Microwave preionization and electron cyclotron resonance plasma current startup in the EXL-50 spherical tokamak

Preionization has been widely employed to create initial plasma and help the toroidal plasma current formation.This research focuses on implementing a simple,economical and practical electron cyclotron resonance(ECR)preionization technique on the newly constructed EXL-50 spherical tokamak,and evaluating the effectiveness on improving the plasma current startup.Two types ECR microwave preionization experiments for the plasma initialization without the central solenoid are reported:(1)2.45 GHz microwave preionization and current startup with2.45 GHz ECR source;(2)2.45 GHz microwave preionization and current startup with 28 GHz ECR source.Application of the 2.45 GHz ECR microwave preionization to the experiments has contributed to(1)getting rid of the plasma breakdown delay;(2)the significant improvement of the discharge quality:the discharge is much longer and more stable while the driven plasma current is larger,compared to the discharge without preionization.

Color-tunable hypersensitive temperature sensor based on metal organic framework doped with Eu^(3+)and Dy^(3+)via phonon-assisted energy transfer

In this work,catena-[(μ-benzene-1,3,5-tricarboxylato)-(1,10-phenanthroline)-(N,N-dimethylfo rmamide)-gadolinium(ⅲ)-N,N-dimethylformamide solvate](denoted as Gd-MOF)co-doped with Eu^(3+)and Dy^(3+)was successfully synthesized.The entire X-ray diffraction peaks of the sample match well with the GdMOF phase.A detailed characterization by inductively coupled plasma mass spectrometry(ICP-MS)shows that the actual concentration is basically consistent with the design concentration.The temperature sensing properties of Gd-MOF:Eu^(3+),Dy^(3+)were analyzed by temperature-dependent fluorescence spectra from 213 to 453 K.As temperature rises,the emission color of Gd-MOF:Eu^(3+),Dy^(3+)changes from yellow to red.The relative sensitivity reaches a maximum of 5.87%/K at 383 K in the Gd-MOF:1%Eu^(3+),30%Dy^(3+)sample.The high relative sensitivity of this MOF is due to the phonon-assisted energy transfer from Dy^(3+)to Eu^(3+),which is proved via fluorescence decay curves and fluoresce nce spectra.The major route of this energy transfer is^(4)F_(9/2)(Dy^(3+))→^(5)D_(1)(Eu^(3+)).