title: Analysis of bifurcation phenomena in the electron internal transport barrier in the large helical device.
abstract: The electron internal transport barrier (eITB) formation in the Large Helical Device (LHD) is studied with the transport code TOTAL and a GyroBohm-like model. The reduction of anomalous transport by the E x B shear has been introduced by means of the factor [1 + (tauomega(ExB))(gamma)](-1). Simulation results show a clear critical transition between plasma regimes with rather flat electron temperature profiles (non-) to a steeped one (with eITB) when average density is low enough. With the aim of studying the eITB formation as a phase transition phenomenon, the electron average density is taken as the control parameter and the E x B shearing rate as the order parameter. Results show how the eITB formation in LHD is compatible with a continuum phase transition with critical exponent beta = 0.40.
authors.affiliation: Fusion Energy Engineering Laboratory, FEEL, Departament de Física i Enginyeria Nuclear, ETSEIB, Universitat Politècnica de Catalunya, UPC, Barcelona, Spain.
authors.forename: J
authors.initials: J
authors.lastname: García
authors.forename: K
authors.initials: K
authors.lastname: Yamazaki
authors.forename: J
authors.initials: J
authors.lastname: Dies
authors.forename: J
authors.initials: J
authors.lastname: Izquierdo