# Physics projects for Y3 and Y4 students

## Project description

### Magnetic confinement

#### (supervisor: Rudi Winter)

Nature of project: experimental, theory

Available to students on full-time physics degree schemes only.

#### Project description and methodology

Fusion reactors require a hot plasma to be shaped and confined to a prescribed volume. If the plasma touches the reactor walls, it would lead to physical damage to the reactor as well as loss of energy in the plasma, ending the fusion reaction. Since plasma consists of charged particles, it is possible to confine a plasma using strong magnetic fields. In addition to protecting the reactor vessel, the shape of the confinement volume also determines how efficient a fusion reaction can be, by concentrating the plasma in certain hot spots. The most common confinement designs used in fusion research are the tokamak and stellarator geometries.

In this project, we will investigate how various coil geometries produce differently shaped magnetic fields. Geometries to be studied include toroids, starship coils and a Rodin geometry. This allows us to keep the length of wire and core volume to be constant while manipulating the shape of the field produced.

The three-dimensional shape of the magnetic field will be measured quantitatively using a sensor rig built from several magnetometer (digital magnetic compass) chips controlled by a Raspberry. Therefore, designing, building and testing the sensor rig is an important component of this project.

For the core component of this project, the rig will then be used to measure and plot the magnetic field of a simple toroid and one other geometry.

A successful project will develop beyond the above in one/some of the following directions:
Further geometries could be investigated, such as a systematic study of the effect of progressively adding corners to the starship coil design.

Theoretical distributions of magnetic field could be arrived at either algebraically (starting from Ampere's law) or by computer simulation, which could then be compared with the experimental results.

When considering where to take your project, please bear in mind the time available. It is preferable to do fewer things well than to try many and not get conclusive results on any of them. However, sometimes it is useful to have a couple of strands of investigation in parallel to work on in case delays occur.

Additional scope or challenge if taken as a Year-4 project: A Y4 student would be expected to produce calculated or simulated magnetic field distributions and discuss their relationship with the experimental results obtained.

Please speak to Rudi Winter (ruw) if you consider doing this project.

Initial literature for students:

1. R Alexander, PR Garabedian; PNAS 104 (2007) 12250
2. Yuhong Xu; Matter and Radiation at Extremes 1 (2016) 192

#### Novelty, degree of difficulty and amount of assistance required

This project combines challenging experimental as well as theoretical aspects. While measurements of magnetic fields are routinely done, calibrating the sensor to obtain quantitative vector data will be difficult.

#### Project milestones and deliverables (including timescale)

milestoneto be completed by
coil and sensor designs finalisedend of November
sensor rig calibratedend of February
measurements taken on at least two coil designsmid-March
data plotted, interpreted and compared with theory/simulationEaster

Students taking this project will have to submit a full risk assessment form