T. Hellsten

Publication List Details

Period

1984 - 2008

Number

112

Co-Authors

1 IT08 Self-consistent Study of Fast Particle Redistribution by Alfvén Eigenmodes During Ion Cyclotron Resonance Heating (2008)

T. Bergkvist, T. Hellsten, T. Johnson

Abstract. Alfvén eigenmodes (AEs) excited by fusion born α particles can degrade the heating efficiency of a burning plasma and throw out αs. To experimentally study the effects of excitation of...

Non-linear Alfvén Eigenmode Dynamics of a Burning Plasma in the Presence of Ion Cyclotron Resonance Heating (2008)

T. Bergkvist, T. Hellsten, K. Holmström

Alfvén eigenmodes (AEs) excited by α particles in a burning plasma can degrade the heating efficiency by spatial redistribution of the resonant α particles. Changes of the orbit invariants in...

On the Dynamics of Alfvén Eigenmode Excitation (2008)

K. Holmström, T. Bergkvist, T. Hellsten

Alfvén eigenmodes (AEs) excited by fast ions can cause losses of fast ions in thermonu-clear experiments. To describe the dynamics of the AE excitation, it is necessary to include the decorrelation...

Upgrade of the Monte Carlo code FIDO (2007)

J. Hedin, T. Johnson, T. Hellsten

During rf heating on minority ions and current drive the velocity distribution is determined by the balance between the wave-particle interaction and the relaxation through Coulomb collision. This is...

Parasitic Absorption By Fusion Born α-particles in ICRF Heated Plasmas (2007)

J. Hedin, J. Carlsson, T. Hellsten, A. Jaun

Abstract. A method has been developed to calculate the dielectric tensor in a

New Mechanisms of Minority Ion Cyclotron Current Drive (2007)

J. Carlsson, T. Hellsten, J. Hedin

Minority ion cyclotron current drive is studied by solving the Fokker-Planck equation in toroidal geometry keeping the ∂/∂v�-term in the quasilinear operator, hereby including the important...

SELF-CONSISTENT CALCULATIONS OF THE POWER DEPOSITION AND VELOCITY DISTRIBUTION DURING ICRH INCLUDING FINITE ORBIT WIDTHS, SPATIAL RF-INDUCED DRIFT AND (2007)

T. Hellsten, J. Carlsson, J. Hedin, J. Källbäck

Self-consistent calculations of ICRH for toroidally directed wave spectrum have revealed the importance of including finite orbit width and RF-induced spatial transport. This is in particular...

On ion cyclotron current drive for sawtooth control (2006)

Eriksson, L. G., Johnson, T., Mayoral, M. L., Coda, S., Sauter, O., Buttery, R. J., ...

Experiments using ion cyclotron current drive (ICCD) to control sawteeth are presented. In particular, discharges demonstrating shortening of fast ion induced long sawteeth reported in (Eriksson et...

On parasitic absorption in FWCD experiments in JET ITB plasmas (2005)

Hellsten, T., Laxåback, M., Bergkvist, T., Johnson, T., Meo, F., Mantsinen, M., ...

32nd EPS Conference on Controlled Fusion and Plasma Physics. Tarragona, ES, 27 June - 1 July 2005. Europhysics Conference Abstracts. Vol. 29C, P-5.095

Plasma rotation induced by directed waves in the ion-cyclotron range of frequencies (2004)

Eriksson, L. G., Johnson, T., Hellsten, T., Giroud, C., Kiptily, V. G., Kirov, K., ...

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...

Progress towards steady-state operation and real-time control of internal transport barriers in JET (2003)

Litaudon, X., Becoulet, A., Crisanti, F., Wolf, R. C., Baranov, Yu. F., Barbato, E., ...

In JET, advanced tokamak research mainly focuses on plasmas with internal transport barriers (ITBs) that are strongly influenced by the current density profile. A previously developed optimized shear...

Heating, current drive and energetic particle studies on JET in preparation of ITER operation (2003)

Budny, R., Cardinali, A., Castaldo, C., Cesario, R., Crisanti, F., ...

This paper summarizes the recent work on JET in the three areas of heating, current drive and energetic particles. The achievements have extended the possibilities of JET, have a direct connection to...

Spatially resolved toroidal plasma rotation with ICRF on JET (2003)

Righi, E., Chan, V., DeGrassie, J., Kirov, K., Mantsinen, M., ...

Plasmas heated by ICRF only in the JET tokamak show distinct structures in the toroidal rotation profile, with regions where &ddiff;ω/&ddiff;r>0 when the minority cyclotron resonance layer is far...

Progress towards steady-state operation and real time control of internal transport barriers in JET (2003)

Litaudon, X., Bécoulet, A., Crisanti, F., Wolf, R. C., Baranov, Yu. F., Barbato, E., ...

In JET advanced tokamak research mainly focuses on plasmas with internal transport barriers (ITBs), generated by modifications of the current profile. The formerly developed optimised shear regime...

