using an appropriate lattice Boltzmann algorithm. The close to ideal parallelization of the lattice Boltzmann codes permitted us to be Gordon Bell finalists on using the Earth Simulation in Japan. We have also been involved in the radio frequency propagation of waves into a tokamak and into a spherical overdense tokamak plasma. Initially we investigated the use of a quasi-optical grill for the launching of lower hybrid waves into a tokamak. It was found that the conducting walls do not prevent the rods from being properly irradiated, the overloading of the quasi-optical grill is not severe with the electric field only being about three times higher than in the ideal case. Moreover, the quasi-optical grill was significantly fewer structural elements that the multijunction grill. Nevertheless there has not been much interest from experimental fusion groups to implementing these structures. Hence we have returned to optimizing the multijunction grill so that the large number of coupling matrix elements can be efficiently evaluated using symmetry arguments. In overdense plasmas, the standard electromagnetic waves cannot propagate into the plasma center, but are reflected at the plasma edge. By optimizing mode conversion processes (in particular, the O-X-B wave propagation of Ordinary Mode converting to an Extraordinary mode which then converts into an electrostatic Bernstein wave) one can excite within the plasma an electrostatic Bernstein wave that does not suffer density cutoffs and is absorbed on the electron cyclotron harmonics. Finally we have started looking at other mesoscopic lattice algorithms that involve unitary collision and streaming steps. Because these algorithms are unitary they can be run on quantum computers when they become available – unlike their computational cousin of lattice Boltzmann which is a purely classical code. These quantum lattice gas algorithms have been tested successfully on exact analytic soliton collision solution. These calculations are hoped to be able to study Bose Einstein condensed atomic gases and their ground states in an optical lattice.

  19. Ablation plasma ion implantation

    NASA Astrophysics Data System (ADS)

    Qi, Bo

    The novel hybrid technique, Ablation Plasma Ion Implantation (APII), has been characterized and optimized for ion implantation and/or thin film deposition. In APII, a solid target is ablated by a laser; the resulting plasma plume is the source of ions, which are accelerated to high energy by a negative bias voltage imposed on the substrate. The ions are implanted into the substrate, and the neutral atoms in the ablation plume deposit on the substrate in the form of a thin film. Two configurations of APII are characterized and compared. The parallel target-substrate configuration yields ion-beam-assisted deposition and/or ion implantation, and the perpendicular target-substrate configuration yields pure ion implantation mode. A novel theory of the ion matrix sheath has been developed for APII. The ion current predicted by the Child-Langmuir sheath theory matches well with the experimental ion current. Two different target-substrate orientations have been compared for APII. Parallel target-substrate orientation yields ion-beam-assisted-deposition and ion implantation; to prevent arcing, a laser-voltage delay of several microseconds is required for this mode. For the optimized perpendicular target-substrate orientation, the laser can be fired during the voltage pulse, thereby accelerating ions to full energy. Furthermore, the ion dose is higher than that of the parallel target-substrate orientation by a factor of two. The parameters of plasma plumes have been thoroughly characterized by numerous diagnostics, which include electrical characteristics, optical emission spectroscopy, dye laser resonance absorption photography, resonant/non-resonant interferometry, and Langmuir probe. The total number of ions measured by Langmuir probe, and resonant interferometry, is in the range of 1014 ions per laser pulse. Ion dose measured by plasma diagnostics, has been correlated to the ion dose obtained from material analysis, including sputtering yield calculation, X-ray Energy Dispersive Spectroscopy and X-ray Photoelectron Spectroscopy. The retained and delivered ion doses are in the range of 10 12/cm2 per pulse, which is favorable compared to the ion dose obtained from conventional Plasma Immersion Ion Implantation (PHI). The APII ion implantation efficiency is estimated to be about 2%. Ion acceleration and implantation was demonstrated for both of the APB configurations. The feasibility of APII was verified by Cross-Sectional Transmission Electron Microscopy and X-ray Photoelectron Spectroscopy. For parallel target-substrate configuration, the average deposition rate is 0.0075 nm/shot for the Ti -10 kV APII film. Atomic Force Microscopy implemented at Timken Research Lab indicates that the -4 kV APII film has the smoothest surface. Scratch tests performed at Timken Research lab also prove that APR produces excellent film adhesion.

  20. Plasma wave propagation with a plasma density gradient

    SciTech Connect

    Cho, Guangsup; Choi, Eun-Ha; Uhm, Han Sup

    2011-03-15

    Plasma waves with the plasma diffusion velocity u{sub n} due to a plasma density gradient are described in a positive column plasma. The ion wave is generated by the perturbation of the operating frequency 10{sup 6} s{sup -1} and it propagates with the group velocity u{sub g{approx}}c{sub s}{sup 2}/u{sub n{approx}}(10{sup 5}-10{sup 6}) m/s, where c{sub s} is the acoustic velocity in a fine tube fluorescent lamp, while the electron wave cannot be generated with a turbulence of low frequency less than the electron oscillation frequency {omega}{sub pe}. The propagation of the lighting signal observed in long tube fluorescent lamps is well understood with the propagation of ion waves occurring along the plasma density gradient.

  1. Nonlinear plasma and beam physics in plasma wake-fields

    SciTech Connect

    Rosenzweig, J.B.

    1990-02-12

    In experimental studies of the Plasma Wake-field Accelerator performed to date at the Argonne Advanced Accelerator Test Facility, significant nonlinearities in both plasma and beam behavior have been observed. The plasma waves driven in the wake of the intense driving beam in these experiments exhibit three-dimensional nonlinear behavior which has as yet no quantitative theoretical explanation. This nonlinearity is due in part to the self-pinching of the driving beam in the plasma, as the denser self-focused beam can excite larger amplitude plasma waves. The self-pinching is a process with interesting nonlinear aspects: the initial evolution of the beam envelope and the subsequent approach to Bennett equilibrium through phase mixing. 35 refs., 10 figs.

  2. Dynamics of filamentary plasma jets used in plasma medicine

    NASA Astrophysics Data System (ADS)

    Reuter, Stephan

    2015-09-01

    Atmospheric plasmas exhibit large gradients in space and time. This challenges diagnostics such as LIF or other quantitative species detection methods. Single shot and 2D measurements can supply information otherwise hidden in averaging single point measurements. Especially the interaction of jet like plasmas with ambient surroundings poses unmet challenges. In the present work, several approaches of laser diagnostics of plasma and gas phase combined with numerical simulation sow how a careful study of the plasma initiated processes can lead to an at least partial understanding of plasma interaction with liquid and biological systems. In collaboration with Ansgar Schmidt-Bleker, INP Greifswald e.V.; Sylvain Iseni, GREMI, UMR 7344, CNRS/Université d'Orléans and Jörn Winter, Helena Jablonowski, and Klaus-Dieter Weltmann, INP Greifswald e.V. BMBF FKZ 03Z2DN12.

  3. Characteristics of plasma sterilizer using microwave torch plasma with AC high-voltage discharge plasma

    NASA Astrophysics Data System (ADS)

    Itarashiki, Tomomasa; Hayashi, Nobuya; Yonesu, Akira

    2016-01-01

    Microwave plasma sterilization has recently been attracting attention for medical applications. However, it is difficult to perform low-temperature sterilization in short time periods. Increasing the output power shortens the time required for sterilization but causes the temperature to increase. To overcome this issue, we have developed a hybrid plasma system that combines a microwave torch plasma and a high-voltage mesh plasma, which allows radicals to be produced at low temperatures. Using this system, successful sterilization was shown to be possible in a period of 45 min at a temperature of 41 °C.

  4. MHD control in burning plasmas MHD control in burning plasmas

    NASA Astrophysics Data System (ADS)

    Donné, Tony; Liang, Yunfeng

    2012-07-01

    Fusion physics focuses on the complex behaviour of hot plasmas confined by magnetic fields with the ultimate aim to develop a fusion power plant. In the future generation of tokamaks like ITER, the power generated by the fusion reactions substantially exceeds the external input power (Pfusion}/Pin >= 10). When this occurs one speaks of a burning plasma. Twenty per cent of the generated fusion power in a burning plasma is carried by the charged alpha particles, which transfer their energy to the ambient plasma in collisions, a process called thermalization. A new phenomenon in burning plasmas is that the alpha particles, which form a minority but carry a large fraction of the plasma kinetic energy, can collectively drive certain types of magneto-hydrodynamic (MHD) modes, while they can suppress other MHD modes. Both types of MHD modes can have desirable effects on the plasma, as well as be detrimental to the plasma. For example, the so-called sawtooth instability, on the one hand, is largely responsible for the transport of the thermalized alpha particles out of the core, but, on the other hand, may result in the loss of the energetic alphas before they have fully thermalized. A further undesirable effect of the sawtooth instability is that it may trigger other MHD modes such as neoclassical tearing modes (NTMs). These NTMs, in turn, are detrimental to the plasma confinement and in some cases may even lead to disruptive termination of the plasma. At the edge of the plasma, finally, so-called edge localized modes or ELMs occur, which result in extremely high transient heat and particle loads on the plasma-facing components of a reactor. In order to balance the desired and detrimental effects of these modes, active feedback control is required. An additional complication occurs in a burning plasma as the external heating power, which is nowadays generally used for plasma control, is small compared to the heating power of the alpha particles. The scientific challenge in the field of burn control is to find the proper balance between desired and detrimental effects of the various MHD modes and to develop the methods and tools for active feedback control of MHD modes in burning plasmas. Therefore, it is necessary to understand the dynamics of the system, in this case the mutual interactions between the fast alpha particles and the MHD instabilities. Since burning plasmas do not yet exist, the relevant experimental work until ITER comes into full operation needs to be largely based on alpha-particle simulation experiments in which the alpha particles are accelerated to high energies by means of special heating techniques. The precise conditions of a burning plasma can be only partly mimicked in present tokamaks. Hence, also a detailed computational modelling effort is needed, in order to understand the impact of findings in present machines for those of the future. In 2011 two dedicated workshops were devoted to MHD control. Firstly, there was a workshop on Control of Burning Plasmas that took place from 21-25 March 2011 at the Lorentz Centre in Leiden, The Netherlands. Secondly, the 480th Wilhelm and Else Heraeus Seminar that took place from 16-18 June in Bad Honnef, Germany was devoted to Active Control of Instabilities in Hot Plasmas. This special issue presents a collection of papers that have been presented at the two workshops, along with a few papers that are the result of an open call to contribute to this special issue.

  5. Plasma chemistry and organic synthesis

    NASA Technical Reports Server (NTRS)

    Tezuka, M.

    1980-01-01

    The characteristic features of chemical reactions using low temperature plasmas are described and differentiated from those seen in other reaction systems. A number of examples of applications of plasma chemistry to synthetic reactions are mentioned. The production of amino acids by discharge reactions in hydrocarbon-ammonia-water systems is discussed, and its implications for the origins of life are mentioned.

  6. Programable Plasma-Spray System

    NASA Technical Reports Server (NTRS)

    Fetheroff, C. W.; Derkacs, T.; Matay, I. M.; Toth, I.

    1982-01-01

    NASA-funded research led to development of automated plasma-spray system programable and reproducible. System utilizes standard plasma-spray equipment with noncoherent light-measuring system and microprocessor. System monitors and controls surface contours and coating thickness. Other advantages of system are consistant coating reproducibility, exact blending and feathering operations, ability to handle complex shapes and ease of changing spray parameters.

  7. Plasma technology for waste treatment

    SciTech Connect

    Cohn, D.R.

    1995-04-01

    Improved environmental cleanup technology is needed to meet demanding goals for remediation and treatment of future waste streams. Plasma technology has unique features which could provide advantages of reduced secondary waste, lower cost, and onsite treatment for a wide variety of applications. Plasma technology can provide highly controllable processing without the need for combustion heating. It can be used to provide high temperature processing ({approximately}10,000{degrees}C). Plasma technology can also be employed for low temperature processing (down to room temperature range) through selective plasma chemistry. A graphite electrode arc plasma furnace at MIT has been used to investigate high temperature processing of simulated solid waste for Department of Energy environmental cleanup applications. Stable, non-leachable glass has been produced. To ensure reliable operation and to meet environmental objectives, new process diagnostics have been developed to measure furnace temperature and to determine metals emissions in the gaseous effluent. Selective plasma destruction of dilute concentrations of hazardous compounds in gaseous waste streams has been investigated using electron beam generated plasmas. Selective destruction makes it possible to treat the gas steam at relatively low temperatures in the 30-300{degrees}C range. On-line infrared measurements have been used in feedback operation to maximize efficiency and ensure desired performance. Plasma technology and associated process diagnostics will be used in future studies of a wide range of waste streams.

  8. Polarization spectroscopy of tokamak plasmas

    SciTech Connect

    Wroblewski, D.

    1991-09-01

    Measurements of polarization of spectral lines emitted by tokamak plasmas provide information about the plasma internal magnetic field and the current density profile. The methods of polarization spectroscopy, as applied to the tokamak diagnostic, are reviewed with emphasis on the polarimetry of motional Stark effect in hydrogenic neutral beam emissions. 25 refs., 7 figs.

  9. Plasma Processes for Semiconductor Fabrication

    NASA Astrophysics Data System (ADS)

    Hitchon, W. N. G.

    1999-01-01

    Plasma processing is a central technique in the fabrication of semiconductor devices. This self-contained book provides an up-to-date description of plasma etching and deposition in semiconductor fabrication. It presents the basic physics and chemistry of these processes, and shows how they can be accurately modeled. The author begins with an overview of plasma reactors and discusses the various models for understanding plasma processes. He then covers plasma chemistry, addressing the effects of different chemicals on the features being etched. Having presented the relevant background material, he then describes in detail the modeling of complex plasma systems, with reference to experimental results. The book closes with a useful glossary of technical terms. No prior knowledge of plasma physics is assumed in the book. It contains many homework exercises and serves as an ideal introduction to plasma processing and technology for graduate students of electrical engineering and materials science. It will also be a useful reference for practicing engineers in the semiconductor industry.

  10. Fully relativistic plasma dispersion function

    NASA Astrophysics Data System (ADS)

    Kamp, Léon P. J.

    1994-12-01

    Properties of a relativistic plasma dispersion function (PDF) that is required for the description of waves propagating perpendicular to a magnetic field in a fully relativistic, magnetized, Maxwellian plasma, are presented. Series, asymptotic series, recurrence relations, integral representations, derivatives, generating functions, approximations, differential equations, and connections with standard transcendental functions are discussed, as are the PDF's analytic properties.

  11. Hollow Plasma in a Solenoid

    SciTech Connect

    Anders, Andre; Kauffeldt, Marina; Oks, Efim M.; Roy, Prabir K.

    2010-11-30

    A ring cathode for a pulsed, high-current, multi-spot cathodic arc discharge was placed inside a pulsed magnetic solenoid. Photography is used to evaluate the plasma distribution. The plasma appears hollow for cathode positions close the center of the solenoid, and it is guided closer to the axis when the cathode is away from the center.

  12. Space plasma contactor research, 1987

    NASA Technical Reports Server (NTRS)

    Wilbur, Paul J.

    1988-01-01

    A simple model describing the process of electron collection from a low pressure ambient plasma in the absence of magnetic field and contactor velocity effects is presented. Experimental measurments of the plasma surrounding the contactor are used to demonstrate that a double-sheath generally develops and separates the ambient plasma from a higher density, anode plasma located adjacent to the contactor. Agreement between the predictions of the model and experimental measurements obtained at the electron collection current levels ranging to 1 A suggests the surface area at the ambient plasma boundary of the double-sheath is equal to the electron current being collected divided by the ambient plasma random electron current density; the surface area of the higher density anode plasma boundary of the double-sheath is equal to the ion current being emitted across this boundary divided by the ion current density required to sustain a stable sheath; and the voltage drop across the sheath is determined by the requirement that the ion and electron currents counterflowing across the boundaries be at space-charge limited levels. The efficiency of contactor operation is shown to improve when significant ionization and excitation is induced by electrons that stream from the ambient plasma through the double-sheath and collide with neutral atoms being supplied through the hollow cathode.

  13. Plasma homocysteine and menopausal status.

    PubMed

    Wouters, M G; Moorrees, M T; van der Mooren, M J; Blom, H J; Boers, G H; Schellekens, L A; Thomas, C M; Eskes, T K

    1995-11-01

    The aim of the study was to measure the concentrations of plasma homocysteine in premenopausal and postmenopausal women, and to examine a possible relationship between plasma homocysteine and oestrogen status. Homocysteine metabolism was studied by a standardized oral methionine loading test, and oestrogen status was assessed by the measurement of serum 17 beta-oestradiol. Forty-six premenopausal and 26 postmenopausal healthy women without a history of vascular disease or adverse pregnancy outcome were recruited by public advertisement. The main outcome measures were the concentrations of fasting and postmethionine plasma homocysteine, and serum 17 beta-oestradiol. Fasting plasma homocysteine concentrations (mean +/- SD) were significantly higher in postmenopausal women as compared to premenopausal women (12 +/- 4 mumol L-1 and 10 +/- 3 mumol L-1, respectively) as well as postmethionine plasma homocysteine concentrations (46 +/- 16 mumol L-1 and 32 +/- 9 mumol L-1, respectively). In premenopausal women, postmethionine plasma homocysteine was negatively and significantly correlated to serum 17 beta-oestradiol (r = -0.34). It is concluded that plasma homocysteine concentrations, both fasting and after methionine loading, are significantly higher in postmenopausal women than in premenopausal women. In premenopausal women, the higher concentrations of serum 17 beta-oestradiol may account in part for the lower concentrations of postmethionine plasma homocysteine. PMID:8582443

  14. Plasma digital density determining device

    DOEpatents

    Sprott, Julien C.; Lovell, Thomas W.; Holly, Donald J.

