Transcript Overview
MURI KICK-OFF MEETING June 5, 2007 PARTICIPATING UNIVERSITIES UNIVERSITY OF MARYLAND, COLLEGE PARK STANFORD UNIVERSITY UNIVERSITY OF CALIFORNIA, LOS ANGELES DARTMOUTH COLLEGE VIRGINIA TECH BOSTON COLLEGE OUTLINE • • • • • • • Radiation Belts (RB) –Topology - Fundamentals RB Remediation (RBR) Why? MURI – Overarching Objectives MURI – Methodology , Governance, Transition MURI – Resources The Physics of Loss Rate Physics and Technology Challenges – Radiate, Amplify, Propagate, Precipitate • • VLF Radiation from Space Transmitters Novel ULF/VLF Radiation Concepts – ULF Injection Using Neutral Gas Releases at Orbital Speed – Rotating Magnetic Fields (RMF) • • • • • Amplification – Artificially Stimulated Emissions Propagation – Natural and Artificial Ducts Cyclotron Masers – Resonators and Guides – Ion Precipitation ULF Injection in Space Stimulated ULF Triggering and Ion Precipitation RADIATION BELTS – TOPOLOGY e-/cm2/sec , >1 MeV 104 >105 >106 L=7 L=2 L=3 Inner RB 1.5<L<2, Slot 2<L<3, Outer RB L>3 Lifetime and functionality of satellites ~ Energetic particle dose Plasmapause (L~4) appears to mark transition from high to low flux of energetic particles RB – PHYSICS ISSUES Energetic particle flux as a function of L controlled by 1 4 1. Particle Injection 2. Radial Transport 2,3 3. Energization 4. Particle Loss Leaky Bucket Model in in=out out RB REMEDIATION (RBR) 1 4 Sudden natural or artificial injection of relativistic electrons in the inner magnetosphere (e.g. by accidental or deliberate High Altitude Nuclear Detonation -HAND ) Inject a bucket of water 2,3 in 104 105 106 Teq>2 yr >108 in=out out Time to return to equilibrium depends on the size of the hole THE HALLOWEEN STORM FROM 1-10 NOVEMBER, 2003 OUTER BELT CENTERED NEAR L2.5 AND PLASMASPHERE WAS DISPLACED INWARDS LEADING IN NEW RADIATION BELT POPULATION IN THE SLOT AND INNER BELT. DECAY RATES DEPENDED HIGHLY ON L VALUE AND VARIED FROM 35 DAYS TO MORE THAN A YEAR BAKER AND KANEKAL 2007 OVERARCHING OBJECTIVES • DEVELOP QUANTITATIVE DATA DRIVEN MODELS OF THE LOSS RATE OF ENERGETIC PARTICLES IN THE INNER MAGNETOSPHERE AND TEST AGAINST OBSERVATIONS • PROVIDE THE PHYSICS UNDERPINNINGS THAT CAN LEAD TO PRACTICAL SPACE OR GROUND BASED SYSTEMS THAT CAN ARTIFICIALLY CONTROL THE ENERGETIC PARTICLE LOSS RATE • DEVELOP THE SCIENTIFIC AND ENGINEERING MANPOWER WITH THE INTERDISCIPLINARY SKILLS REQUIRED TO ADDRESS FUTURE MAJOR TECHNICAL ISSUES OF NATIONAL SIGNIFICANCE METHODOLOGY - GOVERNANCE • TOPICS ADDRESSED BY AN INTERPLAY OF THEORY/COMPUTATION, LABORATORY EXPERIMENTS, FIELD EXPERIMENTS, SATELLITE MEASUREMENTS AND DATA ANALYSIS • CONSORTIUM WILL OPERATE AS A COHERENT ENTITY WITH PARTICIPATING UNIVERSITIES AND ASSOCIATED GOVERNMENT LABORATORIES AND INDUSTRY PROVIDING COMPLEMENTARY EXPERTISE AND NOT AS A SERIES OF INDPENDENT PROJECTS • CONTINUOUS INTERACTION AND QUICK TRANSITION OF RESULTS TO RELEVANT DoD LABORATORIES (AFOSR, NRL) • OVERALL CONSORTIUM COORDINATION BY PAPADOPOULOS AND INAN WITH ADVICE FROM SENIOR MEMBERS – SAGDEEV, MORALES, LIU, MAGGS, MISHIN,FUNG,… • THE FORMATION OF AN EXTERNAL SCIENCE ADVISORY COMMITTEE WITH MEMBERS SUCH AS KENNEL, COFFEY, WALT, LANZEROTTI HAS BEEN RAISED WITH THE PM BUT NOT YET RESOLVED RESOURCES HAARP DEMETER LAPD CONJUGATE BUOYS DMSP WIDE RANGE OF CODES THAT COUPLE TO THE ABOVE EXPERIMENTS PHYSICS OF LOSS RATE B0 V|| trapped V^ k z vz n e / SCATTERING