DrBrian Appelbe
Research Fellow
Department of Physics - Faculty of Natural Sciences
Orcid identifier0000-0003-4781-7010 (opens in a new tab)
- Research FellowDepartment of Physics - Faculty of Natural Sciences
- 020 7594 7651 (Work)
- 740, Blackett Laboratory, South Kensington Campus, United Kingdom
RESEARCH
Overview
Here is a selection of topics that I am currently, or have recently been, working on:
Nuclear Physics in a Plasma Environment - Measuring capture cross sections of excited nuclei
Neutron capture is responsible for the production of many isotopes heavier than iron. In the stellar conditions in which it occurs, nuclei are part of a hot, dense plasma. Nuclear-plasma interactions can cause these nuclei to be in excited energy states which can alter the neutron capture cross section. ICF plasmas provide a means of measuring these cross sections and studying the NPIs that generate excited state populations.
ICF - Measuring Temperature
A key parameter for assessing the performance of ICF experiments is the temperature of ions during the burn phase. The energy spectrum of neutrons produced by fusion reactions is dependent on the ion temperature. Accurate modelling of ICF experiments can be used to infer the ion temperature from the neutron spectra measured in experiments. To do this successfully we need to understand how other physical processes, such as fluid motion and hydrodynamic gradients, affect the neutron spectrum.
Magneto-Inertial Fusion - Measuring magnetic field
The MagLIF concept involves the addition of a large magnetic field to a hot, dense deuterium-tritium plasma. The magnetic field reduces energy losses from the plasma meaning that ignition and energy gain can be achieved at lower plasma density than in ICF. Computational models are used to understand how the magnetic field strength and topology can be inferred from secondary neutron spectra.
Pulsed Neutron Sources
The Dense Plasma Focus (DPF) is a device which uses large electric currents (~100kA-3MA) to implode plasma and produce sub-microsecond bursts of fast neutrons. MHD and kinetic modelling of the DPF helps us to understand the physical processes occurring in the device and to optimize the neutron yield.
Transient Chaos
Transient chaos is chaotic motion with a finite duration. Its transient nature means that it cannot be studied using standard asymptotic methods. The Bunimovich stadium billiard is a system that displays transient chaotic behaviour. This system consists of an infinite number of point particles that reflect from the stadium boundary. By introducing a moving leak into the boundary of the stadium billiard we can study how particle dynamics evolve within the billiard.
Here is a selection of topics that I am currently, or have recently been, working on:
Nuclear Physics in a Plasma Environment - Measuring capture cross sections of excited nuclei
Neutron capture is responsible for the production of many isotopes heavier than iron. In the stellar conditions in which it occurs, nuclei are part of a hot, dense plasma. Nuclear-plasma interactions can cause these nuclei to be in excited energy states which can alter the neutron capture cross section. ICF plasmas provide a means of measuring these cross sections and studying the NPIs that generate excited state populations.
ICF - Measuring Temperature
A key parameter for assessing the performance of ICF experiments is the temperature of ions during the burn phase. The energy spectrum of neutrons produced by fusion reactions is dependent on the ion temperature. Accurate modelling of ICF experiments can be used to infer the ion temperature from the neutron spectra measured in experiments. To do this successfully we need to understand how other physical processes, such as fluid motion and hydrodynamic gradients, affect the neutron spectrum.
Magneto-Inertial Fusion - Measuring magnetic field
The MagLIF concept involves the addition of a large magnetic field to a hot, dense deuterium-tritium plasma. The magnetic field reduces energy losses from the plasma meaning that ignition and energy gain can be achieved at lower plasma density than in ICF. Computational models are used to understand how the magnetic field strength and topology can be inferred from secondary neutron spectra.
Pulsed Neutron Sources
The Dense Plasma Focus (DPF) is a device which uses large electric currents (~100kA-3MA) to implode plasma and produce sub-microsecond bursts of fast neutrons. MHD and kinetic modelling of the DPF helps us to understand the physical processes occurring in the device and to optimize the neutron yield.
Transient Chaos
Transient chaos is chaotic motion with a finite duration. Its transient nature means that it cannot be studied using standard asymptotic methods. The Bunimovich stadium billiard is a system that displays transient chaotic behaviour. This system consists of an infinite number of point particles that reflect from the stadium boundary. By introducing a moving leak into the boundary of the stadium billiard we can study how particle dynamics evolve within the billiard.