Evolution of PUI Distributions Evolution of PUI Distributions

E. Möbius1, B. Klecker2, P. Bochsler1, G. Gloeckler3, H. Kucharek1, P.A. Isenberg1E. Möbius1, B. Klecker2, P. Bochsler1, G. Gloeckler3, H. Kucharek1, P.A. Isenberg1

1Institute for the Study of Earth, Oceans & Space and Department of Physics, University of New Hampshire, Durham, NH, USA2Max-Planck-Institut für extraterrestrische Physik, Garching, Germany3Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, USA

1Institute for the Study of Earth, Oceans & Space and Department of Physics, University of New Hampshire, Durham, NH, USA2Max-Planck-Institut für extraterrestrische Physik, Garching, Germany3Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, USA

Supported by NASA SR&T, STP, ACE, Prodex, Swiss NF, & DLRSupported by NASA SR&T, STP, ACE, Prodex, Swiss NF, & DLR

Strong Variations in Pickup Ion Distributions

Pickup Ion Distributions are Highly Variable

Pickup Ions React to:- IMF Orientation (early Rollover)- IMF Strength (Compression and Rarefaction)- SW Density (Compression and Rarefaction)- Ionization rates & probably several unknown causes

For Deduction of LIC Parameters Mitigation Sought with:- Long Integration Times

Plan: Attempt to Understand Causes- Also Provides Handle on Ion Transport and Acceleration

STEREO A,B & ACE Provide Simultaneous Observations

Pickup Ion Distributions are Highly Variable

Pickup Ions React to:- IMF Orientation (early Rollover)- IMF Strength (Compression and Rarefaction)- SW Density (Compression and Rarefaction)- Ionization rates & probably several unknown causes

For Deduction of LIC Parameters Mitigation Sought with:- Long Integration Times

Plan: Attempt to Understand Causes- Also Provides Handle on Ion Transport and Acceleration

STEREO A,B & ACE Provide Simultaneous Observations

STEREO-A & STEREO-B He+ Cone Observations in 2007

At STEREO-B:

• Cone has Double Peak

At STEREO-B:

• Cone has Double Peak

At STEREO A:

• Cone has Single Peak

• Cone appears narrower

At STEREO A:

• Cone has Single Peak

• Cone appears narrower

Phasing with SW StreamsDetermines Shape Phasing with SW StreamsDetermines Shape

STEREO-A & STEREO-B He+ Cone Observations in 2007

He+ relates to Nsw, particularly at CIR compressions

STEREO-A He+ Observations in 2007 & 2008

• He+ Peaks Related to Jsw

but not much better than with Nsw

• He+ Peaks Related to Jsw

but not much better than with Nsw

Phasing with SW StreamsDetermines Shape Phasing with SW StreamsDetermines Shape

Pickup Ions are Relatedto SW Density and Flux, but not the full story

Pickup Ions are Relatedto SW Density and Flux, but not the full story

• Sorting according to IMF Orientation doesn’t improve correlation

• Sorting according to IMF Orientation doesn’t improve correlation

Additional Cone Variations Could Transport with IMF Play a Role?

• IMF Could Transport PUIs out of the Cone• IMF Could Transport PUIs out of the Cone

• Different IMF Orientation Could Enable Varying Transport

• Different IMF Orientation Could Enable Varying Transport

• Implicit Assumption: PUIs ride with SW - But only part of the PUI phase space does

• Implicit Assumption: PUIs ride with SW - But only part of the PUI phase space does

• Other phase space parts ride (along B) from different directions

• Other phase space parts ride (along B) from different directions

STEREO A&B April 1, 2007ap

prox

. Par

ker

ACE

Pickup Ion Phase Space Distribution and their Observation

Assume Isotropic DistributionAssume Isotropic Distribution- Fast pitch-angle scattering- Fast pitch-angle scattering- Adiabatic Cooling- Adiabatic Cooling- Mapping of Neutral Source- Mapping of Neutral Source

PUI PSD Centered on SWPUI PSD Centered on SW- V- Vswsw cut symmetric about SW cut symmetric about SW

- But not in flux!- But not in flux!

Observed PUI PSD Observed PUI PSD - Integrated over ∆- Integrated over ∆ & ∆E & ∆E in SW Sector in SW Sector

Good Agreement 1.4<w< 1.8!Good Agreement 1.4<w< 1.8!Differences: Differences: - At Cut-off- At Cut-off - Near SW- Near SW

Study of Variations Requires Baseline of Neutral Distribution and Mapping into PUI Distributions via Ionization & Cooling

Start to Tackle this Issue!