    1976-01-01

    The density of a decaying plasma in an electrically conducting enclosure is determined by applying an excitation to the cavity formed by the enclosure and counting digitally the number of resonant frequencies traversed by the combination of the cavity and the decaying plasma.

  15. Model for resonant plasma probe.

    SciTech Connect

    Warne, Larry Kevin; Johnson, William Arthur; Hebner, Gregory Albert; Jorgenson, Roy E.; Coats, Rebecca Sue

    2007-04-01

    This report constructs simple circuit models for a hairpin shaped resonant plasma probe. Effects of the plasma sheath region surrounding the wires making up the probe are determined. Electromagnetic simulations of the probe are compared to the circuit model results. The perturbing effects of the disc cavity in which the probe operates are also found.

  16. Control of impurities in toroidal plasma devices

    DOEpatents

    Ohkawa, Tihiro

    1980-01-01

    A method and apparatus for plasma impurity control in closed flux plasma systems such as Tokamak reactors is disclosed. Local axisymmetrical injection of hydrogen gas is employed to reverse the normally inward flow of impurities into the plasma.

  17. Arc Plasma Gun With Coaxial Powder Feed

    NASA Technical Reports Server (NTRS)

    Zaplatynsky, Isidor

    1988-01-01

    Redesigned plasma gun provides improved metallic and ceramic coatings. Particles injected directly through coaxial bore in cathode into central region of plasma jet. Introduced into hotter and faster region of plasma jet.

  18. Turbulence in Hall MHD Plasmas

    SciTech Connect

    Shaikh, Dastgeer; Shukla, P. K.

    2010-12-14

    The Hall MHD description of magnetized plasma is invoked in many space, laboratory and astrophysical plasmas when the characteristic frequency is bigger than the ion cyclotron frequency where the MHD description is inapplicable. In this paper, we present fully self consistent 3D simulations of compressible Hall MHD plasma to describe spectral features relevant to the solar wind plasma. We find that a k{sup -7/3} spectrum sets in for the fluctuations that are smaller than ion gyro radius. We further investigate scale dependent anisotropy led by nonlinear processes relevant to the solar wind plasma. Our work is important particularly in understanding the role of wave and nonlinear cascades in the evolution of the solar wind, structure formation at the largest scales.

  19. Helicon plasma thruster discharge model

    SciTech Connect

    Lafleur, T.

    2014-04-15

    By considering particle, momentum, and energy balance equations, we develop a semi-empirical quasi one-dimensional analytical discharge model of radio-frequency and helicon plasma thrusters. The model, which includes both the upstream plasma source region as well as the downstream diverging magnetic nozzle region, is compared with experimental measurements and confirms current performance levels. Analysis of the discharge model identifies plasma power losses on the radial and back wall of the thruster as the major performance reduction factors. These losses serve as sinks for the input power which do not contribute to the thrust, and which reduce the maximum plasma density and hence propellant utilization. With significant radial plasma losses eliminated, the discharge model (with argon) predicts specific impulses in excess of 3000 s, propellant utilizations above 90%, and thruster efficiencies of about 30%.

  20. Plasma waves near the magnetopause

    NASA Technical Reports Server (NTRS)

    Anderson, R. R.; Eastman, T. E.; Harvey, C. C.; Hoppe, M. M.; Tsurutani, B. T.; Etcheto, J.

    1982-01-01

    Plasma waves associated with the magnetosphere from the magnetosheath to the outer magnetosphere are investigated to obtain a clear definition of the boundaries and regions, to characterize the waves observed in these regions, to determine which wave modes are present, and to determine their origin. Emphasis is on high time resolution data and a comparison between measurements by different antenna systems. It is shown that the magnetosheath flux transfer events, the magnetopause current layer, the outer magnetosphere, and the boundary layer can be identified by their magnetic field and plasma wave characteristics, as well as by their plasma and energetic particle signatures. The plasma wave characteristics in the current layer and in the boundary layer are very similar to the features in the flux transfer events, and upon entry into their outer magnetosphere, the plasma wave spectra are dominated by intense electromagnetic chorus bursts and electrostatic emissions.

  1. Cyclic olefin copolymer plasma millireactors.

    PubMed

    Schelcher, G; Guyon, C; Ognier, S; Cavadias, S; Martinez, E; Taniga, V; Malaquin, L; Tabeling, P; Tatoulian, M

    2014-08-21

    The novelty of this paper lies in the development of a multistep process for the manufacturing of plasma millireactors operating at atmospheric pressure. The fabrication process relies on the integration of metallic electrodes over a cyclic olefin copolymer chip by a combination of photopatterning and sputtering. The developed plasma millireactors were successfully tested by creating air discharges in the gas volume of the millichannel. A sputtered silica layer was deposited on the channel walls to provide a barrier between the plasma and the polymer in order to prevent the alteration of polymer surfaces during the plasma treatment. Interest in this process of employing plasma millireactor as a high reactive environment is demonstrated here by the degradation of a volatile organic compound (acetaldehyde) in ambient air. In this miniaturized device, we obtained a high acetaldehyde conversion (98%) for a specific input energy lower than 200 J L(-1). PMID:24957952

  2. Filters for cathodic arc plasmas

    DOEpatents

    Anders, Andre; MacGill, Robert A.; Bilek, Marcela M. M.; Brown, Ian G.

    2002-01-01

    Cathodic arc plasmas are contaminated with macroparticles. A variety of magnetic plasma filters has been used with various success in removing the macroparticles from the plasma. An open-architecture, bent solenoid filter, with additional field coils at the filter entrance and exit, improves macroparticle filtering. In particular, a double-bent filter that is twisted out of plane forms a very compact and efficient filter. The coil turns further have a flat cross-section to promote macroparticle reflection out of the filter volume. An output conditioning system formed of an expander coil, a straightener coil, and a homogenizer, may be used with the magnetic filter for expanding the filtered plasma beam to cover a larger area of the target. A cathodic arc plasma deposition system using this filter can be used for the deposition of ultrathin amorphous hard carbon (a-C) films for the magnetic storage industry.

  3. Turbulence in Hall MHD Plasmas

    NASA Astrophysics Data System (ADS)

    Shaikh, Dastgeer; Shukla, P. K.

    2010-12-01

    The Hall MHD description of magnetized plasma is invoked in many space, laboratory and astrophysical plasmas when the characteristic frequency is bigger than the ion cyclotron frequency where the MHD description is inapplicable. In this paper, we present fully self consistent 3D simulations of compressible Hall MHD plasma to describe spectral features relevant to the solar wind plasma. We find that a k-7/3 spectrum sets in for the fluctuations that are smaller than ion gyro radius. We further investigate scale dependent anisotropy led by nonlinear processes relevant to the solar wind plasma. Our work is important particularly in understanding the role of wave and nonlinear cascades in the evolution of the solar wind, structure formation at the largest scales.

  4. Photovoltaic Plasma Interaction Test 2

    NASA Technical Reports Server (NTRS)

    Kaufman, Bradford A.; Chrulski, Daniel; Myers, Roger M.

    1996-01-01

    The International Space Station (ISS) program is developing a plasma contactor to mitigate the harmful effects of charge collection on the station's large photovoltaic arrays. The purpose of the present test was to examine the effects of charge collection on the solar array electrical circuit and to verify the effectiveness of the plasma contactor. The results showed that the plasma contactor was able to eliminate structure arcing for any array output voltage. However, the current requirements of the plasma contactor were higher than those for prior testing and predicted by analysis. Three possible causes for this excess current demand are discussed. The most likely appeared to be a high local pressure on or very near the surface of the array as a result of vacuum tank conditions. Therefore, in actual space conditions, the plasma contactor should work as predicted.

  5. Helicon plasma thruster discharge model

    NASA Astrophysics Data System (ADS)

    Lafleur, T.

    2014-04-01

    By considering particle, momentum, and energy balance equations, we develop a semi-empirical quasi one-dimensional analytical discharge model of radio-frequency and helicon plasma thrusters. The model, which includes both the upstream plasma source region as well as the downstream diverging magnetic nozzle region, is compared with experimental measurements and confirms current performance levels. Analysis of the discharge model identifies plasma power losses on the radial and back wall of the thruster as the major performance reduction factors. These losses serve as sinks for the input power which do not contribute to the thrust, and which reduce the maximum plasma density and hence propellant utilization. With significant radial plasma losses eliminated, the discharge model (with argon) predicts specific impulses in excess of 3000 s, propellant utilizations above 90%, and thruster efficiencies of about 30%.

  6. [Sterilization by the plasma procedure].

    PubMed

    Pelletier, J

    1992-01-01

    Plasma sterilisation of heat sensitive materials appears as an attractive substitute for ethylene oxide processing which leaves adsorbed toxic residues. In oxygen-based plasmas, the de-activation of pathogenic organisms is assumed to be due to their slow combustion with the active species which produces CO2 and H2O. In the absence of ion bombardment, the concentration of oxygen atoms is an important parameter entering the plasma sterilisation efficiency. Means for achieving high production of oxygen atoms are reviewed and discussed. In particular, an initial improvement would be to generate the plasma in the sterilisation volume itself. Uniform plasma excitation at electron cyclotron resonance (ECR) which allows resonant coupling in the whole treatment volume (no shadowing) and requires reduced electric fields to sustain the discharge (no heating of biomaterials) is particularly adapted to this purpose. PMID:1340091

  7. Advances in plasma melting technology

    NASA Astrophysics Data System (ADS)

    Eschenbach, R.; Hoffelner, W.

    The quest for 'defect-free' high performance metals has benefited from the expansion of plasma hearth melting capacity. 'Skull' melting in water-cooled copper containers under an inert gas atmosphere allows elimination of ceramic and refractory metal inclusions when melting reactive metals and superalloys, while retaining the input alloy content. The interactions of operating variables such as furnace pressure, nature of gas, arc current and heat input pattern with product properties such as homogeneity, grain size, and inclusions are described. By proper process control, plasma hearth melting has been qualified as one of only two processes suitable for particularly demanding rotating grade engine parts made of titanium alloy. Costs of plasma hearth melting are less than with electron beam. Extension of plasma processing to other alloys is being actively pursued. Powder production is currently practical with plasma melting and bottom pouring to make powder. Some speculations on future trends in materials and operating temperatures are offered.

  8. [Plasma exchange therapy].

    PubMed

    Mori, Masaaki

    2014-09-01

    By the Kawasaki disease, it is important that treatment is effective before the tenth day of illness when a coronary lesion can occur, and it is a well-known fact that early disappearance of inflammation leads directly to the onset restraint of the coronary lesions. Plasma exchange (PE) removes inflammatory cytokine and chemokines in the blood for Kawasaki disease directly and suppresses the inflammation early. The treatment result of the PE for the IVIG-resistant Kawasaki disease is so good, and if it could be started before particularly coronary lesion develops, we will expect an extremely big effect. In addition, when immunoglobulin therapy, steroid pulse therapy or neutrophilic elastase inhibitor therapy is invalid, we can perform PE therapy with the insurance applica- tion in Japan. PMID:25518418

  9. Research in plasma physics

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Three aspects of barium ion cloud dynamics are discussed. First, the effect of the ratio of ion cloud conductivity to background ionospheric conductivity on the motion of barium ion clouds is investigated and compared with observations of barium ion clouds. This study led to the suggestion that the conjugate ionosphere participates in the dynamics of barium ion clouds. Second, analytic work on the deformation of ion clouds is presented. Third, a linearized stability theory was extended to include the effect of the finite extent of an ion cloud, as well as the effect of the ratio of ion cloud to ionospheric conductivities. The stability properties of a plasma with contra-streaming ion beams parallel to a magnetic field are investigated. The results are interpreted in terms of parameters appropriate for collisionless shock waves. It is found that this particular instability can be operative only if the up-stream Alfven Mach number exceeds 5.5.

  10. Moon's Plasma Wake

    NASA Astrophysics Data System (ADS)

    Halekas, J. S.; Brain, D. A.; Holmström, M.

    2015-01-01

    The interaction of the solar wind with planets gives rise to planetary magnetospheres with an extended region stretching in the antisunward direction, called the "magneotail". This chapter uses the major satellites of Jupiter and Saturn as examples to illustrate the variety of ways in which planetary moons interact with their external plasma environments as inferred from in situ and remote observations as well as physics-based numerical simulations, with a focus on the structures and properties of their resulting magnetotails (or wake regions). It then presents the general properties of the major satellites of Jupiter and Saturn. The large-scale interaction and wake structure associated with inert moons are then described. The chapter also discusses the conducting/mass-loading moons. Finally, it covers the magnetotail structure in the case of a strongly magnetized moon, Ganymede.

  11. Solid state plasmas

    NASA Astrophysics Data System (ADS)

    Manfredi, Giovanni; Hurst, Jérôme

    2015-05-01

    Magnetic fusion devices operate at regimes characterized by extremely high temperatures and low densities, for which the charged particles motion is well described by classical mechanics. This is not true, however, for solid-state metallic objects: their density approaches 1028 m-3, so that the average interparticle distance is shorter than the de Broglie wavelength, which characterizes the spread of the electron wave function. Under these conditions, the conduction electrons behave as a true quantum plasma even at room temperature. Here, we shall illustrate the impact of quantum phenomena on the electron dynamics in metallic objects of nanometric size, particularly thin metallic films excited by short laser pulses. Further, we will discuss more recent results on regimes that involve spin and relativistic effects.

  12. Aerospace applications of pulsed plasmas

    NASA Astrophysics Data System (ADS)

    Starikovskiy, Andrey

    2012-10-01

    The use of a thermal equilibrium plasma for combustion control dates back more than a hundred years to the advent of internal combustion (IC) engines and spark ignition systems. The same principles are still applied today to achieve high efficiency in various applications. Recently, the potential use of nonequilibrium plasma for ignition and combustion control has garnered increasing interest due to the possibility of plasma-assisted approaches for ignition and flame stabilization. During the past decade, significant progress has been made toward understanding the mechanisms of plasma chemistry interactions, energy redistribution and the nonequilibrium initiation of combustion. In addition, a wide variety of fuels have been examined using various types of discharge plasmas. Plasma application has been shown to provide additional combustion control, which is necessary for ultra-lean flames, high-speed flows, cold low-pressure conditions of high-altitude gas turbine engine (GTE) relight, detonation initiation in pulsed detonation engines (PDE) and distributed ignition control in homogeneous charge-compression ignition (HCCI) engines, among others. The present paper describes the current understanding of the nonequilibrium excitation of combustible mixtures by electrical discharges and plasma-assisted ignition and combustion. Nonequilibrium plasma demonstrates an ability to control ultra-lean, ultra-fast, low-temperature flames and appears to be an extremely promising technology for a wide range of applications, including aviation GTEs, piston engines, ramjets, scramjets and detonation initiation for pulsed detonation engines. To use nonequilibrium plasma for ignition and combustion in real energetic systems, one must understand the mechanisms of plasma-assisted ignition and combustion and be able to numerically simulate the discharge and combustion processes under various conditions.

  13. Plasma vertical stabilisation in ITER

    NASA Astrophysics Data System (ADS)

    Gribov, Y.; Kavin, A.; Lukash, V.; Khayrutdinov, R.; Huijsmans, G. T. A.; Loarte, A.; Snipes, J. A.; Zabeo, L.

    2015-07-01

    This paper describes the progress in analysis of the ITER plasma vertical stabilisation (VS) system since its design review in 2007-2008. Two indices characterising plasma VS were studied. These are (1) the maximum value of plasma vertical displacement due to free drift that can be stopped by the VS system and (2) the maximum root mean square value of low frequency noise in the dZ/dt measurement signal used in the VS feedback loop. The first VS index was calculated using the PET code for 15 MA plasmas with the nominal position and shape. The second VS index was studied with the DINA code in the most demanding simulations for plasma magnetic control of 15 MA scenarios with the fastest plasma current ramp-up and early X-point formation, the fastest plasma current ramp-down in a divertor configuration, and an H to L mode transition at the current flattop. The studies performed demonstrate that the VS in-vessel coils, adopted recently in the baseline design, significantly increase the range of plasma controllability in comparison with the stabilising systems VS1 and VS2, providing operating margins sufficient to achieve ITER's goals specified in the project requirements. Additionally two sets of the DINA code simulations were performed with the goal of assessment of the capability of the PF system with the VS in-vessel coils: (i) to control the position of runaway electrons generated during disruptions in 15 MA scenarios and (ii) to trigger ELMs in H-mode plasmas of 7.5 MA/2.65 T scenarios planned for the early phase of ITER operation. It was also shown that ferromagnetic structures of the vacuum vessel (ferromagnetic inserts) and test blanket modules insignificantly affect the plasma VS.

  14. Ultracold Neutral Plasma Density Waves

    NASA Astrophysics Data System (ADS)

    Killian, Thomas

    2012-06-01

    Ultracold neutral plasmas, which are created by photoionizing laser cooled atoms near the ionization threshold, have been extensively studied in order to probe strong Coulomb coupling effects, low-energy atomic processes, equilibration, and collective phenomena [1]. The experimental study of collective modes, however, has previously been limited to phenomena involving electrons. By spatially modulating the intensity pattern of the photoionizing laser, we are now able to create controlled density perturbations on the plasma, which enables study of ion collective behavior. Periodic modulation excites ion acoustic waves [2]. We have also created two distinct plasmas that stream into each other. In the hydrodynamic regime, the central gap between the two plasmas splits into two density ``holes'' that propagate away from the plasma center at the ion acoustic velocity. At lower densities and higher particle velocities, plasmas are less collisional, and we observe kinetic effects such as plasma streams penetrating each other, with a penetration depth that reflects the ion stopping power. This general technique for sculpting the density opens many new possibilities, such as investigation of non-linear phenomena, instabilities, and shock waves in the ultracold regime, and determination of the effects of strong coupling on dispersion relations. The low temperature, small size, plasma expansion, and strongly coupled nature of ultracold plasmas make these studies fundamentally interesting. They may also shed light on similar phenomena in high energy density, laser-produced plasmas that can be near the strongly coupled regime. [4pt] [1] T. C. Killian, T. Pattard, Thomas Pohl, and J. M. Rost, Phys. Rep., 449, 77 (2007).[0pt] [2] J. Castro, P. McQuillen, and T. C. Killian, Phys. Rev. Lett. 105, 065004 (2010).

