Pub Date : 1987-12-01DOI: 10.1109/irmm.1987.9126918
S. Riyopoulos, C. Tang
The problem of sideband growth in a free electron laser (FEL) is studied using canonical formalism. The exact unperturbed orbits, without sidebands, are obtained in action-angle variables for all particles. Integration of the linearized Vlasov equation with sidebands over the unperturbed orbits yields the sideband growth that includes both trapped and untrapped particles. It is found that the upper and lower sidebands that are symmetric about the FEL frequency have opposite growth rates, with equal magnitude. The stability of the upper or lower sidebands is determined by the sign of dfo/dΩb, i.e., the relative population of oscillation quanta hΩb, Ωb = bounce frequency around resonance.
{"title":"Sidebands in free electron lasers","authors":"S. Riyopoulos, C. Tang","doi":"10.1109/irmm.1987.9126918","DOIUrl":"https://doi.org/10.1109/irmm.1987.9126918","url":null,"abstract":"The problem of sideband growth in a free electron laser (FEL) is studied using canonical formalism. The exact unperturbed orbits, without sidebands, are obtained in action-angle variables for all particles. Integration of the linearized Vlasov equation with sidebands over the unperturbed orbits yields the sideband growth that includes both trapped and untrapped particles. It is found that the upper and lower sidebands that are symmetric about the FEL frequency have opposite growth rates, with equal magnitude. The stability of the upper or lower sidebands is determined by the sign of dfo/dΩb, i.e., the relative population of oscillation quanta hΩb, Ωb = bounce frequency around resonance.","PeriodicalId":399243,"journal":{"name":"1987 Twelth International Conference on Infrared and Millimeter Waves","volume":"252 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1987-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131492454","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1987-12-01DOI: 10.1109/irmm.1987.9127052
R. B. McCowan, A. Fliflet, W. M. Manheimer, Steven H. Gold, W. M. Black, G. Bergeron, A. Kinkead, V. Granatstein, M. Sucy
The design of a 10-20 MW, 40 nsec cyclotron autoresonance maser is presented. The basic components of the CARM are a novel 600 kV, 200 A. field emission gun and a “whispering gallery” mode rippled wall cavity.
{"title":"The NRL100 GHz carm oscillator experiment","authors":"R. B. McCowan, A. Fliflet, W. M. Manheimer, Steven H. Gold, W. M. Black, G. Bergeron, A. Kinkead, V. Granatstein, M. Sucy","doi":"10.1109/irmm.1987.9127052","DOIUrl":"https://doi.org/10.1109/irmm.1987.9127052","url":null,"abstract":"The design of a 10-20 MW, 40 nsec cyclotron autoresonance maser is presented. The basic components of the CARM are a novel 600 kV, 200 A. field emission gun and a “whispering gallery” mode rippled wall cavity.","PeriodicalId":399243,"journal":{"name":"1987 Twelth International Conference on Infrared and Millimeter Waves","volume":"489 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1987-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116531062","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1987-12-01DOI: 10.1109/irmm.1987.9126945
L. Lesyna, T. Roellig, M. Werner
We have constructed composite bolometers operating at temperatures near 0.1 K to detect one millimeter continuum radiation. Our most sensitive detector has a measured electrical noise equivalent power (NEP) of 7 × 10−17 W Hz−1/2, which is about three times more sensitive than previously reported. We present our experimental results, and design considerations for 0.1 K bolometers.
我们已经构建了在接近0.1 K的温度下工作的复合辐射热计，以检测一毫米连续辐射。我们最灵敏的探测器测量到的电噪声等效功率(NEP)为7 × 10−17 W Hz−1/2，比以前报道的灵敏度高约三倍。本文介绍了0.1 K测热计的实验结果和设计考虑。
{"title":"Millimeter Wavelength Bolometers Cooled by Adiabatic Demagnetization Refrigeration","authors":"L. Lesyna, T. Roellig, M. Werner","doi":"10.1109/irmm.1987.9126945","DOIUrl":"https://doi.org/10.1109/irmm.1987.9126945","url":null,"abstract":"We have constructed composite bolometers operating at temperatures near 0.1 K to detect one millimeter continuum radiation. Our most sensitive detector has a measured electrical noise equivalent power (NEP) of 7 × 10−17 W Hz−1/2, which is about three times more sensitive than previously reported. We present our experimental results, and design considerations for 0.1 K bolometers.","PeriodicalId":399243,"journal":{"name":"1987 Twelth International Conference on Infrared and Millimeter Waves","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1987-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121233604","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1987-12-01DOI: 10.1109/irmm.1987.9127006
J. Shively, K. Felch, H. Jory, J. Neilson
A second harmonic gyrotron was designed and constructed for operation at 106.4 GHz, 100 kw peak output power, utilizing a TE021/TE031 complex cavity. Design calculation results for 80 kV 8 A operation are presented. Initial tube tests have been carried out. Peak output powers of 120 kW have been achieved.
