Lanthanum hexaboride (LaB6) resistivity measurement

Abstract

In the development of high-power free-electron lasers, intense electron beams are required. Large area, directly heated lanthanum hexaboride cathodes have been proposed as the electron emitter. To aid in the design of the cathode, the resistivity of lanthanum hexaboride as a function of material density and temperature has been measured.

Effect of sputtered lanthanum hexaboride film thickness on field emission from metallic knife edge cathodes

“…20 However, other experimental works have observed increased resistivity in LaB 6 thin films 7,14,15 with respect to bulk material. 21,22 As will be discussed, our experimental data and computational modeling support the hypothesis of a significantly lower conduction electron density in the as-deposited film due to defects, disorder, and non-stoichiometry.…”

Consolidation and high‐temperature strength of monolithic lanthanum hexaboride

“…As already noted, when heated, the LaB 6 may act as a source of electrons or plasma discharges. Due to a difference in resistivity of the porous and bulk LaB 6 , 16 local overheating is quite plausible. Using the approach of Raitchenko 35 described in Demirskyi et al 37 .…”

“…As already noted, when heated, the LaB 6 may act as a source of electrons or plasma discharges. Due to a difference in resistivity of the porous and bulk LaB 6 , 16 local overheating is quite plausible. Using the approach of Raitchenko 35 described in Demirskyi et al 37 for YSZ, one can estimate that for LaB 6 at 1600 • C a maximum tempera-ture gradient should lie within 300−350 • C. Data regarding the resistivity, thermal capacity, and specific heat capacity are taken from.…”

“…Using the approach of Raitchenko 35 described in Demirskyi et al 37 for YSZ, one can estimate that for LaB 6 at 1600 • C a maximum tempera-ture gradient should lie within 300−350 • C. Data regarding the resistivity, thermal capacity, and specific heat capacity are taken from. 16,5,38 Here it is important to stress the short processing time during the FSPS. Note that the melting was not observed during any of the FSPS runs.…”

“…LaB 6 is known to have an increase in electrical resistivity from 20 μΩ cm at room-temperature to 120 μΩ cm at 1600 • C. 15 Furthermore, the resistivity at 2000 • C can be as high as 350 μΩ cm for LaB 6 with a relative density of 60% of the TD. 16 As a cathode material, when heated to above 1200 • C, the lanthanum hexaboride will emit its own electrons, making it a de facto local plasma source. Macroscale devices of LaB 6 operating in helium were recently proposed as a plasma source for the next generation of tokamaks.…”