ProfessorBoris Kuhlmey

Project Opportunities

Title:  Stabilizing lightsails 

Summary of opportunity:

Proxima Centauri is the closest star to the Sun, and is orbited by a planet that could cost harbour liquid water and even life. How can we explore this system? At more than 4 light years away, it would take thousands of years to send a probe with current rocket technology. The travel time could be brought down to 20 years using reflective lightsails accelerated to 20% of the speed of light by gigantic earth-based lasers. There are many practical and conceptual challenges that must be overcome for this to become a reality. One of these challenges is sail stability. The stochastic perturbations of the laser beam unavoidably lead to sideway motion and to torques which could cause the sail to veer off. This can be overcome by sail designs that are self-correcting, and exploit relativistic effects for damping residual oscillations. Such effects are intrinsically weak, but can be enhanced with metasurfaces. This theoretical and numerical PhD project will use relativistic mechanics, optics and electromagnetism, to design metasurface-based sails, and develop dynamical simulation and statistical tools to assess and optimise their motion in the presence of perturbations.

Title: Structuring textiles for radiative cooling

Summary of opportunity:

Clothing keeps us warm not only because they limit convection and evaporation, but also because they absorb and re-emit thermal radiation of the sun and from our own body. Even the lightest, whitest cotton shirt will still absorb 40% of the sun’s heat, and reflect half of our own body’s radiative heat back towards our skin, creating a local personal greenhouse effect. Radiative properties can be modified through nanostructuring, and with the right modifications even sustainable fabrics such as cotton, wool or bamboo fibre could be made to have increased reflectivity over the solar spectrum, and high transparency in the mid-infrared, letting our body heat escape. A textile with such radiative properties would feel cooler in the sun than exposed skin, and could even reduce the need for air conditioning indoors, thereby reducing energy consumption in a warming world. 

This theoretical and numerical project will investigate radiative properties of aperiodic nanostructured natural materials, in close collaboration with experimental colleagues making and characterising radiative cooling textiles. The successful candidate will have a strong affinity for mathematical methods and coding. 

Opportunity synopsis:

This theoretical and numerical project will investigate radiative properties of aperiodic nanostructured natural materials, in close collaboration with experimental colleagues making and characterising radiative cooling textiles. The successful candidate will have a strong affinity for mathematical methods and coding. 

For more information, contact me at boris.kuhlmey@sydney.edu.au. Please indicate why you think you are suitable for the project, and include your CV, academic transcripts, and a master's thesis or internship report as a single pdf. If the master's thesis or internship report is not yet completed, a draft or report from any previous research experience is suitable.

----------Current Research Projects----------

• Starshot - lightsail mechanical stability (in collaboration with Martijn de Sterke, Alex Song and Michael Wheatland)
  See our recent papers: All-optical damping forces enhanced by metasurfaces for stable relativistic lightsail propulsion; Relativistic damping of laser-beam-driven light sails ; Self-stabilization of light sails by damped internal degrees of freedom
• Textiles for radiative cooling, with Alex Song, Martijn de Sterke, Simon Fleming, Maryanne Large, Alessandro Tuniz, Chiara Neto, Ollie Jay, Arianna Brambilla
• THz cavities for electron-photon quantum coupling, with Juliette Mangeney, Alessandro Tuniz
• Physics of evanescent fields (with Alessandro Tuniz, Martijn de Sterke and the Institut Frensel, Marseille, France)