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**Harvard**

Hesslow, L. (2016) *Effect of Screened Nuclei on Fast Electron Beam Dynamics*. Göteborg : Chalmers University of Technology

** BibTeX **

@misc{

Hesslow2016,

author={Hesslow, Linnea},

title={Effect of Screened Nuclei on Fast Electron Beam Dynamics},

abstract={In a plasma, particles can be accelerated to relativistic speeds by an electric eld.
These relativistic particles are of importance to, for example, fusion research, where
they pose a risk of damaging the walls of a reactor. In order to understand the dynamics
of runaway particles, the Coulomb interaction between particles (\collisions")
is a central concept. In this thesis we focus on the collisions between particles and
partially ionized ions. The interaction strength depends on the incoming particle
momentum: at low momentum the nucleus is screened by the bound electrons and
the net ion charge will dene the interaction strength; at high momentum the particle
may penetrate the electron cloud around the nucleus and the relevant charge
is then the nuclear charge. Since the collision cross section is proportional to the
charge squared, this can be expected to have a signicant impact on the runaway
dynamics.
In this thesis we investigate the energy dependence of screening. Starting from a
quantum mechanical collision cross section, we derive the form of the Fokker{Planck
collision operator appropriate for the many-body plasma system. When accurately
accounting for screening, we nd that the collision rates can be signicantly enhanced
compared to the fully screened case, in particular at high momentum. Furthermore,
we derive general forms of the high energy behavior of the collision frequencies,
which hold regardless of the details of the model used to describe the electron cloud
of the ion. Finally, we nd indications that the use of the Fokker{Planck operator
might have to be improved by considering the Boltzmann operator, in order to take
large-angle collisions into account.},

publisher={Institutionen för fysik (Chalmers), Chalmers tekniska högskola,},

place={Göteborg},

year={2016},

keywords={plasma, runaway, Fokker{Planck, Boltzmann, fusion.},

note={60},

}

** RefWorks **

RT Generic

SR Electronic

ID 236294

A1 Hesslow, Linnea

T1 Effect of Screened Nuclei on Fast Electron Beam Dynamics

YR 2016

AB In a plasma, particles can be accelerated to relativistic speeds by an electric eld.
These relativistic particles are of importance to, for example, fusion research, where
they pose a risk of damaging the walls of a reactor. In order to understand the dynamics
of runaway particles, the Coulomb interaction between particles (\collisions")
is a central concept. In this thesis we focus on the collisions between particles and
partially ionized ions. The interaction strength depends on the incoming particle
momentum: at low momentum the nucleus is screened by the bound electrons and
the net ion charge will dene the interaction strength; at high momentum the particle
may penetrate the electron cloud around the nucleus and the relevant charge
is then the nuclear charge. Since the collision cross section is proportional to the
charge squared, this can be expected to have a signicant impact on the runaway
dynamics.
In this thesis we investigate the energy dependence of screening. Starting from a
quantum mechanical collision cross section, we derive the form of the Fokker{Planck
collision operator appropriate for the many-body plasma system. When accurately
accounting for screening, we nd that the collision rates can be signicantly enhanced
compared to the fully screened case, in particular at high momentum. Furthermore,
we derive general forms of the high energy behavior of the collision frequencies,
which hold regardless of the details of the model used to describe the electron cloud
of the ion. Finally, we nd indications that the use of the Fokker{Planck operator
might have to be improved by considering the Boltzmann operator, in order to take
large-angle collisions into account.

PB Institutionen för fysik (Chalmers), Chalmers tekniska högskola,

LA eng

LK http://publications.lib.chalmers.se/records/fulltext/236294/236294.pdf

OL 30