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| 2. |
- Lloyd, B., et al.
(author)
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Overview of physics results from MAST
- 2011
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In: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 51:9, s. 094013 (paper no.)-
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Journal article (peer-reviewed)abstract
- Major developments on the Mega Amp Spherical Tokamak (MAST) have enabled important advances in support of ITER and the physics basis of a spherical tokamak (ST) based component test facility (CTF), as well as providing new insight into underlying tokamak physics. For example, L-H transition studies benefit from high spatial and temporal resolution measurements of pedestal profile evolution (temperature, density and radial electric field) and in support of pedestal stability studies the edge current density profile has been inferred from motional Stark effect measurements. The influence of the q-profile and E x B flow shear on transport has been studied in MAST and equilibrium flow shear has been included in gyro-kinetic codes, improving comparisons with the experimental data. H-modes exhibit a weaker q and stronger collisionality dependence of heat diffusivity than implied by IPB98(gamma, 2) scaling, which may have important implications for the design of an ST-based CTF. ELM mitigation, an important issue for ITER, has been demonstrated by applying resonant magnetic perturbations (RMPs) using both internal and external coils, but full stabilization of type-I ELMs has not been observed. Modelling shows the importance of including the plasma response to the RMP fields. MAST plasmas with q > 1 and weak central magnetic shear regularly exhibit a long-lived saturated ideal internal mode. Measured plasma braking in the presence of this mode compares well with neo-classical toroidal viscosity theory. In support of basic physics understanding, high resolution Thomson scattering measurements are providing new insight into sawtooth crash dynamics and neo-classical tearing mode critical island widths. Retarding field analyser measurements show elevated ion temperatures in the scrape-off layer of L-mode plasmas and, in the presence of type-I ELMs, ions with energy greater than 500 eV are detected 20 cm outside the separatrix. Disruption mitigation by massive gas injection has reduced divertor heat loads by up to 70%.
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| 3. |
- Sharapov, S.E., et al.
(author)
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Energetic particle instabilities in fusion plasmas
- 2013
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In: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 53:10, s. 104022-
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Journal article (peer-reviewed)abstract
- Remarkable progress has been made in diagnosing energetic particle instabilities on present-day machines and in establishing a theoretical framework for describing them. This overview describes the much improved diagnostics of Alfvén instabilities and modelling tools developed world-wide, and discusses progress in interpreting the observed phenomena. A multi-machine comparison is presented giving information on the performance of both diagnostics and modelling tools for different plasma conditions outlining expectations for ITER based on our present knowledge.
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| 4. |
- Anderson, D., et al.
(author)
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A variational approach to spherical aberrations in the thermal-wave model for beam dynamics in charged particle accelerators
- 1998
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In: Physica Scripta. - : Institute of Physics Publishing. - 0031-8949 .- 1402-4896. ; 58:6, s. 608-612
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Journal article (peer-reviewed)abstract
- A direct variational approach involving trial functions and Ritz optimization, which has previously been found very useful in nonlinear optics, is applied to analyze the effects of spherical aberrations on the focusing properties of charged particle beams in particle colliders. As compared to conventional perturbation theory, the variational approach provides a simple and physically clear analysis. Explicit expressions are given for the transverse particle beam density, the spot size, and the luminosity reduction factor at the interaction point, in good agreement with the perturbative results.
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| 5. |
- Anderson, D., et al.
(author)
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Modulational instabilities within the thermal wave model description of high energy charged particle beam dynamics
- 1999
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In: Physics Letters A. - : Elsevier. - 0375-9601 .- 1873-2429. ; 258:4-6, s. 244-248
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Journal article (peer-reviewed)abstract
- Within the thermal wave model (TWM) description, an investigation was made of the longitudinal instability properties of a coasting high energy charged particle beam, where the interaction between the beam and its surroundings is characterized in terms of a complex impedance. The analysis is shown to correctly reproduce the characteristic features of the coherent instability as obtained previously by conventional techniques based on the Vlasov equation for the beam distribution. The results further validate the TWM approach as a consistent alternative description for analyzing the dynamics of high energy charged particle beams.
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| 6. |
- Armiens, C., et al.
(author)
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Detection of multipaction using AM signals
- 2005
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In: Proc. 5th International Workshop on Multipactor, Corona and Passive Intermodulation, September 12 – 14, 2005, ESTEC, Noordwijk, The Netherlands, In: Space RF Hardware (MULCOPIM' 2005). ; , s. 143-149
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Conference paper (peer-reviewed)
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| 7. |
- Ding, R., et al.
(author)
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Gold-modified paper as microfluidic substrates with reduced biofouling in potentiometric ion sensing
- 2021
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In: Sensors and actuators. B, Chemical. - : Elsevier. - 0925-4005 .- 1873-3077. ; 344
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Journal article (peer-reviewed)abstract
- Microfluidic sampling media based on paper and its modifications with either gold nanoparticles or sputtered gold were evaluated for potentiometric determination of Na+, K+, and Cl– ions in clinically relevant samples. The measurements were conducted in comparison to other commonly considered microfluidic substrates, i.e. sponge, polyester textile, and polyamide textile. Ion determination was done by using solid-contact ion-selective electrodes based on plasticized PVC membranes for Na+, K+, and Cl– ions and utilizing PEDOT(PSS) or PEDOT(Cl) as the ion-to-electron transducer. The solid-contact ion-selective electrodes and a solid-state reference electrode were placed directly on the substrate into which the sample solution was wicked. Transport of bovine serum albumin (BSA) through the paper substrate was studied by ellipsometry. Modification of the paper substrates by gold nanoparticles (AuNPs) was found to slow down the transport of BSA through the paper, when compared with unmodified paper substrates and when compared with all the other alternative sampling matrices studied. The retention of BSA obtained with AuNP-modified paper substrates significantly improved the accuracy of the potentiometric ion determinations in sweat, saliva, artificial tears, and artificial serum. The potentiometric results were validated by inductively coupled plasma optical emission spectrometry (ICP-OES) and ion chromatography (IC). The study indicates that modification of paper by AuNPs is a feasible approach to reduce biofouling of sensors that are used in the paper-based analysis of clinically relevant samples. © 2021 Elsevier B.V.
