An absolute measure of heating by suprathermal electrons in a gas puff Z-pinch

X-ray spectroscopy of high density (n e approximately=10 21 cm -3 ) hot spots in an argon gas puff Z-pinch device has shown resolved K alpha -like transitions from various ionisation stages. An investigation into hot-spot physics suggests that collisional excitation by runaway electrons drives the inner shell emission. The intensity of the inner transitions provides a measure of the suprathermal electron energy deposition, which is sometimes greater than the energy content of a hot spot. However the authors argue that suprathermal electrons are not a principal heating source for the X-ray hot spots.