Carbon nano tubes effectiveness proven in new paper

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AVA Fellow Bruno Galante working at CERN has recently had a paper published titled “Stability and lifetime study of carbon nanotubes as cold electron field emitters for electron cooling in the CERN extra low energy antiproton ring“.

As Electron cooling is a fundamental process to guarantee beam quality in low energy antimatter facilities such as ELENA. The electron cooler is used to reduce emittance blow up of the low energy antiproton beam, requiring a supply of a monoenergetic relatively intense electron beam. In the paper an optimization of the ELENA electron cooler gun involving a cold cathode is studied, with the aim of investigating the feasibility of using carbon nanotubes (CNTs) as cold electron field emitters. CNTs are considered among the most promising field emitting material. However, stability data for emission operation over hundreds of hours, as well as lifetime and conditioning process studies to ensure optimal performance, are still incomplete or missing.

Within the paper several CNT samples are characterised focusing on two main arrangement geometries, with the aim of assessing if they can be considered good candidates for being used operationally in ELENA as cold electron field emitters. The samples tested so far have shown promising results if operated in optimal conditions i.e. low pressure and vacuum bakeout greater than 200°C which match perfectly the requirements of ELENA.

Concerns around CNT’s still exist around their lifetime and stability and as such a honeycomb structure is examined which reached the 1500h mark still whilst still maintaining emission. Within the tested arrays the honeycomb structure proved to have the best performance, whilst also allowing for the maximal space optimization.

The results achieved open the way for designing a new style of electron gun for the ELENA electron cooler, further tests are planned for the near future to further confirm this approach. These results will help to inform about introducing a new CNT based gun over the currently existing thermionic electron gun.

Bruno’s paper which contains much more detail on the topic was published in ‘Physical review accelerators and beams 24’ and can be found at:

https://journals.aps.org/prab/abstract/10.1103/PhysRevAccelBeams.24.113401