A HELIAS-HELIAC HYBRID STELLARATOR

Placing an l = 1 continuous helical coil with a pitch modulation in an axisymmetric toroidal magnetic field, a helical axis configuration wa s obtained with characteristics similar to the Helias configuration fo r Wendelstein 7-X (W7-X). In the four pitch case, a device with an asp ect ratio of 4-5 and good accessibility becomes possible, although a v ery weak magnetic hill exists. In a particular finite beta magnetohydr odynamic (MHD) equilibrium, the magnetic well appears in the whole reg ion for a central beta value of beta(0) approximately 1%. About a quar ter of the particles at half radius are lost at beta = 0; however, bot h the radial electric field and the finite beta effect improve the par ticle orbit confinement significantly. The possibility of an open dive rtor is shown.