Investigations on advanced ceramics for window applications in radiofrequency heating concepts
Investigations on advanced ceramics for window applications in radiofrequency heating concepts
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射频加热概念中窗户应用先进陶瓷的研究
DOI：
10.1016/0022-3115(88)90268-1
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发表时间：
1988
期刊：
影响因子：
--
通讯作者：
F. Königer
中科院分区：
文献类型：
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作者：
R. Heidinger;F. Königer
在与核聚变中的各种射频加热概念有关的频率范围内，对高级陶瓷进行了测量。在30-40 GHz的介电损耗角正切低至4× 10− 4已被确定在氧化铝。单晶MgAl 2 O 4、ZrO 2强化Al 2 O3和透明AlN的介电常数可以相互竞争，这是由于其它物理性能所获得的优势。在52 MHz下，单晶材料被证明具有非常低的损耗，而在多晶材料中，不同样品之间存在显著变化。在最高样品温度约为200° C时，用2.6× 1020 n/cm 2的快中子注量辐照多晶氧化铝（AL 23）和单晶（蓝宝石）。介电常数增加，在AL 23中比在蓝宝石中更强。在30-40 GHz时，仅AL 23的介电损耗显著上升，而在52 MHz时，两种材料的介电损耗均显著上升。蓝宝石的退火研究表明，在30-40 GHz的介电常数随温度的线性恢复，但在52 MHz的阶梯状恢复。
Advanced ceramics have been measured in frequency ranges related to the various radiofrequency heating concepts in nuclear fusion. At 30–40 GHz dielectric loss tangents as low as 4× 10− 4 have been determined in Al 2 O 3. The dielectric parameters of single crystal MgAl 2 O 4, ZrO 2-strengthened Al 2 O 3 and transparent A1N can compete because of the advantages gained by other physical properties. At 52 MHz, single crystal material proves to be of very low loss, while in polycrystalline material there exists substantial variation between different samples. Polycrystalline alumina (AL23) and a single crystal (sapphire) were irradiated to a fast neutron fluence of 2.6× 10 20 n/cm 2 at maximum sample temperatures of about 200° C. Permittivity is increased, stronger in AL23 than in sapphire. At 30–40 GHz, dielectric loss has gone up markedly in AL23 only, and at 52 MHz in both materials. Annealing studies in sapphire showed a linear recovery of permittivity with temperature at 30–40 GHz, but a step-like recovery at 52MHz.