An atmospheric pressure plasma jet generated with Ar with H2O vapor is characterized and applied to inactivation of Bacillus subtilis spores. The emission spectra obtained from Ar/H2O plasma shows a higher intensity of OH radicals com- pared to pure argon at a specified H2O concentration. The gas temperature is estimated by comparing the simulated spectra of the OH band with experimental spectra. The excitation electron temperature is determined from the Boltzmann＇s plots and Stark broadening of the hydrogen Balmer H/3 line is applied to measure the electron density. The gas temperature, ex- citation electron temperature, and electron density of the plasma jet decrease with the increase of water vapor concentration at a fixed input voltage. The bacteria inactivation rate increases with the increase of OH generation reaching a maximum reduction at 2.6% （v/v） water vapor. Our results also show that the OH radicals generated by the Ar/H2O plasma jet only makes a limited contribution to spore inactivation and the shape change of the spores before and after plasma irradiation is discussed.
Experimental Advanced Superconducting Tokamak(EAST) is the fully superconducting Tokamak.The EAST magnet system comprises 16 D-shaped toroidal field coils and 14 poloidal field coils which are cooled by supercritical helium at 4.2 K and 3.8 K.The temperature of superconducting coils is measured by Cernox as a new type low-temperature sensor,and monitored during the cooling and operation.The helium temperature can offer reference for quench signal.In this paper,a technique for the weak temperature signal measurement of superconducting coils is introduced,and its weak voltage is extracted from the intrinsic noise of the amplifier by the low-noise instrumentation amplifier,filter circuit,and high-linearity analog optocoupler.The temperature detection circuit works accurately and safely whether in cooling or operating process.This technique is an effective for the temperature detection on the low-temperature superconducting coils.
