Beta: Difference between revisions
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== Normalized beta == | == Normalized beta == | ||
The normalized beta (or Troyon factor) is an operational parameter indicating how close the plasma is to reaching the [[Greenwald limit]] or destabilizing major MHD activity. Its definition is (for tokamaks): | The normalized beta (or Troyon factor)<ref>[[doi:10.1088/0741-3335/26/1A/319|F. Troyon, R. Gruber, H. Saurenmann, S. Semenzato and S. Succi, ''MHD-Limits to Plasma Confinement'', Plasma Phys. Control. Fusion '''26''' (1984) 209]]</ref> is an operational parameter indicating how close the plasma is to reaching the [[Greenwald limit]] or destabilizing major MHD activity. Its definition is (for tokamaks): | ||
<ref>K. Miyamoto, ''Plasma Physics and Controlled Nuclear Fusion'', Springer-Verlag (2005) ISBN 3540242171</ref> | <ref>K. Miyamoto, ''Plasma Physics and Controlled Nuclear Fusion'', Springer-Verlag (2005) ISBN 3540242171</ref> | ||
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* [[Internal inductance]] | * [[Internal inductance]] | ||
* [[:Wikipedia:Beta_(plasma_physics)]] | |||
== References == | == References == | ||
<references /> | <references /> | ||
Revision as of 20:59, 13 August 2012
Plasma performance is often expressed in terms of beta (β), defined as: [1]
i.e., the ratio of the plasma pressure to the magnetic pressure. Here, <p> is the mean plasma pressure, and B the mean total field strength. It is customary to introduce also the poloidal β (βp) and the toroidal β (βt), in which B is replaced by the poloidal and toroidal magnetic field component, respectively. One has:
Normalized beta
The normalized beta (or Troyon factor)[2] is an operational parameter indicating how close the plasma is to reaching the Greenwald limit or destabilizing major MHD activity. Its definition is (for tokamaks): [3]
where B is in T, a in m, and Ip in MA. Typically, the maximum value of βN before the onset of deleterious instability is 3.5, although significantly higher values have been achieved. [4]
See also
References
- ↑ J.P. Freidberg, Plasma physics and fusion energy, Cambridge University Press (2007) ISBN 0521851076
- ↑ F. Troyon, R. Gruber, H. Saurenmann, S. Semenzato and S. Succi, MHD-Limits to Plasma Confinement, Plasma Phys. Control. Fusion 26 (1984) 209
- ↑ K. Miyamoto, Plasma Physics and Controlled Nuclear Fusion, Springer-Verlag (2005) ISBN 3540242171
- ↑ S.A. Sabbagh et al, Resistive wall stabilized operation in rotating high beta NSTX plasmas, Nucl. Fusion 46 (2006) 635-644