Community Research and Development Information Service - CORDIS

FP5

HP NIS Report Summary

Project ID: HPRI-CT-2001-50021
Funded under: FP5-HUMAN POTENTIAL
Country: Ireland

External cavity ring down technique as plasma diagnostic

DCU has primarily carried out work on plasma modeling and plasma diagnostics in an effort to understand H- formation.
- A 2D Particle-in-Cell code with Monte-Carlo-Collisions and the Global Model Solver has been developed, with some limitations, for plasma modelling purposes. This model has been benchmarked against the energy distribution functions measured experimentally using an energy resolved quadrupole mass spectrometer on a symmetric, capacitively coupled system operating at 13.56MHz. However, it should be noted that the model fails to predict certain experimental structure in some instances. (D. O Connell, R. Zorat, M.M. Turner and A.R. Ellingboe)

- The 2D Particle-in-Cell code with Monte-Carlo-Collisions and the Global Model Solver has also been used to simulate magnetic confinement and unconfinement in the diffusion region of a two-turn ICP rf source operated at 13.56MHz. The expected behavioural trends such as increased negative hydrogen ion density and the peaking of this density at lower pressures with magnetic confinement are predicted by the code. These trends in hydrogen ion density have also been measured experimentally using the Cavity Ring Down diagnostic which has been successfully implemented on this low density negative ion source. The successful implementation of CRD on this source required a protective gas flow near the CRD mirrors, operation of the source in pulsed mode and data acquisition with a fast digitiser. (R. Faulkner, F. Soberón, R. Zorat , M.M. Turner, M.B. Hopkins and A.R. Ellingboe)

- A novel optical cavity technique, referred to as the External Cavity Technique has been introduced in an effort to measure line-integrated negative hydrogen ion density in a high density ion source. This technique is a variation of the traditional Cavity Ring Down technique, which was proving difficult to implement on high density ion sources where mirror degradation and cavity misalignment issues became restrictive to the proper application of the technique under ion source operation. (R. Faulkner, M. Bowden and M.B. Hopkins)

- Two visits were made to Ecole Polytechnique in 2005 to understand laser photodetachment techniques and to perform such experiments close to the extraction region of the Camembert III source. (R. Faulkner)

- Investigations into the existence of a double layer at the boundary between the source and diffusion region were carried out in collaboration with the Australian National University in an effort to increase source efficiency for the production of H-. (A.R. Ellingboe)

- Development of an analytical model of a Dual-Frequency-Capacitive (DFC) Sheath was completed with the view to modelling of a small-volume, scaleable H- source. (J. Robiche , P.C. Boyle, M.M. Turner nd A.R. Ellingboe)

- The HPNIS website at http://www.hpnis.dcu.ie has been developed at DCU and has undergone significant development over the course of the project.. (R. Faulkner, J. Robiche and A.R. Ellingboe).

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