| 1. |
- Johnson, Thomas, et al.
(författare)
-
Numerical Modelling of Ripple Induced Transport
- 2006
-
Ingår i: Proceedings of the 33rd EPS Conference on Plasma Physics. - 9781622763337 ; , s. 408-411
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The ASCOT code has been used to analyse transport and calculate the thermal conductivity in plasmas with toroidal field ripple. The scaling of the thermal conductivity with dimensionless plasma parameters is similar to transport in the ripple plateau regime [1]. The ripple in machines with toroidal field coils similar to those in JET and JT-60U are quite different; while the maximum ripple is larger with 16 JET coils, the ripple at the X-point is larger with the JT-60U coils. The results are that the heat conductivity is similar in the two plasmas, while the particle losses are higher with the JT-60U coils.
|
|
| 2. |
- Lonnroth, J. S., et al.
(författare)
-
Effects of ripple-induced ion thermal transport on H-mode plasma performance
- 2007
-
Ingår i: Plasma Physics and Controlled Fusion. - : IOP Publishing. - 0741-3335 .- 1361-6587. ; 49:3, s. 273-295
-
Tidskriftsartikel (refereegranskat)abstract
- A recent series of dimensionless pedestal identity experiments at JET and JT-60U failed to produce a match in the dimensional pedestal parameters and edge-localized mode (ELM) frequency despite a good match in the main dimensionless plasma parameters. This paper describes the progress made in understanding these experimental results. First, it is investigated whether differences in the magnetohydrodynamic stability of the pedestal, including those potentially arising from the 10% difference in the aspect ratio between the two tokamaks, can explain the results. The potential effects of differences in plasma rotation between the two machines are also examined. Given the result that these mechanisms fail to explain the experimental observations and the fact that JT-60U features considerably stronger toroidal magnetic field ripple than JET, the bulk of the paper, however, discusses the effects of ripple losses. The analysis shows that ripple losses of thermal ions can affect H-mode plasma performance very sensitively. Orbit-following simulations indicate that losses due to diffusive transport give rise to a wide radial distribution of enhanced ion thermal transport, whereas non-diffusive losses have a very edge-localized distribution. In predictive transport simulations with an energy sink term in the continuity equation for the ion pressure representing non-diffusive losses, reduced performance as well as an increase in the ELM
|
|
| 3. |
- Lönnroth, J. -S, et al.
(författare)
-
Integrated ELM modelling
- 2006
-
Ingår i: Contributions to Plasma Physics. - : Wiley. - 0863-1042 .- 1521-3986. ; 46:7-9, s. 726-738
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a short overview of current trends and progress in integrated ELM modelling. First, the concept of integrated ELM modelling is introduced, various interpretations of it are given and the need for it is discussed. Then follows an overview of different techniques and methods used in integrated ELM modelling presented roughly according to physics approached in use and in order of increasing complexity. The paper concludes with a short discussion of open issues and future modelling requirements within the field of integrated ELM modelling.
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
- Salmi, A., et al.
(författare)
-
ASCOT modelling of ripple effects on toroidal torque
- 2008
-
Ingår i: Contributions to Plasma Physics. - : Wiley. - 0863-1042 .- 1521-3986. ; 48:1-3, s. 77-81
-
Tidskriftsartikel (refereegranskat)abstract
- Toroidal field ripple, delta=(B-max-B-min)/(B-max+B-min) in ITER will be relatively large, about 0.5% at the outer midplane. Due to the importance of toroidal rotation on plasma stability and confinement it is important to understand the consequences of a non-negligible ripple field on rotation. Guiding centre following Monte Carlo code ASCOT is used to evaluate the torque on plasma from co-current NBI in presence of toroidal magnetic field ripple. Simulations are made for a JET discharge from 2007 Ripple Campaign aimed to clarify the effect of ripple on fusion plasmas in preparation for ITER. ASCOT results show large reduction of torque from co-NBI and negative torque from thermal ions, which together could create a counter rotating edge plasma.
|
|
