Deuterium behavior in tungsten exposed to deuterium plasma with rising or declining temperature

Exposure temperature is a key factor affecting the behavior of hydrogen isotopes (H) in tungsten (W). This work focuses on the effect of temperature variations in plasma exposure on deuterium (D) behavior in recrystallized W. Low-energy and high-flux D plasma exposure was conducted in the linear plasma generator STEP. Exposure temperature was set as three patterns, keeping constant at 520 K, rising from 420 K to 590 K, and declining from 590 K to 420 K. Surface observations show that as compared to the constant type the declining type leads to a much more severe surface blistering, whilst the rising type gives rise to a mitigation of intragranular blisters. Thermal desorption spectra indicate that D retention is remarkably enhanced in the declining case while a slight enhancement is found in the rising type. This study demonstrates that the trend of temperature variation during plasma exposure has a great influence on the behavior of D in W, providing a new insight into the temperature effect of H behavior in W.