Overcoming the Impossible: Developing Nuclear Fusion

The ITER project, an acronym for International Thermonuclear Experimental Reactor,  seeks to do the possible with impractical tools. There is no doubt that humanity can accomplish fusion in a quick and dirty way by making a bomb, or run reactions that don’t produce useful amounts of energy outputs, but unlike fission the ability to run a steady state reaction that produces more energy than it takes to drive the reaction eludes us.

The ITER effort is based on the tokamak, a donut looking thing that circulates fuel plasma around endlessly at temperatures and pressures that could get a net energy gain if the fuels are hot enough and at high enough pressure.  It really is the leading way to get to solar temperatures and pressures here on earth.  It is very possible – and incredibly impractical.

ITER has the money to worry away at the problem.  Very hot, light element plasmas, and incredible pressures are huge problems. Hydrogen at room temperature is a devil to contain for any length of time, warm it up to perhaps billions of degrees and pressurized to perhaps millions of atmospheres and the control problems are, shall we say, monumental.

Still, the tokamak is the strongest potential to get to hot fusion containment. To solve the control problems electronics engineer Maria Goretti Sevillano has come up with some tools in her thesis defended at the University of the Basque Country. Her thesis is entitled Tools for plasma control in Tokamak nuclear fusion reactors: Astra-Matlab integration and control in real time.  Two papers have been published about her work, one in the journal Informatica and the other in the journal Energy.

Maria Goretti Sevillano
Maria Goretti Sevillano

Sevillano has detailed how they function: “The materials used in fusion must have certain specific features, and these materials have to be turned into plasma. At the same time, the plasma has to be restricted to a limited space to enable the reaction to be generated and the energy to be used. To achieve this, magnetic confinement is applied in the case of the tokamaks.” In other words, the magnetic field creates lines that act as a wall to keep the plasma in the space where it is meant to remain. But the plasma and the device itself have several problems that have yet to be solved, and Sevillano has been working on some of them.

Sevillano explains, “To develop Tokamaks, many of the plasma’s parameters must be controlled, as well as the whole device itself; the currents that are going to be used, the voltage, the intensity, etc. Until all these things are controlled, it will not be possible to use these machines to produce marketable energy,” she points out.

In connection with this, Sevillano has embedded a code known as ASTRA into the Matlab software; ASTRA is frequently used to simulate the behavior of Tokamak reactors, and the embedding of this code into Matlab will facilitate the development of controllers suited to these devices. The control problems are of several kinds, but in this case some very specific parameters relating to the plasma have been explored in depth.

Sevillano continues, “Control of the parameters is necessary to obtain the maximum energy possible from the plasma, and the amount of this energy that can be extracted is calculated on the basis of the current: the greatest amount of current possible has to be maintained during the longest time possible. That is why these parameters have to be controlled by means of the control, in turn, of the numerous coils and voltages within the structure.”

Sevillano points out that her PhD thesis has produced only a single branch of what would be a complete tree by saying, “All I have achieved is no more than a step towards doing more things. The aim of all these tasks is to design a machine capable of generating marketable energy within the ITER project.”

Its an awe inspiring challenge with a five decade history stacked up so far and the scientists calculate they will obtain some results around the year 2050, some four more decades.

Tokamak and Problems.
Tokamak and Problems.

Fusion is a tantalizing power source and emulating the sun seems a logical and sensible path.  Fusion is possible, we use its’ natural form continuously.  Yet the primary question remains unanswered.  By what means can humanity get matter to fuse?  Then, which is the most practical?

Taxpayers in the EU, India, Russia, China, South Korea, Japan and the United States must wonder how the political momentum got so far on such thin practical certainty.   French Nobel laureate in physics, Pierre-Gilles de Gennes, said, “We say that we will put the sun into a box. The idea is pretty. The problem is, we don’t know how to make the box.”

The building of the tokamak has begun, with no clear idea how to control it successfully.  Whether or not Sevillano’s concepts will make a difference is a question to be answered years out.

Meanwhile the basic question about what the most practical means are to generate fusion is off limits for most of the research world.  The research system is very serious about the ITER project – the competency and credibility of the research system’s desire to get to the goal of commercial fusion is not.

By. Brian Westenhaus

Source: Fusion- Where the Possible Meets Impractical

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Posted by on May 9 2012. Filed under Headlines. You can follow any responses to this entry through the RSS 2.0. You can leave a response or trackback to this entry

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