  15. NCSX Plasma Heating Methods

    SciTech Connect

    Kugel, H. W.; Spong, D.; Majeski, R.; Zarnstorff, M.

    2008-01-18

    The National Compact Stellarator Experiment (NCSX) has been designed to accommodate a variety of heating systems, including ohmic heating, neutral beam injection, and radio-frequency (rf). Neutral beams will provide one of the primary heating methods for NCSX. In addition to plasma heating, neutral beams are also expected to provide a means for external control over the level of toroidal plasma rotation velocity and its profile. The experimental plan requires 3 MW of 50-keV balanced neutral beam tangential injection with pulse lengths of 500 ms for initial experiments, to be upgradeable to pulse lengths of 1.5 s. Subsequent upgrades will add 3MW of neutral beam injection (NBI). This paper discusses the NCSX NBI requirements and design issues and shows how these are provided by the candidate PBX-M NBI system. In addition, estimations are given for beam heating efficiencies, scaling of heating efficiency with machine size and magnetic field level, parameter studies of the optimum beam injection tangency radius and toroidal injection location, and loss patterns of beam ions on the vacuum chamber wall to assist placement of wall armor and for minimizing the generation of impurities by the energetic beam ions. Finally, subsequent upgrades could add an additional 6 MW of rf heating by mode conversion ion Bernstein wave (MCIBW) heating, and if desired as possible future upgrades, the design also will accommodate high-harmonic fast-wave and electron cyclotron heating. The initial MCIBW heating technique and the design of the rf system lend themselves to current drive, so if current drive became desirable for any reason, only minor modifications to the heating system described here would be needed. The rf system will also be capable of localized ion heating (bulk or tail), and possiblyIBW-generated sheared flows.

  16. NCSX Plasma Heating Methods

    SciTech Connect

    H.W. Kugel; D. Spong; R. Majeski; M. Zarnstorff

    2003-02-28

    The NCSX (National Compact Stellarator Experiment) has been designed to accommodate a variety of heating systems, including ohmic heating, neutral-beam injection, and radio-frequency. Neutral beams will provide one of the primary heating methods for NCSX. In addition to plasma heating, beams are also expected to provide a means for external control over the level of toroidal plasma rotation velocity and its profile. The plan is to provide 3 MW of 50 keV balanced neutral-beam tangential injection with pulse lengths of 500 msec for initial experiments, and to be upgradeable to pulse lengths of 1.5 sec. Subsequent upgrades will add 3 MW of neutral-beam injection. This Chapter discusses the NCSX neutral-beam injection requirements and design issues, and shows how these are provided by the candidate PBX-M (Princeton Beta Experiment-Modification) neutral-beam injection system. In addition, estimations are given for beam-heating efficiencies, scaling of heating efficiency with machine size an d magnetic field level, parameter studies of the optimum beam-injection tangency radius and toroidal injection location, and loss patterns of beam ions on the vacuum chamber wall to assist placement of wall armor and for minimizing the generation of impurities by the energetic beam ions. Finally, subsequent upgrades could add an additional 6 MW of radio-frequency heating by mode-conversion ion-Bernstein wave (MCIBW) heating, and if desired as possible future upgrades, the design also will accommodate high-harmonic fast-wave and electron-cyclotron heating. The initial MCIBW heating technique and the design of the radio-frequency system lend themselves to current drive, so that if current drive became desirable for any reason only minor modifications to the heating system described here would be needed. The radio-frequency system will also be capable of localized ion heating (bulk or tail), and possibly ion-Bernstein-wave-generated sheared flows.

  17. Gyrotrons for Plasma Heating

    NASA Astrophysics Data System (ADS)

    Temkin, Richard

    1998-11-01

    Advances in gyrotron research have led to a new generation of devices that can operate at the megawatt power level at frequencies up to 170 GHz. These gyrotrons allow electron cyclotron heating (ECH) of plasmas to be conducted at the multimegawatt power levels needed for heating present day tokamaks and stellarators. In recent years, several breakthroughs have occurred in research on gyrotrons. These new insights involve major advances in both the physics of beams and the physics of coherent generation of microwave radiation. Gyrotron electron beams have now been produced at currents of up to 100A at up to 100 kV with excellent beam quality. New diagnostic techniques have been developed to measure this improved beam quality. Research in the physics of microwave generation has included the development of new codes which can predict mode competition in the highly overmoded gyrotron cavity. Experimental results agree well with theory. Gyrotron efficiency has risen to over 50% using the depressed collector. Other advances in the field of gyrotron research include the development of the diamond window, which allows over 1 MW of continuous power to be transmitted, and the development of new mode converters which efficiently transform the high order mode of the gyrotron cavity into a Gaussian beam in free space. Future goals of gyrotron research include going to higher power levels, in the 2 to 5 MW range, achieving higher efficiency, up to 75% using a multi-stage depressed collector, and achieving a wide range of frequency tunability, possibly up to a 25% bandwidth. Progress on ancillary components of an ECH system such as waveguides and antennas has also been impressive. This research has led to many "spinoffs" including gyrotrons for radar and industrial heating. When fully developed, ECH systems could possibly be the least expensive and most reliable means of auxiliary heating of plasmas.

  18. Resonant-cavity antenna for plasma heating

    DOEpatents

    Perkins, F.W. Jr.; Chiu, S.C.; Parks, P.; Rawls, J.M.

    1984-01-10

    This invention relates generally to a method and apparatus for transferring energy to a plasma immersed in a magnetic field, and relates particularly to an apparatus for heating a plasma of low atomic number ions to high temperatures by transfer of energy to plasma resonances, particularly the fundamental and harmonics of the ion cyclotron frequency of the plasma ions. This invention transfers energy from an oscillating radio-frequency field to a plasma resonance of a plasma immersed in a magnetic field.

  19. Nonlinear mixing of electromagnetic waves in plasmas.

    PubMed

    Stefan, V; Cohen, B I; Joshi, C

    1989-01-27

    Recently, a strong research effort has been focused on applications of beat waves in plasma interactions. This research has important implications for various aspects of plasma physics and plasma technology. This article reviews the present status of the field and comments on plasma probing, heating of magnetically confined and laser plasmas, ionospheric plasma modification, beat-wave particle acceleration, beat-wave current drive in toroidal devices, beat wave-driven free-electron lasers, and phase conjugation with beat waves. PMID:17799185

  20. Surface plasma source with anode layer plasma accelerator

    SciTech Connect

    Dudnikov, Vadim

    2012-02-15

    Proposed plasma generation system can be used for high current negative ion beam production and for directed deposition by flux of sputtered neutrals and negative ions. The main mechanism of negative ion formation in surface plasma sources is the secondary emission from low work function surface bombarded by a flux of positive ion or neutrals. The emission of negative ions is enhanced significantly by introducing a small amount of cesium or other substance with low ionization potential. In the proposed source are used positive ions generated by Hall drift plasma accelerator (anode layer plasma accelerator or plasma accelerator with insulated channel, with cylindrical or race track configuration of emission slit). The target-emitter is bombarded by the ion beam accelerated in crossed ExB fields. Negative ions are extracted from the target surface with geometrical focusing and are accelerated by negative voltage applied between emitter and plasma, contacting with the plasma accelerator. Hall drift ion source has a special design with a space for passing of the emitted negative ions and sputtered particles through the positive ion source.

  1. Recording Spatially Resolved Plasma Parameters in Microwave-Driven Plasmas

    NASA Astrophysics Data System (ADS)

    Gerhard, Franz; Florian, Schamberger; Igor, Krstev; Stefan, Umrath

    2013-01-01

    In an almost cubical reactor 90 l in volume which is intended to deposit organic polymers by plasma-enhanced chemical vapor deposition (PECVD), microwave power is coupled into the volume via a quartz window which extends to approximately 1/10 of the sidewall area. Since the plasma is excited locally, plasma parameters like electron temperature and plasma density are expected to exhibit a spatial variation. The compilation of these plasma quantities has been accomplished with a bendable single Langmuir probe. To isolate the tungsten wire against its grounded housing tube, it was coated with polyparylene. After having compared this construction with our Langmuir probe, which has been now in use for more than a decade, we have taken data of more than half the volume of the reactor with argon and have found a definitive radial inhomogenity for all plasma parameters. To investigate whether this conduct can be determined applying optical emission spectroscopy, we improved our spectrometer which had been used for endpoint detection purposes and plasma diagnostics in chlorine-containing ambients where we could detect also a spatial dependence. This behavior is discussed in terms of Lieberman's global model.

  2. Meter scale plasma source for plasma wakefield experiments

    SciTech Connect

    Vafaei-Najafabadi, N.; Shaw, J. L.; Marsh, K. A.; Joshi, C.; Hogan, M. J.

    2012-12-21

    High accelerating gradients generated by a high density electron beam moving through plasma has been used to double the energy of the SLAC electron beam [1]. During that experiment, the electron current density was high enough to generate its own plasma without significant head erosion. In the newly commissioned FACET facility at SLAC, the peak current will be lower and without pre-ionization, head erosion will be a significant challenge for the planned experiments. In this work we report on our design of a meter scale plasma source for these experiments to effectively avoid the problem of head erosion. The plasma source is based on a homogeneous metal vapor gas column that is generated in a heat pipe oven [2]. A lithium oven over 30 cm long at densities over 10{sup 17} cm{sup -3} has been constructed and tested at UCLA. The plasma is then generated by coupling a 10 TW short pulse Ti:Sapphire laser into the gas column using an axicon lens setup. The Bessel profile of the axicon setup creates a region of high intensity that can stretch over the full length of the gas column with approximately constant diameter. In this region of high intensity, the alkali metal vapor is ionized through multi-photon ionization process. In this manner, a fully ionized meter scale plasma of uniform density can be formed. Methods for controlling the plasma diameter and length will also be discussed.

  3. Coupling between electron plasma waves in laser-plasma interactions

    NASA Astrophysics Data System (ADS)

    Everett, M. J.; Lal, A.; Clayton, C. E.; Mori, W. B.; Joshi, C.; Johnston, T. W.

    1996-05-01

    A Lagrangian fluid model (cold plasma, fixed ions) is developed for analyzing the coupling between electron plasma waves. This model shows that a small wave number electron plasma wave (?2,k2) will strongly affect a large wave number electron plasma wave (?1,k1), transferring its energy into daughter waves or sidebands at (?1+n?2,k1+nk2) in the lab frame. The accuracy of the model is checked via particle-in-cell simulations, which confirm that the energy in the mode at (?1,k1) can be completely transferred to the sidebands at (?1+n?2,k1+nk2) by the presence of the electron plasma mode at (?2,k2). Conclusive experimental evidence for the generation of daughter waves via this coupling is then presented using time- and wave number-resolved spectra of the light from a probe laser coherently Thomson scattered by the electron plasma waves generated by the interaction of a two-frequency CO2 laser with a plasma.

  4. Experimental investigation of plasma relaxation using a compact coaxial magnetized plasma gun in a background plasma

    NASA Astrophysics Data System (ADS)

    Zhang, Yue; Lynn, Alan; Gilmore, Mark; Hsu, Scott; University of New Mexico Collaboration; Los Alamos National Laboratory Collaboration

    2013-10-01

    A compact coaxial plasma gun is employed for experimental studies of plasma relaxation in a low density background plasma. Experiments are being conducted in the linear HelCat device at UNM. These studies will advance the knowledge of basic plasma physics in the areas of magnetic relaxation and space and astrophysical plasmas, including the evolution of active galactic jets/radio lobes within the intergalactic medium. The gun is powered by a 120pF ignitron-switched capacitor bank which is operated in a range of 5-10 kV and ~100 kA. Multiple diagnostics are employed to investigate plasma relaxation process. Magnetized Argon plasma bubbles with velocities ~1.2Cs and densities ~1020 m-3 have been achieved. Different distinct regimes of operation with qualitatively different dynamics are identified by fast CCD camera images, with the parameter determining the operation regime. Additionally, a B-dot probe array is employed to measure the spatial toroidal and poloidal magnetic flux evolution to identify detached plasma bubble configurations. Experimental data and analysis will be presented.

  5. PlasmaLab/Eco-Plasma - The future of complex plasma research in space

    NASA Astrophysics Data System (ADS)

    Knapek, Christina; Thomas, Hubertus; Huber, Peter; Mohr, Daniel; Hagl, Tanja; Konopka, Uwe; Lipaev, Andrey; Morfill, Gregor; Molotkov, Vladimir

    The next Russian-German cooperation for the investigation of complex plasmas under microgravity conditions on the International Space Station (ISS) is the PlasmaLab/Eco-Plasma project. Here, a new plasma chamber -- the ``Zyflex'' chamber -- is being developed. The chamber is a cylindrical plasma chamber with parallel electrodes and a flexible system geometry. It is designed to extend the accessible plasma parameter range, i.e. neutral gas pressure, plasma density and electron temperature, and also to allow an independent control of the plasma parameters, therefore increasing the experimental quality and expected knowledge gain significantly. With this system it will be possible to reach low neutral gas pressures (which means weak damping of the particle motion) and to generate large, homogeneous 3D particle systems for studies of fundamental phenomena such as phase transitions, dynamics of liquids or phase separation. The Zyflex chamber has already been operated in several parabolic flight campaigns with different configurations during the last years, yielding a promising outlook for its future development. Here, we will present the current status of the project, the technological advancements the Zyflex chamber will offer compared to its predecessors, and the latest scientific results from experiments on ground and in microgravity conditions during parabolic flights. This work and some of the authors are funded by DLR/BMWi (FKZ 50 WP 0700).

  6. Method & apparatus for monitoring plasma processing operations

    DOEpatents

    Smith, Jr., Michael Lane; Ward, Pamela Denise; Stevenson, Joel O'Don

    2004-10-19

    The invention generally relates to various aspects of a plasma process and, more specifically, to the monitoring of such plasma processes. One aspect relates to a plasma monitoring module that may be adjusted in at least some manner so as to re-evaluate a previously monitored plasma process. For instance, optical emissions data on a plasma process that was previously monitored by the plasma monitoring module may be replayed through the plasma monitoring module after making at least one adjustment in relation to the plasma monitoring module.

  7. Plasma Dark Current in Self-Ionized Plasma Wakefield Accelerators

    SciTech Connect

    Oz, E.; Deng, S.; Katsouleas, T.; Muggli, P.; Iverson, R.; Johnson, D.K.; Krejcik, P.; O'Connell, C.; Siemann, R.H.; Walz, D.; Clayton, C.E.; Huang, C.; Joshi, C.; Lu, W.; Marsh, K.A.; Mori, W.B.; Zhou, M.; /UCLA

    2006-01-30

    Evidence of particle trapping has been observed in a beam driven Plasma Wake Field Accelerator (PWFA) experiment, E164X, conducted at the Stanford Linear Accelerator Center by a collaboration which includes USC, UCLA and SLAC. Such trapping produces plasma dark current when the wakefield amplitude is above a threshold value and may place a limit on the maximum acceleration gradient in a PWFA. Trapping and dark current are enhanced when in an ionizing plasma, that is self-ionized by the beam. Here we present experimental results.

  8. Negative Plasma Densities Raise Questions

    SciTech Connect

    Hazi, A

    2006-01-26

    Nearly all the matter encountered on Earth is either a solid, liquid, or gas. Yet plasma-the fourth state of matter-comprises more than 99 percent of the visible universe. Understanding the physical characteristics of plasmas is important to many areas of scientific research, such as the development of fusion as a clean, renewable energy source. Lawrence Livermore scientists study the physics of plasmas in their pursuit to create fusion energy, because plasmas are an integral part of that process. When deuterium and tritium are heated to the extreme temperatures needed to achieve and sustain a fusion reaction (about 100 million degrees), the electrons in these light atoms become separated from the nuclei. This process of separation is called ionization, and the resulting collection of negatively charged free electrons and positively charged nuclei is known as a plasma. Although plasmas and gases have many similar properties, plasmas differ from gases in that they are good conductors of electricity and can generate magnetic fields. For the past decade, x-ray laser interferometry has been used in the laboratory for measuring a plasma's index of refraction to determine plasma density. (The index of refraction for a given material is defined as the wavelength of light in a vacuum divided by the wavelength of light traveling through the material.) Until now, plasma physicists expected to find an index of refraction less than one. Researchers from Livermore and Colorado State University recently conducted experiments on aluminum plasmas at the Laboratory's COMET laser facility and observed results in which the index of refraction was greater than one. This surprising result implied a negative electron density. Livermore physicist Joseph Nilsen and his colleagues from Livermore and the University of Notre Dame have performed sophisticated calculations to explain this phenomenon. Previously, researchers believed that only free electrons contributed to the index of refraction. Nilsen and his colleagues posit that bound electrons attached to the ions in plasmas can greatly affect the index of refraction and make it greater than one. Furthermore, if the effect of bound electrons is ignored when analyzing experimental results from x-ray interferometry, the electron density of plasmas may be indeterminate or significantly under- or overestimated.

