Outer Magnetospheric Boundaries: Cluster Results

9 Summary and Conclusions 310 References 312 9. 1 Introduction 321 9. 1 Previous work 323 9. 2 How Cluster investigates the cusp 325 9. 1 March 17, 2001 328 9. 2 February 4, 2001 332 9. 3 February 13, 2001 337 9. 3 The Mid-Altitude Cusp 352 9. 1 Structure: Case study 352 9. 2 Structure: Statistical survey 354 9. 3 Ionospheric ions 354 9.