Reply [to “Comment on ‘A feedback model of cyclotron interaction between whistler mode waves and energetic electrons in the magnetosphere’ by R. A. Helliwell and T. L. Crystal”]

Helliwell, R. A.; Crystal, T. L.

doi:10.1029/ja080i031p04399

Cited by 6 publications

(8 citation statements)

References 7 publications

(3 reference statements)

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“…The Laue method is described in the book by Amoros, Buerger & Amoros (1975). Interest in the Laue technique using SR has stemmed in part from an interest in kinetic studies of single crystals (Wood, Thompson & Matthewman, 1983;Moffat, Szebenyi & Bilderback, 1984;Moffat, Schildkamp, Bilderback & Volz, 1986;Moffat, Cruickshank & Helliwell, 1987;Helliwell, 1985;Hajdu et al, 1987a, b) and in part from the use of small crystals either of small molecules (Harding, Maginn, Campbell, Clifton & Machin, 1988) or of proteins (Hedman, Hodgson, Helliwell, Liddington & Papiz, 1985).…”

Section: Background and Previous Workmentioning

confidence: 99%

“…A disadvantage is that reflections will inevitably contain more diffuse X-ray scattering due to thermal vibration and/or crystalline disorder than the narrow-bandpass Laue method or the monochromatic method. It might also be thought (Bragg, 1949(Bragg, , 1975Wyckoff, 1924) that with a broad bandpass most of the Laue reflections would be made up of harmonics: however, as shown by Helliwell (1985) and Cruickshank, Helliweli & Moffat (1987) a large fraction (>80%) of data is single component spots; also the percentage of A-singlet reflections that are recorded is independent of unit-cell size and space group.…”

Section: Background and Previous Workmentioning

confidence: 99%

“…It is worth noting however that pea lectin does scatter strongly compared with many proteins. Laue photographs have been taken for even larger unit cells, E. coil purine nucleoside phosphorylase a=107, c = 240 A (Helliwell, 1986) and tomato bushy stunt virus (Hajdu et al, in preparation).…”

Section: Recorded Laue Patterns: Generalmentioning

confidence: 99%

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The recording and analysis of synchrotron X-radiation Laue diffraction photographs

Helliwell¹,

Habash²,

Cruickshank³

et al. 1989

J Appl Cryst

212

164

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Transmission Laue diffraction photographs can be recorded with short exposure times from stationary macromolecular and small-molecule crystals. With the use of a broad wavelength band a very large number of reflections is stimulated in a single 'snapshot' of large regions of reciprocal space. Processing software has been developed which allows quantitation of the Laue data without resort to monochromatic data. The procedures have been developed and the software strategies optimized by using test data recorded on the SRS wiggler from a protein, pea lectin, and small-molecule crystals. These latter include an organic molecule, trimethyl-lH-2,1,3-benzophosphadiazine-4(3H)-thione 2,2-disulfide, referred to as BPD, and a rhodium complex, [Rh6(CO)~4(dppm)], where dppm is Ph2PCH2PPh2, referred to as RHCOP. Monochromatic data were available for comparison.

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Section: Background and Previous Workmentioning

confidence: 99%

Section: Background and Previous Workmentioning

confidence: 99%

See 1 more Smart Citation

The recording and analysis of synchrotron X-radiation Laue diffraction photographs

Helliwell¹,

Habash²,

Cruickshank³

et al. 1989

J Appl Cryst

212

164

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“…They argued that wave growth saturates when the bounce frequency of a particle in the potential minimum of the wave becomes of the order of the linear growth rate, • • % where & is the particle bounce (or 'trapping') frequency given by 5 = 2rr/T and • is the linear growth rate. The computer simulation study of Ossakow et al [1972] yielded the saturation condition Although there is not general agreement that the modulation period is a direct measure of the phase-bunching period [Nunn, 1975;Helliwell and Crystal, 1975], we will assume that it is and take the radian frequency of the modulation for the phase-bunching frequency, 5) = 2rr/T = 245 s -•. Then the value for a obtained from the •'VLF transmission experiment is 0.12.…”

Section: For One Of the Bi-mentioning

confidence: 99%

A controlled VLF Phase Reversal Experiment in the magnetosphere

Koons¹,

Dazey²,

Dowden³

et al. 1976

J. Geophys. Res.

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During the 1973 operations of the transportable very low frequency transmitter near Anchorage, Alaska (L ∼ 4), an experiment was performed to determine the effect of controlled phase changes of the transmitted wave on the magnetospherically propagated signal received in the conjugate region. At periodic intervals the phase of the driving voltage was changed (essentially instantaneously) by 180°. The amplitude of the 6.6‐kHz signal detected in the conjugate region went to zero and recovered with a characteristic time constant of 33 ms. This is 10 times longer than the antenna current response time and is in fact comparable with characteristic electron interaction times with whistler mode waves. Between the times at which the phase reversals occurred the received signal was amplitude modulated. The period of the modulation was ∼26 ms. An upper side band was present in the spectrum while these pulsations were occurring. These characteristic times are in general agreement with theoretical predictions of bandwidths, growth rates, and particle‐trapping frequencies for whistler instabilities in the magnetosphere. Data obtained from the controlled transmissions and from lightning‐generated whistlers propagating in the same duct were combined to determine the plasma and wave parameters at the geomagnetic equator. Of particular interest is the level at which the magnetic field of the wave saturated. During the time period for which the data were analyzed this was found to be 3.5 pT (mγ).

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“…[Brinca, 1972;Nunn, 1974Nunn, , 1975 . However , Helliwell and Crystal [1975) point out that the amplitude pulsations are a fundamental result of the feedback in their model and not a consequence of the oscillatory electron motion due to the phase bunching . Since the maximum entropy spectrum is an optimally smoothed one , Ulrych and Bishop [1975) conclude that the resolution of the Burg maximum entropy method spectrum is almost twice that of a periodogram spectrum - (Radoski et.al., 1975] .…”

Section: )mentioning

confidence: 99%