  9. BOOK REVIEW: Kinetic theory of plasma waves, homogeneous plasmas

    NASA Astrophysics Data System (ADS)

    Porkolab, Miklos

    1998-11-01

    The linear theory of plasma waves in homogeneous plasma is arguably the most mature and best understood branch of plasma physics. Given the recently revised version of Stix's excellent Waves in Plasmas (1992), one might ask whether another book on this subject is necessary only a few years later. The answer lies in the scope of this volume; it is somewhat more detailed in certain topics than, and complementary in many fusion research relevant areas to, Stix's book. (I am restricting these comments to the homogeneous plasma theory only, since the author promises a second volume on wave propagation in inhomogeneous plasmas.) This book is also much more of a theorist's approach to waves in plasmas, with the aim of developing the subject within the logical framework of kinetic theory. This may indeed be pleasing to the expert and to the specialist, but may be too difficult to the graduate student as an `introduction' to the subject (which the author explicitly states in the Preface). On the other hand, it may be entirely appropriate for a second course on plasma waves, after the student has mastered fluid theory and an introductory kinetic treatment of waves in a hot magnetized `Vlasov' plasma. For teaching purposes, my personal preference is to review the cold plasma wave treatment using the unified Stix formalism and notation (which the author wisely adopts in the present book, but only in Chapter 5). Such an approach allows one to deal with CMA diagrams early on, as well as to provide a framework to discuss electromagnetic wave propagation and accessibility in inhomogeneous plasmas (for which the cold plasma wave treatment is perfectly adequate). Such an approach does lack some of the rigour, however, that the author achieves with the present approach. As the author correctly shows, the fluid theory treatment of waves follows logically from kinetic theory in the cold plasma limit. I only question the pedagogical value of this approach. Otherwise, I welcome this addition to the literature, for it gives the teacher of the subject a valuable reference where the inquisitive student will be able to read up on and satisfy himself about the practicality and reliability of the Vlasov theory in a hot magnetized and collisionless plasma. The book has excellent treatments of several new topics not included in previous textbooks, for example, the relativistic theory of plasma wave propagation, so important in electron cyclotron heating of magnetically confined fusion plasmas, a discussion of current drive theory and there is a welcome introduction to parametric instabilities in the final chapter. There are some things that make the readability of the book somewhat difficult. In the early parts, certain advanced concepts are introduced without much motivation or explanation, although the author is trying to be helpful by providing a list of relevant references at the end of each chapter. Here the teacher's role will be critical. Again, a certain amount of previous knowledge of the subject would prove to be invaluable to the student. The main content of the book is included in 11 chapters. Use is made of CGS Gaussian units, a favourite of plasma theorists. As the author states, these are still widely used in advanced plasma theory, and the student is well advised to become familiar with this system of units (as well as the SI system for applications). To help the reader in the Introduction, the author defines various expressions often used in plasma physics in practical units (frequencies in hertz, lengths in centimetres, temperatures in kiloelectronvolts and magnetic fields in teslas). Chapter 2 is entitled `Plasma Electrodynamics' and it introduces the Maxwell-Vlasov set of equations, as well as the important fundamentals of wave propagation, such as polarization, dispersion and the dielectric tensor, and energy relations. In Chapter 3, `Elementary Plasma Kinetic Theory', the author derives the Vlasov equation and the Fokker-Planck equation from the BBGKY hierarchy. This is a somewhat unusual chapter in a book on plasma waves, but I welcome it since it demonstrates the author's desire to be complete and rigorous in justifying the use of the collisionless Vlasov equation for `high frequency' wave propagation phenomena. Incidentally, it is interesting that while the author derives the Fokker-Planck equation at great length, it is used only to derive the fluid and MHD equations, but not for estimating Coulomb collisional damping of specific waves in later chapters. Chapter 4 gives the derivation of the hot plasma dielectric tensor. There is an extensive and excellent discussion of the relativistic formulation of the dielectric tensor, which is of fundamental importance to practising fusion physicists (for example) involved in ECR heating of high temperature plasmas. Various temperature limits are taken in Chapters 5, 6 and 7, and the author discusses the infinite number of waves in the cold plasma limit (Chapter 5), in the hot plasma limit (Chapter 6) and in the electrostatic limit (Chapter 7). In my opinion, these chapters represent the `meat' of the book. Chapter 7 includes a detailed treatment of electrostatic waves in a hot plasma, including Bernstein waves and their damping at high harmonics. This is a difficult topic, and the extensive treatment presented here is hard to find in other texts. The author also includes a discussion of two stream instabilities here, together with the Nyquist-Penrose criterion for instability. Chapter 8 discusses linear wave-particle interactions, including damping of electromagnetic waves, RF current drive and RF heating. Chapter 9 is called `Collisionless Stochasticity' and institutes an introduction to the subject as well as applications to the heating of ions by high harmonic, lower hybrid waves. Chapter 10 is another key part of the book, on the quasilinear theory of heating and current drive. It deals with the practical aspects of RF heating and current drive in magnetically confined fusion plasmas, and is a `must read' for researchers dealing with RF heating and related transport. Chapter 11 attempts to deal with non-linear effects in the presence of high power RF waves in plasmas. First, the author deals with the difficult subject of mode coupling theory, but, owing to its complexity, the formulation is never reduced to practical applications. Only the `dipole approximation' section can be used to make practical estimates of non-linear effects during RF heating. There are some shortcomings of this book that need to be mentioned here. There are some typographical errors, including spelling errors. The labelling on the figures is often hard to read due to their poor quality and small size. The figures themselves are often too small and are overloaded with curves (e.g., Figs 18.1, 18.2, 21.3, 28.13). The author must have spent a significant effort in producing these curves, and they deserve a better presentation, especially if they are to be used by students. Ease of readability is important for a textbook intended for students and researchers alike. It is hoped that such shortcomings will be improved in future editions, as well as in Volume II, which is to follow. To summarize, this book presents an up to date major contribution to the field of plasma waves and is a `must' on the shelves of active researchers as well as advanced graduate students. Under the guidance of a knowledgeable teacher, the book may be used as a text, with appropriate omissions of certain sections for a one semester course in plasma waves. Alternatively for those who have mastered the fundamentals of wave propagation in plasmas, the book could be used as a basis for an advanced seminar course. I am looking forward with anticipation to Volume II, Waves in Inhomogeneous Plasmas, by Marco Brambilla, one of the eminent plasma wave theorists of our generation.

  10. Plasma Treatments and Biomass Gasification

    NASA Astrophysics Data System (ADS)

    Luche, J.; Falcoz, Q.; Bastien, T.; Leninger, J. P.; Arabi, K.; Aubry, O.; Khacef, A.; Cormier, J. M.; Lédé, J.

    2012-02-01

    Exploitation of forest resources for energy production includes various methods of biomass processing. Gasification is one of the ways to recover energy from biomass. Syngas produced from biomass can be used to power internal combustion engines or, after purification, to supply fuel cells. Recent studies have shown the potential to improve conventional biomass processing by coupling a plasma reactor to a pyrolysis cyclone reactor. The role of the plasma is twofold: it acts as a purification stage by reducing production of tars and aerosols, and simultaneously produces a rich hydrogen syngas. In a first part of the paper we present results obtained from plasma treatment of pyrolysis oils. The outlet gas composition is given for various types of oils obtained at different experimental conditions with a pyrolysis reactor. Given the complexity of the mixtures from processing of biomass, we present a study with methanol considered as a model molecule. This experimental method allows a first modeling approach based on a combustion kinetic model suitable to validate the coupling of plasma with conventional biomass process. The second part of the paper is summarizing results obtained through a plasma-pyrolysis reactor arrangement. The goal is to show the feasibility of this plasma-pyrolysis coupling and emphasize more fundamental studies to understand the role of the plasma in the biomass treatment processes.

  11. Special issue on transient plasmas

    NASA Astrophysics Data System (ADS)

    Bailey, James; Hoarty, David; Mancini, Roberto; Yoneda, Hitoki

    2015-11-01

    This special issue of Journal of Physics B: Atomic, Molecular and Optical Physics is dedicated to the "spectroscopy of transient plasmas" covering plasma conditions produced by a range of pulsed laboratory sources including short and long pulse lasers, pulsed power devices, and free electron lasers (FELs). The full range of plasma spectroscopy up to high energy bremsstrahlung radiation, including line broadening analysis for application to data recorded with the ChemCam instrument on the Mars Science Laboratory rover Curiosity, is covered. This issue is timely as advances in optical lasers and x-ray FELs (XFEL) are enabling transient plasma to be probed at higher energies and shorter durations than ever before. New XFEL facilities being commissioned in Europe and Asia are adding to those operating in the US and Japan and the ELI high power laser project in Europe, due to open this year, will provide short pulse lasers of unprecedented power. This special issue represents a snapshot of the theoretical and experimental research in dense plasmas, electron kinetics, laser-induced breakdown spectroscopy of low temperature plasmas, inertial confinement fusion and non-equilibrium atomic physics using spectroscopy to diagnose plasmas produced by optical lasers, XFELs and pulsed-power machines.

  12. Atmospheric-pressure plasma jet

    DOEpatents

    Selwyn, Gary S.

    1999-01-01

    Atmospheric-pressure plasma jet. A .gamma.-mode, resonant-cavity plasma discharge that can be operated at atmospheric pressure and near room temperature using 13.56 MHz rf power is described. Unlike plasma torches, the discharge produces a gas-phase effluent no hotter than 250.degree. C. at an applied power of about 300 W, and shows distinct non-thermal characteristics. In the simplest design, two concentric cylindrical electrodes are employed to generate a plasma in the annular region therebetween. A "jet" of long-lived metastable and reactive species that are capable of rapidly cleaning or etching metals and other materials is generated which extends up to 8 in. beyond the open end of the electrodes. Films and coatings may also be removed by these species. Arcing is prevented in the apparatus by using gas mixtures containing He, which limits ionization, by using high flow velocities, and by properly shaping the rf-powered electrode. Because of the atmospheric pressure operation, no ions survive for a sufficiently long distance beyond the active plasma discharge to bombard a workpiece, unlike low-pressure plasma sources and conventional plasma processing methods.

  13. Plasma medicine: an introductory review

    NASA Astrophysics Data System (ADS)

    Kong, M. G.; Kroesen, G.; Morfill, G.; Nosenko, T.; Shimizu, T.; van Dijk, J.; Zimmermann, J. L.

    2009-11-01

    This introductory review on plasma health care is intended to provide the interested reader with a summary of the current status of this emerging field, its scope, and its broad interdisciplinary approach, ranging from plasma physics, chemistry and technology, to microbiology, biochemistry, biophysics, medicine and hygiene. Apart from the basic plasma processes and the restrictions and requirements set by international health standards, the review focuses on plasma interaction with prokaryotic cells (bacteria), eukaryotic cells (mammalian cells), cell membranes, DNA etc. In so doing, some of the unfamiliar terminology—an unavoidable by-product of interdisciplinary research—is covered and explained. Plasma health care may provide a fast and efficient new path for effective hospital (and other public buildings) hygiene—helping to prevent and contain diseases that are continuously gaining ground as resistance of pathogens to antibiotics grows. The delivery of medically active 'substances' at the molecular or ionic level is another exciting topic of research through effects on cell walls (permeabilization), cell excitation (paracrine action) and the introduction of reactive species into cell cytoplasm. Electric fields, charging of surfaces, current flows etc can also affect tissue in a controlled way. The field is young and hopes are high. It is fitting to cover the beginnings in New Journal of Physics, since it is the physics (and non-equilibrium chemistry) of room temperature atmospheric pressure plasmas that have made this development of plasma health care possible.

  14. Low Temperature Plasmas and their Industrial Applications

    NASA Astrophysics Data System (ADS)

    Hershkowitz, Noah

    2003-10-01

    Plasma-Aided Manufacturing and Plasma-Based Devices are increasingly important areas of plasma science, in which many members of the plasma science community are currently employed or will be employed in the future. Applications of low temperature plasmas now exist at all neutral pressures ranging from below 1 mTorr to above 1 atmosphere and in liquids. This talk will provide an overview of the subject with examples of industrial uses of plasmas (e.g. 40% of the steps in fabricating Pentium chips require plasma) and plasma-based devices (e.g. new approaches to the reduction of NOx emission from automobile engines). The connection to fundamental processes occurring in the plasma will be elucidated starting from basic processes in partially ionized plasmas (of both charged and neutral species) and ending in plasma-based devices.

  15. Liquid injection plasma deposition method and apparatus

    DOEpatents

    Kong, P.C.; Watkins, A.D.

    1999-05-25

    A liquid injection plasma torch deposition apparatus for depositing material onto a surface of a substrate may comprise a plasma torch for producing a jet of plasma from an outlet nozzle. A plasma confinement tube having an inlet end and an outlet end and a central bore therethrough is aligned with the outlet nozzle of the plasma torch so that the plasma jet is directed into the inlet end of the plasma confinement tube and emerges from the outlet end of the plasma confinement tube. The plasma confinement tube also includes an injection port transverse to the central bore. A liquid injection device connected to the injection port of the plasma confinement tube injects a liquid reactant mixture containing the material to be deposited onto the surface of the substrate through the injection port and into the central bore of the plasma confinement tube. 8 figs.

  16. Liquid injection plasma deposition method and apparatus

    DOEpatents

    Kong, Peter C.; Watkins, Arthur D.

    1999-01-01

    A liquid injection plasma torch deposition apparatus for depositing material onto a surface of a substrate may comprise a plasma torch for producing a jet of plasma from an outlet nozzle. A plasma confinement tube having an inlet end and an outlet end and a central bore therethrough is aligned with the outlet nozzle of the plasma torch so that the plasma jet is directed into the inlet end of the plasma confinement tube and emerges from the outlet end of the plasma confinement tube. The plasma confinement tube also includes an injection port transverse to the central bore. A liquid injection device connected to the injection port of the plasma confinement tube injects a liquid reactant mixture containing the material to be deposited onto the surface of the substrate through the injection port and into the central bore of the plasma confinement tube.

  17. Propagation of an atmospheric pressure plasma plume

    SciTech Connect

    Lu, X.; Xiong, Q.; Xiong, Z.; Hu, J.; Zhou, F.; Gong, W.; Xian, Y.; Zou, C.; Tang, Z.; Jiang, Z.; Pan, Y.

    2009-02-15

    The ''plasma bullet'' behavior of atmospheric pressure plasma plumes has recently attracted significant interest. In this paper, a specially designed plasma jet device is used to study this phenomenon. It is found that a helium primary plasma can propagate through the wall of a dielectric tube and keep propagating inside the dielectric tube (secondary plasma). High-speed photographs show that the primary plasma disappears before the secondary plasma starts to propagate. Both plumes propagate at a hypersonic speed. Detailed studies on the dynamics of the plasma plumes show that the local electric field induced by the charges on the surface of the dielectric tube plays an important role in the ignition of the secondary plasma. This indicates that the propagation of the plasma plumes may be attributed to the local electric field induced by the charges in the bulletlike plasma volume.

  18. EAST First Diverted Plasma Operations -- Plasma Control and Vertical Stabilization

    NASA Astrophysics Data System (ADS)

    Hyatt, A. W.; Leuer, J. A.; Humphreys, D. A.; Jackson, G. L.; Johnson, R. D.; Penaflor, B. G.; Piglowski, D. A.; Walker, M. L.; Welander, A. S.; Mueller, D.; Xiao, B. J.; Yuan, Q. P.; Wang, H. Z.; Fu, P.; Gong, X.; Luo, J.; Wan, Y.; Li, J.

    2007-11-01

    EAST, the first operational fully superconducting tokamak, has a poloidal field (PF) coil set that is similar to ITER. The EAST digital plasma control system (PCS), based on the DIII-D PCS, allowed EAST to rapidly progress from first plasma to diverted operations in a few months, and GA personnel to remotely support the initial rollout of the PCS. Effective combined Ip, Rp, and Zp control with a fully independent PF coil set has been demonstrated. Careful current programming of the PF coils demonstrated stable diverted plasma operation. AC heating and breakdown concerns limited the PF coils' power supplies' bandwidth, voltage, and ability to counter the growth of n=0 instabilities when the plasma elongation kappa, κ>=1.15. Auxiliary internal PF coils driven by a fast power supply (3 kHz, 5 kA, 600 V), provided effective vertical stabilization at κ>=1.8. Examples and simulations will be shown.

  19. The absence of plasma in ``spark plasma sintering''

    NASA Astrophysics Data System (ADS)

    Hulbert, Dustin M.; Anders, André; Dudina, Dina V.; Andersson, Joakim; Jiang, Dongtao; Unuvar, Cosan; Anselmi-Tamburini, Umberto; Lavernia, Enrique J.; Mukherjee, Amiya K.

    2008-08-01

    Spark plasma sintering (SPS) is a remarkable method for synthesizing and consolidating a large variety of both novel and traditional materials. There are a number of mechanisms proposed to account for the enhanced sintering abilities of the SPS process. Of these mechanisms, the one most commonly put forth and the one that draws the most controversy involves the presence of momentary plasma generated between particles. This study employs three separate experimental methods in an attempt to determine the presence or absence of plasma during SPS. The methods employed include in situ atomic emission spectroscopy, direct visual observation, and ultrafast in situ voltage measurements. Using these experimental techniques, no evidence of plasma was found during the SPS process. This result was confirmed using several different powders across a wide spectrum of SPS conditions.

  20. Surface plasma source with saddle antenna radio frequency plasma generator

    SciTech Connect

    Dudnikov, V.; Johnson, R. P.; Murray, S.; Pennisi, T.; Piller, C.; Santana, M.; Stockli, M.; Welton, R.

    2012-02-15

    A prototype RF H{sup -} surface plasma source (SPS) with saddle (SA) RF antenna is developed which will provide better power efficiency for high pulsed and average current, higher brightness with longer lifetime and higher reliability. Several versions of new plasma generators with small AlN discharge chambers and different antennas and magnetic field configurations were tested in the plasma source test stand. A prototype SA SPS was installed in the Spallation Neutron Source (SNS) ion source test stand with a larger, normal-sized SNS AlN chamber that achieved unanalyzed peak currents of up to 67 mA with an apparent efficiency up to 1.6 mA/kW. Control experiments with H{sup -} beam produced by SNS SPS with internal and external antennas were conducted. A new version of the RF triggering plasma gun has been designed. A saddle antenna SPS with water cooling is fabricated for high duty factor testing.

