COPS Instrument Modes T. Semon U. Rohner K. Altwegg University of Bern Physikalisches Institut Sidlerstrasse 5 CH-3012 Bern Switzerland {| TABLE !Document Reference: !!RO-ROS-MAN-1019 ! |- |Issue: 1 ||Rev.: |- |Date 06-12-2001 ||Pages: |} {{{Document Change Record}}} Document Change Record| {| TABLE !Issue !!Rev. !!Pages changed, added, removed !!Date !!Reasons for Changes !! Approval ! |- |1 ||- ||All ||16-11-2001 ||Initial Issue || |- |1 ||1 ||All ||26-11-2001 ||Updates proposed by Kathrin Altwegg || |- |1 ||2 ||Page 7,9 ||06-12-2001 ||Add flux formula Add DPU Action Mode || |- |1 ||3 ||All ||19-12-2001 ||Consolidation by K. Altwegg || |} Table of Contents Document Change Record 2 List of Abbreviations 3 1 Scope 4 1.1 Reference documents 4 1.2 Introduction 4 2 COPS Modes and measurement sequences 5 3 Explanations of the COPS Parameters 6 3.1 Channel 6 3.2 Task 6 3.3 Data acquisition 6 4 Example of COPS Modes 6 5 Power Consumption 7 6 Example of COPS measurement sequences 8 7 Tabels necessary to run COPS autonomously 8 7.1 Calibration factor Table 9 7.2 Table of General settings 10 {{{}}} {{{List of Abbreviations}}} COPS Comet Pressure Sensor DPU Digital Processing Unit FM Flight Model HK Housekeeping ROSINA Rosetta Orbiter Spectrometer for Ion and Neutral Analysis S/C Space Craft TBD To Be Defined TBC To Be Confirmed {{{1 Scope}}} The Comet Pressure Sensor will measure the ambient total pressure as well as the comet ram pressure. These two quantities can be used to derive the speed andthe Mach number of the cometary gas. COPS will also serve as a pressure monitor for safety purposes. It will distribute the total pressure to all Rosetta instruments. This document contains the COPS instrument modes and measurement sequences. {{1.1 Reference documents}} {| TABLE !No !!Institution !!Document Title !!Reference !!Issue ! |- |[1] ||UoB ||EID-B: ROSETTA-Rosina Experiment Interface Document ||RO-EST-RS30 3/EID B ||Issue 1, Rev. 0 15-01-1999 |- |[1] ||UoB ||Rosina Users Manual ||RO-ROS-MAN-1007 prepared by Kathrin Altweg ||Draft 2, Rev. 0 19-09-2000 |} {{}} {{1.2 Introduction}} The Comet Pressure Sensor (COPS) consists of two gauges. The first gauge called "nude gauge" measures the total pressure (more exactly the density) of comet gas. The second called the "ram gauge" measures the ram pressure (equivalent to the comet gas flux). The nude gauge uses filaments to emit electrons and the ionize the gas, the ram gauge uses microtip arrays. {{{2. COPS Modes and measurement sequences}}} COPS Instrument Parameters Settings {| TABLE !Channel !!NUDe gauge !! ! |- | ||RAM gauge || |- | ||BOTh || |- |Task ||NONe AMBient OFfSet OPTimization || |- |Emission ||EMIssion{ Fil, Mic, IF, IM } || |- |Data acquisition ||ALGorithm{A} || |} {{{3. Explanations of the COPS Parameters}}} To measure the pressure, COPS can work with the both gauges (nude and ram gauges) or just one. {{3.1 Channel}} The NUDe gauge mode is used for monitoring purposes. In case there is not enou h power available the RAM gauge mode (which uses less power) can also be used or monitoring, however the result is somewhat less precise. The mode BOTh is t e science mode of COPS. From this mode only the gas dynamics can be derived. {{3.2 Task}} AMBient means that the instrument measures the cometary (asteroidal) ambient p essure. OFfSet is the measurement of the offsets of one or both gauges. OPTimization means that the instrument performs