1. Cold plasma: a previously hidden solar system particle population Mats André and Chris Cully Swedish Institute of Space Physics, Uppsala

2. Cold plasma Cold: thermal energy, and drift energy, less than a few eV. From the Terrestrial ionosphere, planets or moons. Cold ions hard to detect on SC charged to a few Volts The more we look for cold plasmas, the more we find…

3. Cold plasma: The ionosphere Atmosphere + sunlight/precipitating particles Observations: Groundbased: magnetometers (currents), radio/ionosonds (density), radars/incoherent scatter radars… Low altitude SC (not much charged, but instr. threshold, SC velocity…)

4. Cold flowing plasma: Wake behind a charged SC Tail lobes Density from SC potential (calibrated) Cluster Engwall et al., (2009)

5. Cold plasma: Particle instrument vs wake detection Cluster SC 4 SC potential control (60 V => 7 V) -5050 vXvX -50 vZvZ km/s H+H+ Particles (black) SC 4 Wake E (red) SC 3 07:4008:20 UT -20 +20 km/s Engwall et al., (2006)

6. Outflowing cold plasma H + outflow about 10 26 ions/s Cluster Engwall et al. (2009)

7.  High altitude, high energy – likely to escape (ion detector) 2 × 10 25 /s (0.5 kg/s) 0 + (Nilsson et al., 2010)  Path to the lobes, where cold ion outflow has been detected (E-field instr.) 10 26 /s H + (Engwall et al., 2009) Oxygen ion heating and outflow (Cluster)

8. Cold plasma: Total vs hot density Just inside the magnetopause Total density from plasma frequency (WHISPER instrument) Cluster Sauvaud et al., 2001 2001-01-31 1000 eV 10 cm -3 10 0.1 05:5006:00 UT

9. Magnetic reconnection, Cluster (magnetopause) 20 min 10s 6000km 2 min Reconnection jet

10. Magnetic reconnection, Cluster (magnetopause)  Cold (eV) ions at the magnetopause  Important for E N at edge of recon. jet (acceleration) ENEN 30 s (1500 km) 4 s (200 km) André et al. (2010)

11. Cold plasma: Recent results from the magnetopause Cluster SC 4, 2008 Total about 150 MP crossings Percent of crossings Status report, to be continued… 10 30 14 Time from MP (hours) Cold ions, from wake E, within certain time inside MP Red: high lat Blue: low lat Black: total

12. Cold plasma: Titan 0.1 cm -3 100 0.1 T e (eV) 0.1 10.0 18:0019:00 UT2009-06-22 Cassini Langmuir probe Edberg et al., 2011

13. Cold plasma How much cold plasma is there? Cold plasma missing in estimates of ion outflow?  Cold plasma changes dynamics.  How can cold plasma stay cold? Always stay tuned to find cold plasma when anywhere near a planet, moon or comet!