Anders Smith

Improving Magnet Designs With High and Low Field Regions

A general scheme for increasing the difference in magnetic flux density between a high and a low magnetic field region by removing unnecessary magnet material is presented. This is important in, e.g., magnetic refrigeration where magnet arrays have to deliver high field regions in close proximity to low field regions. Also, a general way to replace magnet material with a high permeability soft magnetic material where appropriate is discussed. As an example, these schemes are applied to a two dimensional concentric Halbach cylinder design resulting in a reduction of the amount of magnet material used by 42% while increasing the difference in flux density between a high and a low field region by 45%.

Magnetoresistance of a two-dimensional electron gas in a random magnetic field

We report magnetoresistance measurements on a two-dimensional electron gas made from a high-mobility GaAs/

Solution of the Boltzmann equation in a random magnetic field.

{\mathrm{Al}}_{\mathit{x}}

Magnetoresistance of a two-dimensional electron gas in random magnetic fields

{\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathit{x}}

Optimising Magnetostatic Assemblies

As heterostructure, where the externally applied magnetic field was expelled from regions of the semiconductor by means of superconducting lead grains randomly distributed on the surface of the sample. A theoretical explanation in excellent agreement with the experiment is given within the framework of the semiclassical Boltzmann equation.

Worldwide SOFC Overview from a Scandinavian and a European Perspective

A general framework for solving the Boltzmann equation for a 2-dimensional electron gas (2DEG) in random magnetic fields is presented, when the random fields are included in the driving force. The formalism is applied to some recent experiments, and a possible extension to composite fermions at

Structural instabilities in the t-J model.

\nu=1/2

Magnetocaloric materials and first order phase transitions

is discussed.

Using a Linux Cluster for Parallel Simulations of an Active Magnetic Regenerator Refrigerator

The magnetic force between a permanent magnet and different blocks of ferromagnetic materials was measured and calculated as a function of distance and temperature in the vicinity of the Curie temperature of the materials. The calculations were carried out using a 3-D finite-element model of the system. On the basis of forces predicted by the model a number of equilibrium points were calculated for a system where the magnetic force on a ferromagnetic block of material is balanced by a linear spring force. It is shown how these calculation procedures can be used as a tool for designing autonomous temperature dependent and temperature adjustable actuation systems. A shunt valve utilizing such a system was designed, built and tested.