Rare earth doped high temperature ceramic selective emitters

Rare earth doped yttrium aluminum garnet (YAG) selective emitters

“…These quantities were obtained from measured transmittance and reflectance data (ref. 15). Also, the reflectances at the film-vacuum interlace, Pro and film-substrate interface, Pfs, (efs = I -Pfs) must be known.…”

“…Error in the measured extinction coefficient is the reason the calculated e_, is larger than the measured value in the 1800 < _ -< 4000 nm region (ref. 15). For the region 4000 < _, < 6000 nm the vibrational modes of the crystal lattice are the primary source of the emission.…”

Emittance theory for cylindrical fiber selective emitter

“…(9)). Results for the uniform temperature cylinder can be obtained from these results by setting Cfs = 0 (Pfs = 1) and AT = 0 in equations (33) to (36) of reference (5). When this is done the following result is obtained for the spectral emittance.…”

“…Figure 3 shows the calculated spectral emittance for an erbium-holmium aluminum garnet cylinder (R = 0.4 cm) with 10% erbium and 90% holmium, Er0.3Ho2.7A15012. This single crystal material is being considered for a film type selective emitter (5). The extinction coefficient and index of refraction were obtained from reference (5).…”

“…This single crystal material is being considered for a film type selective emitter (5). The extinction coefficient and index of refraction were obtained from reference (5). Holmium has its main emission band centered at _, = 2000 um with smaller bands centered at _, = 1100, 890 and 750 nm.…”