Welcome
Wish you a very warm welcome on my home page and since that's its purpose,
let me introduce myself as a resonably young Swiss scientist, mountaineer,
traveler and would like to be more of a sailor.
I am currently working in the
numerical analysis
department of the Royal Institute of Technology
in Stockholm and, in the limited time granted to the faculty for private
entreprises, pursue the development of the educational website
www.lifelong-learners.com
offering courses in
numerical methods in
general.
I am interested in number of topics in natural-, financial- and social
sciences, with numerical simulation being the common denominator for my
research in applied mathematics and physics.
Since the beginning of my scientific career, I have been studying the toroidal
confinement of plasmas, aiming at the development of a new clean and unlimited
source of energy based on the energy released by the fusion of hydrogen isotopes
into helium--in a similar way as it occurs inside the stars.
Another topic where I am active, is the development of distance-learning methods
and more generally pedagogical tools for the numerical simulation in science.
In my spare time, I like to go out with friends, listen to fine Jazz and why not,
dance some salsa. With my constant professional traveling, the climbing, sailing
and volleyball I used to practice almost every day at home in Switzerland have
been reduced to activities for holidays.
During 1997, I took the opportunity to climb the second highest peak in
the former USSR, the Pic Lenina (7134m,
Kyrghiztan). More recently in 2001, I reached an easier peak in the Andes
called Huayana Potosi (6088m, Bolivia).
I had no time for major mountaineering since...
Research
| Summary | |
(last update: Jan 2004)
|
The work carried out for research generally deals with the modeling and
the numerical simulation of in physical sciences and engineering.
Waves, diffusion, convection and non-linear interactions are phenomena
encountered in applications as different as telecomunications, biology,
finance and fusion energy research.
They can very nicely be described using differential equations, but only
in the very simplest (and often limiting) approximations is it generally
possible to find solutions in terms of analytic functions.
Numerical calculations are then needed and obtained from computer programs
built around robust methods to ensure that the computed solutions are also
meaningfull.
The progress in the understanding of a basic phenomenon often starts from an
intuition of what may be the basic ingredients. Analytic skills are
then necessary to formulate approxiations leading to a mathematical
model often in terms of integral / differential equations.
Using appropriate numerical methods to exploit the power of digital
computers, the solutions obtained need always first to be
checked against limiting cases and the approximations
validated against measurements before it may be possible to make a
leap forward in the undestanding and to extrapolate into new
regimes.
In fusion energy research, this procedure is routinely applied for the
propagation of waves in toroidal plasmas.
Gyrokinetic effects (where the statistical distribution of charged particles
and their finite Larmor excursion around magnetic field lines come into play)
are studied on the world largest experiments (such as the
JET,
DIII-D,
TCV tokamaks)
in order to design and predict the behaviour of future reactors
(such as ITER).
Our contributions focus on the stability of global eigenmodes of the
toroidal cavity and the propagation / absorption of waves ranging from
the ion-cyclotron frequency down to nearly zero.
Increasingly sophisticated models
have been formulated for the interaction between electromagnetic waves and
the plasma particles; they lead to a set of coupled integro- / differential
equations that have been implemented in the PENN code.
The large linear system resulting from a discretization with bi-cubic finite
elements can just about be solved with the largest super-computers using
iterative Krylov space methods.
This unique capability of computing global electromagnetic wavefields with
gyrokinetic models for the plasma explains why the PENN code is at present
the state of the art for studying Alfvén eigenmodes (AE) and is being
used to revisit a number of predictions for macro-instabilities that have
up to now been modeled with a simpler magneto-hydrodynamic (MHD)
description of the plasma.
Original results have been obtained showing how the linear
mode-conversion
between fast and slow wave is an interesting phenomenon that often plays
a crucial role in tokamak physics.
Slow wavefields have for the first time been numerically resolved, with
localized wavefield structures
predicted in the ion-cyclotron frequency range that remain to be
identified experimentally.
Drift- / kinetic Alfvén eigenmodes (D-/KAE) have been
predicted, and compared with
wavefield and
damping measurements
from the JET (Oxford, UK) and DIII-D (San Diego, USA) tokamaks.
(If your computer has some sound support, take a minute to listen to a plasma
with /
without
macro-instabilities in JET. The sound files are produced by downsampling the
magnetic probe measurements.
Alfvén instabilities appear as violin like sounds bursts at high pitch,
but are absent in the world record discharge where 16 MW of fusion power were
produced. Many other modes do however affect the plasma while it reaches
thermonuclear conditions. Courtesy of
Prof. A. Fasoli, MIT).
