Investigating the characteristics of high heat-flux plasma beams is essential for the development and testing of first-wall materials in future fusion reactors. This study conducts experimental research using the linear plasma device HIT-PSI. By systematically adjusting external discharge parameters (confinement magnetic field, discharge current, and gas flow rate), the discharge characteristics of a high-power cascaded arc source and the heat flux characteristics of the plasma beam are investigated. Results show that: (1) the discharge voltage of the cascaded arc source increases significantly with rising magnetic field and discharge current; (2) the influence of gas flow rate on the discharge voltage exhibits a non-monotone trend, primarily affected by the confinement magnetic field; (3) the heat flux increases with magnetic field and discharge current but decreases as gas flow rate rises. The HIT-PSI platform generates steady-state plasma beams with heat flux up to 40 MW·m−2 under the 2.0 T magnetic field, demonstrating its capability to simulate extreme high heat-flux environments (>10 MW·m−2). This platform is suitable for plasma-facing component/ materials irradiation testing, novel material development, and plasma-material interaction research for future fusion reactors and spacecraft applications.