2004 was a productive year – the group
moved into purpose-built laboratories in the new Weigold
wing, work began on recasting the business plan to suit the operational phase
of the facility, and the automation of H-1 was largely completed. Automation by the use of programmable logic controllers
accelerates data-taking, improves the quality of data by extensive logging of
measurements, and reduces the manpower required to operate the H-1 facility. As a result over 3,100 plasma pulses were
recorded, amounting to 20 Gigabytes of raw data. New systems
included a directional gas injection system (DISH – section III) and an ECRH
incident energy monitor.
The heliac is also being used to develop
experimental techniques that can be applied on large-scale international fusion
experiments. Dr. John Howard and
his colleagues in the Advanced Imaging and Inverse Methods Group have developed
a series of instruments known as coherence imaging spectrometers. These are novel imaging spectrometers that
use electro-optic technology and advanced image and signal processing to
determine temperatures and flows in radiating media such as plasmas. This
year Dr Howard has expanded the development of novel multi-spectral imaging
systems with two recent provisional patents on instruments suitable for
industrial colour pyrometry for temperature and emissivity imaging, and for
high-speed high-resolution spectroscopic imaging. Cameras similar to those successfully
employed on the H-1 heliac, and optimized for high-speed plasma Doppler studies
have been sold to Consorzio RFX Italy, Max Planck Institute
for Plasma Physics (
Ground-breaking experimental studies of
plasma turbulence in the heliac by Dr. Michael Shats and his colleagues
demonstrated the role of self-organisation, zonal flows and spectral energy
transfer in regulating the outward transport of particles and achieving
enhanced plasma confinement. This
physics is essential to achieving efficient confinement of fusion plasmas, but
is also a universal phenomenon in complex dynamical systems, such fluid flows
and both Earth and planetary atmospheric physics, and is a rapidly developing
research area worldwide. The heliac has
been shown to be a uniquely effective experimental environment for precise
studies of these phenomena.
The computer controlled precision magnet
power supplies (12,000,000 Watts) together with the above-mentioned automation allow
precise adjustment of the complex magnetic geometry. With a large operational range of magnetic
fields (>20:1), gases, and the variety of heating systems,
H‑1NF is the most flexible
plasma machine in the world. This facilitates
detailed investigation of the effect of spatial resonances on magnetic
configuration and confinement. Experiments
carried out by Dr. Boyd Blackwell, Prof. Jeffrey Harris and their
colleagues demonstrated the sensitivity of confinement and fluctuations to
these resonance effects, and a related collaborative experiment on the large
D3D tokamak facility in the USA demonstrated the use of spatially-resonant
magnetic fields to control the stability of the plasma edge to sudden pulses of
heat and particle flux which present control problems for fusion reactors.