| 1. |
- Eriksson, L-G, et al.
(författare)
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Plasma rotation induced by directed waves in the ion-cyclotron range of frequencies
- 2004
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 92:23
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Tidskriftsartikel (refereegranskat)abstract
- Changes of the toroidal plasma rotation induced by directed waves in the ion-cyclotron range of frequencies (ICRF) have been identified experimentally for the first time on the JET tokamak. The momentum carried by the waves is initially absorbed by fast resonating ions, which subsequently transfer it to the bulk plasma. Thus, the results provide evidence for the influence of ICRF heated fast ions on plasma rotation.
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| 2. |
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| 3. |
- Noterdaeme, J. M., et al.
(författare)
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Spatially resolved toroidal plasma rotation with ICRF on JET
- 2003
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 43:4, s. 274-289
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Tidskriftsartikel (refereegranskat)abstract
- Plasmas heated by ICRF only in the JET tokamak show distinct structures in the toroidal rotation profile, with regions where domega/dr > 0 when the minority cyclotron resonance layer is far off-axis. The rotation is dominantly co-current with a clear off-axis maximum. There is only a slight difference between a high-field side (HFS) or a low-field side position of this resonance layer: the off-axis maximum in the rotation profile is modestly higher for the HFS position. This is in contrast to the predictions of theories that rely mainly on the effects arising from ICRF-driven fast ions to account for ICRF-induced plasma rotation. The differences due to the direction of the antenna spectrum (co- or counter-) are small. A more central deposition of the ICRF power in L-mode and operation in H-mode both lead to more centrally peaked profiles, both in the co-direction. Strong MHD modes brake the rotation and lead to overall flat rotation profiles.
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| 4. |
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| 5. |
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| 6. |
- Pamela, J., et al.
(författare)
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Overview of results and possibilities for fast particle research on JET
- 2002
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 42:8, s. 1014-1028
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Tidskriftsartikel (refereegranskat)abstract
- The large physical size of the JET tokamak, its heating systems and diagnostics, and its capability to operate with full deuterium-tritium (D-T) plasmas, including high-power tritium neutral beam injection (NBI), give it unique possibilities in fast particle research in fusion plasmas. These have already been used to generate significant (2-3 MW level) power in fusion a-particles in the 1997 D-T campaign. Recent JET experiments have concentrated on two important scenarios of relevance to next-step tokamak devices: the ELMy H-mode plasmas and plasmas with strong internal transport barriers (ITBs). The achieved progress will help in preparation for a possible second D-T experiment on JET. Fast particle studies have also been carried out recently using ion cyclotron resonance heating (ICRH)-accelerated particles and external-excitation methods to study Alfven eigenmodes (AEs). Looking towards the future, the capability of JET will be enhanced by upgrades to the NBI system, ICRH system and various diagnostics. Results of the first JET D-T experiment (DTE1) form a basis on which to elaborate a second D-T experiment (DTE2) which could be proposed after these enhancements. The alpha-physics part of this programme would be divided between the investigation of alpha-particle confinement, heating and loss processes in the 'integrated scenarios' (where the discharge is as close as possible to an ITER-relevant scenario), and dedicated 'alpha-physics' experiments, with specially prepared plasmas. In ELMy H-mode plasmas the fusion performance could roach Q(=P-fusion/P-input) of similar to0.33 at the highest combined heating powers, corresponding to similar to 6x10(-4), allowing a test of the margins of TAE stability in quasi-steady-state conditions. The integrated-scenario fast particle programme could concentrate on the instabilities and heating in plasma regimes with strong steady-state ITBs, with expected Q values similar to0.58 and similar to2x10(-3), demonstrating the compatibility of these operating scenarios with alpha-effects. Excitation of TAEs by alpha-particles in the plasma core could also be studied in such integrated scenarios. An issue which will receive attention is the confinement of MeV energy ions in the centre of ITB plasmas with strongly reversed shear, where the low current density in the centre may lead to the alpha-particles entering loss orbits. In preparation for a D-T campaign, studies of triton burn-up in deuterium ITB plasmas will begin in the 2002 experimental campaigns. Special 'afterglow' experiments to measure TAEs after the termination of the (stabilizing) NBI have already been explored in JET deuterium ITB scenarios and would be planned for DTE2. It is intended to develop special versions of ITB plasmas with dominant ion heating which would maximize the sensitivity to degradation of alpha-heating effects.
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| 7. |
- Testa, D., et al.
(författare)
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Alfven mode stability and wave-particle interaction in the JET tokamak : prospects for scenario development and control schemes in burning plasma experiments
- 2004
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Ingår i: Plasma Physics and Controlled Fusion. - 0741-3335 .- 1361-6587. ; 46:7, s. S59-S79
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated the effect of different ion cyclotron resonance frequency (ICRF) heating schemes, of error field modes, of the plasma shape and edge magnetic shear, and of the ion delB drift direction on the stability of Alfven eigenmodes (AEs). The use of multi-frequency or 2nd harmonic minority ICRF heating at high plasma density gives rise to a lower fast ion pressure gradient in the plasma core and to a reduced mode activity in the Alfven frequency range. Externally excited low-amplitude error fields lead to a much larger AE instability threshold, which we attribute to a moderate radial redistribution of the fast ions. The edge plasma shape has a clear stabilizing effect on high-n, radially localized AEs. The damping rate of n = 1 toroidal AEs is a factor 3 higher when the ion VB drift is directed towards the divertor. These results represent a useful step towards the extrapolation of current scenarios to the inclusion of fusion-born alpha particles in ITER, with possible application for feedback control schemes for the various ITER operating regimes.
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| 8. |
- Czene, S, et al.
