Target heat loading due to fast, transient heat pulses produced from a conical θ-pinch as a prototype for benchmarking simulations of transient heat loads

The ELM simulating plasma gun (ESP-gun) has been developed to study the effects of transient, blob-like plasmas on the plasma facing components of TOKAMAKs. ESP-gun utilizes a RF helicon plasma to pre-ionize a plasma column underneath a conical, θ-pinch coil, which is used to compress and eject plasmas. Measurements have been made of the existing RF plasma and the subsequent compressed plasma. A copper target was placed downstream of the θ-pinch, and its temperature rise was measured with respect to time. For modest argon plasmas, n_e ∼ 10¹⁸ m^-3 and T_e ≤ 100 eV, the target temperature was observed to have an equivalent heat loading of up to 90 kJ/m². Given that the plasma density and temperature are low, it is believed that the target heat loading will scale linearly with plasma density such that plasmas of 10²⁰-10²¹ m^-3 would reach target heat loading in excess of 1 MJ/m². A zero dimensional thermal model will be presented to estimate the expected target heat loading.