{"title":"Second harmonic 106.4 GHz gyrotron","authors":"J. Shively, K. Felch, H. Jory, J. Neilson","doi":"10.1109/irmm.1987.9127006","DOIUrl":"https://doi.org/10.1109/irmm.1987.9127006","url":null,"abstract":"A second harmonic gyrotron was designed and constructed for operation at 106.4 GHz, 100 kw peak output power, utilizing a TE021/TE031 complex cavity. Design calculation results for 80 kV 8 A operation are presented. Initial tube tests have been carried out. Peak output powers of 120 kW have been achieved.","PeriodicalId":399243,"journal":{"name":"1987 Twelth International Conference on Infrared and Millimeter Waves","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1987-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121267680","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1987-12-01DOI: 10.1109/irmm.1987.9127014
S. Perkowitz
Intricate semiconductor microstructures require varied methods to examine their properties. Far infrared (FIR) spectroscopy (10–400 cm−1) is contactless and nondestructive. A key to the technique is the simplicity of the FIR superlattice (SL) dielectric function, which at normal incidence is (1)
{"title":"Far infrared characterization of semiconductor microstructures","authors":"S. Perkowitz","doi":"10.1109/irmm.1987.9127014","DOIUrl":"https://doi.org/10.1109/irmm.1987.9127014","url":null,"abstract":"Intricate semiconductor microstructures require varied methods to examine their properties. Far infrared (FIR) spectroscopy (10–400 cm−1) is contactless and nondestructive. A key to the technique is the simplicity of the FIR superlattice (SL) dielectric function, which at normal incidence is (1)","PeriodicalId":399243,"journal":{"name":"1987 Twelth International Conference on Infrared and Millimeter Waves","volume":"127 18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1987-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128025272","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1987-12-01DOI: 10.1109/irmm.1987.9126886
P. Batelaan, M. Frerking
A quantum well double barrier diode has been tested as a frequency tripler from 63.7 GHz to 191 GHz in a crossed waveguide mount designed for use with GaAs varactor diodes. Output power of 250 μw has been generated with an efficiency of 0.61 %. This performance is comparable to that obtained from a GaAs varactor diode with the same cutoff frequency.
{"title":"Quantum well multipliers","authors":"P. Batelaan, M. Frerking","doi":"10.1109/irmm.1987.9126886","DOIUrl":"https://doi.org/10.1109/irmm.1987.9126886","url":null,"abstract":"A quantum well double barrier diode has been tested as a frequency tripler from 63.7 GHz to 191 GHz in a crossed waveguide mount designed for use with GaAs varactor diodes. Output power of 250 μw has been generated with an efficiency of 0.61 %. This performance is comparable to that obtained from a GaAs varactor diode with the same cutoff frequency.","PeriodicalId":399243,"journal":{"name":"1987 Twelth International Conference on Infrared and Millimeter Waves","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1987-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132906593","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1987-12-01DOI: 10.1109/irmm.1987.9127027
S. Spira, K. Kreischer, R. Temkin
High power, submillimeter gyrotron oscillator experiments are presently being conducted at M.I.T. These experiments are designed to operate at second harmonic and generate output powers up to 100 kW for 1 μsec pulses. To achieve second harmonic emission three different cavity configurations have been explored, a tapered cavity, a slotted cavity, and a cavity with an output iris. In the last cavity, second harmonic emission was observed at 301 GHz and 339 GHz, with output powers of 4-6 kW.
{"title":"High power submillimeter gyrotrons","authors":"S. Spira, K. Kreischer, R. Temkin","doi":"10.1109/irmm.1987.9127027","DOIUrl":"https://doi.org/10.1109/irmm.1987.9127027","url":null,"abstract":"High power, submillimeter gyrotron oscillator experiments are presently being conducted at M.I.T. These experiments are designed to operate at second harmonic and generate output powers up to 100 kW for 1 μsec pulses. To achieve second harmonic emission three different cavity configurations have been explored, a tapered cavity, a slotted cavity, and a cavity with an output iris. In the last cavity, second harmonic emission was observed at 301 GHz and 339 GHz, with output powers of 4-6 kW.","PeriodicalId":399243,"journal":{"name":"1987 Twelth International Conference on Infrared and Millimeter Waves","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1987-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124972073","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1987-12-01DOI: 10.1109/IRMM.1987.9127056
M. Thumm, H. Kumrić
Elliptic deformation of oversized, smooth-wall circular waveguide can produce arbitrary elliptical or circular polarization from a linearly polarized TE11 or TM11 mode, used as intermediates between TE01 and HE11 in electron cyclotron heating (ECH) of magnetically confined thermonuclear fusion plasmas with high-power gyrotrons. Mode coupling in overmoded elliptically distorted circular waveguide has been studied theoretically and experimentally in order to optimize TE11 (and TM11) polarizers (I.D. = 27.79 mm) for use in the 1 MW/70 GHz ECH system on the Garching Stellarator W VII-AS. Accurate differential phase characteristics and very low levels of spurious modes have been achieved.