  1. Plasma diagnostics of non-equilibrium atmospheric plasma jets

    NASA Astrophysics Data System (ADS)

    Shashurin, Alexey; Scott, David; Keidar, Michael; Shneider, Mikhail

    2014-10-01

    Intensive development and biomedical application of non-equilibrium atmospheric plasma jet (NEAPJ) facilitates rapid growth of the plasma medicine field. The NEAPJ facility utilized at the George Washington University (GWU) demonstrated efficacy for treatment of various cancer types (lung, bladder, breast, head, neck, brain and skin). In this work we review recent advances of the research conducted at GWU concerned with the development of NEAPJ diagnostics including Rayleigh Microwave Scattering setup, method of streamer scattering on DC potential, Rogowski coils, ICCD camera and optical emission spectroscopy. These tools allow conducting temporally-resolved measurements of plasma density, electrical potential, charge and size of the streamer head, electrical currents flowing though the jet, ionization front propagation speed etc. Transient dynamics of plasma and discharge parameters will be considered and physical processes involved in the discharge will be analyzed including streamer breakdown, electrical coupling of the streamer tip with discharge electrodes, factors determining NEAPJ length, cross-sectional shape and propagation path etc.

  2. The Absence of Plasma in"Spark Plasma Sintering"

    SciTech Connect

    Hulbert, Dustin M.; Anders, Andre; Dudina, Dina V.; Andersson, Joakim; Jiang, Dongtao; Unuvar, Cosan; Anselmi-Tamburini, Umberto; Lavernia, Enrique J.; Mukherjee, Amiya K.

    2008-04-10

    Spark plasma sintering (SPS) is a remarkable method for synthesizing and consolidating a large variety of both novel and traditional materials. The process typically uses moderate uni-axial pressures (<100 MPa) in conjunction with a pulsing on-off DC current during operation. There are a number of mechanisms proposed to account for the enhanced sintering abilities of the SPS process. Of these mechanisms, the one most commonly put forth and the one that draws the most controversy involves the presence of momentary plasma generated between particles. This study employees three separate experimental methods in an attempt to determine the presence or absence of plasma during SPS. The methods employed include: in-situ atomic emission spectroscopy, direct visual observation and ultra-fast in-situ voltage measurements. It was found using these experimental techniques that no plasma is present during the SPS process. This result was confirmed using several different powders across a wide spectrum of SPS conditions.

  3. Plasma acceleration processes in an ablative pulsed plasma thruster

    SciTech Connect

    Koizumi, Hiroyuki; Noji, Ryosuke; Komurasaki, Kimiya; Arakawa, Yoshihiro

    2007-03-15

    Plasma acceleration processes in an ablative pulsed plasma thruster (APPT) were investigated. APPTs are space propulsion options suitable for microspacecraft, and have recently attracted much attention because of their low electric power requirements and simple, compact propellant system. The plasma acceleration mechanism, however, has not been well understood. In the present work, emission spectroscopy, high speed photography, and magnetic field measurements are conducted inside the electrode channel of an APPT with rectangular geometry. The successive images of neutral particles and ions give us a comprehensive understanding of their behavior under electromagnetic acceleration. The magnetic field profile clarifies the location where the electromagnetic force takes effect. As a result, it is shown that high density, ablated neutral gas stays near the propellant surface, and only a fraction of the neutrals is converted into plasma and electromagnetically accelerated, leaving the residual neutrals behind.

  4. Surface plasma source with saddle antenna radio frequency plasma generator.

    PubMed

    Dudnikov, V; Johnson, R P; Murray, S; Pennisi, T; Piller, C; Santana, M; Stockli, M; Welton, R

    2012-02-01

    A prototype RF H(-) surface plasma source (SPS) with saddle (SA) RF antenna is developed which will provide better power efficiency for high pulsed and average current, higher brightness with longer lifetime and higher reliability. Several versions of new plasma generators with small AlN discharge chambers and different antennas and magnetic field configurations were tested in the plasma source test stand. A prototype SA SPS was installed in the Spallation Neutron Source (SNS) ion source test stand with a larger, normal-sized SNS AlN chamber that achieved unanalyzed peak currents of up to 67 mA with an apparent efficiency up to 1.6 mA∕kW. Control experiments with H(-) beam produced by SNS SPS with internal and external antennas were conducted. A new version of the RF triggering plasma gun has been designed. A saddle antenna SPS with water cooling is fabricated for high duty factor testing. PMID:22380221

  5. Interactions between satellites and plasma

    NASA Technical Reports Server (NTRS)

    Isensee, U.; Lehr, W.; Maassberg, H.

    1984-01-01

    The interactions of a spacecraft with the surrounding, streaming plasma were determined by the following effects: the fade out of the plasma in the wake of the probe, the emission of photoelectrons and secondary electrons, the differential charging of the surface of the probe, and a spatial potential distribution in the vicinity of the space probe. These effects and their importance are discussed and following plasma conditions are considered: (1) geostationary satellite orbits; (2) in the solar wind (HELIOS mission); and (3) in the ionosphere at an altitude of 250 km (the projected OSV on Spacelab). The fundamental models are reviewed.

  6. Radioimmunoassay of ACTH in plasma

    PubMed Central

    Berson, Solomon A.; Yalow, Rosalyn S.

    1968-01-01

    Techniques are described in detail for a radioimmunoassay of plasma adrenocorticotropin (ACTH) that is capable of detecting hormone in unextracted normal human plasma at 1:5 dilution under the conditions described. The sensitivity of the assay is at the level of 1 μμg/ml (equivalent to 0.014 mU/100 ml). In normal subjects ACTH concentrations averaged 22 μμg/ml (equivalent to 0.308 mU/100 ml) plasma at 8-10 a.m. In a smaller group the concentrations averaged 9.6 μμg/ml (equivalent to 0.134 mU/100 ml) at 10-11 p.m. Although a circadian rhythm in normal subjects was not always well marked throughout the daytime hours, plasma ACTH usually fell to its lowest value in the late evening. In hospital patients who were not acutely ill, concentrations were infrequently above 100 μμg/ml in the morning and usually fell to significantly lower levels in the late evening. Severely ill hospital patients occasionally exhibited a.m. concentrations above 200 μμg/ml. In a group of subjects showing frequent spiking of plasma 17-OHCS concentrations throughout the day parallel spiking of plasma ACTH as well was generally observed. Metyrapone produced marked increases in plasma ACTH within 24 hr in all cases and generally within 3-6 hr except when started late in the day. Dexamethasone brought about a persistent reduction in plasma ACTH in a patient under continued treatment with metyrapone. Hypoglycemia, electroshock, surgery under general anesthesia, histalog and vasopressin administration were usually followed by significant increases in plasma ACTH concentration. Prior administration of dexamethasone blocked the response to hypoglycemia. Marked elevations in plasma ACTH were observed in patients with adrenal insufficiency off steroid therapy, in Cushing's disease after adrenalectomy even in the presence of persistent hypercortisolemia, and in some untreated patients with Cushing's disease. Umbilical cord blood contained higher plasma ACTH concentrations than maternal blood at delivery in seven of eight cases. After suppression of ACTH secretion by dexamethasone or cortisol. ACTH disappeared from plasma with half-times ranging from 22 min to 30 min in three cases studied. Images PMID:4302180

  7. Dynamics of acetylene plasma polymerization

    NASA Astrophysics Data System (ADS)

    Shin, Eunsung

    The purpose of this study was to investigate the characteristics of plasmas generated during plasma polymerization of acetylene and to investigate the correlation between the plasma and film properties. Specifically, orthogonal acceleration time-of-flight mass spectrometry as well as residual gas analysis and optical emission spectroscopy were employed to detect the ions, neutrals, and excited species present in the plasmas with different conditions such as power and pressure. Since oxygen plasmas are used for cleaning substrates and plasma reactors that are contaminated by carbon, the investigation included oxygen plasmas. The species present in the plasmas generated in a capacitively coupled reactor with 40 kHz of radio frequency were identified, and the detected ion species from Ar/C2H2 plasmas were C+, CH+, CH2+, CH3 +, H3O+, C2+, C2H+, C2H2+, C2H3+, C3H+, C3H2+, C3H3 +, Ar+, C3H5+, C4+, C4H+, C4H2+, C4H3 +, and C4H4+. The results indicate that plasma polymerization process efficiently dissociates the C2H 2 feed gas, and that there was an evidence of some gas phase polymerization. Obtained ion mass spectra and ion kinetic energy distributions showed a decrease in energetic (˜400 eV) ion signal with increasing pressure and a change in the ion kinetic energy distributions. The results are attributed to charge transfer reactions within the plasma sheath, and it is expected that high energy neutral particles generated from such reactions may have considerable influence in determining the properties of films grown by the plasma polymerization process. The films deposited during such process were characterized by analysis techniques such as reflection-absorption infrared spectroscopy, Raman spectroscopy, ultraviolet/visible absorption spectroscopy, variable-angle spectroscopic ellipsometry, and atomic force microscopy. The results indicate that the films grown in such processes have the properties of hydrogenated amorphous carbon films, and that the films grown under low power and low pressure conditions show efficient deposition rate.

  8. CONFINEMENT OF HIGH TEMPERATURE PLASMA

    DOEpatents

    Koenig, H.R.

    1963-05-01

    The confinement of a high temperature plasma in a stellarator in which the magnetic confinement has tended to shift the plasma from the center of the curved, U-shaped end loops is described. Magnetic means are provided for counteracting this tendency of the plasma to be shifted away from the center of the end loops, and in one embodiment this magnetic means is a longitudinally extending magnetic field such as is provided by two sets of parallel conductors bent to follow the U-shaped curvature of the end loops and energized oppositely on the inside and outside of this curvature. (AEC)

  9. Special topics in plasma confinement

    NASA Astrophysics Data System (ADS)

    Taylor, J. B.; Newton, S. L.

    2015-10-01

    > These notes are based on lectures given by one of us (J.B.T.) at the University of Texas in Austin in 1991. Part I concerns some basic features of plasma confinement by magnetic fields as an introduction to an account of plasma relaxation in Part II. Part III discusses confinement by magnetic mirrors, especially minimum- systems. It also includes a general discussion of adiabatic invariants and of the principle of maximal ordering in perturbation theory. Part IV is devoted to the analysis of perturbations in toroidal plasmas and the stability of ballooning modes.

  10. Laboratory experiments on plasma contactors

    NASA Technical Reports Server (NTRS)

    Wilbur, Paul J.; Williams, John D.

    1990-01-01

    Experimental results describing the operation of hollow cathode plasma contactors collecting and emitting electrons from and to an ambient plasma at current levels of the order of one ampere are presented. The voltage drops induced between a contactor and an ambient plasma are shown to be a few tens of volts at such current levels. The development of a double sheath and the production of substantial numbers of ions by electrons streaming across it are associated with the electron collection process. The development of a complex potential structure including a high potential hill just downstream of the cathode orifice is shown to characterize typical contactor emitting electrons.

  11. Fast pulse nonthermal plasma reactor

    DOEpatents

    Rosocha, Louis A.

    2005-06-14

    A fast pulsed nonthermal plasma reactor includes a discharge cell and a charging assembly electrically connected thereto. The charging assembly provides plural high voltage pulses to the discharge cell. Each pulse has a rise time between one and ten nanoseconds and a duration of three to twenty nanoseconds. The pulses create nonthermal plasma discharge within the discharge cell. Accordingly, the nonthermal plasma discharge can be used to remove pollutants from gases or break the gases into smaller molecules so that they can be more efficiently combusted.

  12. The Diagnostics of the External Plasma for the Plasma Rocket

    NASA Technical Reports Server (NTRS)

    Karr, Gerald R.

    1997-01-01

    The plasma rocket is located at NASA Johnson Space Center. To produce a thrust in space. an inert gas is ionized into a plasma and heated in the linear section of a tokamak fusion device to 1 x 10(exp 4) - 1.16 x 10(exp 6)K(p= 10(exp 10) - 10(exp 14)/cu cm ). The magnetic field used to contain the plasma has a magnitude of 2 - 10k Gauss. The plasma plume has a variable thrust and specific impulse. A high temperature retarding potential analyzer (RPA) is being developed to characterize the plasma in the plume and at the edge of the magnetically contained plasma. The RPA measures the energy and density of ions or electrons entering into its solid angle of collection. An oscilloscope displays the ion flux versus the collected current. All measurements are made relative to the facility ground. A RPA is being developed in a process which involves the investigation of several prototypes. The first prototype has been tested on a thermal plasma. The knowledge gained from its development and testing were applied to the development of a RPA for collimated plasma. The prototypes consist of four equally spaced grids and an ion collector. The outermost grid is a ground. The second grid acts as a bias to repel electrons. The third is a variable v voltage ion suppressor. Grid four (inner grid) acts to repel secondary electrons, being biased equal to the first. Knowledge gained during these two stages are being applied to the development of a high temperature RPA Testing of this device involves the determination of its output parameters. sensitivity, and responses to a wide range of energies and densities. Each grid will be tested individually by changing only its voltage and observing the output from the RPA. To verify that the RPA is providing proper output. it is compared to the output from a Langmuir or Faraday probe.

  13. The Diagnostics of the External Plasma for the Plasma Rocket

    NASA Technical Reports Server (NTRS)

    Karr, Gerald R.

    1997-01-01

    Three regions of plasma temperature/energy are being investigated to understand fully the behavior of the plasma created by the propulsion device and the operation of the RPA. Each type of plasma has a RPA associated with it; i.e. a thermal RPA, a collimated RPA, and a high temperature RPA. Through the process of developing the thermal and collimated RPAs, the proper knowledge and experience has been gained to not only design a high temperature RPA for the plasma rocket, but to understand its operation, results, and uncertainty. After completing a literature search for, reading published papers on, and discussing the operation of the RPA with electric propulsion researchers, I applied the knowledge gained to the development of a RPA for thermal plasma. A design of a thermal RPA was made which compensates for a large Debye length and low ionized plasma. From this design a thermal RPA was constructed. It consists of an outer stainless steel casing, a phenolic insulator (outgases slightly), and stainless steel mesh for the voltage screens. From the experience and knowledge gained in the development of the thermal RPA, a RPA for collimated plasma was developed. A collimated RPA has been designed and constructed. It compensate for a smaller Debye length and much higher ionization than that existing in the thermal plasma. It is 17% of the size of the thermal RPA. A stainless steel casing shields the detector from impinging electrons and ions. An insulating material, epoxy resin, was utilized which has a negligible outgassing. This material can be molded in styrofoam and machined quite nicely. It is capable of withstanding moderately high temperatures. Attached to this resin insulator are inconel screens attached by silver plated copper wire to a voltage supply. All the work on the RPAs and thermal ion source, I performed in the University of Alabama in Huntsville's (UAH) engineering machine shop.

  14. Pulse-discharge plasmas for plasma-accelerator applications

    SciTech Connect

    Clayton, C. E.; Joshi, C.; Lopes, N. C.

    2012-12-21

    For particle-beam-driven plasma wakefield accelerators, a long and fully-ionized plasma is desirable. We describe an experiment at UCLA to develop a prototype of such plasma using a pulsed-current discharge. Scaling of the plasma density with glass-tube diameter and with discharge-circuit parameters is currently underway. We have found that 4 Torr of Argon can be fully ionized to a density of about 1.3 Multiplication-Sign 10{sup 17} cm{sup -3} when the current density in the 1 inch diameter, 1.2 meter-long tube is around 2 kA/cm{sup 2}, at least at one point along the discharge. The homogeneity of the plasma density in the longitudinal direction is crucial to prevent slippage of the driven plasma structures with the particles. Equally important are the transverse gradients since any dipole asymmetry in the transverse direction can lead to 'steering' of the particle beam. The longitudinal and transverse gradients may be a function of time into the discharge, the shape of the electrodes, the tube size, and the fractional ionization for a given fill pressure. These issues are currently under investigation.

  15. Plasma Sheath Modeling Using The Three Fluid Plasma Model

    NASA Astrophysics Data System (ADS)

    Lilly, Robert; Shumlak, Uri

    2010-11-01

    There has been renewed interest in the use of plasma actuators for high speed flow control applications. In the plasma actuator, current is driven through the surrounding weakly ionized plasma to impart control moments on the hypersonic vehicle. Accurate modeling of plasma sheath physics is of particular importance for the plasmas found in high speed flight applications. This study employs the three-fluid (electrons, ions, neutrals) plasma model as it allows the capture of electron inertial effects without the unbounded whistler wave that accompanies Hall MHD, as well as energy and momentum transfer between the charged and neutral species. Previous investigations have typically assumed an electrostatic electric field. This work includes the full electrodynamics. Floating potential sheath formation is investigated initially. We then present a method of voltage control that allows for control of the sheath. The resulting boundary scheme, in conjunction with the use of the purely hyperbolic Maxwells equation set, will be reviewed and the results in 1D and 2D discussed. Finally the outlook for incorporating transport will be presented.

  16. Plasma physical and plasma chemical aspects of nanoparticle formation in hydrocarbon plasmas

    NASA Astrophysics Data System (ADS)

    Berndt, Johannes; Kovacevic, Eva; Stefanovic, Ilija

    2013-09-01

    Low temperature plasmas are a breeding place for a great variety of different species, that can be used for different applications as the deposition of thin films or the the synthesis of nanoparticles and nanocomposites. However the distinctive nonequilibrium character of theses plasmas makes their understanding and their control a rather challenging task. The solution of this task is in addition hampered by the fact that decisive factors like cross sections for electron impact processes or rate coefficients for molecule-molecule reactions are very often completely unknown. In particular reactions including the walls of the plasma reactor are difficult to account for since they depend on the nature of the involved molecules and on the nature of the wall itself. This contribution deals with two simple approaches to control plasma chemical processes in a reactive low temperature plama: the variation of the diffusion length and the pulsing of the discharge. The contribution will focus on experiments performed in rf low pressure hydrocarbon plasmas with special emphasis on the influence of plasma physical and plasma chemical processes on the formation and properties of nanoparticles.

