High latitude ionospheric scintillations

Abstract

The statistical characteristics of ionosphcric irrcgularitics arc often dcscribcd by specifying onc or two of thc statistical parametcrs of thc scintillations that the irregularities producc in satcllitc radio signals. Thc most commonly used paramctcr for this purposc is thc spectral indcx (slope of thc powcr spcctral density function on a log-log plot). While it is becoming increasingly clcar that thc characterization of cithcr phasc or arnplitudc scintillations by a singlc pararnctcr may obscure significant characteristics of thc scintillations, this simple approach has provcn to bc ~rscful for the prediction of thc bchaviour of transionosphcric propagation paths such as thosc used in wrious space application systcms. This papcr cxplorcs the use, in addition to thc usual phase and amplitudc obscrvations, of measurcmcnts of anglc-of-arrival, in ordcr to charactcrizc thc scintillations. Sincc cach of these obscrvations rcprcscnt a diffcrcnt kind of obscrvational "filtering", the combination of one statistical paralnctcr from each typc of rncasurcmcnt should providc a morc adcquatc characterization of thc scintillations. I t is found that thc usc of thc widths of thc autocorrclation functions for this purposc is prcfcrrcd ovcr thc usc of spcctral indices.On dicrit souvcnt Ics caractdristiqucs statistiqucs dcs irrdgularitds ionosphdriqucs cn spdcifiant un ou deux dcs paramttres statistiqucs dcs scintillations quc Ics irrdgularitds produiscnt dans Ics signaux radio, dcs satcllitcs. LC parametre lc plus comrnun6rncnt utilisd h cctte fin cst I'indice spectral (la pentc dc la fonction dcnsitd spectralc dc puissance en Cchcllc log-log). Bien qu'il dcviennc de plus cn plus dvidcnt que la caractkrisation dcs scintillations dc phase ou d'amplitude par un scul paramttrc pcut obscurcir lcs calacteristiqucs significatives dcs scintillations. ccttc approchc simple s'cst averde utile pour la prediction du comportcnicnt dcs parcours de propagation trans-ionosphdricluc comme ccux qu'on utilisc dans divers systemes d'applications spatialcs. Dans cet article, on explore I'utilisation. en plus dcs obscrvations usucllcs de phase ct d'amplitude, de mcsurcs dc I'anglc d'arrivdc pour caracteriscr lcs scintillations. Etant donne quc chacune de ccs obscrvations rcprescnte une diffCrcntc sortc de "filtrage" obscrvationnel, on dcvrait obtenir, en prenant un paranittre statistiquc vcnant dc chaque type de mcsure, Lrne combinaison donnnnt une caractkrisation plus adequate dcs scintillations. On trouve qu'il cst prefCrablc d'utiliscr h cette fin lcs largeurs dcs fonctions d'autocorrdlation, plutBt que les indices spcctraux.[Traduit par le journal]Can.

The hows and whys of ion trapping

“…Other attempts to simplify the construction of the quistor-type trap include the use of a cylindrical geometry. The cylindrical ion trap (see Figure lb) has been well characterized (17) and has been used to store ions for up to 100 ms. Also, ring electrodes with spherical rather than hyperbolic cross sections have been proposed (J5). Such simplifications become necessary when the experiment demands the construction of a small ion trap (submillimeter size) for laser spectroscopy (15).…”

“…(b) Cylindrical ion trap. This design, which maintains the same end cap and ring electrode configuration and applied electric fields as the quistor, has been evaluated as a simplification of the quistor geometry (17). (c) The histor, or hexapole ion trap, is ideally constructed of three two-sheet hyperbolic electrodes situated along the three major axes.…”

The Hows and Whys of Ion Trapping

“…Although not required, many quistors have a perforated lower end cap, which allows for ion ejection to an analyzer, A, which may be an ion flux detector or a mass spectrometer. (b) Cylindrical ion trap, This design, which maintains the same end cap and ring electrode configuration and applied electric fields as the quistor, has been evaluated as a simplification of the quistor geometry (17). (c) The histor, or hexapole ion trap, is ideally constructed of three two-sheet hyperbolic electrodes situated along the three major axes.…”

“…Other attempts to simplify the construction of the quistor-type trap include the use of a cylindrical geometry. The cylindrical ion trap (see Figure lb) has been well characterized (17) and has been used to store ions for up to 100 ms. Also, ring electrodes with spherical rather than hyperbolic cross sections have been proposed (15). Such simplifications become necessary when the experiment demands the construction of a small ion trap (submillimeter size) for laser spectroscopy (15).…”