A one-dimensional numerical study of ultrashort-pulse reflectometry

Journal Article · Tue Jan 31 23:00:00 EST 1995 · Review of Scientific Instruments; (United States)

DOI:https://doi.org/10.1063/1.1146516· OSTI ID:6850178

Cohen, B I; Afeyan, B B ^[1]; Chou, A E ^[2]; Luhmann, Jr, N C ^[3]

---

1. Lawrence Livermore National Laboratory, University of California, Livermore, California 94550 (United States)
2. Department of Electrical Engineering, University of California at Los Angeles, Los Angeles, California 90024 (United States) Department of Applied Science, University of California at Davis, Livermore, California 94550 (United States)
3. Department of Applied Science, University of California at Davis, Livermore, California 94550 (United States)

This article presents a first analysis elucidating theoretical aspects of ultrashort-pulse reflectometry. It is studied by means of the numerical integration of a one-dimensional full-wave equation for ordinary modes propagating in a plasma. The numerical calculations illustrate the potential of using the reflection of ultrashort-pulse microwaves as an effective probe even in the presence of significant density fluctuations. The difference in time delays of differing frequency components of the microwaves can be used to deduce the density profile. The modification of the reflected pulses in the presence of density fluctuations is examined and can be understood based on considerations of Bragg resonance. A simple and effective profile-reconstruction algorithm using the zero crossings of the reflected pulse and subsequent Abel inversion is demonstrated. The robustness of the profile reconstruction algorithm in the presence of a sufficiently small amplitude density perturbation is assessed.

• DOE Contract Number: W-7405-ENG-48; FG02-87ER53255
• OSTI ID: 6850178
• Journal Information: Review of Scientific Instruments; (United States), Journal Name: Review of Scientific Instruments; (United States) Vol. 66:2; ISSN 0034-6748; ISSN RSINAK
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700320* -- Plasma Diagnostic Techniques & Instrumentation-- (1992-)
ALGORITHMS
DIFFERENTIAL EQUATIONS
ELECTROMAGNETIC RADIATION
EQUATIONS
MATHEMATICAL LOGIC
MICROWAVE RADIATION
ONE-DIMENSIONAL CALCULATIONS
PARTIAL DIFFERENTIAL EQUATIONS
PLASMA DENSITY
PLASMA DIAGNOSTICS
PULSE TECHNIQUES
RADIATIONS
REFLECTION
WAVE EQUATIONS