A high brightness plasma ion source has been developed to address focused ion beam ͑FIB͒ applications not satisfied by the liquid metal ion source ͑LMIS͒ based FIB. The plasma FIB described here is capable of satisfying applications requiring high mill rates ͑Ͼ100 m 3 / s͒ with non-gallium ions and has demonstrated imaging capabilities with sub-100-nm resolution. The virtual source size, angular intensity, mass spectra, and energy spread of the source have been determined with argon and xenon. This magnetically enhanced, inductively coupled plasma source has exhibited a reduced brightness ͑␤ r ͒ of 5.4ϫ 10 3 A m −2 sr −1 V −1 , with a full width half maximum axial energy spread ͑⌬E͒ of 10 eV when operated with argon. With xenon, ␤ r = 9.1 ϫ 10 3 A m −2 sr −1 V −1 and ⌬E = 7 eV. With these source parameters, an optical column with sufficient demagnification is capable of forming a sub-25-nm spot size at 30 keV and 1 pA. The angular intensity of this source is nominally three orders of magnitude greater than a LMIS making the source more amenable to creating high current focused beams, in the regime where spherical aberration dominates the LMIS-FIB. The source has been operated on a two lens ion column and has demonstrated a current density that exceeds that of the LMIS-FIB for current greater than 50 nA. Source lifetime and current stability are excellent with inert and reactive gases. Additionally, it should be possible to improve both the brightness and energy spread of this source, such that the ͑␤ r / ⌬E 2 ͒ figure-of-merit could be within an order of magnitude of a LMIS.

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BepiColombo is a joint mission between the European Space Agency, ESA, and the Japanese Aerospace Exploration Agency, JAXA, to perform a comprehensive exploration of Mercury. Launched on $20^{\mathrm{th}}$ 20 th October 2018 from the European spaceport in Kourou, French Guiana, the spacecraft is now en route to Mercury.Two orbiters have been sent to Mercury and will be put into dedicated, polar orbits around the planet to study the planet and its environment. One orbiter, Mio, is provided by JAXA, and one orbiter, MPO, is provided by ESA. The scientific payload of both spacecraft will provide detailed information necessary to understand the origin and evolution of the planet itself and its surrounding environment. Mercury is the planet closest to the Sun, the only terrestrial planet besides Earth with a self-sustained magnetic field, and the smallest planet in our Solar System. It is a key planet for understanding the evolutionary history of our Solar System and therefore also for the question of how the Earth and our Planetary System were formed.The scientific objectives focus on a global characterization of Mercury through the investigation of its interior, surface, exosphere, and magnetosphere. In addition, instrumentation onboard BepiColombo will be used to test Einstein’s theory of general relativity. Major effort was put into optimizing the scientific return of the mission by defining a payload such that individual measurements can be interrelated and complement each other.

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A one-dimensional model of a small plasma ion source ͑10 cm long͒ is studied. A hybrid simulation where ions are treated as particles and electrons as a fluid obeying the Boltzmann relation is used to investigate ion heating in the plasma presheath. At low pressure ͑below a few mTorr͒, the ion velocity distribution is Maxwellian in the bulk and becomes a drifting Maxwellian distribution while transiting the presheath. The distribution remains essentially isotropic as the ions are accelerated through the presheath to satisfy the Bohm criterion. At intermediate pressures ͑around 10 mTorr͒, ion-neutral collisions scatter a significant part of the ion kinetic energy from the parallel direction to the perpendicular direction, leading to a net heating of the ions. In addition, the ion velocity distribution becomes distinctly anisotropic. At higher pressure ͑above a few tens of mTorr͒, ion heating is still observed, but yields isotropic ion velocity distributions.