a routine to find automaticall the best configuration (emission range and electrometer range) to have the b st pressure precision. EMIssion means that the COPS set up the voltages to have the specified emissio . The parameters that set the emission current and the active emitter(s) are: Fil (1bit): 0 for left filament or 1 for right filament active. Mic (8 bits): Microtip group status Bit 1: Mic 1 status (0 = disable, 1=enable) Bit 2: Mic 2 status (0 = disable, 1=enable) Bit 3: Mic 3 status (0 = disable, 1=enable) Bit 4: Mic 4 status (0 = disable, 1=enable) Bit 5: Mic 5 status (0 = disable, 1=enable) Bit 6: Mic 6 status (0 = disable, 1=enable) Bit 7: Mic 7 status (0 = disable, 1=enable) Bit 8: Mic 8 status (0 = disable, 1=enable) The current levels (parameters II and IM) set the filament and the microtip(s) emission. II (0-3): emission filament to 0, 5, 15, 100 A IM (0-3):: emission microtip(s) to 0, 5, 15, 100 A {{3.3 Data acquisition}} Algorithm indicates which method used the DPU to calculate the ambient pressur (TBD). {{{4 Example of COPS Modes }}} The numbering of the Mode used the following last digits (combination of chann l and task): 0: General for COPS Instrument / DPU action modes 1: NUD, OFS 2: NUD, AMB 3: NUD, OPT 4: RAM, OFS 5: RAM, AMB 6: RAM, OPT 7: BOT, OFS 8: BOT, AMB 9: BOT, OPT The numbering should be arranged as follows: 0 to 49: Basic modes for switch on/off 49 to 99: Basic offset modes 100 to 299: Basic optimization modes 300 to 399: Basic emission modes 400 to 499: Standard survey modes 500 to 599: Basic conditioning modes 600 to 999: Custom modes M57: Mode (BOT, OFS, EMI(0,0,0,0) In this mode the instrument would check the offsets level of both gauges. M106: Mode (RAM, OPT , EMI{0,15,0,0}) In this mode the instrument would be optimized, the emission and ion range of he Ram gauge (all microtips on) would automatically be set for the best pressu e precision. M339: Mode (BOT, AMB, EMI {1,3,3,3}) In this mode the instrument would step up the filament 1 emission to 100 A and the microtips 1 and 2 emission also to 100 A. M402: Mode (NUD, AMB, EMI {0,0,1,0} In this mode, the nude gauge measures the ambient pressure with an emission of 5 {{{5 Power Consumption}}} The power consumption of COPS is composed of two main components, namely of th standby power (low voltage converters and main controller), and of the filame t. The power used by the microtips can be neglected. The following table shows the two contributions: {| TABLE ! !!Power (W) ! |- |Standby mode (LVPS, MC) ||4.5 |- |Filament ||2 |} Not run in parallel to analyzer part, filament or cover motor The power used in each mode can therefore be calculated. A normal measurement mode with microtips needs 4.5 W; with the filament 6.5 W. {{{6 Example of COPS measurement sequences}}} Standard monitoring sequence Step no Mode Description Time 10 M0 COPS on 0.5min 20 M1 Nude gauge 12 V on 1 min 30 M51 Offset measurement 5min 40 M333 filament emission to 100 A (2h) 120min 50 go to 30 Standard science mode Step no Mode Description Time 10 M0 COPS on 0.5min 20 M7 Ram and nude gauge 12 V on 1 min 30 M57 Offset measurement 5min 40 M107 Optimization 10 min 50 M329 filament emission to 15 A (2h) 120min 60 go to 30 {{{7 Tabels necessary to run COPS autonomously}}} To calculated the pressure, the DPU use the following formula: For the nude gauge: For the ram gauge: The Ion offset value is measured in background mode. S is the calibration factor, it is about 30 for the nude gauge and 5 for the r m gauge. This factor depends of the temperature and the ambient gas. Flux formula for the Ram gauge: phi_out = gas flux [1/m2*s] kB = Boltzmann-constant = 1.38e-23 [J/K] T_RG = ram gauge temp. [K] mass = 18 amu = 2.9889e-26 [ Kg] (H2o is the default mass) p_RG = ram pressure [Pa] = 100*[p(mbar)RG] {{7. 