Announcements
6 October 2025
Plasma | Interview with One of the Authors—Prof. Viviane Pierrard
Prof. Viviane Pierrard is one of the authors of the highly cited article entitled “Exospheric Solar Wind Model Based on Regularized Kappa Distributions for the Electrons Constrained by Parker Solar Probe Observations” published in Plasma (ISSN: 2571-6182).
The following is a short interview with Prof. Pierrard:
I am head of the Solar Wind section at the Royal Belgian Institute for Space Aeronomy and an invited Professor of Physics at the Université Catholique de Louvain. I am a space plasma physicist specializing in the solar wind and its interactions with the Earth’s magnetosphere, especially the radiation belts, the population of suprathermal particles, the plasmasphere, the ionosphere, and, more generally, space weather. I have more than 30 years of experience in the development of kinetic dynamic models for space plasmas and analysis of spacecraft observations. The presence of suprathermal particles in all space plasmas made me highly interested in Kappa (power-law) velocity distribution functions that better describe the observations and produce more realistic models than Maxwellians for space plasmas, especially in what concerns the heating of the corona and the acceleration of the solar wind.
2. What made you decide to publish a plasma article? Why did you choose Plasma?
Our new results concerning our solar wind kinetic model using regularized Kappa distributions perfectly corresponded to the excellent journal MDPI Plasma.
3. What was your experience publishing with Plasma?
The experience with Plasma MDPI was extremely positive, with a rigorous review and a fast process. The journal gave us the possibility to provide an animated abstract that perfectly illustrated our important results.
4. Was it important to you that the journal is open access? How does open access publishing advance the field of plasma?
Open access was very important because it was imposed by the project Biosphere.
5. What do you hope that readers will learn from your paper?
- Regularized Kappa has no diverging moments, allowing us to generalize the solar wind model to cases with kappa indices lower than 2, as sometimes observed for the electron distributions at large distances characterized by very important suprathermal populations;
- The solar wind model shows that the acceleration of the wind to supersonic velocities is mainly due to the ambipolar electric field;
- Using observations of Parker Solar Probe and Solar Orbiter at different radial distances, averaged conditions in the solar corona are deduced for fast and slow winds.
6. What critical scientific or engineering problems did your research initially aim to address? What are the current bottlenecks in this field, and how did you identify the breakthrough point of your research?
The acceleration of fast wind coming from low-temperature coronal holes is a hot topic in the solar wind community. We show that due to open field lines and lower density in coronal holes, the collisionality is lower than in the equatorial streamers, leading to a lower exobase from which the wind starts to blow. Thus, this generates faster wind due to a higher electric potential in the acceleration region.
Maximilien Péters de Bonhome is a PhD student who did excellent work to analyze spacecraft data for comparison with the model.