  17. Plasma core reactor applications

    NASA Technical Reports Server (NTRS)

    Latham, T. S.; Rodgers, R. J.

    1976-01-01

    Analytical and experimental investigations were conducted to demonstrate the feasibility of fissioning uranium plasma core reactors and to characterize space and terrestrial applications for such reactors. Uranium hexafluoride fuel is injected into core cavities and confined away from the surface by argon buffer gas injected tangentially from the peripheral walls. Radiant heat transfer calculations were performed for a six-cavity reactor configuration. Axial working fluid channels are located along a fraction of each cavity peripheral wall. Results of calculations for outward-directed radiant energy fluxes corresponding to radiating temperatures of 2000 to 5000 K indicate total operating pressures from 80 to 650 atm, centerline temperatures from 6900 to 30,000 K, and total radiated powers from 25 to 2500 MW, respectively. Applications are described for this type of reactor such as (1) high-thrust, high specific impulse space propulsion, (2) highly efficient systems for generation of electricity, and (3) hydrogen or synthetic fuel production systems using the intense radiant energy fluxes.

  18. Circulating Plasma Tumor DNA.

    PubMed

    Parsons, Heather A; Beaver, Julia A; Park, Ben H

    2016-01-01

    Circulating cell-free DNA (ccfDNA)-first identified in 1947-is "naked" DNA that is free-floating in the blood, and derived from both normal and diseased cells. In the 1970s, scientists observed that patients with cancer had elevated levels of ccfDNA as compared to their healthy, cancer-free counterparts. The maternal fetal medicine community first developed techniques to identify the small fraction of fetal-derived ccfDNA for diagnostic purposes. Similarly, due to the presence of tumor-specific (somatic) variations in all cancers, the fraction of circulating cell-free plasma tumor DNA (ptDNA) in the larger pool of ccfDNA derived from normal cells can serve as extremely specific blood-based biomarkers for a patient's cancer. In theory this "liquid biopsy" can provide a real-time assessment of molecular tumor genotype (qualitative) and existing tumor burden (quantitative). Historically, the major limitation for ptDNA as a biomarker has been related to a low detection rate; however, current and developing techniques have improved sensitivity dramatically. In this chapter, we discuss these methods, including digital polymerase chain reaction and various approaches to tagged next-generation sequencing. PMID:26987539

  19. Compact plasma accelerator

    NASA Technical Reports Server (NTRS)

    Foster, John E. (Inventor)

    2004-01-01

    A compact plasma accelerator having components including a cathode electron source, an anodic ionizing gas source, and a magnetic field that is cusped. The components are held by an electrically insulating body having a central axis, a top axial end, and a bottom axial end. The cusped magnetic field is formed by a cylindrical magnet having an axis of rotation that is the same as the axis of rotation of the insulating body, and magnetized with opposite poles at its two axial ends; and an annular magnet coaxially surrounding the cylindrical magnet, magnetized with opposite poles at its two axial ends such that a top axial end has a magnetic polarity that is opposite to the magnetic polarity of a top axial end of the cylindrical magnet. The ionizing gas source is a tubular plenum that has been curved into a substantially annular shape, positioned above the top axial end of the annular magnet such that the plenum is centered in a ring-shaped cusp of the magnetic field generated by the magnets. The plenum has one or more capillary-like orifices spaced around its top such that an ionizing gas supplied through the plenum is sprayed through the one or more orifices. The plenum is electrically conductive and is positively charged relative to the cathode electron source such that the plenum functions as the anode; and the cathode is positioned above and radially outward relative to the plenum.

  20. Welding arc plasma physics

    NASA Technical Reports Server (NTRS)

    Cain, Bruce L.

    1990-01-01

    The problems of weld quality control and weld process dependability continue to be relevant issues in modern metal welding technology. These become especially important for NASA missions which may require the assembly or repair of larger orbiting platforms using automatic welding techniques. To extend present welding technologies for such applications, NASA/MSFC's Materials and Processes Lab is developing physical models of the arc welding process with the goal of providing both a basis for improved design of weld control systems, and a better understanding of how arc welding variables influence final weld properties. The physics of the plasma arc discharge is reasonably well established in terms of transport processes occurring in the arc column itself, although recourse to sophisticated numerical treatments is normally required to obtain quantitative results. Unfortunately the rigor of these numerical computations often obscures the physics of the underlying model due to its inherent complexity. In contrast, this work has focused on a relatively simple physical model of the arc discharge to describe the gross features observed in welding arcs. Emphasis was placed of deriving analytic expressions for the voltage along the arc axis as a function of known or measurable arc parameters. The model retains the essential physics for a straight polarity, diffusion dominated free burning arc in argon, with major simplifications of collisionless sheaths and simple energy balances at the electrodes.

  1. Space Plasma Physics

    NASA Technical Reports Server (NTRS)

    Wu, S. T.

    2000-01-01

    Dr. James L. Horwitz and R. Hugh Comfort's studies with the high altitude TIDE data have been progressing well. We concluded a study on the relationship of polar cap ion properties observed by TIDE near apogee with solar wind and IMF conditions. We found that in general H+ did not correlate as well as O+ with solar wind and IMF parameters. O+ density correlated(sub IMF), and Kp. At lower solar wind speeds, O+ density decreased with increasing latitude, but this trend was not observed at higher solar wind speeds. By comparing these results with results from other studies of O+ in different parts of the magnetosphere, we concluded that O+ ions often leave the ionosphere near the foot point of the cusp/cleft region, pass through the high-altitude polar cap lobes, and eventually arrive in the plasma sheet. We found that H+ outflows are a persistent feature of the polar cap and are not as dependent on the geophysical conditions; even classical polar wind models show H+ ions readily escaping owing to their low mass. Minor correlations with solar wind drivers were found; specifically, H+ density correlated best with IMF By, V(sub sw)B(sub IMF), and ESW(sub sw).

  2. Coupled plasma filtration adsorption.

    PubMed

    Formica, Marco; Inguaggiato, Paola; Bainotti, Serena; Wratten, Mary Lou

    2007-01-01

    Sepsis is one of the main causes of death in critically ill patients worldwide, and in many cases it is associated with renal and/or other organ failure. However, we do not have a unique efficient therapy to reduce this extremely high mortality rate. In the last years interest around the use of extracorporeal blood purification techniques has increased. One of the emerging treatments in patients with severe sepsis and septic shock is coupled plasma filtration adsorption (CPFA), a novel extracorporeal blood purification therapy aimed at a nonselective reduction of the circulating levels and activities of both pro- and anti-inflammatory mediators. Early experimental studies and the following clinical trials have demonstrated impressive results regarding hemodynamics and respiratory parameters, even in patients without concomitant acute renal injury, paralleled by a quick tapering of vasoactive drugs. Considering the still high morbidity and mortality rates in septic shock patients, this new blood purification technique seems to have benefits when applied early in the course of sepsis, also without renal indications, suggesting that it might be performed to prevent rather than to treat acute kidney injury. PMID:17464151

  3. Layered plasma polymer composite membranes

    DOEpatents

    Babcock, W.C.

    1994-10-11

    Layered plasma polymer composite fluid separation membranes are disclosed, which comprise alternating selective and permeable layers for a total of at least 2n layers, where n is [>=]2 and is the number of selective layers. 2 figs.

  4. Coherent control of plasma dynamics.

    PubMed

    He, Z-H; Hou, B; Lebailly, V; Nees, J A; Krushelnick, K; Thomas, A G R

    2015-01-01

    Coherent control of a system involves steering an interaction to a final coherent state by controlling the phase of an applied field. Plasmas support coherent wave structures that can be generated by intense laser fields. Here, we demonstrate the coherent control of plasma dynamics in a laser wakefield electron acceleration experiment. A genetic algorithm is implemented using a deformable mirror with the electron beam signal as feedback, which allows a heuristic search for the optimal wavefront under laser-plasma conditions that is not known a priori. We are able to improve both the electron beam charge and angular distribution by an order of magnitude. These improvements do not simply correlate with having the 'best' focal spot, as the highest quality vacuum focal spot produces a greatly inferior electron beam, but instead correspond to the particular laser phase front that steers the plasma wave to a final state with optimal accelerating fields. PMID:25975737

  5. Space Flight Plasma Data Analysis

    NASA Technical Reports Server (NTRS)

    Wright, Kenneth H.; Minow, Joseph I.

    2009-01-01

    This slide presentation reviews a method to analyze the plasma data that is reported on board the International Space station (ISS). The Floating Potential Measurement Unit (FPMU), the role of which is to obtain floating potential and ionosphere plasma measurements for validation of the ISS charging model, assess photo voltaic array variability and interpreting IRI predictions, is composed of four probes: Floating Potential Probe (FPP), Wide-sweep Langmuir Probe (WLP), Narrow-sweep Langmuir Probe (NLP) and the Plasma Impedance Probe (PIP). This gives redundant measurements of each parameter. There are also many 'boxes' that the data must pass through before being captured by the ground station, which leads to telemetry noise. Methods of analysis for the various signals from the different sets are reviewed. There is also a brief discussion of LP analysis of Low Earth Orbit plasma simulation source.

  6. Plasma in the Jovian magnetosphere

    NASA Technical Reports Server (NTRS)

    Goertz, C. K.

    1975-01-01

    It is shown that the plasma in Jupiter's ionosphere is collisionless above a certain level. In the outer magnetosphere, where the rotational force dominates the gravitational force, the collisionless plasma has a beam-like distribution and gives rise to a two-stream instability. This leads to trapping of plasma in the centrifugally dominated region of the magnetosphere. Plasma is lost by recombination. Equilibrium-trapped particle densities are calculated by requiring a balance between trapping by wave-particle interaction and loss by recombination. The results are compared with recent observations from Pioneer 10. It is suggested that the observations require an unexplained ion-heating mechanism. Some consequences of the model are discussed.

  7. Catecholamines, Plasma and Urine Test

    MedlinePlus

    ... page: Was this page helpful? Also known as: Dopamine; Epinephrine; Norepinephrine; Free Catecholamines, plasma and urine; Fractionated ... physical or emotional stress. The primary catecholamines are dopamine, epinephrine (adrenaline), and norepinephrine. These hormones are broken ...

  8. Outreach Activities for Plasma Science

    NASA Astrophysics Data System (ADS)

    Haynes, M.; Bannan, K.; Delooper, J.; Eastman, T.; Sweet, P.; Smith, T.

    1997-11-01

    The need for communication beyond experts from subfields of scientific inquiry has been long identified. In response to this need, new outreach activities for plasma science have begun to take shape and grow. One example of this increase in activity is the formation of the Coalition for Plasma Science. The focus of the Coalition's efforts is to enhance the understanding and support for plasma science in the scientific community, the education community, business and the general public. One of the Coalition's first activities was to coordinate the assembly of an eight panel exhibit entitled "Plasmas: Science and Technology for the 21st Century". The formation of the Coalition and the display will be described and some possible future activities will be outlined.

  9. MHD stability of tokamak plasmas

    SciTech Connect

    Chance, M.S. Sun, Y.C.; Jardin, S.C.; Kessel, C.E.; Okabayashi, M.

    1992-08-01

    This paper will give an overview of the some of the methods which are used to simulate the ideal MHD properties of tokamak plasmas. A great deal of the research in this field is necessarily numerical and the substantial progress made during the past several years has roughly paralleled the continuing availability of more advanced supercomputers. These have become essential to accurately model the complex configurations necessary for achieving MHD stable reactor grade conditions. Appropriate tokamak MHD equilibria will be described. Then the stability properties is discussed in some detail, emphasizing the difficulties of obtaining stable high {beta} discharges in plasmas in which the current is mainly ohmically driven and thus demonstrating the need for tailoring the current and pressure profiles of the plasma away from the ohmic state. The outline of this paper will roughly follow the physics development to attain the second region of stability in the PBX-M device at The Princeton Plasmas Physics Laboratory.

  10. Plasma reactor waste management systems

    NASA Technical Reports Server (NTRS)

    Ness, Robert O., Jr.; Rindt, John R.; Ness, Sumitra R.

    1992-01-01

    The University of North Dakota is developing a plasma reactor system for use in closed-loop processing that includes biological, materials, manufacturing, and waste processing. Direct-current, high-frequency, or microwave discharges will be used to produce plasmas for the treatment of materials. The plasma reactors offer several advantages over other systems, including low operating temperatures, low operating pressures, mechanical simplicity, and relatively safe operation. Human fecal material, sunflowers, oats, soybeans, and plastic were oxidized in a batch plasma reactor. Over 98 percent of the organic material was converted to gaseous products. The solids were then analyzed and a large amount of water and acid-soluble materials were detected. These materials could possibly be used as nutrients for biological systems.

  11. Atomic phenomena in dense plasmas

    SciTech Connect

    Weisheit, J.C.

    1981-03-01

    The following chapters are included: (1) the plasma environment, (2) perturbations of atomic structure, (3) perturbations of atomic collisions, (4) formation of spectral lines, and (5) dielectronic recombination. (MOW)

  12. Plasma Heating: An Advanced Technology

    NASA Technical Reports Server (NTRS)

    1994-01-01

    The Mercury and Apollo spacecraft shields were designed to protect astronauts from high friction temperatures (well over 2,000 degrees Fahrenheit) when re-entering the Earth's atmosphere. It was necessary to test and verify the heat shield materials on Earth before space flight. After exhaustive research and testing, NASA decided to use plasma heating as a heat source. This technique involves passing a strong electric current through a rarefied gas to create a plasma (ionized gas) that produces an intensely hot flame. Although NASA did not invent the concept, its work expanded the market for commercial plasma heating systems. One company, Plasma Technology Corporation (PTC), was founded by a member of the team that developed the Re-entry Heating Simulator at Ames Research Center (ARC). Dr. Camacho, President of PTC, believes the technology has significant environmental applications. These include toxic waste disposal, hydrocarbon, decomposition, medical waste disposal, asbestos waste destruction, and chemical and radioactive waste disposal.

  13. Plasma transport near material boundaries

    SciTech Connect

    Singer, C.E.

    1985-06-01

    The fluid theory of two-dimensional (2-d) plasma transport in axisymmetric devices is reviewed. The forces which produce flow across the magnetic field in a collisional plasma are described. These flows may lead to up-down asymmetries in the poloidal rotation and radial fluxes. Emphasis is placed on understanding the conditions under which the known 2-d plasma fluid equations provide a valid description of these processes. Attempts to extend the fluid treatment to less collisional, turbulent plasmas are discussed. A reduction to the 1-d fluid equations used in many computer simulations is possible when sources or boundary conditions provide a large enough radial scale length. The complete 1-d fluid equations are given in the text, and 2-d fluid equations are given in the Appendix.

  14. Hall Effect in a Plasma.

    ERIC Educational Resources Information Center

    Kunkel, W. B.

    1981-01-01

    Describes an apparatus and procedure for conducting an undergraduate laboratory experiment to quantitatively study the Hall effect in a plasma. Includes background information on the Hall effect and rationale for conducting the experiment. (JN)

  15. Plasma Rain - Duration: 33 seconds.

    NASA Video Gallery

    On April 19, 2010 AIA observed one of the largest prominence eruptions in years. The huge structure erupts, but a great deal of the plasma (hundreds of millions of tons) is unable to escape the gra...

  16. Tandem mirror plasma confinement apparatus

    DOEpatents

    Fowler, T. Kenneth

    1978-11-14

    Apparatus and method for confining a plasma in a center mirror cell by use of two end mirror cells as positively charged end stoppers to minimize leakage of positive particles from the ends of the center mirror cell.

  17. PLASMA HEATING AND CONFINING DEVICE

    DOEpatents

    Baker, W.R.; Bratenahl, Al.; Kunkel, W.B.

    1962-02-13

    ABS> A device is designed for generating, heating, and containing a very pure electrical plasma. Plasma purity is maintained by preventing the hot plasma from contacting insulators, which are a principal source of impurities in prior constructions. An insulator is disposed at each end of a pair of long coaxial cylinders forming an annular chamber therebetween. High voltage is applied between the cylinders and an axial magnetic field is created therethrough. At a middle position on the inner cylinder, a fastopening valve releases a quantity of gas into the chamber, and before the gas can diffuse to the distant insulators, a discharge occurs between the cylinders and plasma is formed in the central region of the chamber away from the insulators. (AEC)

  18. Conductivity of a relativistic plasma

    SciTech Connect

    Braams, B.J.; Karney, C.F.F.

    1989-03-01

    The collision operator for a relativistic plasma is reformulated in terms of an expansion in spherical harmonics. This formulation is used to calculate the electrical conductivity. 13 refs., 1 fig., 1 tab.

  19. Laser Assisted Plasma Arc Welding

    SciTech Connect

    FUERSCHBACH,PHILLIP W.

    1999-10-05

    Experiments have been performed using a coaxial end-effecter to combine a focused laser beam and a plasma arc. The device employs a hollow tungsten electrode, a focusing lens, and conventional plasma arc torch nozzles to co-locate the focused beam and arc on the workpiece. Plasma arc nozzles were selected to protect the electrode from laser generated metal vapor. The project goal is to develop an improved fusion welding process that exhibits both absorption robustness and deep penetration for small scale (< 1.5 mm thickness) applications. On aluminum alloys 6061 and 6111, the hybrid process has been shown to eliminate hot cracking in the fusion zone. Fusion zone dimensions for both stainless steel and aluminum were found to be wider than characteristic laser welds, and deeper than characteristic plasma arc welds.

  20. Mobile inductively coupled plasma system

    DOEpatents

    D'Silva, Arthur P.; Jaselskis, Edward J.

