Bachelor- and master theses

The scope of the topics can be adjusted. Feel free to contact us.

• 28 GHz gyrotron installation for TJ-K needs high power dummy load for testing and conditioning
• Adapt existing design of cylindrical box with water-filled teflon hoses to this frequency
• Build and test design

• For the 2D version
• Hexagonal grid: finite difference time domain (FDTD) scheme exists for vacuum, need to add plasma effects, UPML absorbing boudary conditions
• 4^th order methods: central differences in time and space AND coupling to plasma, simultaneous 4^th order (simultaneous may not be possible)

• Microwave beam sent to plasma with several receiving antennas
• Each receiving antenna defines different beam geometry, probing a different poloidal position
• Correlation of signals from different positions yields poloidal rotation direction or the pitch angle of magnetic field lines
• Turbulence from codes can be used as input for realistic scenarios

• Mitre-bends are the typical waveguide components for highly oversized waveguides because they are more compact than continuous bends
• For moderately oversized waveguides, diffraction effects can partly be compensated with quasi-optical designs
• Quasi-optical mitre-bends can accurately be calculated with PROFUSION.
• The work consists of parameter studies for different ratios of wavelength and waveguide diameter and the investigation of the broadband performance.

• Rectangular waveguides have imaging properties, which allow the design of remote steering antennas for the heating of fusion plasmas
• The angular range is, however, limited to about +/- 12°.
• By choosing a slightly deformed waveguide cross-section, the dispersion relation of the modes can be changed, leading to a possibly enlarged steering range.
• An eigenmode solver for deformed cross sections is already available and can be used for parameters studies.

• ECE plasma diagnostics work in wide frequency bands that include the multi-megawatt ECR heating system frequency
• Narrow band notch filters with +80dB rejection at the heating frequency are necessary to protect the delicate diagnostic receivers
• Waveguide notch filters are an established technology, but such waveguides typically only support bandwidths of about 1 octave, but the diagnostic signal spans several octaves (e.g. ECE fundamental plus 2 harmonics)
• A new optical filter design using only highpass elements combined with an interferometer setup promises ultrawide passbands
• The work in this topic includes simple and fullwave modelling of the device and an assessment of the performance in the presence of alignment errors
• Time permitting, a prototype can be build and measured