(författare)
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DNA fragmentation and morphological changes in apoptotic human lymphocytes
- 2002
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Ingår i: Biochemical and Biophysical Research Communications - BBRC. - 0006-291X .- 1090-2104. ; 294:4, s. 872-878
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Tidskriftsartikel (refereegranskat)abstract
- Cell suspensions enriched in cells at various stages of apoptosis were obtained by separation of irradiated human peripheral blood lymphocytes on density gradients at different post-irradiation times. The state of DNA fragmentation in the cells was determined by comet assay and pulsed field gel electrophoresis. The morphologically distinguishable features of apoptosis such as chromatin condensation and cell shrinkage correlated with discrete stages of DNA fragmentation. It was found that greater than or equal to50kbp fragmentation of DNA occurs already in cells of normal density whereas the subsequent DNA fragmentation onto fragments <50 kbp occurs in parallel with cell shrinkage and simultaneous increase in cell density. The observed stages of DNA fragmentation seem to be separated in time that could allow in case of abortive apoptosis formation of chromosomal aberrations.
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| 9. |
- Magnusson, Per, et al.
(författare)
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Monoclonal antibodies against tissue-nonspecific alkaline phosphatase : Report of the ISOBM TD9 Workshop
- 2002
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Ingår i: Tumor Biology. - : Springer Science and Business Media LLC. - 1010-4283 .- 1423-0380. ; 23:4, s. 228-248
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Tidskriftsartikel (refereegranskat)abstract
- Nineteen monoclonal antibodies (MAbs) against tissue-nonspecific (liver/bone/kidney) alkaline phosphatase (TNALP) were investigated in the ISOBM TD-9 Workshop. These MAbs were generated with antigens obtained from human bone tissue (n = 9), human osteosarcoma cell lines (SaOS-2 and TPX, n = 7) and human liver tissue (n = 3). The evaluation included the following antigen forms: (a) commercially available preparations of human bone ALP (BALP) and liver ALP (LALP), (b) human BALP isoforms, B/I, B1 and B2, and (c) soluble secreted epitope-tagged recombinant human TNALP (setTNALP) expressed in COS-1, osteosarcoma (SaOS-2) and hepatoma (Huh2) cell lines. In addition, 16 TNALP mutant cDNAs corresponding to a wide spectrum of reported hypophosphatasia mutations were used in an attempt to map specific immunoreactive epitopes on the surface of the TNALP molecule. The TD-9 MAbs were evaluated by immunoradiometric (IRMA) assays, cross-inhibition and different enzyme immunoassay designs. No indications of explicit tissue discriminatory immunoreactivities of the investigated MAbs against TNALP were found. However, certain IRMA combinations of MAbs increased the specificity of BALP measurements. All MAbs bound to the three BALP isoforms B/I, B1 and B2, but none of the investigated MAbs were specific for any of the isoforms. Significant differences were, however, found in immunoreactivity between these isoforms, with cross-reactivities ranging from 21 to 109% between the two major BALP isoforms B1 and B2. Desialylation with neuraminidase significantly increased the MAb affinity for the BALP isoforms B/I, B1 and B2, and also decreased the observed differences in cross-reactivity between these isoforms. We suggest, therefore, that the MAb affinity is dependent on the amount/number of terminal sialic acid residues located at the five putative N-glycosylation sites. Based on the overall results, we present a putative three-dimensional model of the TNALP molecule with positioning of the four major antigenic domains (designated A-D) of the investigated MAbs. The TNALP molecule is depicted as a homodimer, hence most, but not necessarily all, epitopes are displayed twice. The antigenic domains were positioned with the following assumptions: domain A was positioned close to the active site since most of these MAbs interfered with the catalytic activity. Interestingly, both MAbs included in the commercial BALP kits were grouped with domain A. Moreover, 4 of the 5 putative N-glycosylation sites (with terminal sialic acid residues) are located within, or with close proximity to, domain A. Domain B was localized at the top flexible loop (crown domain) of the TNALP molecule. Domain C was clearly defined by the IRMA assay combinations and by site-directed mutants of TNALP to be close to residue E281, which is located near the fourth metal binding site, likely to be occupied by a calcium ion. Domain D was positioned close to residues A115, A162 and E174, but this domain was also close to the GPI anchor site. In conclusion, none of the 19 investigated TD-9 MAbs were entirely specific for BALP or LALP, thus indicating that all MAbs bind mainly to epitopes on the common protein core of BALP and LALP and/or common glycosylated epitopes. However, some MAbs (either single or in combination with other MAbs) work sufficiently well to measure BALP when the assayed samples do not contain elevated levels of LALP. Copyright © 2002 S. Karger AG, Basel.
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| 10. |
- Schlatter, C, et al.
(författare)
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Error estimation and parameter dependence of the calculation of the fast ion distribution function, temperature, and density using data from the KF1 high energy neutral particle analyzer on Joint European Torus
- 2004
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 75:10, s. 3547-3549
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Tidskriftsartikel (refereegranskat)abstract
- Joint European Torus high energy neutral particle analyzer measures the flux of fast neutrals originating from the plasma core. From this data, the fast ion distribution function f(i)(fast), temperature T-i,perpendicular to(fast), and density n(i)(fast) are derived using knowledge of various plasma parameters and of the cross section for the required atomic processes. In this article, a systematic sensitivity study of the effect of uncertainties in these quantities on the evaluation of the neutral particle analyzer f(i)(fast), T-i,perpendicular to(fast), and n(i)(fast) is reported. The dominant parameter affecting n(i)(fast) is the impurity confinement time and therefore a reasonable estimate of this quantity is necessary to reduce the uncertainties in n(i)(fast) below 50%. On the other hand, T-i,perpendicular to(fast) is much less sensitive and can certainly be provided with an accuracy of better than 10%.
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