A nanowire based cryogenic electron source

Metallic nanowires can be produced with a large length-to-diameter ratio. They show remarkable field enhancement properties. With the polymer template technique, a copper based ensemble of nanowires can be fabricated with high areal densities up to 107 per cm2. Thus, such a nanowire array is suitable to be used as a field emission electron source delivering high and stable current densities at low voltages. Since the properties of the free electron gas inside the metal show weak temperature dependencies, stable field emission performance can be observed in a wide temperature range. The behavior of such a nanowire ensemble has been tested in a temperature range between 4 K and 300 K. Furthermore, in a superconducting magnet the field emission properties were tested in variable magnetic fields up to 1.9T. In the talk the results of the measurements will be presented and discussed. One possible application of these field emission arrays are electron impact sources operated at cryogenic temperatures in high magnetic fields. In our experiment - the ultra precise measurement of the g-factor of a single isolated proton, stored in a Penning trap - we plan to use the arrays to create the charged particles under such extreme conditions