{"title":"High-power te11 and tm11 circular polarizers in oversized waveguide at 70 ghz","authors":"M. Thumm, H. Kumrić","doi":"10.1109/IRMM.1987.9127056","DOIUrl":"https://doi.org/10.1109/IRMM.1987.9127056","url":null,"abstract":"Elliptic deformation of oversized, smooth-wall circular waveguide can produce arbitrary elliptical or circular polarization from a linearly polarized TE11 or TM11 mode, used as intermediates between TE01 and HE11 in electron cyclotron heating (ECH) of magnetically confined thermonuclear fusion plasmas with high-power gyrotrons. Mode coupling in overmoded elliptically distorted circular waveguide has been studied theoretically and experimentally in order to optimize TE11 (and TM11) polarizers (I.D. = 27.79 mm) for use in the 1 MW/70 GHz ECH system on the Garching Stellarator W VII-AS. Accurate differential phase characteristics and very low levels of spurious modes have been achieved.","PeriodicalId":399243,"journal":{"name":"1987 Twelth International Conference on Infrared and Millimeter Waves","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1987-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130049762","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1987-12-01DOI: 10.1109/irmm.1987.9126994
N. Erickson, P. Goldsmith, C. R. Predmore, P. Viscuso
A heterodyne imaging array is under construction to tune the 95-115 GHz range with a 3×5 array. The mixers will use Schottky diodes operated at 20 K with integrated HEMT IF amplifiers. Image sideband rejection is done with a quasi-optical filter which terminates the image at 20 K. Polarization interleaving is used to minimize the array size on the sky.
{"title":"A 3mm heterodyne imaging array","authors":"N. Erickson, P. Goldsmith, C. R. Predmore, P. Viscuso","doi":"10.1109/irmm.1987.9126994","DOIUrl":"https://doi.org/10.1109/irmm.1987.9126994","url":null,"abstract":"A heterodyne imaging array is under construction to tune the 95-115 GHz range with a 3×5 array. The mixers will use Schottky diodes operated at 20 K with integrated HEMT IF amplifiers. Image sideband rejection is done with a quasi-optical filter which terminates the image at 20 K. Polarization interleaving is used to minimize the array size on the sky.","PeriodicalId":399243,"journal":{"name":"1987 Twelth International Conference on Infrared and Millimeter Waves","volume":"54 5","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1987-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114010016","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1987-12-01DOI: 10.1109/irmm.1987.9126972
U. Buchenau
The temperature dependence of the inelastic neutron scattering intensity from vitreous silica has been studied between 50 and 300 K down to frequencies of 150 GHz. Above 500 GHz one finds essentially harmonic behaviour. The anharmonic behaviour at low frequencies can be described in a relaxational model using parameters determined from mechanical measurements. From their dynamic structure factor, the relaxations are coupled rotational jumps of SiO4 tetrahedra. The jump width of the atoms in these relaxations is shown to be smaller than 0.8 Å. The results support the hypothesis of a common origin of the low temperatures glass anomalies.
{"title":"Neutron scattering from low-frequency excitations in a-sio2","authors":"U. Buchenau","doi":"10.1109/irmm.1987.9126972","DOIUrl":"https://doi.org/10.1109/irmm.1987.9126972","url":null,"abstract":"The temperature dependence of the inelastic neutron scattering intensity from vitreous silica has been studied between 50 and 300 K down to frequencies of 150 GHz. Above 500 GHz one finds essentially harmonic behaviour. The anharmonic behaviour at low frequencies can be described in a relaxational model using parameters determined from mechanical measurements. From their dynamic structure factor, the relaxations are coupled rotational jumps of SiO4 tetrahedra. The jump width of the atoms in these relaxations is shown to be smaller than 0.8 Å. The results support the hypothesis of a common origin of the low temperatures glass anomalies.","PeriodicalId":399243,"journal":{"name":"1987 Twelth International Conference on Infrared and Millimeter Waves","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1987-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122467729","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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