| 1. |
- Ongena, J., et al.
(författare)
-
Recent progress on JET towards the ITER reference mode of operation at high density
- 2001
-
Ingår i: Plasma Physics and Controlled Fusion. - 0741-3335 .- 1361-6587. ; 43, s. A11-A30
-
Tidskriftsartikel (refereegranskat)abstract
- Recent progress towards obtaining high density and high confinement in JET as required for the ITER reference scenario at Q = 10 is summarized. Plasmas with simultaneous confinement H-98(y.2) = 1 and densities up to n/n(Gw) similar to 1 are now routinely obtained. This has been possible (i) by using plasmas at high (delta similar to 0.5) and medium (delta similar to 0.3-0.4) triangularity with sufficient heating power to maintain Type I ELMs, (ii) with impurity seeded plasmas at high (delta similar to 0.5) and low (delta less than or equal to 0.2) triangularity, (iii) with an optimized pellet injection sequence, maintaining the energy confinement and raising the density, and (iv) by carefully tuning the gas puff rate leading to plasmas with peaked density profiles and good confinement at long time scales. These high performance discharges exhibit Type I ELMs, with a new and more favourable behaviour observed at high densities, requiring further studies. Techniques for a possible mitigation of these ELMs are discussed, and first promising results are obtained with impurity seeding in discharges at high triangularity. Scaling studies using the new data of this year show a strong dependence of confinement on upper triangularity, density and proximity to the Greenwald limit. Observed MHD instabilities and methods to avoid these in high density and high confinement plasmas are discussed.
|
|
| 2. |
- McDonald, C., et al.
(författare)
-
ELMy H-modes in JET helium-4 plasmas
- 2004
-
Ingår i: Plasma Physics and Controlled Fusion. - : IOP Publishing. - 0741-3335 .- 1361-6587. ; 46:3, s. 519-534
-
Tidskriftsartikel (refereegranskat)abstract
- ELMy H-modes in helium-4 plasmas provide valuable information on ELMy H-mode physics as well as a possible early low activation operational phase for next-step tokamaks, such as ITER. With this in mind, a series of helium-4 H-mode experiments were performed on JET with pure helium-4 NBI auxiliary heating (up to 12 MW). A set of ELMy H-mode plasmas were produced, in both the Type I ELM regime and a second regime, which showed characteristics similar to the deuterium Type III regime, but with a reverse ELM frequency dependence on power. Sawteeth were also observed, and had similar behaviour to those seen in deuterium. Compared with deuterium plasmas, Type I ELMy H-mode confinement is seen to be 28 +/- 6% poorer in helium-4 plasmas and the L-H power threshold 42 +/- 10% larger. This is the opposite of the behaviour predicted by experimental isotope mass scalings from hydrogenic plasmas.Comparison with a wider hydrogenic database, enables the effects of isotopic charge and mass to be studied independently.
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
- Forsum, Urban, et al.
(författare)
-
An international study of the inter-observer variation between the interpretations of vaginal smear criteria of Bacterial Vaginosis
- 2002
-
Ingår i: APMIS. - : Wiley. - 1600-0463 .- 0903-4641. ; 110:11, s. 811-818
-
Tidskriftsartikel (refereegranskat)abstract
- An international workshop on vaginal smear-based diagnosis of bacterial vaginosis was organized where 13 investigators scoring 258 slides with smears from vaginal fluid. Interobserver reproducibility of interpretations of Nugent scores, Hay/Ison scores and wet smear scores for the diagnosis of bacterial vaginosis was shown to be high. Detailed analysis of individual scoring results however indicated that basic standards of quality control to ensure robust individual readings of slides must be adhered to.
|
|
| 6. |
- Hellgren, A-C, et al.
(författare)
-
New techniques for determining the extent of crosslinking in coatings
- 2001
-
Ingår i: Progress in organic coatings. - 0300-9440 .- 1873-331X. ; 43, s. 85-98
-
Tidskriftsartikel (refereegranskat)abstract
- Crosslinking reactions in latex and alkyd systems offer an attractive way to achieve film formation at low temperatures while also achieving a final hard coating. There is a strong need for techniques to characterise the extent of crosslinking as a function of time and depth in this type of coating. Here magnetic resonance imaging (MRI) (using a magnet specifically designed for coatings) and a quartz crystal microbalance with energy dissipation are both used as non-invasive techniques for this purpose. The crosslinking in alkyd films containing a cobalt drier is found to be non-uniform with depth. In a latex, crosslinking depth profiles are likewise non-uniform, most likely as a result of oxygen inhibition of the initiator
|
|
| 7. |
- Valovic, M., et al.
(författare)
-
Density peaking in low collisionality ELMy H-mode in JET
- 2004
-
Ingår i: Plasma Physics and Controlled Fusion. - : IOP Publishing. - 0741-3335 .- 1361-6587. ; 46:12, s. 1877-1889
-
Tidskriftsartikel (refereegranskat)abstract
- Low collisionality, low particle source. ELMy H-modes (type-III) with sawteeth are produced in JET in order to address the question of density profile evolution in the reference q(95) = 3 ITER scenario. The paper focuses on particle transport in the core zone around the mid-radius. The pedestal region including ELMs and the region affected by sawteeth are not considered. By replacing a significant part of the neutral beam heating by RF power the beam particle flux at mid-radius has been reduced to Gamma(Beam)/n(e) = 0.07 m s(-1). The additional flux due to wall neutrals is estimated as Gamma(Wall)/n(e) = 0.12 m s(-1). Density profiles are found to be modestly peaked under these conditions with a relative density difference of Deltan/(n) = 0.23 across the zone not affected by sawteeth and ELMs. In a region around the mid-radius the ratio of effective particle diffusivity to electron thermal diffusivity is found to be D-e,D-eff/chi(e) approximate to 0.2, which might indicate an anomalous pinch provided the particle diffusivity D-e is sufficiently lame. The measured values of D-e,D-eff/chi(e) are at the lower end of the range used in ITER models.
|
|
| 8. |
- Wallin, M, et al.
(författare)
-
Depth profiles of polymer mobility during the film formation of a latex dispersion undergoing photoinitiated cross-linking
- 2000
-
Ingår i: Macromolecules. - 0024-9297 .- 1520-5835. ; 33, s. 8443-8452
-
Tidskriftsartikel (refereegranskat)abstract
- The first use of one-dimensional magnetic resonance imaging (MRI) to provide information on concentration and molecular mobility (as revealed by the spin-spin relaxation time, T2) as a function of depth into cross-linking latex coatings during their film formation is reported. These materials are of interest because they provide hard, chemically resistant coatings and because, being waterborne, they do not release organic solvents into the atmosphere. MRI profiles, with a pixel resolution of 9 m, are obtained at regular time intervals from a poly(vinyl acetate-co-ethylene) latex dispersion containing a difunctional cross-linker and a photoinitiator. In this complete formulation, MRI reveals that the rate of cross-linking is fastest in the middle regions of the coating. This result is explained by considering the combined effects of light scattering in the turbid latex, the inhibition of the free-radical cross-linking reaction by initial molecular oxygen, and the further ingress of oxygen from the atmosphere. A numerical model, using measured and known parameters, predicts MRI profiles that are in good qualitative agreement with those found experimentally.
|
|
