Can we constructing a small system of heat generating fusion plant using tokamak magnetic confinement geometry, to produce a winding field in some ways similar to that in a modern stellarator, in the lab?
How small do you want it?
The TBR-1 tokamak [1] had major radius (R) and plasma radius (a) equal to 0.3m and 0.08m. It was constructed in the Plasma Physics Laboratory of University of São Paulo, Brazil [2]. TBR-1 was smaller than the STOR-M tokamak (R=0.46m, a=0.125)[3], which was, according to [4], the smallest tokamak that demonstrated some of the features of H-mode.
Small tokamaks are used primarily for studies of scale law, development of diagnostic tools and techniques, and training of people, since it is not able to produce nuclear fusion reactions due to the low values of key plasma parameters (density, temperature and confinement time) that it can reach.
[1] http://link.springer.com/article/10.1007/BF01079673
[2] http://www5.usp.br/english/?lang=en
[3] http://plasma.usask.ca/fusion/storm.php
[4] http://home.clara.net/balshaw/tokamak/records.htm
To get a fusion relevant environment within the tokamak, the triple product (nTte) criterion has to be achieved. This may not be possible with a small tokamak. The bottleneck may not entirely by physics, but to some extent engineering challenges as well.
The following article explains this concept with a good depth.
http://iopscience.iop.org/journal/0741-3335/labtalk/article/65005
Here is another (even smaller) tokamak from ancient history (R/a=0.22m/0.035m). The device was originally a plasma betatron. It may still exist somewhere!
Article The STOR-1M Tokamak: Experiments on Current Reversal and Fas...
I have seen with my own eyes (in an armoir of ENEA Centro Ricerche Energia - Frascati, Italy) the remains of THORELLO, a small toroidal chamber for magnetic confinement of plasmas, with radius not larger than 20 cm. It had been originally conceived for training on Langmuir probes. I guess Prof. Gabriele Chiodini, a particle physicist now at INFN and who is working on ATLAS, used to work with it - see e.g. Chiodini, G., C. Riccardi, and M. Fontanesi. "A 400 kHz, fast-sweep Langmuir probe for measuring plasma fluctuations." Review of scientific instruments 70.6 (1999): 2681-2688. .
Small Tokamak ETE in Brazil:
Technical Report PROJETO E ANÁLISE DOS CIRCUITOS DE PRODUÇÃO DE CAMPO MAGNÉTI...
Conference Paper PAPER: THE ETE SPHERICAL TOKAMAK - PRESENT STATUS CONSTRUCTI...
Conference Paper PAPER: STATUS OF CONSTRUCTION OF THE ETE SPHERICAL TOKAMAK #...
Conference Paper PAPER: THE ETE SPHERICAL TOKAMAK PROJECT ### ARTIGO: O ETE P...
Conference Paper PAPER: PULSED ELECTRIC SYSTEM FOR PRODUCTION AND CONFINEMENT...
Conference Paper PAPER: OVERVIEW AND INITIAL RESULTS OF THE ETE SPHERICAL TOK...
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