1Calibration factor Table}} *Formula or table (TBD) {| TABLE !S_RG Value !!S_NG Value !!Temperature [DegC] !!Gas !!Emission !!Remark ! |- |4.5 ||29 ||0 || || || |- |5 ||30 ||20 ||N2 ||10 uA ||Default S_RG and S_NG Values |- |5.1 ||31 ||40 || || || |- |5.6 ||34 ||... ||N2 || || |- |...||... || ||H2O || || |- | || || ||CO2 ||10 uA || |- | || || ||... ||100 uA || |} Note: The default gas is N2 (first pressure measurement). The S_RG/NG Gas table element will be optimized after a measurement of the DFM or RTOF (TBD). {{7.2 Table of General settings }} In this table are the parameter values in function of the mode. Table Legend: x : means that the value is defined by the last mode Y: means that it is possible to have an update of this value (Optimization mod s) |Mode|Nude gauge|Ram gauge|Emitter(s)|Remark {| TABLE !- !!- !!Filament current limit !!Filament Anode Grid V !!Filament Regulation alue / Range !!Microtips current limit !!microtips Anode Grid V !!Microtips Re ulation value / Range !!Microtips-Arrays / Filament !!- ! |- |Switch on/off modes ||M0 ||- ||- ||- ||- ||- ||- ||- ||COPS on, 28V |- | ||M1 ||0 ||0 ||0 ||- ||- ||- ||- ||Nude gauge on, +/-12V filament |- | ||M4 ||- ||- ||- ||0 ||0 ||0 ||- ||Ram gauge on, +/-12V microtips |- | ||M7 ||0 ||0 ||0 ||0 ||0 ||0 ||- ||Nude & Ram gauge on, +/-12V |- |Offset ||M51 ||0 ||180V ||0 ||- ||- ||- ||F: x ||Filament offset |- | ||M54 ||- ||- ||- ||0 ||180V ||0 ||M: x ||Microtips offset |- | ||M57 ||0 ||180V ||0 ||0 ||180V ||0 ||F & M: x ||Fil. & Microtips offset |- |Optimization ||M101 ||x ||x ||Y ||- ||- ||- ||F : x ||Filament optimization |- | ||M104 ||- ||- ||- ||x ||x ||Y ||M: x ||Microtips optimization |- | ||M107 ||X ||X ||Y ||x ||x ||Y ||F & M: x ||Fil. & Microtips optimization |- |Measurementmodes ||M312 ||0.85A ||180V ||5uA /LR ||- ||- ||- ||F: 1 (left) || ode(NUD,AMB, EMI{1,0,2,0}) |- | ||M322 ||0.9A ||180V ||15uA /LR ||- ||- ||- ||F: 1 (left) ||Mode(NUD, AMB, E I{1,0,2,0}) |- | ||M332 ||1A ||180V ||100uA /HR ||- ||- ||- ||F: 1 ||Mode(NUD, AMB, EMI{1,0,3 0}) |- | ||... || || || || || || || || |- | ||M316 ||- ||- ||- ||0.15A ||180V ||5uA /LR ||M: 1 ||Mode(RAM, AMB, EMI{0,1, ,1}) |- | ||M326 ||- ||- ||- ||0.2A ||180V ||15uA /LR ||M: 1 ||Mode(RAM, AMB, EMI{0,1, ,2}) |- | ||M336 ||- ||- ||- ||0.25A ||180V ||100uA /HR ||M: 1 ||Mode(RAM, AMB, EMI{0, ,0,3}) |- | ||M319 ||0.8A ||180V ||5uA /LR ||0.15A ||180V ||5uA /LR ||F: 1 M: 1 ||Mode(BOT, AMB, EMI{1,1,1,1}) |- | ||M329 ||0.9A ||180V ||15uA /LR ||0.2A ||180V ||15uA /LR ||F: 1 M: 1 ||Mode(BOT, AMB, EMI{1,1,2,2}) |- | ||M339 ||1A ||180V ||100uA /HR ||0.25A ||180V ||100uA /HR ||F: 1 M: 1 ||Mode(BOT, AMB, EMI{1,1,3,3}) |- | ||... || || || || || || || || |- | ||M399 ||1A ||180V ||100uA /HR ||0.2A ||180V ||15uA /LR ||F: 1 M: 1 ||Mode(BOT, AMB, EMI{1,1,3,1}) |- | ||... || || || || || || || || |- | ||M339 ||1A ||180V ||100uA /HR ||0.25A ||180V ||100uA /HR ||F: 1 M: 1 & 2 ||Mode(RAM, AMB, EMI{1,3,3,3}) |- | ||M519 ||TBC ||180V ||1A /HR ||TBC ||180V ||1A TBD /HR ||F: 1 M: 1 ||Mode(BOT,COND{1,3}), slowly stepped upwards |}