Overview of JET results (2003)

Pamela, J., Solano, E. R., Adams, J. M., Agarici, G., Agarici, M., Akhter, H., ...

Scientific and technical activities on JET focus on the issues likely to affect the ITER design and operation. Our understanding of the ITER reference mode of operation, the ELMy H-mode, has...

Heating, current drive and energetic particle studies on JET in preparation of ITER operation (2003)

Noterdaeme, J. M., Budny, R., Cardinali, A., Castaldo, C., Cesario, R., Crisanti, F., ...

This paper summarizes the recent work on JET in the three areas of heating, current drive and energetic particles. The achievements have extended the possibilities of JET, have a direct connection to...

Control of sawteeth and triggering of NTMs with ion cyclotron resonance frequency waves in JET (2002)

Westerhof, E., Sauter, O., Mayoral, M. L., Howell, D. F., Mantsinen, M. J., Nave, M. F. F., ...

A new scenario to delay or prevent neoclassical tearing mode (NTM) onset is presented. By active sawtooth destabilization, short period and low amplitude sawteeth are generated, such that the...

Control of neoclassical tearing modes by sawtooth control (2002)

Sauter, O., Westerhof, E., Mayoral, M. L., Alper, B., Belo, P. A., Buttery, R. J., ...

The onset of a neoclassical tearing mode (NTM) depends on the existence of a large enough seed island. It is shown in the Joint European Torus that NTMs can be readily destabilized by long-period...

Analysis of ion cyclotron heating and current drive at omega approximate to 2 omega(cH) for sawtooth control in JET plasmas (2002)

Mantsinen, M. J., Angioni, C., Eriksson, L. G., Gondhalekar, A., Hellsten, T., Johnson, T., ...

Ion cyclotron heating and current drive at omega approximate to 2omega(cH) in JET deuterium plasmas with a hydrogen concentration n(H)/(n(D)+n(H)) in the range of 5-15% are analysed, comparing...

MHD stability with strongly reversed magnetic shear in JET (2002)

Hender, T. C., Hennequin, P., Alper, B., Hellsten, T., Howell, D. F., Huysmans, G. T. A., ...

Recent operation of JET with centrally strongly reversed magnetic shear, produced with the help of lower hybrid current drive, has extended the domain in which internal transport barriers (ITBs) can...

Sawtooth, Neo-Classical Tearing Mode and Error Field Studies in JET (2002)

T.C. Hender, O. Sauter, B. Alper, C. Angioni, M. Baar, M. Benedetti, ...

A range of ITER relevant plasma stability issues have been studied in the JET tokamak; these include the effects of fast particles on sawteeth, control of NTMs via sawteeth seeds, scaling of (2,1)...

ICRF current drive experiments on JET (2001)

Nguyen, F., Noterdame, J., Mayoral, M., Hellsten, T., Mantsinen, M., Hartmann, D., ...

Proceedings of the 28th EPS Conference on Controlled Fusion and Plasma Physics. Funchal, Madeira, PT, 18 - 22 June 2001. CD-ROM

Toroidal mode conversion in the ICRF (1998)

Jaun, A., Hellsten, T., Chiu, S. C.

Mode conversion is studied in the ion cyclotron range of frequencies (ICRF), taking into account the toroidal geometry relevant for tokamaks. The global wavefields obtained using the gyrokinetic...

On resonance absorption and continuum damping (1998)

Jaun, A., Appert, K., Hellsten, T., Vaclavik, J., Villard, L.

The absorption of power is studied with fluid and gyrokinetic plasma models, when Alfven resonances provide for a weak damping in a partially standing wave field. Examples chosen in slab and toroidal...

Evidence for a wave induced particle pinch in the presence of toroidally asymmetric ICRF waves (1998)

Eriksson, L., Mantsinen, M., Borba, D., Fasoli A., R. Heeter, R., S. Sharapov, S., ...

The first experimental observation of a radio frequency (rf) wave-induced particle pinch of trapped ions has been made in experiments at the Joint European Torus with nearly on-axis high power...

Kinetic Alfven eigenmodes in a hot tokamak plasma (1997)

Jaun, A., Appert, K., Fasoli, A., Hellsten, T., Lister, J., Vaclavik, J., ...

Kinetic effects such as finite ion Larmor excursions and resonant Landau interactions are studied in the toroidicity Alfven eigenmode (TAE) range of frequencies. A new Alfven mode conversion...

Studies of D-D Fusion Reactivity in High-Temperature Jet Plasmas (1991)

Adams, J. M., Balet, B., Boyd, D. A., Campbell, D. J., Challis, C. D., Christiansen, J. P., ...

The D-D fusion reactivity from JET plasmas has been optimized by using combined neutral beam injection and radiofrequency heating. Reaction rates of up to 2.9 x 10(16) reactions per second...