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| 8. |
- Fedele, R., et al.
(author)
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How the coherent instabilities of an intense high energy charged particle beam in the presence of nonlocal effects can be explained within the context of the Madelung fluid description
- 2006
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In: European Physical Journal B. - : Springer Science and Business Media LLC. - 1434-6028 .- 1434-6036. ; B49:3, s. 275-281
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Journal article (peer-reviewed)abstract
- A hydrodynamical description of coherent instabilities that take place in the longitudinal dynamics of a charged-particle coasting beam in a high-energy accelerating machine is presented. This is done within the framework of the Madelung fluid picture provided by the Thermal Wave Model. The well known coherent instability charts in the complex plane of the longitudinal coupling impedance for monochromatic beams are recovered. The results are also interpreted in terms of the deterministic approach to modulational instability analysis usually given for monochromatic large amplitude wave propagation governed by the nonlinear Schrodinger equation. The instability analysis is then extended to a non-monochromatic coasting beam with a given thermal equilibrium distribution, thought of as a statistical ensemble of monochromatic incoherent coasting beams ("white" beam). In this hydrodynamical framework, the phenomenon of Landau damping is predicted without using any kinetic equation governing the phase space evolution of the system.
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| 9. |
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| 10. |
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| 11. |
- Maslowski, P., et al.
(author)
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Optical frequency comb spectroscopy for gas metrology and trace gas detection
- 2017
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In: 2017 Conference on lasers and electro-optics (CLEO). - : IEEE. - 9781943580279 - 9781538620199
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Conference paper (peer-reviewed)abstract
- We report recent developments of comb-based broadband absorption spectroscopy. The comb-line resolving approaches and Fourier transform spectroscopy with sub-nominal resolution overcome the frequency resolution limits of conventional techniques. Advantages for various applications will be discussed.
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| 12. |
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| 13. |
- Puech, J., et al.
(author)
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Summary of Research Activities on Multipactor phenomenon with dielectric materials within INTAS project
- 2005
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In: Proc. 5th International Workshop on Multipactor, Corona and Passive Intermodulation, September 12 – 14, 2005, ESTEC, Noordwijk, The Netherlands, In: Space RF Hardware (MULCOPIM' 2005). ; , s. 161-167
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Conference paper (peer-reviewed)
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| 14. |
- Semenov, V., et al.
(author)
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Analytical description of the multipactor inside narrow waveguide iris
- 2008
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In: Proceedings of the 7th International Workshop “Strong microwaves: Sources and Applications, Nizhny Novgorod, Russia, July 27 – Aug. 2, 2008, Institute of Applied Physics, Russian Academy of Sciences. ; :paper T42, s. 144-
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Conference paper (peer-reviewed)
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| 15. |
- Semenov, V., et al.
(author)
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Multipactor in QPSK-modulated carriers
- 2008
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In: MULCOPIM08, 23-26 September 2008, Valencia, Spain, European Space Agency, Nordwijk, The Netherlands, available on CD. ; , s. paper MP2-2
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Conference paper (peer-reviewed)
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| 16. |
- Semenov, V., et al.
(author)
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Multipactor inside a Coaxial Line
- 2005
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In: Proc. 5th International Workshop on Multipactor, Corona and Passive Intermodulation, September 12 – 14, 2005, ESTEC Noordwijk, The Netherlands, In: Space RF Hardware (MULCOPIM' 2005). ; , s. 259-265
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Conference paper (peer-reviewed)
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| 17. |
- Semenov, V., et al.
(author)
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Study of multipactor in waveguide irises
- 2008
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In: MULCOPIM08, 23-26 September 2008, Valencia, Spain, European Space Agency, Nordwijk, The Netherlands, available on CD. ; , s. paper MP-3-3-
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Conference paper (peer-reviewed)
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| 18. |
- Udiljak, R., et al.
(author)
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Microwave breakdown in low pressure gas
- 2005
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In: Proc. 5th International Workshop on Multipactor, Corona and Passive Intermodulation , September 12 – 14, 2005, ESTEC Noordwijk, The Netherlands, In: Space RF Hardware (MULCOPIM' 2005). ; , s. 259-265
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Conference paper (peer-reviewed)
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| 19. |
- Zalesny, J., et al.
(author)
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Mechanical analogy of the nonlinear dynamics of a driven unstable mode near marginal stability
- 2009
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In: Physics of Plasmas. - : AIP Publishing. - 1089-7674 .- 1070-664X. ; 16:2, s. 022110-
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Journal article (peer-reviewed)abstract
- The universal integrodifferential model equation derived by Berk [Phys. Rev. Lett. 76, 1256 (1996)] for studying the nonlinear evolution of unstable modes driven by kinetic wave particle resonances near the instability threshold is reduced to a differential equation and next as a further simplification to a nonlinear oscillator equation. This mechanical analogy properly reproduces most of the essential physics of the system and allows an understanding of the qualitative features of the theory of Berk.
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