Beams of Electrosprayed Nanodroplets for Colloid Thrusters and Hypervelocity Impact

Electrosprays are commonly used in mass spectrometry, particle deposition and electrospinning applications. In our group we study applications of this atomization technique in electrical propulsion for spacecraft (colloid thrusters), and hypervelocity impact. A limiting property of colloid thrusters is the very low thrust that a single electrospray emitter can provide. To eliminate this problem, we propose to create a propellant atomizer in the forms of an array of multiple emitters. The only way to achieve the requirements of weight and volume needed in spacecrafts is to use microfabrication techniques. Extractors and emitters of the colloid thruster must be fabricated taking into account the hydraulic and electric forces involved in the formation of electrosprays. The nanoparticles created by an electrospray can be used as projectiles toimpact on the surface of different materials such as Si or Ge. The velocity and number of impacts received by the surface influence the effect on the material structure.  In particular, it has been observed that nanodroplets exceeding a certain velocity induce amorphization of Si. The associated stagnation pressure is similar to the pressure of the transition between the cubic diamond and beta-tin crystalline phases of Si.