Thermionic Emitters (TE)
Cathodes operating in the thermionic regime are heated to high temperatures. Emission occurs when electrons have enough thermal energy to overcome the work function of the material from which the cathode is made.
Our thermionic cathodes are made from lanthanum hexaboride (LaB6) and cerium hexaboride (CeBix®). Both LaB6 and CeBix® are low work function materials that produce relatively high brightness cathodes that have modest vacuum requirements and long shelf-life. These cathodes provide long-term, stable operation at current densities up to 20 A/cm2, making them ideal for small spot applications such as SEM, TEM, electron beam sterilization, surface analysis, and metrology as well as large current applications like x-ray generation, lithography, and additive manufacturing.
At APT, we grow and fabricate our own high-quality, single-crystal LaB6 and CeBix® in-house using a process that produces the purest and lowest work function material commercially available. Once refined, our borides can be custom fabricated into a variety of shapes with different heating, mounting, and base configurations, all designed to match our customers’ operational and performance requirements.
With a slightly lower work function than LaB6, CeBix® cathodes generate higher currents at slightly lower operating temperatures. As a result, CeBix® sources have a slightly higher brightness and longer lifetime. APT is the world’s only commercial producer of CeBix® cathodes.
We can also provide both LaB6 and CeBix® single-crystal rods and disks separately.
APT’s R&D team partners with customers to design cathodes customized to meet their needs. Contact us to speak with one of our specialists, explain your application, and let us partner with you to find a solution.