Speaker
Description
To improve the performance of volume production-based negative hydrogen ion sources, it is crucial to understand the negative ion volume production reactions by vibrationally excited molecules and cold electrons. This requires a thorough understanding of electron kinetics within the plasma, the generation and relaxation processes of vibrationally-excited molecules, and the transport of neutral particles across the magnetic filter.
In this work, we first review the core diagnostic techniques and physical analytical models established in the radio-frequency (RF) $H^-$ ion source research at Seoul National University (SNU). Fulcher-alpha band spectroscopy was utilized to analyze the changes in the vibrational distribution function (VDF) of hydrogen molecules and the behavior of neutral particles passing through the magnetic filter region. Additionally, the laser photo-detachment technique was applied to precisely measure the $H^-$ ion density in the plasma. Based on these diagnostic results, a zero-dimensional (0D) particle balance model and a one-dimensional (1D) neutral particle transport model were combined to successfully elucidate the production and destruction mechanisms of negative ions according to varying pressures and RF powers.
Building on these diagnostic foundations, we highlight two recent studies maximizing plasma confinement in Korea. First, SNU's recent research utilizes the double-layer potential of an anode spot plasma to induce inflow and confine negative ions, significantly enhancing local density. Second, KAERI’s Two-Region Arc Plasma (TRAP) source maximizes volume production efficiency by physically separating the high-energy driver region and low-temperature extraction region using movable filaments and optimized magnetic fields.
| Email address | jjdang@kentech.ac.kr |
|---|---|
| Visitor's Visa | no |
| Classification | Plasma and negative ion diagnostics |