3D-printed capillary for hydrogen filled discharge for plasma based experiments in RF-based electron linac...

Plasma-based acceleration experiments require capillaries with a radius of a few hundred microns to confine plasma up to a centimeter scale capillary length. A long and controlled plasma channel allows to sustain high fields which may be used for manipulation of the electron beams or to accelerate electrons. The production of these capillaries is relatively complicated and expensive since they are usually made with hard materials whose manufacturing requires highly specialized industries. Fine variations of the capillary shape may significantly increase the cost and time needed to produce them. In this article, we demonstrate the possibility of using 3D printed polymeric capillaries to drive a hydrogen-filled plasma discharge up to 1 Hz of repetition rate in an RF based electron linac. The plasma density distribution has been measured after several shot intervals, showing the effect of the surface ablation on the plasma density distribution. This effect is almost invisible in the earlier stages of the discharge. After more than 55000 shots (corresponding to more than 16 h of working time), the effects of the ablation on the plasma density distribution are not evident and the capillary can still be used. The use of these capillaries will significantly reduce the cost and time for prototyping, allowing us to easily manipulate their geometry, laying another building block for future cheap and compact particle accelerators.