The expressions of the second harmonic（2f） signal are derived on the basis of absorption spectral and lock-in theories.A parametric study indicates that the phase shift between the intensity and wavelength modulatio...The expressions of the second harmonic（2f） signal are derived on the basis of absorption spectral and lock-in theories.A parametric study indicates that the phase shift between the intensity and wavelength modulation makes a great contribution to the 2f signal.A self-calibration wavelength modulation spectroscopy（WMS） method based on tunable diode laser absorption spectroscopy（TOLAS） is applied,combining the advantages of ambient pressure,temperature suppression,and phase-shift influences elimination.Species concentration is retrieved simultaneously from selected 2f signal pairs of measured and reference WMS-2f spectra.The absorption line of acetylene（C2H2） at 1530.36 nm near-infrared is selected to detect C2H2 concentrations in the range of 0-400 ppmv.System sensitivity,detection precision and limit are markedly improved,demonstrating that the self-calibration method has better detecting performance than the conventional WMS.展开更多
Background Indirect cooling method is an alternative scheme for magnetic alloy(MA)-loaded cavity because of the feasible structure and MA core treatment process.Stable and long-term operation is not possible without a...Background Indirect cooling method is an alternative scheme for magnetic alloy(MA)-loaded cavity because of the feasible structure and MA core treatment process.Stable and long-term operation is not possible without a powerful cooling system for the high-power MA cavity.Purpose The paper reports a method to evaluate the cooling efficiency of an indirect cooling structure for high-power-loss MA cavity.Methods Two types of helix metallic cooling plate were designed and checked by CFX code considering the average power loss more than 0.13 W/cc.In order to enhance the heat-transfer efficiency between the non-flatness surface of the MA core and metallic cooling plate,a filling material with high thermal conductivity is needed.Different commercial filling materials were investigated,and a high-power test bench was developed to assess the cooling efficiency.A parametric fitting method was adopted to qualify the heat-transfer coefficient according to the temperature rising curve.Conclusion The results indicate that the experimental data maintain good consistency with the CFX simulation results and the cooling structure meets the high-power-loss cooling requirement.The heat-transfer capability of the filling was influenced by the thickness of heat-transfer materials and the painting process.The heat-transfer performance of the thermal grease is better than that of the thermal gasket even though the latter has a higher thermal conductivity.The virtual thermal conductivity of the filling material was less than the product index and affirmed by the CFX transient simulation.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61172047,61502538,and 61501525)
文摘The expressions of the second harmonic（2f） signal are derived on the basis of absorption spectral and lock-in theories.A parametric study indicates that the phase shift between the intensity and wavelength modulation makes a great contribution to the 2f signal.A self-calibration wavelength modulation spectroscopy（WMS） method based on tunable diode laser absorption spectroscopy（TOLAS） is applied,combining the advantages of ambient pressure,temperature suppression,and phase-shift influences elimination.Species concentration is retrieved simultaneously from selected 2f signal pairs of measured and reference WMS-2f spectra.The absorption line of acetylene（C2H2） at 1530.36 nm near-infrared is selected to detect C2H2 concentrations in the range of 0-400 ppmv.System sensitivity,detection precision and limit are markedly improved,demonstrating that the self-calibration method has better detecting performance than the conventional WMS.
基金Key Programme (GrantNo. 11875270) and Major Research Plan (Grant No. U1832210).
文摘Background Indirect cooling method is an alternative scheme for magnetic alloy(MA)-loaded cavity because of the feasible structure and MA core treatment process.Stable and long-term operation is not possible without a powerful cooling system for the high-power MA cavity.Purpose The paper reports a method to evaluate the cooling efficiency of an indirect cooling structure for high-power-loss MA cavity.Methods Two types of helix metallic cooling plate were designed and checked by CFX code considering the average power loss more than 0.13 W/cc.In order to enhance the heat-transfer efficiency between the non-flatness surface of the MA core and metallic cooling plate,a filling material with high thermal conductivity is needed.Different commercial filling materials were investigated,and a high-power test bench was developed to assess the cooling efficiency.A parametric fitting method was adopted to qualify the heat-transfer coefficient according to the temperature rising curve.Conclusion The results indicate that the experimental data maintain good consistency with the CFX simulation results and the cooling structure meets the high-power-loss cooling requirement.The heat-transfer capability of the filling was influenced by the thickness of heat-transfer materials and the painting process.The heat-transfer performance of the thermal grease is better than that of the thermal gasket even though the latter has a higher thermal conductivity.The virtual thermal conductivity of the filling material was less than the product index and affirmed by the CFX transient simulation.
