Product category:
Drives, motors and power transmission, couplings, clutches
News Release from: Hoerbiger-Origa | Subject: Drives and actuators
Edited by the Manufacturingtalk Editorial
Team on 05 November 2002
Drives and actuators help on road to
clean power
The world's most advanced plasma fusion experiments, being undertaken use drives and actuators that can withstand strong vacuum forces and magnetic fields, yet remain fast and accurate.
The world's most advanced plasma fusion experiments, being undertaken by scientists and engineers at the Culham Science centre in Oxfordshire, use drives and actuators from Hoerbiger-Origa that can withstand strong vacuum forces and magnetic fields, yet remain fast and accurate Fusion is the process by which the sun produces heat and light - within a very hot gas or plasma
This article was originally published on Manufacturingtalk on 19 Apr 2004 at 8.00am (UK)
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If harnessed on Earth, fusion has the potential to provide almost unlimited clean, secure energy.
Culham has been developing fusion plasma experiments and technologies with the Joint European Torus (JET) project for almost 20 years, and has recently begun its new MAST (Mega Amp Spherical Tokamak) programme.
One of the requirements of the MAST experiments is to increase the duration of the plasma with high-energy microwaves created by an array of seven 200kW gyrotrons.
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This is difficult because absorption can only be affected at certain precise angles and through moveable 'z-windows'.
To achieve this the Culham scientists have built an Electron Bernstein Wave (EBW) launcher with an array of 21 steerable mirrors that can direct the microwaves to any point of the plasma.
Each of the seven gyrotron lines is equipped with three mirrors (x-y steerable) and a mirror polariser.
Movement of the mirrors is created by the servo driven ballscrew actuators upon which they are mounted.
The actuators were supplied by Hoerbiger-Origa from its standard OSP range and were chosen because of their superb engineering and robust design, which allows them to stand up to the mechanical torque and environmental conditions generated within the tokamak.
"The external design of the Hoerbiger-Origa units is such that mounting them in the close confines of the EBW launcher was simple yet highly accurate," explains Julian Hawes, one of the MAST researchers.
"Internally, we were looking for an actuator that could settle to its position accurately and virtually instantly so that we have time to conduct experiments and collect data as the plasma is generated for only one second.
There are mechanical limits to any mechanism, and we had to ensure that anything we designed was able to meet our specification.
In the future there may be experiments that require the mirrors to track the plasma.
Therefore, speed, repeatability and smooth operation are also important." Ultimately the actuators' performance is intrinsically linked to that of the servomotors and their controllers.
Hoerbiger-Origa was able to advise Culham that the Maxon motors they were intending to specify had already proved themselves on a number of joint projects in which the two companies had previously co-operated in the industrial arena.
By forging close working partnerships with companies like Maxon Motor, which offer complementary technologies, Hoerbiger-Origa can focussed on its core competencies without being constrained to providing solutions based only on its standard product offering.
Thus optimum bespoke solutions to specific needs can be created.
Each motor has its own controller, which communicates via an RS-485 link to a PC running a motion control and positioning programme configured so that any six motors can be moved simultaneously and interdependently.
The purpose of MAST is to potentially simplify and improve the design of future plants needed to create fusion, as scientist Chris Warrick explains: "Our original work with JET is well advanced and will be the backbone (through the next step device ITER) of first generation fusion power plants.
The innovative design of MAST may well (if experimental results are favourable) lead to second generation power plants.
We are working on all concepts simultaneously and hope to be producing commercial fusion power in 30-40 years; this is necessary if we are to keep up with growing world energy demand without choking the planet to death with pollution.
Ultimately the JET and MAST experiments will lead to a standard design 1 GW fusion power stations," In effect fusion releases energy by sticking together small atoms such as hydrogen, rather than by splitting large atoms as in fission.
As such the basic fuels are plentiful and freely available; fusion creates no greenhouse gases and few radioactive waste disposal problems because the activated material's half-life is barely 10 years.
Because there is no excess fuel in the plasma chamber, safety is high and, as there is no material that could be used in weapons, there is no potential terrorist threat.
The sun and indeed the majority of the universe is composed of plasma.
To utilise this in a usable form on Earth, the plasma has to be confined in a very strong and highly controlled magnetic field.
The idea behind Culham's work is to eventually use the energetic fusion neutrons that are ejected from the 150,000,000 degC plasma to heat a surrounding water blanket, create steam and drive a conventional turbine.
JET is already producing encouraging results and is the confirmed route (through ITER) to first generation power plants.
However, the doughnut-shaped torus it requires is large and complex and expensive.
The purpose of MAST is to simplify the design of the torus into a compact and simpler vessel within what is called a spherical tokamak, which is potentially cheaper to operate.
MAST has been built and experiments begun - in these experiments the plasma is generated for only one second every 15 minutes, much of the rest of the time being a cooling cycle.
Many years of experimentation and development lay ahead, but fusion is looking increasing like becoming a major plank in the world's energy strategy.
A network of small, low cost, safe fusion plants complementing the many forms of renewable energy that are also seeing accelerating development, could provide enough power to meet future needs for centuries to come. Request a free brochure from Hoerbiger-Origa ...
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