24.5.2022 Decluttering the instabilities of the fourth state of matter - Plasma (Bhaskar)

Plasma is a collection of freely moving ions, electrons and neutrals and is frequently referred to as the "fourth state of matter". It is recognised that 99.9 percent of the visible universe is made of plasma and it is formed naturally in the Sun, solar wind, Earth’s magnetosphere, interstellar space, pulsars and even in the region around black holes. This work deals with the generation of plasma in laboratory conditions by means of Electron Cyclotron Resonance (ECR) heating mechanism.
Bichu Bhaskar/Jyväskylän yliopisto
Published
24.5.2022

This research concentrates on ion sources that generate plasma via the ECR mechanism and confine it within a magnetic bottle. This type of ion source is commonly called as Electron Cyclotron Resonance Ion Source (ECRIS). These ion sources are used in production of Highly Charged Ions (HCIs) for undertaking various research such as nuclear fusion, atomic and nuclear physics experiments, radiation therapy for cancer treatment, particle physics experiments etc.

ECRIS plasmas have been demonstrated to exhibit kinetic plasma instabilities, which strongly limits the production of highly charged ions. Additionally, it has long been recognised that controlling kinetic instabilities is one of the most challenging issues in the development of high-temperature fusion plasmas and medical accelerators. Consequently, this work focused on comprehending the mechanisms triggering the instabilities in ECR heated plasmas by performing a series of experimental campaigns with multiple ion sources in several highly recognised research institutes in Finland, France and China.

This work is a combination of simulation, experiment and data analysis which resulted in acquiring a deeper understanding of the role of magnetic field and hot electron population in the appearance of kinetic instabilities. One of the experimental campaigns also resulted in the first comprehensive investigation of a special plasma instability phenomenon –instability grouping– observed earlier in space and magnetospheric plasmas.

The research has provided answers to several fundamental questions regarding the development of kinetic instabilities in ECR plasmas, which can be applied while designing future ion sources. The experimental evidence of fundamental limitation of energy emitted during an instability event brings motivation to further theoretical research of plasma instabilities that will be essential in understanding the mechanism of kinetic instability also in other magnetically confined plasma devices, such as tokamaks used for nuclear fusion, and for instability studies in space plasmas.

The dissertation is published in JYU Dissertations series, number 516, Jyväskylä 2022.
ISBN 978-951-39-9137-1 (PDF); URN:ISBN:978-951-39-9137-1 and ISSN 2489-9003
Permanent link to publication:

M.Sc. Bichu Subhash Bhasi Bhaskar defends his doctoral dissertation "Experimental study on kinetic instabilities in electron cyclotron resonance heated plasma" on Tuesday 24th of May 2022 starting at noon. Opponent is  Senior Researcher Pierre Delahaye (GANIL, France) and Custos Professor Iain Moore (Ä¢¹½Ö±²¥). The doctoral dissertation is held in English.

The supervisors of the work are Senior Lecturer Hannu Koivisto (Ä¢¹½Ö±²¥) and Research Engineer Thomas Thuillier (LPSC-CNRS/IN2P3-UGA, France). The work involves a Cotutelle agreement of joint supervision between Ä¢¹½Ö±²¥ and Université Grenoble Alpes.

The audience can follow the dissertation in the lecture hall (YAA303) or online.

Link to the online event: