Solving the Capacitive Effect in the High-Frequency sweep for Langmuir Probe in SYMPLE

10th Asia Plasma and Fusion Association Conference

Pramila^1 ; Patel, J.J.^1 ; Rajpal, R.^1 ; Hansalia, C.J.^1 ; Anitha, V.P.^1 ; Sathyanarayana, K.^1

Institute for Plasma Research, Near Indira Bridge, Bhat, Gandhinagar

382 428, India^1

关键词: Capacitive effect;    Differential signal;    Floating potentials;    Front end electronics;    High frequency HF;    Isolation transformers;    IV characteristics;    Plasma parameter;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/823/1/012019/pdf
DOI  :  10.1088/1742-6596/823/1/012019

来源: IOP

【 摘 要 】

Langmuir Probe based measurements need to be routinely carried out to measure various plasma parameters such as the electron density (ne), the electron temperature (Te), the floating potential (Vf), and the plasma potential (Vp). For this, the diagnostic electronics along with the biasing power supplies is installed in standard industrial racks with a 2KV isolation transformer. The Signal Conditioning Electronics (SCE) system is populated inside the 4U-chassis based system with the front-end electronics, designed using high common mode differential amplifiers which can measure small differential signal in presence of high common mode dc- bias or ac ramp voltage used for biasing the probes. DC-biasing of the probe is most common method for getting its I-V characteristic but method of biasing the probe with a sweep at high frequency encounters the problem of corruption of signal due to capacitive effect specially when the sweep period and the discharge time is very fast and die down in the order of μs or lesser. This paper presents and summarises the method of removing such effects encountered while measuring the probe current.