Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
Characterization of waveguides, beam coupling and propagation for simulated Raman conversion
Thesis (PhD (Physics))--University of Pretoria, 1993.
Saved in:
| Other Authors: | |
|---|---|
| Format: | Thesis |
| Language: | English |
| Published: |
University of Pretoria
2024
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867613728591052800 |
|---|---|
| access_status_str | Open Access |
| author2 | Scheffler, T.B. |
| author_browse | Scheffler, T.B. |
| author_facet | Scheffler, T.B. |
| collection | Thesis |
| dc_rights_str_mv | © 2024 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
| description | Thesis (PhD (Physics))--University of Pretoria, 1993. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/99503 |
| institution | University of Pretoria (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:40:45.814Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2024 |
| publishDateRange | 2024 |
| publishDateSort | 2024 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/99503 Characterization of waveguides, beam coupling and propagation for simulated Raman conversion Scheffler, T.B. Ronander, E. Van Heerden, Stephanus Philipus Waveguides Beam coupling Propagation Simulated Raman conversion UCTD Thesis (PhD (Physics))--University of Pretoria, 1993. The Raman conversion of a 10 μm CO2 laser beam in parahydrogen is an integral part of the 235 UF6 laser isotope enrichment process. The nonlinear Raman process depends strongly on the input laser power density. Lasers providing such high power ( > 2 J in 80 ns pulsed) in a Gaussian mode are complex and sensitive items. To achieve high power ( > 150 mJ in 40 ns pulsed), high repetition rate ( > 1 kHz) 16 μm output, two beam confinement schemes filled with cold (77 K) parahydrogen were investigated: A novel multimirror multipass (35 passes) Raman cell and a hollow metal waveguide. A rate equation model was developed and verified using experimental results obtained from the conventional multipass (25 passes) Raman experiments. The parameters investigated for the waveguide confinement scheme are: ■ the manufacture of minimum loss metal waveguides with an inner germanium layer, ■ the effective coupling of the free space laser mode (TEM00) to the minimum loss HE11 waveguide mode, ■ the power transmission (experimental) through the waveguide, and ■ the effect the waveguide has on the input laser beam polarization. The actual (non-ideal) laser beam propagation parameters differ from the ideal Gaussian parameters (ro 0 and z0). It is characterized by three parameters: W0 (minimum beam radius or "waist"), Zo (position of the "waist" along the propagation axis), and the beam quality parameter (M2 ). Knowing these parameters, the master-oscillator-power-amplifier chain can be optimized for maximum amplifier extraction with as little possible interference from the finite apertures on the propagation path. The characterization of the high repetition rate CO2 oscillator includes the following: ■ the size and position of the intracavity aperture for optimum output beam quality, and ■ the effect of gas lifetime and high pulse rates on the output laser beam quality. Some experimental results obtained from 16 μm line width measurements, Raman threshold measurements (for 10P20 and 10R18 lines), and the influence of the beam quality (M2 ) on the 16 μm output will be given. Physics PhD (Physics) 2024-11-27T09:16:02Z 2024-11-27T09:16:02Z 22/02/07 1993 Thesis http://hdl.handle.net/2263/99503 en © 2024 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. application/pdf University of Pretoria |
| spellingShingle | Waveguides Beam coupling Propagation Simulated Raman conversion UCTD Characterization of waveguides, beam coupling and propagation for simulated Raman conversion |
| title | Characterization of waveguides, beam coupling and propagation for simulated Raman conversion |
| title_full | Characterization of waveguides, beam coupling and propagation for simulated Raman conversion |
| title_fullStr | Characterization of waveguides, beam coupling and propagation for simulated Raman conversion |
| title_full_unstemmed | Characterization of waveguides, beam coupling and propagation for simulated Raman conversion |
| title_short | Characterization of waveguides, beam coupling and propagation for simulated Raman conversion |
| title_sort | characterization of waveguides beam coupling and propagation for simulated raman conversion |
| topic | Waveguides Beam coupling Propagation Simulated Raman conversion UCTD |
| url | http://hdl.handle.net/2263/99503 |