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title:Coating
categories: Infrastructure
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<p>The coating is one of the plasma vessel layers. Unlike the <a href="../Liner/AAAindex">liner</a>, it is possible to see coating from the outside. Because it is made of copper, it has 
characteristic  bronze colour. The main function of the coating is to raise the plasma stability. This is done thanks to inductive nature of copper. Should the plasma instabilities take place, 
as they always do, there will be auto-induced Foucault electrical currents in the coating, which will resultantly influence the plasma column flow. Together with <a href="../../Coils/Stabilization/coils_stabilisation">
stabilisation coils</a> is part of all-important magnetic feedback which allows plasma confinement for much longer than without this system. Another positive side effect of the coating material is, 
that it protects plasma from outer dissipative magnetic fields.</p>
<p>As was said before, the coating is made of copper toroid, main radius 40 cm, secondary radius 10 cm with inner diameter of 245 mm. The copper layer is 15-20 mm strong, much stronger than 
the layer of the liner. The coating is made of several insulated, independent segments integrated together. The coating was constructed in a such way, that 
would be possible to disassemble its construction into two independent sections. This is mainly used for maintenance, however, this process of disablement did take place only once before. 
On the coating there are also mounted 28 <a href="../../Coils/ToroidalMagneticField/coils_toroidal">toroidal field generation coils</a> and pipes of the cooling system, which can be easily seen.</p>
<p>In the past, the coating was used to keep another layer of <a href="/predecessor-CASTOR/Vacuum/vacuum">vacuum</a> in the tokamak <a href="../chamber">chamber</a> between coating and liner. 
The vacuum level was about 10<sup>-3</sup> Pa, which was the value allowed by the pressure insulation of the coating. It was believed that the next layer 
of vacuum would help to raise the plasma stability. However, after proving this theory to be wrong and integration of stabilisation coils 
the vacuum exhaustion system for coating vacuum was removed.</p>
<h3>References</h3>
<ol>
<li><strong>Bardos L., Datlov J., Kopecky V., Kryska L., Musil J., Zacek F. : </strong><a href="/Introduction/History/1977-1984%20TM1-MH/Tomakak%20TM-1-MH%20Ustavni%20zprava%20UFP%2035l77.pdf">Experimental device Tokamak TM-1-MH</a></li>
</ol>
<h3>Current status of the system</h3>
<p>There have never been any problems with the liner. Since the chamber was not disassembled during its transportation, it was not necessary to assemble anything on coating. All the coils stayed as 
they were, installed on coating. So the coating is ready for operation as it was on <a href="http://www.ipp.cas.cz/">IPP CAS</a> premises.</p>
<h3>Images</h3>
<table>
	<tr>
	<td><div align="center"><a href="cimg7944.jpg" ><img src="cimg7944.jpg" width="100" height="150" border="0"/></a></div></td>
	<td><div align="center"><a href="cimg7969.jpg" ><img src="cimg7969.jpg"  width="100" height="150" border="0"/></a></div></td>
	<td><div align="center"><a href="cimg7940.jpg" ><img src="cimg7940.jpg"  width="200" height="134" border="0"/></a></div></td>
	</tr>
</table>