    1999-03-30

    A system for sampling and analyzing a material located at a hazardous site. A laser located remote from the hazardous site is connected to an optical fiber, which directs laser radiation proximate the material at the hazardous site. The laser radiation abates a sample of the material. An inductively coupled plasma is located remotely from the material. An aerosol transport system carries the ablated particles to a plasma, where they are dissociated, atomized and excited to provide characteristic optical reduction of the elemental constituents of the sample. An optical spectrometer is located remotely from the site. A second optical fiber is connected to the optical spectrometer at one end and the plasma source at the other end to carry the optical radiation from the plasma source to the spectrometer.

  1. Mobile inductively coupled plasma system

    DOEpatents

    D`Silva, A.P.; Jaselskis, E.J.

    1999-03-30

    A system is described for sampling and analyzing a material located at a hazardous site. A laser located remotely from the hazardous site is connected to an optical fiber, which directs laser radiation proximate the material at the hazardous site. The laser radiation abates a sample of the material. An inductively coupled plasma is located remotely from the material. An aerosol transport system carries the ablated particles to a plasma, where they are dissociated, atomized and excited to provide characteristic optical reduction of the elemental constituents of the sample. An optical spectrometer is located remotely from the site. A second optical fiber is connected to the optical spectrometer at one end and the plasma source at the other end to carry the optical radiation from the plasma source to the spectrometer. 10 figs.

  2. Layered plasma polymer composite membranes

    DOEpatents

    Babcock, Walter C. (Bend, OR)

    1994-01-01

    Layered plasma polymer composite fluid separation membranes are disclosed, which comprise alternating selective and permeable layers for a total of at least 2n layers, where n is .gtoreq.2 and is the number of selective layers.

  3. Diagnostics of Plasma Propulsion Devices

    NASA Astrophysics Data System (ADS)

    Cappelli, Mark A.

    1998-11-01

    Plasma rockets are rapidly emerging as critical technologies in future space flight. These devices take on various forms, ranging from electro-thermal to electromagnetic accelerators, generally categorized by the method in which electrical energy is converted to thrust. As is the case in many plasma devices, non-intrusive optical (emission, or laser-based) diagnostics is an essential element in the characterization of these plasma sources, as access to the discharges in these plasma engines is often limited. Furthermore, laser-based diagnostics offer additional benefits, including improved spatial resolution, and can provide state-specific measurements of species densities, velocities and energy distributions. In recent years, we have developed and applied a variety of emission and laser-based diagnostics strategies to the characterization of arcjet plasma and closed-drift xenon Hall plasma accelerators. Both of these types of plasma propulsion devices are of immediate interest to the space propulsion community, and are under varying stages of development. Arcjet thrusters have unique properties, with strong plasma density, temperature and velocity gradients, which enhance the coupling between the gasdynamic and plasma physics. Closed-drift Hall plasma thrusters are low density electrostatic devices that are inherently turbulent, and exhibit varying degrees of anomalous cross-field electron transport. Our most extensive, collective effort has been to apply laser-induced fluorescence, Doppler-free laser absorption, and Raman scattering to the characterization of hydrogen and helium arcjet flows. Detailed measurements of velocity, temperatures, and electron densities are compared to the results of magneto-hydrodynamic flowfield simulations. The results show that while the simulations capture many aspects of the flow, there are still some unresolved discrepancies. The database established for Hall thrusters is less extensive, as the laser absorption spectroscopy of xenon is somewhat more complicated due to the hyperfine and isotopic structure of electronic transitions. With an understanding of the spectroscopic absorption lineshape for two select transitions in neutral and ionized xenon, we have successfully mapped out the neutral and singly ionized xenon velocities in the acceleration zone of Hall thrusters. These results indicate that the acceleration zone in a short-channel thruster is outside of the device, consistent with the measurements of plasma potential using more conventional Langmuir electrostatic probes. The spectroscopic data has also been used to identify limitations in ground-test facilities.

  4. Dusty-Plasma Particle Accelerator

    NASA Technical Reports Server (NTRS)

    Foster, John E.

    2005-01-01

    A dusty-plasma apparatus is being investigated as means of accelerating nanometer- and micrometer-sized particles. Applications for the dusty-plasma particle accelerators fall into two classes: Simulation of a variety of rapidly moving dust particles and micrometeoroids in outer-space environments that include micrometeoroid streams, comet tails, planetary rings, and nebulae and Deposition or implantation of nanoparticles on substrates for diverse industrial purposes that could include hardening, increasing thermal insulation, altering optical properties, and/or increasing permittivities of substrate materials. Relative to prior apparatuses used for similar applications, dusty-plasma particle accelerators offer such potential advantages as smaller size, lower cost, less complexity, and increased particle flux densities. A dusty-plasma particle accelerator exploits the fact that an isolated particle immersed in plasma acquires a net electric charge that depends on the relative mobilities of electrons and ions. Typically, a particle that is immersed in a low-temperature, partially ionized gas, wherein the average kinetic energy of electrons exceeds that of ions, causes the particle to become negatively charged. The particle can then be accelerated by applying an appropriate electric field. A dusty-plasma particle accelerator (see figure) includes a plasma source such as a radio-frequency induction discharge apparatus containing (1) a shallow cup with a biasable electrode to hold the particles to be accelerated and (2) a holder for the substrate on which the particles are to impinge. Depending on the specific design, a pair of electrostatic-acceleration grids between the substrate and discharge plasma can be used to both collimate and further accelerate particles exiting the particle holder. Once exposed to the discharge plasma, the particles in the cup quickly acquire a negative charge. Application of a negative voltage pulse to the biasable electrode results in the initiation of a low-current, high-voltage cathode spot. Plasma pressure associated with the cathode spot as well as the large voltage drop at the cathode spot accelerates the charged particles toward the substrate. The ultimate kinetic energy attained by particles exiting the particle holder depends in part on the magnitude of the cathode spot sheath potential difference, which is proportional to the magnitude of the voltage pulse, and the on the electric charge on the dust. The magnitude of the voltage pulse can be controlled directly, whereas the particle s electric charge can be controlled indirectly by controlling the operating parameters of the plasma apparatus.

  5. Inertial Currents in Isotropic Plasma

    NASA Technical Reports Server (NTRS)

    Heinemann, M.; Erickson, G. M.; Pontius, D. H., Jr.

    1993-01-01

    The magnetospheric convection electric field contributes to Birkeland currents. The effects of the field are to polarize the plasma by displacing the bounce paths of the ions from those of electrons, to redistribute the pressure so that it is not constant along magnetic field lines, and to enhance the pressure gradient by the gradient of the bulk speed. Changes in the polarization charge during the convection of the plasma are neutralized by electrons in the form of field-aligned currents that close through the ionosphere. The pressure drives field-aligned currents through its gradient in the same manner as in quasi-static plasma, but with modifications that are important if the bulk speed is of the order of the ion thermal speed; the variations in the pressure along field lines are maintained by a weak parallel potential drop. These effects are described in terms of the field-aligned currents in steady state, isotropic, MED plasma. Solutions are developed by taking the MHD limit of two-fluid solutions and illustrated in the special case of Maxwellian plasma for which the temperature is constant along magnetic field lines. The expression for the Birkeland current density is a generalization of Vasyliunas' expression for the field-aligned current density in quasi-static plasma and provides a unifying expression when both pressure gradients and ion inertia operate simultaneously as sources of field-aligned currents. It contains a full account of different aspects of the ion flow (parallel and perpendicular velocity and vorticity) that contribute to the currents. Contributions of ion inertia to field-aligned currents will occur in regions of strong velocity shear, electric field reversal, or large gradients in the parallel velocity or number density, and may be important in the low-latitude boundary layer, plasma sheet boundary layer, and the inner edge region of the plasma sheet.

  6. Inertial currents in isotropic plasma

    NASA Technical Reports Server (NTRS)

    Heinemann, M.; Erickson, G. M.; Pontius, D. H. JR.

    1994-01-01

    The magnetospheric convection electric field contributes to Birkeland currents. The effects of the field are to polarize the plasma by displacing the bounce paths of the ions from those of electrons, to redistribute the pressure so that it is not constant along magnetic field lines, and to enhance the pressure gradient by the gradient of the bulk speed. Changes in the polarization charge during the convection of the plasma are neutralized by electrons in the form of field-aligned currents that close through the ionosphere. The pressure drives field-aligned currents through its gradient in the same manner as in quasi-static plasma, but with modifications that are important if the bulk speed is of the order of the ion thermal speed; the variations in the pressure along field lines are maintained by a weak parallel potential drop. These effects are described in terms of the field-aligned currents in steady state, isotropic, magnetohyrodynamic (MHD) plasma. Solutions are developed by taking the MHD limit of two-fluid solutions and illustrated in the special case of Maxwellian plasma for which the temperature is constant along magnetic field lines. The expression for the Birkeland current density is a generalization of Vasyliunas' expression for the field-aligned current density in quasi-static plasma and provides a unifying expression when both pressure gradients and ion inertia operate simultaneously as sources of field-aligned currents. It contains a full account of different aspects of the ion flow (parallel and perpendicular velocity and vorticity) that contribute to the currents. Contributions of ion inertia to field-aligned currents will occur in regions of strong velocity shear, electric field reversal, or large gradients in the parallel velocity or number density, and may be important in the low-latitude boundary layer, plasma sheet boundary layer, and the inner edge region of the plasma sheet.

  7. Lysosomes and the plasma membrane

    PubMed Central

    Andrews, Norma W.

    2002-01-01

    Studies of the cell invasion mechanism of the parasite Trypanosoma cruzi led to a series of novel findings, which revealed a previously unsuspected ability of conventional lysosomes to fuse with the plasma membrane. This regulated exocytic process, previously regarded mostly as a specialization of certain cell types, was recently shown to play an important role in the mechanism by which cells reseal their plasma membrane after injury. PMID:12147679

  8. Theory for Plasma Rocket Propulsion

    NASA Astrophysics Data System (ADS)

    Grabbe, Crockett

    2009-11-01

    Electrical propulsion of rockets is developing potentially into the use of 3 different thrusters for future long-distance space missions that primarily involve plasma dynamics. These are the Magnetoplasmadynamic (MPD) Thruster, the Plasma Induction Thruster (PID), and the VASIMIR Thruster. The history of the development of electrical propulsion into these prospects and the current research of particularly the VASIMIR Thruster are reviewed. Theoretical questions that need to be addressed in that development are explored.

  9. Fusion Plasma Theory project summaries

    SciTech Connect

    Not Available

    1993-10-01

    This Project Summary book is a published compilation consisting of short descriptions of each project supported by the Fusion Plasma Theory and Computing Group of the Advanced Physics and Technology Division of the Department of Energy, Office of Fusion Energy. The summaries contained in this volume were written by the individual contractors with minimal editing by the Office of Fusion Energy. Previous summaries were published in February of 1982 and December of 1987. The Plasma Theory program is responsible for the development of concepts and models that describe and predict the behavior of a magnetically confined plasma. Emphasis is given to the modelling and understanding of the processes controlling transport of energy and particles in a toroidal plasma and supporting the design of the International Thermonuclear Experimental Reactor (ITER). A tokamak transport initiative was begun in 1989 to improve understanding of how energy and particles are lost from the plasma by mechanisms that transport them across field lines. The Plasma Theory program has actively-participated in this initiative. Recently, increased attention has been given to issues of importance to the proposed Tokamak Physics Experiment (TPX). Particular attention has been paid to containment and thermalization of fast alpha particles produced in a burning fusion plasma as well as control of sawteeth, current drive, impurity control, and design of improved auxiliary heating. In addition, general models of plasma behavior are developed from physics features common to different confinement geometries. This work uses both analytical and numerical techniques. The Fusion Theory program supports research projects at US government laboratories, universities and industrial contractors. Its support of theoretical work at universities contributes to the office of Fusion Energy mission of training scientific manpower for the US Fusion Energy Program.

  10. ATON-thruster plasma accelerator

    NASA Astrophysics Data System (ADS)

    Morozov, A. I.; Balebanov, V. M.; Bugrova, A. I.; Lipatov, A. S.; Khartchevnikov, V. K.

    2000-08-01

    The concept of a second generation Hall-current plasma accelerator (ATON-thruster), which has record performance characteristics is described. A method is proposed for analyzing the operation parameters of the accelerator on the basis of its performance characteristics. The results of measurements of plasma parameters in the accelerator channel and outflowing jet are presented. Influence of backmoving of particles from vacuum chamber to thruster one has been discussed.

  11. Transport equations in tokamak plasmas

    SciTech Connect

    Callen, J. D.; Hegna, C. C.; Cole, A. J.

    2010-05-15

    Tokamak plasma transport equations are usually obtained by flux surface averaging the collisional Braginskii equations. However, tokamak plasmas are not in collisional regimes. Also, ad hoc terms are added for neoclassical effects on the parallel Ohm's law, fluctuation-induced transport, heating, current-drive and flow sources and sinks, small magnetic field nonaxisymmetries, magnetic field transients, etc. A set of self-consistent second order in gyroradius fluid-moment-based transport equations for nearly axisymmetric tokamak plasmas has been developed using a kinetic-based approach. The derivation uses neoclassical-based parallel viscous force closures, and includes all the effects noted above. Plasma processes on successive time scales and constraints they impose are considered sequentially: compressional Alfven waves (Grad-Shafranov equilibrium, ion radial force balance), sound waves (pressure constant along field lines, incompressible flows within a flux surface), and collisions (electrons, parallel Ohm's law; ions, damping of poloidal flow). Radial particle fluxes are driven by the many second order in gyroradius toroidal angular torques on a plasma species: seven ambipolar collision-based ones (classical, neoclassical, etc.) and eight nonambipolar ones (fluctuation-induced, polarization flows from toroidal rotation transients, etc.). The plasma toroidal rotation equation results from setting to zero the net radial current induced by the nonambipolar fluxes. The radial particle flux consists of the collision-based intrinsically ambipolar fluxes plus the nonambipolar fluxes evaluated at the ambipolarity-enforcing toroidal plasma rotation (radial electric field). The energy transport equations do not involve an ambipolar constraint and hence are more directly obtained. The 'mean field' effects of microturbulence on the parallel Ohm's law, poloidal ion flow, particle fluxes, and toroidal momentum and energy transport are all included self-consistently. The final comprehensive equations describe radial transport of plasma toroidal rotation, and poloidal and toroidal magnetic fluxes, as well as the usual particle and energy transport.

  12. Simplifying plasma chemistry via ILDM

    NASA Astrophysics Data System (ADS)

    Rehman, T.; Kemaneci, E.; Graef, W.; van Dijk, J.

    2016-02-01

    A plasma fluid model containing a large number of chemical species and reactions yields a high computational load. One of the methods to overcome this difficulty is to apply Chemical Reduction Techniques as used in combustion engineering. The chemical reduction technique that we study here is ILDM (Intrinsic Lower Dimensional Manifold). The ILDM method is used to simplify an argon plasma model and then a comparison is made with a CRM (Collisional Radiative Model).

  13. Inertial currents in isotropic plasma

    NASA Technical Reports Server (NTRS)

    Heinemann, M.; Erickson, G. M.; Pontius, D. H., Jr.

    1994-01-01

    The magnetospheric convection electric field contributes to Birkeland currents. The effects of the field are to polarize the plasma by displacing the bounce paths of the ions from those of electrons, to redistribute the pressure so that it is not constant along magnetic field lines, and to enhance the pressure gradient by the gradient of the bulk speed. Changes in the polarization charge during the convection of the plasma are neutralized by electrons in the form of field-aligned currents that close through the ionosphere. The pressure drives field-aligned currents through its gradient in the same manner as in quasi-static plasmas, but with modifications that are important if the bulk speed is of the order of the ion thermal speed; the variations in the pressure along field lines are maintained by a weak parallel potential drop. These effects are described in terms of the field-aligned currents in steady state, isotropic, MHD plasma. Solutions are developed by taking the MHD limit ot two-fluid solutions and illustrated in the special case of Maxwellian plasma for which the temperature is constant along magnetic field lines. The expression for the Birkeland current density is a generalization of Vasyliunas' expression for the field-aligned current density in quasi-static plasma and provides a unifying expression when both pressure gradients and ion inertia operate simultaneously as sources of field-aligned currents. It contains a full account of different aspects of the ion flow (parallel and perpendicular velocity and vorticity) that contribute to the currents. Contributions of ion inertia to field-aligned currents will occur in regions of strong velocity shear, electric field reversal, or large gradients in the parallel velocity or number density, and may be important in the low-latitude boundary layer, plasma sheet boundary layer, and the inner edge region of the plasma sheet.

  14. Analysis of plasma nitrided steels

    NASA Technical Reports Server (NTRS)

    Salik, J.; Ferrante, J.; Honecy, F.; Hoffman, R., Jr.

    1987-01-01

    The analysis of plasma nitrided steels can be divided to two main categories - structural and chemical. Structural analysis can provide information not only on the hardening mechanisms but also on the fundamental processes involved. Chemical analysis can be used to study the kinetics for the nitriding process and its mechanisms. In this paper preliminary results obtained by several techniques of both categories are presented and the applicability of those techniques to the analysis of plasma-nitrided steels is discussed.

  15. Shock Waves in Dusty Plasmas

    NASA Astrophysics Data System (ADS)

    Hammerberg, J. E.; Germann, T. C.; Holian, B. L.

    2002-07-01

    It will soon become possible to create confined dusty plasmas in microgravity environments with particle numbers approaching 106. Very high plasma Gamma's are possible, Gamma>103. Characteristic time and length scales for these systems are of the order 100 msec and 500 mum. Consequently the possibility now exists for observing microscopic dynamics in real time. We present molecular dynamics simulations of such a confined system under shock loading and discuss the nature of the microscopic deformations.

  16. Shock waves in dusty plasmas

    NASA Astrophysics Data System (ADS)

    Hammerberg, J. E.; Germann, T. C.; Holian, B. L.

