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Fast wave heating of cyclotron resonant ions in tokamaks
KTH, Superseded Departments, Alfvén Laboratory.ORCID iD: 0000-0002-7142-7103
2004 (English)Doctoral thesis, comprehensive summary (Other scientific)
Place, publisher, year, edition, pages
Stockholm: KTH , 2004. , xiv, 61 p.
Keyword [en]
Fusion plasma, tokamak, RF heating, fast wave heating, fast wave current drive, ion cyclotron resonance, ICRH, ICRF, ICCD, RF induced rotation, RF induced transport, RF induced pinch, RF pinch, finite orbit width, fast wave current drive, self-consi
National Category
Other Engineering and Technologies
Identifiers
URN: urn:nbn:se:kth:diva-3771ISBN: 91-7283-780-2 (print)OAI: oai:DiVA.org:kth-3771DiVA: diva2:9622
Public defence
2004-06-01, 00:00
Note
QC 20100622Available from: 2004-06-01 Created: 2004-06-01 Last updated: 2010-11-15Bibliographically approved
List of papers
1. Ion cyclotron current drive studies
Open this publication in new window or tab >>Ion cyclotron current drive studies
2000 (English)In: Proceedings of the 2000 international congress on plasma physics, 2000Conference paper, Published paper (Other academic)
National Category
Other Engineering and Technologies
Identifiers
urn:nbn:se:kth:diva-13516 (URN)
Conference
international congress on plasma physics
Note
QC 20100621Available from: 2010-06-21 Created: 2010-06-21 Last updated: 2010-06-22Bibliographically approved
2. Controlling the profile of ion-cyclotron-resonant ions in JET with the wave-induced pinch effect
Open this publication in new window or tab >>Controlling the profile of ion-cyclotron-resonant ions in JET with the wave-induced pinch effect
Show others...
2002 (English)In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 89, no 11Article in journal (Refereed) Published
Abstract [en]

Experiments on the JET tokamak show that the wave-induced pinch in the presence of toroidally asymmetric waves can provide a tool for controlling the profile of ion-cyclotron-resonant He-3 ions. Direct evidence for the wave-induced pinch has been obtained from the measured gamma-ray emission profiles. Concurrent differences in the excitation of Alfven eigenmodes (AEs), sawtooth stabilization, electron temperatures, and fast-ion stored energies are observed. The measured location of the AEs and gamma-ray emission profiles are consistent with the fast-ion radial gradient providing the drive for AEs.

Keyword
TOROIDAL PLASMAS, CURRENT DRIVE, ICRF WAVES, TRANSPORT, TOKAMAKS, INJECTION
National Category
Other Engineering and Technologies
Identifiers
urn:nbn:se:kth:diva-13517 (URN)10.1103/PhysRevLett.89.115004 (DOI)000177676400013 ()
Note
QC 20100621Available from: 2010-06-21 Created: 2010-06-21 Last updated: 2017-12-12Bibliographically approved
3. Effects of finite drift orbit width and RF-induced spatial transport on plasma heated by ICRH
Open this publication in new window or tab >>Effects of finite drift orbit width and RF-induced spatial transport on plasma heated by ICRH
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2004 (English)In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 44, no 8, 892-908 p.Article in journal (Refereed) Published
Abstract [en]

The effects of RF-induced transport and orbit topology of resonant ions are analysed for high power ion cyclotron resonance heating (ICRH). These effects are found to play important roles in the details of the high-energy part of the distribution function, and affect the driven current and momentum transfer to the background plasma. The finite drift orbit width broadens the power deposition and leads to losses of high-energy ions intercepted by the wall. RF-induced transport of resonant ions across magnetic flux surfaces appears due to the toroidal acceleration of resonant ions interacting with waves having a finite toroidal mode number. Heating with waves propagating parallel to the current leads to a drift of the turning points of trapped resonant ions towards the midplane. As the turning points meet, the orbits will de-trap, preferentially into co-current passing orbits, which may ultimately be displaced to the low field side of the magnetic axis. Ions with such orbits are a typical feature in plasmas heated with directed toroidal mode spectra of waves propagating parallel to the plasma current. These ions will be subjected to a strong RF diffusion partly caused by the focusing of the wave field and partly by the Doppler shifted cyclotron resonance, as it approaches tangency with the drift orbit. The resonance condition puts a limitation on the achievable energy for these ions, which is more severe than for corresponding trapped ions. This results in a rather flat tail up to a critical energy, above which the tail rapidly decays. Heating with waves propagating anti-parallel with the plasma current curtails the energy of the trapped ions due to a vertical outward drift of the turning points of the trapped ions. Heating with symmetric spectra, in particular with waves with low magnitude of the toroidal mode numbers, gives rise to high-energy trapped ions with wide orbits, of which the maximum energy is either restricted by the fact that the RF diffusion vanishes due to cancellation of the perpendicular acceleration over a gyro orbit or by the drift orbits being intercepted by the wall. In the steady state the main source for momentum transfer to the bulk plasma comes from the finite momentum of the wave for heating with asymmetric spectra. For heating with symmetric spectra the enhanced losses of high-energy trapped ions can produce a net counter-current torque on the plasma.

