Waves and Turbulence

BRIEF DESCRIPTION

The project is aimed at the application of the newest analytical methods for the wave observations of space plasma. It will utilize data from two ESA projects - CLUSTER and DOUBLE STAR. Study activities will be focussed on wave processes in the Earth magnetosphere, at its border and in solar wind. Analysis of data from the STEREO mission will be used for preparation of the Solar Orbiter project, especially for the onboard spectral analyzer concept. As a part of the preparation an antenna study and numerical simulations will be done. Our previous experience obtained from the international projects “Study of Propagation and Non-Linear Properties of Plasma Waves Using Advanced Techniques” in cooperation with the University of Iowa, “Analysis of Waves and Turbulence in Space Plasma” with University of California (LA), and a PRODEX project “Cluster II: data processing and simulation facility, numerical modeling and interpretation of wave observation” will be utilized.

Principal Investigator :  Ondřej Santolík

WORKING PLAN 

WP1: Analysis of the wave measurements of the Cluster project.
Advanced measurements recorded by the four Cluster spacecraft require advanced methods for their interpretation and analysis of the underlying physical processes. This proposal aims at application of such state-of-the-art analysis techniques to wave measurements in space plasmas. Observed wave data will be analyzed with different methods such as wave distribution functions, higher order spectra, and correlative methods for multipoint/multiscale measurements. We will examine sources and propagation of different types of plasma waves in space plasmas, such as equatorial noise, extremely low frequency hiss, auroral hiss, and waves and turbulence near magnetospheric boundaries and in the solar wind. We plan to contribute to understanding of non-linear wave-wave interactions, wave-particle interactions, and detection techniques.  Travel to cooperating laboratories in Meudon and Orleans (France) and to international conferences is anticipated.

WP2:  Analysis of the wave measurements of the Double Star project.
We will investigate propagation and source mechanisms of plasma waves occurring in the Earth's magnetosphere. Two Double Star Project spacecraft will be orbiting the Earth in different regions of the magnetosphere. We plan to use the data of the European wave instrument on board the equatorial spacecraft as well as the data of the wave and particle instruments on board both spacecraft. Combination of these data is expected to give new insight into the physical processes connected to the magnetospheric plasma waves. We will investigate the equatorial noise emissions which consist of intense electromagnetic plasma waves propagating in the close vicinity of the geomagnetic equatorial plane at frequencies from a few hertz to several hundreds of hertz. The magnetic field fluctuations are nearly linearly polarized, but  the spatio-temporal variability and propagation of equatorial noise are still unknown as well as the exact nature of wave-particle interactions responsible for the generation of these emissions. Travel to cooperating laboratories in Meudon and Orleans (France) in Beijing (China) and to international conferences is anticipated.

WP3: Antenna theory
In the course of wave analysis by means of wave distribution function both amplitudes and phases of magnetic and electric components are needed. It was shown that the measurements of the electric field do not always provide correct values of the ambient wave field. In this respect we propose to investigate both the impedance of electric antennas used in the experiments in question and their effective length. As in the treatment of the antenna self-impedance there will be a number of parameters not well known, we will adjust the sheath impedance by trial and error in a case where the wave distribution method gives reliable results, e.g. in hiss measurements in the plasmasphere. We also plan to adjust the parameters and models to other relevant cases of observed electromagnetic modes

WP4: Analysis methods for the Stereo project.
The wave instrument onboard the STEREO mission (SWAVES) will provide observations of the generation of coronal mass ejections (CMEs), their evolution, and their interaction with Earth’s magnetosphere. We will take part in the development of a tool for the data analysis using direction finding techniques. We will participate on the in-situ analysis (thermal noise). This is important for tracking the CME-driven shocks and flare electrons and for measurement of the spatial extent and structure of CME-driven shocks and flare and CME-associated electron beams which can be mapped back to the Sun. These remote and in situ measurements of the radio sources will enable the understanding of the generation of type II (CME) and type III (flare) radio bursts. The electron density and temperature will be obtained from quasi-thermal noise properties, in regions of cold, dense plasma within CME-associated magnetic clouds.  We will also be active in the public outreach program and in creating possibilities for participation of students on the SWAVES research. Travel to the cooperating laboratory in Meudon  (France) and to international conferences is anticipated.

WP5: Preparation of the wave experiment for the Solar Orbiter project.
A preparative study of a special onboard spectral analyzer using the common antennas is proposed in cooperation with our colleagues from Observatoire Paris-Meudon. Its main purpose will be to investigate properties of the Langmuir waves in the solar wind. We assume that the core of the data processing unit will be based on a precise analog-to-digital converter (16 bit) and a digital signal processor. We suppose to develop special data processing software to reduce the amount of data and to transmit only that part of spectral region that corresponds to the interval in which the Langmuir waves occur. Frequent travel to the cooperating laboratory in Meudon  (France) is anticipated.

WP6: Computer simulations.
Many large-scale and low-frequency physical processes in space plasmas are connected with proton dynamics. These processes are typically nonlinear and their study is possible using  numerical simulations. The fluid approach to plasma as used in MHD numerical codes is not adequate to describe the proton kinetic effects. When the electrons kinetic effects are negligible then a hybrid code, a cross between fluid and particle description, is useful. The hybrid code approximates electrons as a zero-mass, charge neutralizing fluid and protons are treated as particles. Hybrid codes has been widely used in the context of space plasma for study of collisionless shocks, magnetic reconnections and various proton instabilities. We have at our disposal 1-D, 2-D, and 3-D versions of hybrid code with different boundary conditions (periodic, open, reflecting). We will use the hybrid code to study the structure of quasi-parallel and quasi-perpendicular shock waves and ion instabilities in collisionless plasmas. Travel to the cooperating laboratory in Meudon  (France) and to international conferences is anticipated.