The quantitative agreement achieved between the numerical predictions and
the damping rate measured in JET allowed us to identify a key stabilizing
mechanism associated with the plasma shape (e.g. the cusp at the bottom),
drawing on our calculations made in Sweden to
predict the stability of ITER --
the future International Thermonuclear Experimental Reactor.
|
| Slides from selected talks/seminars | |
(last update: Aug 2001)
|
- Jun 01, Invited,
Eur. Phys. Soc. Conf., Madeira, Portugal
- May 01, Oral,
Int. Conf. Comp. Sci, San Francisco, USA
- April 01, Poster,
World Conf. Open Learning and Distance Education, Düsseldorf, Germany
- Mar 01, Flash,
Eur. Fusion Development Agreement, Germany
- Oct 00, Invited,
CEPROFS, Geneva, Switzerland
- Sep 00, Invited,
Int. Fusion Theory Conference, Varenna, Italy
- Apr 00, Invited,
Easter Plasma Meeting, Turin, Italy
- Feb 00, Oral,
NSTX Forum at PPPL, Princeton, USA
- Fall 98, Sabbatical
at MIT, U.Columbia, General Atomics, UC Irvine, UC Berkeley,
UW Madison and PPPL Princeton
- Jun 98, Lecture,
Docent Lecture at the Royal Institute of Technology, Stockholm
|
| Projects proposed to students | |
(last update: Mar 2002)
|
|
| Reprints of selected publications | |
(last update: Aug 2001)
|
- The Physics and Modeling of Macro-Instabilities in High Performance
Tokamaks,
Plasma Phys. Contr. Fusion 43 (2001) A207
- A Ray-Based Algorithm for Numerical Computation of Multi-Dimensional
Linear Conversion,
Phys. Lett. A 290 (2001) 309
- Learning Computational Methods for Partial Differential Equations
from the Web,
(Proc. 2001 Int. Conf. Comput. Sci, San Francisco, May 2001)
Springer-Verlag LNCS 2073 (2001) 1170
- Teaching Computational Methods for Partial Differential Equations
using the Web,
Comput. Sci. Eng. 3 (2001) 83
- Teaching Numerical Methods for Partial Differential Equations with
the Internet
(Proc. 20th ICDE World Congress on Open Learning, Duesseldorf, April 2001)
- Iterative Solution of Global Electromagnetic Wavefields with Finite
Elements, Comput. Phys. Commun. 135 (2001) 74
- Drift-/ Kinetic Alfvén Eigenmodes in High Performance Tokamak
Plasmas
(Proc. 18th Fusion Energy Conf., Sorrento, 2000) IAEA-CN-77/THP2-19
- Mode Conversion and Models for the Stability of Alfvén
Eigenmodes,
"Theory of Fusion Plasmas" (Proc. Int. Workshop, Varenna, 2000)
Editrice Compository, Bologna (2000)
- Iterative Solution of Global Electromagnetic Wavefields with Finite
Elements,
Comput. Phys. Commun. 135 (2000) 74
- Stability of Alfvén Eigenmodes in Optimized Tokamaks,
Nucl. Fusion 40 (2000) 1343
- Isotope Mass Scaling of AE Damping Rates in the JET Tokamak plasmas,
Phys. Lett. A 265 (2000) 288
- Review of Mode-Conversion Calculations in Toroidal Plasmas,
"Recent Research Developments in Plasmas",
(Transworld Research Network Publications, Vallakkadavu, Kerala, India),
Lausanne Report LRP 647/99 (1999)
- Global Alfvén Eigenmodes Stability in Thermonuclear Tokamak
Plasmas,
Nucl. Fusion 39 Vol.11Y (1999) 2095
- On Resonance Absorption and Continuum Damping,
Phys. Plasmas 5 (1998) 3801
- Toroidal Mode-Conversion in the ICRF,
Nucl. Fusion 38 (1998) 153
- Ion-Bernstein Wave Mode Conversion in a Hot Tokamak Plasma,
"Radio-Frequancy Power in Plasmas", (Proc. 12th Topical Conf.,
Savannah, Georgia, 1-3 April 1997) American Institute of Physics,
Woodbury, NY (1997) 281
- Global Alfvén Eigenmodes Stability in ITER,
"Alpha-Particles in Fusion Research", (Proc. 5th IAEA Tech.Com. Meeting,
JET, Abingdon, 8-11 September 1997), Edited by J. Jacquinot,
JET Report O.Mo.02 (1997) 5
- Prediction of Alfvén Eigenmode Dampings in JET,
Phys. Plasmas 5 (1998) 2952
- Stable Ellipticity-Induced Alfvén Eigenmodes in JET,
Phys. Plasmas 4 (1997) 3663
- Comparison Between Measurements of the Poloidal Distribution of
Magnetic Fluctuations and Theoretical Models during TAE Activity,
Nucl. Fusion 37 (1997) 1411
- Stability of Global Drift-Kinetic Alfvén Eigenmodes in DIII-D,
Phys. Plasmas 4 (1997) 1110
- Kinetic Alfvén Eigenmodes in a Hot Tokamak Plasma,
Plasma Phys. Contr. Fusion 39 (1997) 549, also in "Fusion Energy",
