Culham Electron Cyclotron Model | culecd()

• iefrf/iefrffix = 7

This routine calculates the current drive parameters for a electron cyclotron system, based on the AEA FUS 172 model¹

1. Local electron temperature $(\mathtt{tlocal})$ is calculated using the teprofile method

2. Local electron density $(\mathtt{dlocal})$ is calculated using the neprofile method

3. Calculate the inverse aspect ratio epsloc.

$$\mathtt{epsloc} = \frac{1}{3A}$$

1. Calculate the Coulomb logarithm for ion-electron collisions coulog.²

$$\mathtt{coulog} = 15.2 - 0.5\log({\mathtt{dlocal}}) + \log({\mathtt{tlocal}})$$

Calculate normalised current drive efficiency at four different poloidal angles, and average. cosang = cosine of the poloidal angle at which ECCD takes place = +1 outside, -1 inside.

Normalised current drive efficiency

Uses the eccdef model found here

1. Calculate the normalised current drive efficiency at four different poloidal angles, and average. - Set cosang to 1.0 and calculate ecgam1. - Set cosang to 0.5 and calculate ecgam2. - Set cosang to -0.5 and calculate ecgam3. - Set cosang to -1.0 and calculate ecgam4.

   cosang = 1.0e0
   ecgam1 = self.eccdef(tlocal, epsloc, zlocal, cosang, coulog)
   cosang = 0.5e0
   ecgam2 = self.eccdef(tlocal, epsloc, zlocal, cosang, coulog)
   cosang = -0.5e0
   ecgam3 = self.eccdef(tlocal, epsloc, zlocal, cosang, coulog)
   cosang = -1.0e0
   ecgam4 = self.eccdef(tlocal, epsloc, zlocal, cosang, coulog)
   

2. Calculate the normalised current drive efficiency ecgam as the average of ecgam1, ecgam2, ecgam3, and ecgam4.

$$\mathtt{ecgam} = 0.25(\mathtt{ecgam1} + \mathtt{ecgam2} +\mathtt{ecgam3} + \mathtt{ecgam4})$$

1. Calculate the current drive efficiency by dividing ecgam by (dlocal * physics_variables.rmajor).

$$\text{Current drive efficiency [A/W]} = \frac{\mathtt{ecgam}}{\mathtt{dlocal} \times R_0}$$

Note: The eccdef method is called to calculate the current drive efficiency at each poloidal angle.

---

1. Hender, T.C., Bevir, M.K., Cox, M., Hastie, R.J., Knight, P.J., Lashmore-Davies, C.N., Lloyd, B., Maddison, G.P., Morris, A.W., O’Brien, M.R. and Turner, M.F., 1992. "Physics assessment for the European reactor study." AEA FUS, 172. ↩

2. Wesson, J. and Campbell, D.J., 2011. "Tokamaks" (Vol. 149). Oxford university press. ↩