|Energy confinement time and estimation of the heating system in UST_1|
Abstract : The energy confinement time for UST_1 and for other real experiments is calculated. The heating system is outlined.
Calculations in UST_1
Some scenarios are calculated and analysed:
Estimation of the heating system
In order to manufacture the vacuum vessel, a rough idea of the heating system is necessary.
ICRH is not considered due to the big antennas.
NBI is not possible due to cost and complexity.
ECH is the only alternative. For Bo = 0.1T , value calculated in , we have:
Electron cyclotron frequency = 2.8GHz. (For B=0.5 it is 14GHz)
Cut off density ~ 2x 10^17
In WEGA a simple heating system is described . They use a 2.45GHz magnetron which has the same frequency as the one in a commercial microwave oven. This is supposed to be the cheapest alternative. Some data reflects a cost of 2 - 4$ per watt injected by means of scientific generators. This cost is excessive.
Bo = 0,0875 is selected in , maybe, to obtain 2.45Ghz as electron cyclotron frequency.
A metallic circular tube is used as a waveguide, sometimes with a modified tip. Diameter of the tube towards the chamber = 85mm. Power of the system = 6kW.
* ECH is the only heating candidate. One or two 40mm diameter ports should be sufficient for one or two 1kW emitters.
* Alternative F is the most feasible. In the others the minor radius "a" is scaled with CTH plasma but this optimised wide plasma has not been obtained yet for UST_1 . One or two 1kW standard magnetrons will suffice (supposition P inyected / Pabsorbed = 10% -20% ). Heating should be possible at 1 x1017m-3, having little influence the cut off frequency . Higher densities would need mode conversion .
* Table1 shows that notable increments in “T” or "ne" cannot be achieved even installing 4 * 1Kw magnetrons.
The heating system will be further studied and built.
 Stellarator news , nº 92 , May 2004
 “Design and construction progress of the compact toroidal hybrid" Hartwell, G.J., Knowlton, S.F. Watts, C.Hanson, J.D., Brown, T.
 "Study of Impurity Influx of H-mode Plasma in Hot-Cathode-Biasing Experiment in the Tohoku University Heliac" , TANAKA Yutaka, KITAJIMA Sumio, et al. J. Plasma Fusion Res. SERIES, Vol. 6 (2004)
 "Study of Magnetic Fourier Components Effect on Ion Viscosity in Tohoku University Heliac" , S. Kitajima, H. Takahashi, Y. Tanaka, et al. . Stellarator workshop 2005
 Stellarator news , nº 54
 "First results from the WEGA stellarator" J. Lingertat, K. Horvath, H. P. Laqua, M. Otte, Y. Podoba, F. Wagner
 "Electron cyclotron heating at the WEGA stellarator" Y. Podoba, K. Horvath, H.P. Laqua, J. Lingertat, F. Wagner
 "Fusion research", Dolan , Chapter 14A, pg 405
 Forces on HF coil of the first outline of the UST_I Vicente M. Queral . See “All Past R&D"
 Influence of coil misalignments and manufacturing errors in magnetic surfaces , Vicente M. Queral . See “All Past R&D"
 "Stellarator and heliotron devices", Masahiro Wakatami, pg 401
Last Update 19-11-2005