(Proc. 16th IAEA Conf., Montreal 1996), IAEA-CN-64/DP-4 (1997)
- Observation of Multiple Kinetic Alfvén Eigenmodes,
Phys. Rev. Lett. 76 (1996) 1067
- Non Perturbative Kinetic Effects on GAE modes in Tokamak Plasmas,
Proc. Eur. Conf. Bournemouth, vol. 19C, part II-245 (1995)
- Linear Wave Propagation in Resistive and Hot Tokamak Plasmas,
PhD Thesis no 1022, Ecole Polytechnique Fédérale de
Lausanne (Switzerland),CRPP-EPFL Laboratory Report LRP 513/95, also
Comput. Phys. Commun. 92 (1995) 153
- Equilibrium Gradient Effects in the Theory of Alfvén Wave
Heating Plasma Phys. Contr. Fusion 33, (1991) 521
- Local Absorption Of Linear Electromagnetic Waves In Uniformly
Magnetized, Inhomogeneous Plasmas,
Theory of Fusion Plasmas, Proc. Int. Conf. Varenna, (1990)
|
| International collaborations | |
(last update: Mar 2002)
|
- Alfvén Eigenmode measurements in JET (
Prof. A. Fasoli, MIT Cambridge, USA & EPF Lausanne, Switzerland)
- Mode-conversion modeling with ray-tracing
(Profs. A. Kaufman, Lawrence Berkeley Lab. &
E. Tracy, William Mary, USA)
- Linear modeling of global wavefields in tokamaks
(Theory group, CRPP Lausanne, Switzerland)
- Alfvén Eigenmode measurements in DIII-D
(Prof. W. W. Heidbrink, UC Irvine, USA)
- European Fusion Development Agreement: EFDA/MHD-task force
(Dr T. Hender, UKAEA, Culham, UK)
- International Tokamak Physics Activity for Energetic Particles in ITER
(Dr D. Campbell, Max Plank Institut, Garching, Germany)
Teaching
(last update: August 2002)
|
Introduction to Numerical Methods (KTH 02)
| |
Second year undergraduate introductory course for students in electrical
engineering.
|
- Abstract.
Description and course material in Swedish under
this link
(4 credits, 28 h lectures, 12 h exercises, 14 h lab).
- Litterature.
Scientific Computing, an Introductory Survey by M.T.Heath,
distributed on-line from
this link.
|
|
Hedging your Portfolio: Options, Swaptions & Derivatives (KTH 02-03)
| |
Graduate level course for students from KTH and the Swedish Netuniversity,
can be studied entirely at a distance.
|
- Abstract.
Description in English under Home/Overview under the course
main page
(4 credit points, 6h video lectures, 120h problem based learning, 42h project).
- Lecture notes.
Java-powered document under syllabus in the course
index
- Software.
The VMARKET
can be edited and modified by the course participants after
registration.
|
|
Numerical Methods for Partial-Differential Equations (KTH 97-03)
| |
Graduate level course for students from KTH, the Swedish Netuniversity
and EPFL/Lausanne can be studied entirely at a distance.
|
- Abstract.
Description in English under Home/Overview in the course
main page
(4 credit points, 6h video lectures, 120h exercises, 42h project).
(4 credit points, 6h video lectures, 120h problem based learning, 42h project).
- Lecture notes.
Java-powered document under syllabus in the course
index
- Software.
The JBONE
can be edited and modified by the course participants after
registration.
|
|
Introduction to Plasma Physics with Applications (CTH 99-01)
| |
Advanced undergraduate level course taught to physics and electrical
engineering students at Chalmers.
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Distance-learning courses for everyone distributed by
www.lifelong-learners.com (since 2000).
| |
Courses are organised on a private basis for companies and students from
outside the Swedish academic system, as part of the commercial activity
granted to the members of the faculty.
|
Hobbies
(last update: March 2002)
Mountaineering.
Mountaineering has been one of my favourite hobbies for a long time.
In the good old days, I used to spend up to 60 days skiing, rock+ice
climbing every year...
This is how I got enrolled as an avalanche specialist in the Swiss army.
Today, I limit myself to a couple of excursions every year.
Double-click on the picture to
visit the album from the expeditions to
Pic Lenina (7134m, Kyrghistan),
Mt Whitney (4460m, USA) we did
together with my friend
François
and a more recent climb to
Huayana Potosi (6088m, Bolivia).
That's the disclaimer which has to be on every home page of our university.