RATE DEPENDS ON 1. AMPLITUDE OF RESONANT WAVES 2. PRESENCE OF LARGE B GRADIENTS 3. PATCHES OF LARGE AMPLITUDE NON-RESONANT ES OR EM WAVES k z vz e / (1/ e )( Bo / Bw )2 REQUIRES LARGE MAGNETIC WAVE ENERGY IN THE PROPER WAVELENGTH RANGE (~1-3 KM) TO BE INJECTED AND GUIDED IN THE PUMPED BELT REGION PHYSICS AND TECHNOLOGY CHALLENGES • WAVE INJECTION: • VLF INJECTION FROM SPACE BASED ANTENNAS • VLF INJECTION FROM GROUND TRANSMITTERS • ULF INJECTION FROM SPACE – NEUTRAL GAS INJECTION • INNOVATIVE INJECTION CONCEPTS - ROTATING MAGNETS • GLOBAL WAVE AMPLIFICATION • VLF AMPLIFICATION – ARTIFICIALLY STIMULATED EMISSIONS • STIMULATED ULF EMISSIONS – PROTON PRECIPITATION • GLOBAL WAVE PROPAGATION • VLF DUCTED AND NON-DUCTED PROPAGATION • ULF WAVE PROPAGATION • PHYSICS OF PRECIPITATION • WEAK VS. STRONG DIFFUSION • RELIABLE MODELING TESTED AGAINST AVAILABLE DATA (GROUND TRUTH) EFFICIENCY OF VLF RADIATION FROM SPACE-BASED TRANSMITTERS WHAT PHYSICAL PROCESSES CONTROL THE EFFICIENCY AND FAR FIELD COUPLING OF HIGH POWER, LOW FREQUENCY ANTENNAE IN A LOW DENSITY PLASMA. ELECTRIC VS MAGNETIC DIPOLES. STANFORD ANTENNA IN PLASMA AND OTHER THEORETICAL AND EMPIRICAL MODELS (SAIC, UMass) HAVE BEEN USED TO DESIGN DSX EXPERIMENT INPUT IMPEDANCE FUNCTION OF SHEATH. REQUIRES DYNAMIC TUNING NEED FOR CODE VALIDATION USE LAB EXPERIMENTS IN LAPD CHAMBER TO VALIDATE PERFORMANCE CODES FOR ELECTRIC AND MAGNETIC DIPOLES NOVEL WAVE INJECTION CONCEPTS NEUTRAL GAS INJECTION USE ENERGY (30 GJ/Ton) STORED IN RELEASING A LARGE AMOUNT OF LOW IONIZATION POTENTIAL GAS (e.g. Li) AT ORBITAL VELOCITY TO GENERATE THE RESONANT WAVES – GANGULI ET AL (2007) RELEASE Step 2. PHOTO Step 1. IONIZA TION PHYSICS CHALLENGES • CONVERSION EFICIENCY FROM FREE ENERGY TO RESONANT SPECTRAL ENERGY • SATURATION LEVEL OF PRIMARY ALFVEN ION CYCLOTRON INSTABILITY – VT • WAVE CASCADE IN k-SPACE TRANSFERS ENERGY TO RESONANT REGION – UMCP • INJECTION REQUIREMENTS FOR STRONG SCATTERING – UMCP • TRAPPING OF WAVES IN MULTI-IONIC BUCHSBAUM RESONANCES - DC EFFORT MAINLY THEORETICAL FEEDS DIRECTLY TO NRL – POSSIBLE CHAMBER EXPS IN OPTION PHASE NOVEL WAVE INJECTION CONCEPTS ROTATING MAGNETIC FIELDS How are currents generated and maintained ? RMF GENERATED EITHER BY ROTATING A PERMANENT OR SUPERCONDUCTING MAGNET OR BY PHASED ANTENNAS PHYSICS OF INTERACTION OF A RMF WITH MAGNETOPLASMA NOT UNDERSTOOD Novel Antenna Concepts 3-D EMHD MODELING AT UMCP PARALLEL LAB EXPS AT LAPD - GEKELMAN 17.2 c/pe 0 17.2 c/pe B- FIELD GRADIENTS DRIVEN BY RFM Courtesy R. Winglee • DIFFERENTIAL MOTION OF ELECTRONS AND IONS GENERATES PLASMA CURRENTS RESULTING IN INDUCED FIELD DECAYING AS 1/rn WITH n<<3 • LARGE QUASI- STATIC B- FIELD GRADIENTS CAN BREAK THE ADIABATIC INVARIANCE OF ELECTRONS AND SCATTER THEM INTO THE LOSS CONE CARTOON OF CONCEPT OPTION PHASE – ASSESS INDIVIDUAL PLATFORM PROTECTION Primary field (blue lines) Electron motion (red dots) Secondary field (red lines) AMPLIFICATION Artificially Stimulated Emissions (ASE) COHERENT GROWTH 20-30 dB Helliwell Stanford Siple exps THRESHOLD SIGNAL SATURATION PHASE ADVANCE PRIOR TO TRIGGERING TRIGGERED EMISSIONS – risers, fallers, hooks ENTRAINMENT GROWTH SUPPRESSION for 2 signals with Df< 30 IMPORTANCE OF CHIRPING Probably the most serious challenge to our current understanding of nonlinear plasma physics 20-30 dB amplification major leverage to RBR Artificially Stimulated Emissions ASE - ISSUES • • • • • • • Physics of coherent amplification and saturation Role of chirping and optimization Role of ducts Physics and control of threshold – inhomogeneity, F(v),else ? Reason for frequency shift – inhomogeneity or nonlinearity? Is threshold related to oscillator behavior (BWO) Is amplification affected by relativistic effects or a nuclear environment? APPROACH 1. Specialized codes and parallel architectures; UMCP + NRL, DC 2. Targeted field experiments – HAARP, Alpha transmitter; Inan 3. Targeted Lab experiments – TBD (Need ECRH source) UCLA VLF PROPAGATION - DUCTS The perturbed plasmasphere contains field-aligned density irregularities that efficiently guide whistler waves CRRES orbit 766 • In addition to loss-cone distribution amplification requires the presence of ducts (field-aligned irregularities with dn/n>.01) 1. Model ducted propagation in inhomogeneous media and test against lab experiments (DC – Streltsov, UCLA Gekelman) 2. Understand and predict time and location of natural ducts (BC – Mishin) 3. Model and conduct field tests of artificial duct formation using Fregion heating with HAARP (UMCP) Plasmaspheric Duct Formation 1. Analyze magnetically-conjugate observations from the Cluster and DMSP satellites to find the response time of the plasmasphere to sub-storms. 2. Analyze available satellite (CRRES/Cluster/IMAGE/DMSP) data to find the drivers of plasmaspheric field-aligned irregularities (FAI) and their spatial/temporal characteristics. 3. Conduct theoretical and numerical studies of the (sub) storm-time ring currentplasmasphere interaction resulting in the FAI (ducts) generation. 4. Analyze observations from Siple and HAARP to determine geophysical conditions necessary and sufficient for the formation of ducts. 5. Develop algorithms that allow location and time of duct formation ARTIFICIAL TRANSIONOSPHERIC DUCTS 2D MODELING SHOWS THAT TRANSIONOSPHERIC DUCTS WITH dn/n> .5 FORM IN 15 MINUTES WITH FULL HAARP F-REGION HEATING • CONDUCT 3D SIMULATIONS - UMCP • CONDUCT HAARP EXPS DIAGNOSED WITH OVERFLYING SATS (DMSP, DEMETER) AND STANFORD VLF RECEIVERS – UMCP • DETERMINE RELEVANCE OF LAB EXPERIMENT Temporal Evolution of Density CYCLOTRON MASERS - RESONATORS AND GUIDES – ION PRECIPITATION B SHEAR ALFVEN WAVE Ion Cyclotron Instability R n VA Cash et al. 2006 (Dh) Fabry-Perot like Resonator MASER ELEMENTS - FEEDBACK INVERTED POPULATION LOSS-CONE • CONTROL OF CYCLOTRON MASERS BY IONOSPHERIC HEATING • TRIGGERING STMULATED ULF WAVES AND ION PRECIPITATION • INJECTING ULF POWER IN THE MAGNETOSPHERE IONOSPHERIC ULF GENERATION 1. SAW – REQUIRES EJet AND D/E REGION X-MODE HEATING – OBSERVED ONLY IN NEAR ZONE, ALONG THE FLUX TUBEAND POSSIBLY CONJUGATE SAT REFLECTION F-PEAK B D/E Region heating+ Electrojet BAE v1 10 pT BAE-UMCP E1 Bo Shear Alfven wave IONOSPHERIC ULF GENERATION 2. MSONIC WAVE – REQUIRES F-REGION O-MODE, UPPER HYBRID HEATING; INDEPENDENT OF EJet – WEAK OR NO NEAR FIELD dB / B UH heating Bo k E1 Magnetosonic Alfven Wave (compressional) Bill Bristow UAL ULF POWER INJECTION IN THE MAGNETOSPHERE BAE-UMCP-STANFORD COLLABORATION 1OO nT ULF MODULATION O-MODE .1 Hz BETWEEN 6:47.30 AND 6:59.30. DEMETER FLYOVER DETECTED .1 Hz ACTIVITY IN THE ELECTRIC FIELD AND DENSITY BETWEEN 6:51.30 AND 6:53.00. NO DETECTION ON THE GROUND MSONIC WAVE DETECTION Courtesy of Denys Pidyachiy Stanford STIMULATED ULF EMISSION ? Stimulated Ion Precipitation ?