  The RFP is a toroidal magnetic configuration in which plasmas can
spontaneously transform into different self-organized states. Among various
states, the QSH state has a dominant component for the magnetic field and
significantly improves confinement. Many theoretical and experimental efforts
have investigated the transitions among different states. This paper employs
the MRxMHD model to study the properties of QSH and other states. The SPEC is
used to compute MHD equilibria for the KTX. The toroidal volume of KTX is
partitioned into two subvolumes by an internal transport barrier. The geometry
of this barrier is adjusted to achieve force balance across the interface,
ensuring that the plasma in each subvolume is force-free and that magnetic
helicity is conserved. By varying the parameters, we generate distinct
self-organized states in KTX. Our findings highlight the crucial role of
magnetic helicity in shaping these states. In states with low magnetic helicity
in both subvolumes, the plasma exhibits axisymmetric behavior. With increasing
core helicity, the plasma gradually transforms from an axisymmetric state to a
double-axis helical state and finally to a single-helical-axis state. Elevated
core magnetic helicity leads to a more pronounced dominant mode of the boundary
magnetic field and a reduced core magnetic shear. This is consistent with
previous experimental and numerical results in other RFP devices. We find a
linear relationship between the plasma current and helicity in different
self-organized states. Our findings suggest that KTX may enter the QSH state
when the toroidal current reaches 0.72 MA. This study demonstrates that the
stellarator equilibrium code SPEC unveils crucial RFP equilibrium properties,
rendering it applicable to a broad range of RFP devices and other toroidal
configurations.
