| 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. |
- Mantsinen, M. J., et al.
(författare)
-
Localized bulk electron heating with ICRF mode conversion in the JET tokamak
- 2004
-
Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 44:1, s. 33-46
-
Tidskriftsartikel (refereegranskat)abstract
- Ion cyclotron resonance frequencies (ICRF) mode conversion has been developed for localized on-axis and off-axis bulk electron heating on the JET tokamak. The fast magnetosonic waves launched from the low-field side ICRF antennas are mode-converted to short-wavelength waves on the high-field side of the He-3 ion cyclotron resonance layer in D and He-4 plasmas and subsequently damped on the bulk electrons. The resulting electron power deposition, measured using ICRF power modulation, is narrow with a typical full-width at half-maximum of approximate to30 cm (i.e. about 30% of the minor radius) and the total deposited power to electrons comprises at least up to 80% of the applied ICRF power. The ICRF mode conversion power deposition has been kept constant using He-3 bleed throughout the ICRF phase with a typical duration of 4-6 s, i.e. 15-40 energy confinement times. Using waves propagating in the counter-current direction minimizes competing ion damping in the presence of co-injected deuterium beam ions.
|
|
| 3. |
- Mattioli, M, et al.
(författare)
-
Experimental and simulated M-shell nickel spectra in the 14.4-18.0 nm region from magnetic fusion devices
- 2004
-
Ingår i: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 37:1, s. 13-40
-
Tidskriftsartikel (refereegranskat)abstract
- Experimental M-shell nickel spectra in the 14.4-16.5 nm region from the JET tokamak (from both divertor and limiter configurations) and from the reversed field pinch RFX have been simulated. These spectra include lines from five ionization states, namely from K-like N-i9+ to P-like Ni13+ ions. For the JET limiter configuration the spectrum upper wavelength limit was higher (18.0 nm) and lines from Si-like Ni14+ ions were also observed. Collisional-radiative (CR) models have been built for these six Ni ions, considering electron collisional excitation and radiative decay as the main populating processes for the excited states. These models give photon emission coefficients (PECs) for the emitted tines at electron density (n(e)) and temperature (T-e) values corresponding to the experimental situations. Impurity modelling is performed using a 1D impurity transport code, calculating the steady state radial distribution of the Ni ions. The Ni line brightnesses are evaluated in a post-processing subroutine and simulated spectra are obtained. The spectrum from a single ion, in the absence of blendings, depends only on the T-e and n(e) values in the emitting shell of the ionization state considered. On the other hand, the superposition of these spectra depends on the experimental conditions, as a consequence of the fact that the ion charge distribution depends not only on the radial profiles of T-e and n(e) but also on the chosen ionization and recombination rate coefficients and on the radial profiles of the impurity transport coefficients in the region of the emitting shells. Since the aim of the paper is the investigation of the atomic physics of the M-shell ions, the section discussing the plasma physics phenomena is purposely limited. For each experimental spectrum a few simulations are presented, since a unique choice has not been found by selecting the input parameters of the transport code. The effect of the T-e and n(e) values on the emitting shells as well as the influence of line blendings on the single-ionization-degree spectra are stressed. These, in turn, are then compared with the predictions. For the n(e) range considered the PECs are practically independent of n(e). The T-e dependence is much reduced due to the fact that the spectral fits performed are actually comparisons of line ratios. The agreement found between experimental and simulated single-ionization-degree spectra gives confidence in the atomic data used in the CR models.
|
|
| 4. |
- 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.
|
|
| 5. |
- Neuzil, J., et al.
(författare)
-
Induction of cancer cell apoptosis by a-tocopheryl succinate : Molecular pathways and structural requirements
- 2001
-
Ingår i: The FASEB Journal. - : Wiley. - 0892-6638 .- 1530-6860. ; 15:2, s. 403-415
-
Tidskriftsartikel (refereegranskat)abstract
- The vitamin E analog a-tocopheryl succinate (a-TOS) can induce apoptosis. We show that the proapoptotic activity of a-TOS in hematopoietic and cancer cell lines involves inhibition of protein kinase C (PKC), since phorbol myristyl acetate prevented a-TOS-triggered apoptosis. More selective effectors indicated that a-TOS reduced PKCa isotype activity by increasing protein phosphatase 2A (PP2A) activity. The role of PKCa inhibition in a-TOS-induced apoptosis was confirmed using antisense oligonucleotides or PKCa overexpression. Gain- or loss-of-function bcl-2 mutants implied modulation of bcl-2 activity by PKC/PP2A as a mitochondrial target of a-TOS-induced proapoptotic signals. Structural analogs revealed that a-tocopheryl and succinyl moieties are both required for maximizing these effects. In mice with colon cancer xenografts, a-TOS suppressed tumor growth by 80%. This epitomizes cancer cell killing by a pharmacologically relevant compound without known side effects.
|
|
| 6. |
- Coffey, M, et al.
(författare)
-
Revised European core curriculum for RTs
- 2004
-
Ingår i: Radiotherapy and Oncology. - : Elsevier BV. - 1879-0887 .- 0167-8140. ; 70:2, s. 137-158
-
Forskningsöversikt (refereegranskat)abstract
- Aim: To update the first version of the European core curriculum to reflect many developments in radiotherapy and educational philosophy that have taken place in the interim period. Materials and methods: The first version of the European core curriculum was reviewed by the Steering Group together with current education programmes from the various member states and taking into account the developments and changes that have taken place in radiotherapy. From these initial meetings, a working document and provisional timetable were prepared, Given the diversity of the existing programmes, the language difficulties and lack of national curricula it was agreed that a representative from both the clinical and academic areas endorsed by their national professional body would be identified for each country. These participants were then invited to participate in two workshops and the working document and timetable were circulated. Two workshops were held and a final draft document was circulated to the professional bodies and other interested groups. Results: The revised European Core Curriculum for RTTs was endorsed by the participants of the workshops representing academic and clinical areas of all the member states and was welcomed by the wider circulation. Compared to the first version the revised curriculum describes the background underpinning the practice of radiation therapy and the variation across the member states, issues of staffing, educational philosophy, certification level, legislation governing recognition of qualifications and a core syllabus. Conclusion: The revised core curriculum is an important step in the progress of professional recognition for RTTs, towards harmonisation of education programmes in Europe and meeting the aim of best practice and equality of care for all patients receiving radiotherapy. Responsibility for developing education programmes from the curriculum will rest with the local and/or national education bodies and authorities. (C) 2003 Elsevier Ireland Ltd. All rights reserved.
|
|
| 7. |
|
|
