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Of Plasma Stimulated Electrostatic Sideband Emission and Harmonic Distortion : Evidences of Over-dense Plasma Generation inside a Microwave Discharge Ion Source
| Content Provider | Semantic Scholar |
|---|---|
| Author | Mallick, C. |
| Copyright Year | 2018 |
| Abstract | Microwave discharge ion source (MDIS) is used in many applications including accelerators based neutron generators on suitable target through D-D or D-T fusion. In this device, the electromagnetic (EM) pump wave ( ) can propagate through plasma beyond cut-off plasma density by changing its polarity and/or decomposing into different daughter waves through which it transfer its energy and produces over dense plasma. In the present experiment, the plasma stimulated emission spectra was measured in the frequency range 0.5 to 3 to understand the different probable energy decay channels role; e.g. Electron Bernstein waves (EBWs), Ion cyclotron waves (ICWs), Lower hybrid oscillations (LHOs), Ion Bernstein waves (IBWs) and Ion Acoustic Waves (IAWs) etc. Present experimental device, MDIS contains eight distinct cavity modes under vacuum conditions (also called vacuum mode) within 300 MHz bandwidth around pump wave ( ) of the launched MW. Some of these vacuum modes are found to match with the plasma induced modes (plasma mode) and depends on the different plasma loading conditions. Resonant interaction between these two types of modes (vacuum mode and plasma mode) leads to the parametric decay into another lower frequency microwave and also electrostatic ion/electron type waves. The energy decays through different ion-type waves by parametric instability is studied by observing the different side-bands generation around the pump frequency ( ) and also around the electron cyclotron (EC) harmonic frequencies. The density threshold of each electrostatic IAWS/ICWs was measured by stepping pump wave amplitude and external magnetic field. The IAWs lines appeared at lower density threshold than the ICWs emission lines. The measured IAWs and ICWs ranges from 238873 kHz and 1.2 3 MHz respectively with a density jump from 9.3×10/m to 4.9×10/m. At higher density (>3.3×10/m), the electrostatic ICWs lines dominates over the IAWs thereby yielding negligible damping through ion waves. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://conferences.iaea.org/indico/event/151/papers/5932/files/4616-Preprint_EX-P2-17.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
