Triangularity: Difference between revisions

Revision as of 14:24, 17 June 2014

Sketch of tokamak geometry, including separatrix

The triangularity refers to the shape of the poloidal cross section of the Last Closed Flux surface (LCFS) or separatrix of a tokamak. Assuming^[1]:

R_max is the maximum value of R along the LCFS or separatrix.
R_min is the minimum value of R along the LCFS or separatrix.
R_geo is the geometric major radius, defined as (R_max + R_min)/2.
a is the minor radius of the plasma, defined as (R_max - R_min)/2.
R_upper is the major radius of the highest vertical point of the LCFS or separatrix.
R_lower is the major radius of the lowest vertical point of the LCFS or separatrix.

The upper triangularity is then defined as follows:

\delta _{upper}=(R_{geo}-R_{upper})/a

and similar for δ_lower. The overall triangularity is defined as the mean of δ_upper and δ_lower.

@@ Line 6: / Line 6: @@
 * ''R<sub>geo</sub>'' is the geometric major radius, defined as ''(R<sub>max</sub> + R<sub>min</sub>)/2''.
 * ''a'' is the minor radius of the plasma, defined as ''(R<sub>max</sub> - R<sub>min</sub>)/2''.
-* ''R<sub>upper</sub>'' is the major radius of the highest vertical point of the LCFS.
+* ''R<sub>upper</sub>'' is the major radius of the highest vertical point of the LCFS or separatrix.
-* ''R<sub>lower</sub>'' is the major radius of the lowest vertical point of the LCFS.
+* ''R<sub>lower</sub>'' is the major radius of the lowest vertical point of the LCFS or separatrix.
 The upper triangularity is then defined as follows:
 :<math> \delta_{upper} = (R_{geo}-R_{upper})/a</math>