PDS_VERSION_ID = PDS3 LABEL_REVISION_NOTE = "2010-03-17, SONC, initial release 2015-01-31, PIship modified, new PI added P.Henri LPC2E/CNRS 2015- 2018-01-19, LPC2E, update values of INSTRUMENT_TYPE and INSTRUMENT_DESC 2018-02-22, LPC2E, information updated following L3 archives corrections" RECORD_TYPE = STREAM OBJECT = INSTRUMENT INSTRUMENT_HOST_ID = RO INSTRUMENT_ID = "RPCMIP" OBJECT = INSTRUMENT_INFORMATION INSTRUMENT_NAME = "ROSETTA PLASMA CONSORTIUM - MUTUAL IMPEDANCE PROBE" INSTRUMENT_TYPE = "PLASMA ANALYZER" INSTRUMENT_DESC = " Instrument Overview =================== The Mutual Impedance Probe instrument (RPC-MIP) is part of the set of Rosetta orbiter instruments known as the Rosetta Plasma Consortium (RPC). The purpose of the RPC-MIP instrument is to provide several plasma parameters, derived from measurements, such as the electron plasma density. RPC-MIP is composed of an electric antenna and a HF analyser. The RPC-MIP antenna comprises two receivers and two transmitters, supported by a conductive bar. This antenna is mounted on the upper boom of the spacecraft. Scientific Objectives ===================== The RPC-MIP instrument measures the electrical coupling between a transmitting antenna and a receiving antenna. From the on-ground analysis of the mutual impedance frequency spectra acquires on-board and depending on plasma conditions, one may retrieve the electron plasma density and potentially the electron temperature. In its passive mode, this instrument has also the capability of a plasma wave analyser. It is therefore used to detect the electric fields of electrostatic and electromagnetic waves. Combining measurements from different instruments, for instance RPC-MIP and RPC-LAP enables to better constrain bulk plasma parameters such as the electron temperature and, under certains hypothesis, the ion bulk velocity. Calibration =========== RPC-MIP has no specific testing mode, it is nevertheless checked at each switching on command of the instrument in the first 32 s sequence called Control sequence. This Control sequence is sent with the science data, and contains : - one byte test with results of watchdogs and memory tests, - one loop Survey mode in which the transmission signal is directly connected to the receiving electronics, and - samples of the input FIFO. When a new command is sent to RPC-MIP, a Table sequence is generated. It is identical to the Control sequence, except for the byte concerning results of watchdogs and memory tests, which is replaced by a counter. Operational Considerations ========================== There is no particular operational constraints. The best results are obtained when the antenna is in front of the spacecraft, refer to its velocity vector. Detectors ========= The antenna comprises two receiving electrodes, 1 m apart, closely coupled with preamplifiers. Their sensitivity varies from 4 micro-Volt per square root Hz at 7 kHz, to 0.12 micro-Volt per square root Hz at 3.5 kHz. Electronics =========== The RPC-MIP electronics is based on : - a digital frequency synthesizer working from 7 kHz to 3.5 MHz, - one analogue acquisition channel followed by a 7.17 MHz sampling system, and - a data processor which delivers spectra computed by FFT. Filters ======= The bandwidth is limited from 1 kHz to 3.5 MHz by an antialiasing filter. Location ======== The RPC-MIP antenna is mounted on the upper boom of the spacecraft. Operational Modes ================= The RPC-MIP instrument can be used in active mode, or in passive mode. In active mode the ambiant plasma is excited by one or two, among the three transmitters. There is three main active modes : - the Survey mode consists of a sweep over the frequency bandwidth which can be selected from 28 kHz to 3.5 MHz, - the Sweep mode is always triggered by a Survey mode, it allows us to scan a limited frequency bandwidth around the resonance with a better frequency resolution, - the LDL mode consists of a sweep over the frequency bandwidth 7 - 168 kHz, the signal is transmitted by the LAP2 probe. In passive mode no signal is transmitted, it consists of a power spectrum over all the 7 kHz - 3.5 MHz frequency bandwidth . Measured Parameters =================== An alternating current, I, with a frequency lying in a programmed or pre-defined frequency range hopefully containing the plasma frequency, is driven through a transmitting electrode. The induced difference in voltage, V, measured on open circuit between two receiving electrodes is fed into a high input impedance amplifier. The mutual impedance, Z, is equal to the ratio of V to I. As Z depends essentially on the properties of the surrounding plasma, the frequency response of the mutual impedance probe may be used for plasma diagnosis. Due to the resistive, capacitive, and/or inductive nature of the plasma, the frequency response has both real and imaginary components that provide valuable insights into the plasma characteristics. In the active mode, the electron density of the ionized outflowing atmosphere can be determined from the shapes of the real and imaginary parts of the RPC-MIP frequency response. In the passive mode, when no current is injected through the transmitting electrode, the sensor is actually a receiving electric antenna. It detects natural waves, and impulsive signals, generated in the surrounding plasma by external phenomena (not associated to any transmission from the MIP experiment). RPC-MIP responsibilities ======================== PIship: Pierre Henri LPC2E/CNRS 2015-End of Mission Jean-Pierre Lebreton LPC2E/CNRS 2012-2015 Jean-Gabriel Trotignon LPC2E/CNRS 1996-2012 Hardware and science operations management: Xavier Vallieres LPC2E/CNRS 2008-End of Mission Jean-Louis Michau LPC2E/CNRS 1996-2007 RPC-MIP hardware and ground support equipment have been developed by: - LPC2E/CNRS, for the flight electronics board and software - ESA/RSSD, for the RPC-MIP electrical antenna manufacturing and testing - IRF-U contributed to the implementation of the Long Debye Length mode - FMI has partly provided the electrical ground support equipment The overall responsibility is ensured by LPC2E/CNRS. " END_OBJECT = INSTRUMENT_INFORMATION OBJECT = INSTRUMENT_REFERENCE_INFO REFERENCE_KEY_ID = "TROTIGNONETAL2007" END_OBJECT = INSTRUMENT_REFERENCE_INFO END_OBJECT = INSTRUMENT END