Previous Paradigm: Cooling is Completely AdiabaticImplies- Expansion as 1/r2 for SW and IMF- Immediate Isotropization of PUIs

Yet: - Evidence for Compressions & Decompressions- Evidence for Slow Scattering for PUIs

How Can We Separate the Cooling Coefficient?

Study of Variations Requires Baseline of Neutral Distribution and Mapping into PUI Distributions via Ionization & Cooling

Start to Tackle this Issue!

Previous Paradigm: Cooling is Completely AdiabaticImplies- Expansion as 1/r2 for SW and IMF- Immediate Isotropization of PUIs

Yet: - Evidence for Compressions & Decompressions- Evidence for Slow Scattering for PUIs

How Can We Separate the Cooling Coefficient?

Perplexing Variations of Pickup Ions- Impact of Ionization & Cooling

Influence of Ionization & Cooling

PUI Distribution Determined by Ionization & Cooling:

Along Inflow Axis

Assume = 1.5

Assume = 1.2

PUI Distribution Determined by Ionization & Cooling:

Along Inflow Axis

Assume = 1.5

Assume = 1.2

€

f (v /Vsw )=3

8π

ν ion E rEVsw

4 N(r(v /Vsw ))•v

Vsw

⎛

⎝ ⎜ ⎞

⎠ ⎟

−α

Influence of Ionization & Cooling

PUI Distribution Determined by Ionization & Cooling:

Along Inflow Axis

Use = 1.5 & 1.2

Assume = 1 AU (SolMax)

Assume = 0.3 AU (SolMin)

PUI Distribution Determined by Ionization & Cooling:

Along Inflow Axis

Use = 1.5 & 1.2

Assume = 1 AU (SolMax)

Assume = 0.3 AU (SolMin)

€

f (v /Vsw )=3

8π

ν ion E rEVsw

4 N(r(v /Vsw ))•v

Vsw

⎛

⎝ ⎜ ⎞

⎠ ⎟

−α

Requires Pickup Ion DataRequires Pickup Ion DataOver Full Solar CycleOver Full Solar Cycle

Available from ACE SWICS!Available from ACE SWICS!

Influence of Ionization & Cooling

PUI Distribution Determined by Ionization & Cooling

ACE SWICS PUI PSDs June 2001 & 2007- Along Inflow Axis- 2001 = 0.85 AU (SolMax)- 2007 = 0.34 AU (SolMin)

Use = 2.0, 1.5 & 1.2in Model

Looks Tantalizing!Acceptable V/Vsw

To Do PSD Integration!!

PUI Distribution Determined by Ionization & Cooling

ACE SWICS PUI PSDs June 2001 & 2007- Along Inflow Axis- 2001 = 0.85 AU (SolMax)- 2007 = 0.34 AU (SolMin)

Use = 2.0, 1.5 & 1.2in Model

Looks Tantalizing!Acceptable V/Vsw

To Do PSD Integration!!

Summary & ConclusionsInterstellar He Cone Traversals with STEREO A & B

Show remarkable substructure aligned with SW density enhancements, but neither SW density, flux, ionization and IMF variations explain all PUI variations

Potential Culprits: a) Deviations from adiabatic cooling b) Transport effects not aligned with SW

a) First attempt to separate effects of ionization rates and cooling behavior on PUI spectra appear to suggest a deviation from plain adiabatic dependence (w3/2), but so far only pseudo phase space density evaluated

b) ACE & STEREO Spring 2007 at 0.01AU along <B>

Interstellar He Cone Traversals with STEREO A & B Show remarkable substructure aligned with SW density enhancements, but neither SW density, flux, ionization and IMF variations explain all PUI variations

Potential Culprits: a) Deviations from adiabatic cooling b) Transport effects not aligned with SW

a) First attempt to separate effects of ionization rates and cooling behavior on PUI spectra appear to suggest a deviation from plain adiabatic dependence (w3/2), but so far only pseudo phase space density evaluated

b) ACE & STEREO Spring 2007 at 0.01AU along <B>

Thank You!Support for this Project:- NASA SR&T- NASA ACE- NASA Solar Terrestrial Probes- PRODEX & Swiss National Foundation- DLR in Germany