Keyword
High energy ions, Ion cyclotron resonance heating, Power deposition, Spatial transport, Cyclotron resonance, High energy physics, Ions, Magnetic field effects, Natural frequencies, Orbits, Torque, Wave propagation
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-12712 (URN)10.1088/0029-5515/44/8/008 (DOI)000223954400008 ()2-s2.0-4344607797 (Scopus ID)
Note
QC 20100507Available from: 2010-05-07 Created: 2010-05-07 Last updated: 2017-12-12Bibliographically approved
4. Modelling of ICRH induced current and rotation
Open this publication in new window or tab >>Modelling of ICRH induced current and rotation
2003 (English)In: RADIO FREQUENCY POWER IN PLASMAS / [ed] Forest CB, 2003, Vol. 694, 479-482 p.Conference paper, Published paper (Other academic)
Abstract [en]

The scenario of He-3(He-4) minority ICRH has been studied with the SELFO code, revealing the importance of finite orbit width and orbit topology for ICRH induced currents and torques.

Series
AIP CONFERENCE PROCEEDINGS, 694
Keyword
CYCLOTRON CURRENT DRIVE, TOKAMAKS, WAVES
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-13580 (URN)000188894000092 ()0-7354-0158-6 (ISBN)
Conference
15th Topical Conference on Radio Frequency Power in Plasmas
Note
QC 20100621Available from: 2010-06-21 Created: 2010-06-21 Last updated: 2010-06-22Bibliographically approved
5. Plasma rotation induced by directed waves in the ion-cyclotron range of frequencies
Open this publication in new window or tab >>Plasma rotation induced by directed waves in the ion-cyclotron range of frequencies
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2004 (English)In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 92, no 23Article in journal (Refereed) Published
Abstract [en]

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.

Keyword
ICRF-HEATED DISCHARGES, FAST ALFVEN WAVES, TOROIDAL ROTATION, JET, TOKAMAK, DYNAMICS, IMPURITY
National Category
Other Engineering and Technologies
Identifiers
urn:nbn:se:kth:diva-13592 (URN)10.1103/PhysRevLett.92.235001 (DOI)000221961900020 ()
Note
QC 20100622Available from: 2010-06-22 Created: 2010-06-22 Last updated: 2017-12-12Bibliographically approved
6. Destabilization of fast-ion-induced long sawteeth by localized current drive in the JET tokamak.
Open this publication in new window or tab >>Destabilization of fast-ion-induced long sawteeth by localized current drive in the JET tokamak.
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2004 (English)In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 92, no 23Article in journal (Refereed) Published
Abstract [en]

In a tokamak fusion reactor the energetic alpha particles will transiently stabilize the magnetohydrodynamic activity causing sawtooth oscillations. The crash events terminating long sawtooth free periods can provide seed islands for neoclassical tearing modes [Phys. Rev. Lett. 88, 105001 (2002)]]. To shorten the sawtooth periods localized current drive near the q=1 surface is a possibility. This Letter provides the first experimental evidence for the effectiveness of this method in the different physics regime associated with fast-ion-induced long sawteeth on the JET tokamak.

National Category
Other Engineering and Technologies
Identifiers
urn:nbn:se:kth:diva-13593 (URN)10.1103/PhysRevLett.92.235004 (DOI)000221961900023 ()15245165 (PubMedID)2-s2.0-3242727020 (Scopus ID)
Note

QC 20100622

Available from: 2010-06-22 Created: 2010-06-22 Last updated: 2017-12-12Bibliographically approved
7. Analysis of a quasilinear model for ion cyclotron interactions in tokamaks
Open this publication in new window or tab >>Analysis of a quasilinear model for ion cyclotron interactions in tokamaks
2006 (English)In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 46, no 7, S433-S441 p.Article in journal (Refereed) Published
Abstract [en]

An orbit averaged quasilinear operator for resonant ion cyclotron interactions is analysed. The regions in phase space where the interactions are strong and the boundaries between regions with resonant and non-resonant ion orbits are identified. At these boundaries the quasilinear diffusion coefficient becomes discontinuous, causing the standard Monte Carlo scheme to induce an unphysical flow of test particles into the region with lower diffusion coefficient. A new Monte Carlo scheme that balances the flows across discontinuities is proposed. Moreover, the quasilinear diffusion coefficient is shown to deviate significantly from the lowest order Larmor radius scaling vertical bar delta H vertical bar(2) proportional to v(perpendicular to)(2n), where delta H is the perturbed Hamiltonian. This is not only caused by the finite Larmor radius effects, but also by the inhomogeneous electric field polarization and by the changes to the guiding centre orbits during the wave-particle interactions.

Keyword
icrf waves, plasmas, transport, dynamics, orbits, jet
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-15887 (URN)10.1088/0029-5515/46/7/S06 (DOI)000239478900007 ()2-s2.0-33745727676 (Scopus ID)
Note
QC 20100525 QC 20110927. Conference: 16th Topical Conference on RF Power in Plasmas. Park City, UT. APR, 2005Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2017-12-12Bibliographically approved
8. On the parasitic absorption in FWCD experiments in JET ITB plasmas
Open this publication in new window or tab >>On the parasitic absorption in FWCD experiments in JET ITB plasmas
Show others...
2005 (English)In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 45, no 7, 706-720 p.Article in journal (Refereed) Published
Keyword
WAVE CURRENT DRIVE, JOINT EUROPEAN TORUS, DIII-D TOKAMAK, MODE CONVERSION, ICRF ANTENNAS, RESONANCE, SCENARIOS, EMISSION, SCREENS, SHEATHS
Identifiers
urn:nbn:se:kth:diva-12763 (URN)10.1088/0029-5515/45/7/020 (DOI)000231000300021 ()
Note
QC 20100510Available from: 2010-05-10 Created: 2010-05-10 Last updated: 2017-12-12Bibliographically approved

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Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
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  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
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Output format
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  • asciidoc
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