    2001-06-01

    It will soon become possible to create confined dusty plasmas in zero gravity environments with particle numbers approaching 10^6. Very high plasma Γ's are possible, Γ > 10^3. Time scales for these systems are of the order msec and consequently the possibility now exists for observing microscopic dynamics in real time. We present molecular dynamics simulations of such a confined system under shock loading and discuss the nature of the microscopic deformations.

  17. APPARATUS FOR HEATING A PLASMA

    DOEpatents

    Stix, T.H.

    1962-01-01

    The system contemplates the use of ion cyclotron motions for transferring energy to a plasma immersed in a confining magnetic field such as is found in thermonuclear reactors of the stellarator class. Oppositely directed windings are provided for producing ion-accelerating fields having a time and spatial periodicity and these have the advantage of producing ion cyclotron motions without the development of space charges which preclude the efficient energy transfer to the plasma. (AEC)

  18. Electrorheological Plasma in PK-4

    NASA Astrophysics Data System (ADS)

    Thoma, Markus

    Electrorheological systems are complex fluids which can change their behavior, e.g. viscosity, if an external electric field is applied. In dusty plasmas a similar phenomenon can be observed. Such experiments with the dusty plasma experiment facility PK-4, which will be operated on the ISS starting in 2015, were performed under microgravity in 3 parabolic flight campaigns. The experiments as well as their results will be discussed here.

  19. 21 CFR 866.2160 - Coagulase plasma.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

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  20. 21 CFR 640.60 - Source Plasma.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 7 2010-04-01 2010-04-01 false Source Plasma. 640.60 Section 640.60 Food and... ADDITIONAL STANDARDS FOR HUMAN BLOOD AND BLOOD PRODUCTS Source Plasma § 640.60 Source Plasma. The proper name of the product shall be Source Plasma. The product is defined as the fluid portion of human...

  1. 21 CFR 640.30 - Plasma.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 7 2010-04-01 2010-04-01 false Plasma. 640.30 Section 640.30 Food and Drugs FOOD... STANDARDS FOR HUMAN BLOOD AND BLOOD PRODUCTS Plasma § 640.30 Plasma. (a) Proper name and definition. The proper name of this component is Plasma. The component is defined as: (1) The fluid portion of one...

  2. 21 CFR 640.60 - Source Plasma.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 7 2011-04-01 2010-04-01 true Source Plasma. 640.60 Section 640.60 Food and Drugs... STANDARDS FOR HUMAN BLOOD AND BLOOD PRODUCTS Source Plasma § 640.60 Source Plasma. The proper name of the product shall be Source Plasma. The product is defined as the fluid portion of human blood collected...

  3. 21 CFR 640.30 - Plasma.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 7 2011-04-01 2010-04-01 true Plasma. 640.30 Section 640.30 Food and Drugs FOOD... STANDARDS FOR HUMAN BLOOD AND BLOOD PRODUCTS Plasma § 640.30 Plasma. (a) Proper name and definition. The proper name of this component is Plasma. The component is defined as: (1) The fluid portion of one...

  4. 21 CFR 866.2160 - Coagulase plasma.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Coagulase plasma. 866.2160 Section 866.2160 Food... DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices § 866.2160 Coagulase plasma. (a) Identification. Coagulase plasma is a device that consists of freeze-dried animal or human plasma that...

  5. 21 CFR 866.2160 - Coagulase plasma.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

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  6. 21 CFR 640.60 - Source Plasma.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 7 2012-04-01 2012-04-01 false Source Plasma. 640.60 Section 640.60 Food and... ADDITIONAL STANDARDS FOR HUMAN BLOOD AND BLOOD PRODUCTS Source Plasma § 640.60 Source Plasma. The proper name of the product shall be Source Plasma. The product is defined as the fluid portion of human...

  7. 21 CFR 640.30 - Plasma.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 7 2012-04-01 2012-04-01 false Plasma. 640.30 Section 640.30 Food and Drugs FOOD... STANDARDS FOR HUMAN BLOOD AND BLOOD PRODUCTS Plasma § 640.30 Plasma. (a) Proper name and definition. The proper name of this component is Plasma. The component is defined as: (1) The fluid portion of one...

  8. 21 CFR 640.30 - Plasma.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 7 2013-04-01 2013-04-01 false Plasma. 640.30 Section 640.30 Food and Drugs FOOD... STANDARDS FOR HUMAN BLOOD AND BLOOD PRODUCTS Plasma § 640.30 Plasma. (a) Proper name and definition. The proper name of this component is Plasma. The component is defined as: (1) The fluid portion of one...

  9. 21 CFR 866.2160 - Coagulase plasma.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Coagulase plasma. 866.2160 Section 866.2160 Food... DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices § 866.2160 Coagulase plasma. (a) Identification. Coagulase plasma is a device that consists of freeze-dried animal or human plasma that...

  10. 21 CFR 640.60 - Source Plasma.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 7 2013-04-01 2013-04-01 false Source Plasma. 640.60 Section 640.60 Food and... ADDITIONAL STANDARDS FOR HUMAN BLOOD AND BLOOD PRODUCTS Source Plasma § 640.60 Source Plasma. The proper name of the product shall be Source Plasma. The product is defined as the fluid portion of human...

  11. 21 CFR 640.60 - Source Plasma.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

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  12. 21 CFR 866.2160 - Coagulase plasma.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

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  13. 21 CFR 640.30 - Plasma.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 7 2014-04-01 2014-04-01 false Plasma. 640.30 Section 640.30 Food and Drugs FOOD... STANDARDS FOR HUMAN BLOOD AND BLOOD PRODUCTS Plasma § 640.30 Plasma. (a) Proper name and definition. The proper name of this component is Plasma. The component is defined as: (1) The fluid portion of one...

  14. Recent developments in DBD plasma flow control

    NASA Astrophysics Data System (ADS)

    Wang, Jin-Jun; Choi, Kwing-So; Feng, Li-Hao; Jukes, Timothy N.; Whalley, Richard D.

    2013-10-01

    Flow control using DBD (dielectric-barrier-discharge) plasma actuators is a relatively new, but rapidly expanding area of research. There are a number of review papers available on this subject, but few discuss on their latest developments. The purpose of the present article is to “fill the gap” by reviewing the recent trend of plasma actuator design and to summarise aerodynamic control techniques. Here, we review new plasma actuators, such as plasma synthetic jet actuators, plasma spark jet actuators, three-dimensional plasma actuators and plasma vortex generators, which can induce three-dimensional flows away from the wall. We also review the starting vortex that leads to formation of a plasma wall jet. This is an important subject not only for a better understanding of the flow induced by DBD plasma actuators, but also as a database that can be used to calibrate the numerical models for plasma flow control. Design of DBD plasma actuators to obtain turbulent skin-friction reduction is shown and the modifications to near-wall turbulence structures are summarised. Novel applications of DBD plasma actuators for aerodynamic control are then discussed, including pitch and roll control, plasma jet vectoring, circulation control and plasma flap, showing a potential of DBD plasma actuators for replacing movable, aircraft control surfaces. Finally, vortex shedding control techniques by a number of different plasma actuators are surveyed.

  15. Variability of Plasmas Near Europa

    NASA Astrophysics Data System (ADS)

    Paterson, W. R.; Sittler, E. C.; Cooper, J. F.; Hartle, R. E.; Lipatov, A. S.; Gershman, D. J.

    2013-12-01

    Observations of particles and fields acquired at the orbit of Europa during the Gailileo mission indicate significant variability of the plasma environment there. It is found that the background plasma density can vary by a factor ~10. Potential causes include changes in the production or transport of plasmas from the Io torus, local-time and longitudinal effects, such as systematic changes in the location of plasma-sheet gradients, or inherent variability of the plasma production rate at Europa. Measurements of the energy and angular distributions of the ions provide a capability for distinguishing thermalized torus ions from pickup ions that have recently been produced within a Europa neutral cloud. Thus the relative density of thermal ions and pickup ions is a measure that can provide insight into the cause of the overall variability of the plasma density at Europa's orbit. In this presentation, we provide an overview of the Galileo observations and discuss their significance in relationship with this above-identified ambiguity.

  16. Biogenesis of plasma membrane cholesterol

    SciTech Connect

    Lange, Y.

    1986-05-01

    A striking feature of the molecular organization of eukaryotic cells is the singular enrichment of their plasma membranes in sterols. The authors studies are directed at elucidating the mechanisms underlying this inhomogeneous disposition. Cholesterol oxidase catalyzes the oxidation of plasma membrane cholesterol in intact cells, leaving intracellular cholesterol pools untouched. With this technique, the plasma membrane was shown to contain 95% of the unesterified cholesterol of cultured human fibroblasts. Cholesterol synthesized from (/sup 3/H) acetate moved to the plasma membrane with a half-time of 1 h at 37/sup 0/C. They used equilibrium gradient centrifugation of homogenates of biosynthetically labeled, cholesterol oxidase treated cells to examine the distribution of newly synthesized sterols among intracellular pools. Surprisingly, lanosterol, a major precursor of cholesterol, and intracellular cholesterol both peaked at much lower buoyant density than did 3-hydroxy-3-methylglutaryl-CoA reductase. This suggests that cholesterol biosynthesis is not taken to completion in the endoplasmic reticulum. The cholesterol in the buoyant fraction eventually moved to the plasma membrane. Digitonin treatment increased the density of the newly synthesized cholesterol fractions, indicating that nascent cholesterol in transit is associated with cholesterol-rich membranes. The authors are testing the hypothesis that the pathway of cholesterol biosynthesis is spatially organized in various intracellular membranes such that the sequence of biosynthetic steps both concentrates the sterol and conveys it to the plasma membrane.

  17. EDITORIAL: Focus on Plasma Medicine

    NASA Astrophysics Data System (ADS)

    Morfill, G. E.; Kong, M. G.; Zimmermann, J. L.

    2009-11-01

    'Plasma Healthcare' is an emerging interdisciplinary research topic of rapidly growing importance, exploring considerable opportunities at the interface of plasma physics, chemistry and engineering with life sciences. Some of the scientific discoveries reported so far have already demonstrated clear benefits for healthcare in areas of medicine, food safety, environmental hygiene, and cosmetics. Examples include ongoing studies of prion inactivation, chronic wound treatment and plasma-mediated cancer therapy. Current research ranges from basic physical processes, plasma chemical design, to the interaction of plasmas with (i) eukaryotic (mammalian) cells; (ii) prokaryotic (bacteria) cells, viruses, spores and fungi; (iii) DNA, lipids, proteins and cell membranes; and (iv) living human, animal and plant tissues in the presence of biofluids. Of diverse interests in this new field is the need for hospital disinfection, in particular with respect to the alarming increase in bacterial resistance to antibiotics, the concomitant needs in private practices, nursing homes etc, the applications in personal hygiene—and the enticing possibility to 'design' plasmas as possible pharmaceutical products, employing ionic as well as molecular agents for medical treatment. The 'delivery' of the reactive plasma agents occurs at the gaseous level, which means that there is no need for a carrier medium and access to the treatment surface is optimal. This focus issue provides a close look at the current state of the art in Plasma Medicine with a number of forefront research articles as well as an introductory review. Focus on Plasma Medicine Contents Application of epifluorescence scanning for monitoring the efficacy of protein removal by RF gas-plasma decontamination Helen C Baxter, Patricia R Richardson, Gaynor A Campbell, Valeri I Kovalev, Robert Maier, James S Barton, Anita C Jones, Greg DeLarge, Mark Casey and Robert L Baxter Inactivation factors of spore-forming bacteria using low-pressure microwave plasmas in an N2 and O2 gas mixture M K Singh, A Ogino and M Nagatsu Degradation of adhesion molecules of G361 melanoma cells by a non-thermal atmospheric pressure microplasma H J Lee, C H Shon, Y S Kim, S Kim, G C Kim and M G Kong The acidification of lipid film surfaces by non-thermal DBD at atmospheric pressure in air A Helmke, D Hoffmeister, N Mertens, S Emmert, J Schuette and W Vioel Reduction and degradation of amyloid aggregates by a pulsed radio-frequency cold atmospheric plasma jet D L Bayliss, J L Walsh, G Shama, F Iza and M G Kong The effect of low-temperature plasma on bacteria as observed by repeated AFM imaging René Pompl, Ferdinand Jamitzky, Tetsuji Shimizu, Bernd Steffes, Wolfram Bunk, Hans-Ulrich Schmidt, Matthias Georgi, Katrin Ramrath, Wilhelm Stolz, Robert W Stark, Takuya Urayama, Shuitsu Fujii and Gregor Eugen Morfill Removal and sterilization of biofilms and planktonic bacteria by microwave-induced argon plasma at atmospheric pressure Mi Hee Lee, Bong Joo Park, Soo Chang Jin, Dohyun Kim, Inho Han, Jungsung Kim, Soon O Hyun, Kie-Hyung Chung and Jong-Chul Park Cell permeabilization using a non-thermal plasma M Leduc, D Guay, R L Leask and S Coulombe Physical and biological mechanisms of direct plasma interaction with living tissue Danil Dobrynin, Gregory Fridman, Gary Friedman and Alexander Fridman Nosocomial infections-a new approach towards preventive medicine using plasmas G E Morfill, T Shimizu, B Steffes and H-U Schmidt Generation and transport mechanisms of chemical species by a post-discharge flow for inactivation of bacteria Takehiko Sato, Shiroh Ochiai and Takuya Urayama Low pressure plasma discharges for the sterilization and decontamination of surfaces F Rossi, O Kylián, H Rauscher, M Hasiwa and D Gilliland Contribution of a portable air plasma torch to rapid blood coagulation as a method of preventing bleeding S P Kuo, O Tarasenko, J Chang, S Popovic, C Y Chen, H W Fan, A Scott, M Lahiani, P Alusta, J D Drake and M Nikolic A two-dimensional cold atmospheric plasma jet array for uniform treatment of large-area surfaces for plasma medicine QY Nie, Z Cao, C S Ren, D Z Wang and M G Kong A novel plasma source for sterilization of living tissues E Martines, M Zuin, R Cavazzana, E Gazza, G Serianni, S Spagnolo, M Spolaore, A Leonardi, V Deligianni, P Brun, M Aragona, I Castagliuolo and P Brun Designing plasmas for chronic wound disinfection T Nosenko, T Shimizu and G E Morfill Plasma medicine: an introductory review M G Kong, G Kroesen, G Morfill, T Nosenko, T Shimizu, J van Dijk and J L Zimmermann

  18. Electric field divertor plasma pump

    DOEpatents

    Schaffer, M.J.

    1994-10-04

    An electric field plasma pump includes a toroidal ring bias electrode positioned near the divertor strike point of a poloidal divertor of a tokamak, or similar plasma-confining apparatus. For optimum plasma pumping, the separatrix of the poloidal divertor contacts the ring electrode, which then also acts as a divertor plate. A plenum or other duct near the electrode includes an entrance aperture open to receive electrically-driven plasma. The electrode is insulated laterally with insulators, one of which is positioned opposite the electrode at the entrance aperture. An electric field E is established between the ring electrode and a vacuum vessel wall, with the polarity of the bias applied to the electrode being relative to the vessel wall selected such that the resultant electric field E interacts with the magnetic field B already existing in the tokamak to create an E [times] B/B[sup 2] drift velocity that drives plasma into the entrance aperture. The pumped plasma flow into the entrance aperture is insensitive to variations, intentional or otherwise, of the pump and divertor geometry. Pressure buildups in the plenum or duct connected to the entrance aperture in excess of 10 mtorr are achievable. 11 figs.

  19. Electric field divertor plasma pump

    DOEpatents

    Schaffer, Michael J.

    1994-01-01

    An electric field plasma pump includes a toroidal ring bias electrode (56) positioned near the divertor strike point of a poloidal divertor of a tokamak (20), or similar plasma-confining apparatus. For optimum plasma pumping, the separatrix (40) of the poloidal divertor contacts the ring electrode (56), which then also acts as a divertor plate. A plenum (54) or other duct near the electrode (56) includes an entrance aperture open to receive electrically-driven plasma. The electrode (56) is insulated laterally with insulators (63,64), one of which (64) is positioned opposite the electrode at the entrance aperture. An electric field E is established between the ring electrode (56) and a vacuum vessel wall (22), with the polarity of the bias applied to the electrode being relative to the vessel wall selected such that the resultant electric field E interacts with the magnetic field B already existing in the tokamak to create an E.times.B/B.sup.2 drift velocity that drives plasma into the entrance aperture. The pumped plasma flow into the entrance aperture is insensitive to variations, intentional or otherwise, of the pump and divertor geometry. Pressure buildups in the plenum or duct connected to the entrance aperture in excess of 10 mtorr are achievable.

  20. Plasma chemistry in wire chambers

    SciTech Connect

    Wise, J.

    1990-05-01

    The phenomenology of wire chamber aging is discussed and fundamentals of proportional counters are presented. Free-radical polymerization and plasma polymerization are discussed. The chemistry of wire aging is reviewed. Similarities between wire chamber plasma (>1 atm dc-discharge) and low-pressure rf-discharge plasmas, which have been more widely studied, are suggested. Construction and use of a system to allow study of the plasma reactions occurring in wire chambers is reported. A proportional tube irradiated by an {sup 55}Fe source is used as a model wire chamber. Condensable species in the proportional tube effluent are concentrated in a cryotrap and analyzed by gas chromatography/mass spectrometry. Several different wire chamber gases (methane, argon/methane, ethane, argon/ethane, propane, argon/isobutane) are tested and their reaction products qualitatively identified. For all gases tested except those containing methane, use of hygroscopic filters to remove trace water and oxygen contaminants from the gas resulted in an increase in the average molecular weight of the products, consistent with results from low-pressure rf-discharge plasmas. It is suggested that because water and oxygen inhibit polymer growth in the gas phase that they may also reduce polymer deposition in proportional tubes and therefore retard wire aging processes. Mechanistic implications of the plasma reactions of hydrocarbons with oxygen are suggested. Unresolved issues in this work and proposals for further study are discussed.