Tangential Image of Helical SXR Emissivity Structure in Low-Aspect-Ratio RFP

A hot helical structure in low-aspect-ratio (
A
) reversed field pinch (RFP) is obtained with the soft X-ray (SXR) imaging technique. Tangential SXR imaging camera and high-speed camera system is applied to low-
A
RFP for studying quasi-single-helicity RFP state. The helical structure correlated with
m
= 1/
n
= 4 tearing mode is identified by means of a subtraction technique.