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.1987.9126972
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}
Pub Date : 1987-12-01DOI: 10.1109/IRMM.1987.9127002
S. Smith, N. Cronin, J. Harris, C. Foxon
We have shown that a Ga1-xAlxAs/GaAs heterostructure can be used as a sensitive tunable detector of mm-wave/sübmm-wave radiation. The mechanism for detection requires the application of a magnetic field varying from approximately 0.2T at 94GHz (3.2mm wavelength) to 6.2T at 2500GHz (119μm wavelength). The speed of such a detector could be several orders of magnitude greater than comparable InSb detectors.
{"title":"A new submillimetre-wave detector using cyclotron resonance in ga1-xalxas/gaas heterostructures","authors":"S. Smith, N. Cronin, J. Harris, C. Foxon","doi":"10.1109/IRMM.1987.9127002","DOIUrl":"https://doi.org/10.1109/IRMM.1987.9127002","url":null,"abstract":"We have shown that a Ga1-xAlxAs/GaAs heterostructure can be used as a sensitive tunable detector of mm-wave/sübmm-wave radiation. The mechanism for detection requires the application of a magnetic field varying from approximately 0.2T at 94GHz (3.2mm wavelength) to 6.2T at 2500GHz (119μm wavelength). The speed of such a detector could be several orders of magnitude greater than comparable InSb detectors.","PeriodicalId":399243,"journal":{"name":"1987 Twelth International Conference on Infrared and Millimeter Waves","volume":"13 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":"131399706","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.1987.9126981
K. Kreischer, R. Temkin
A pulsed (3μsec) gyrotron oscillator which can be scaled to cw operation has generated high output powers at frequencies between 126 and 243 GHz. Peak powers of 645 kW and total efficiencies of 28% were measured. By varying the cavity magnetic field, step tuning through a sequence of TEm,p,1 modes with p = 2,3 and 4 was observed. The highest order mode observed was the TE22,4,1 at 243 GHz, which corresponds to a cavity diameter of 12 free space wavelengths. An output power of 470 kW was measured in this mode at 80 kV and 35 A.
{"title":"A 120–240 GHz step tunable megawatt gyrotron","authors":"K. Kreischer, R. Temkin","doi":"10.1109/irmm.1987.9126981","DOIUrl":"https://doi.org/10.1109/irmm.1987.9126981","url":null,"abstract":"A pulsed (3μsec) gyrotron oscillator which can be scaled to cw operation has generated high output powers at frequencies between 126 and 243 GHz. Peak powers of 645 kW and total efficiencies of 28% were measured. By varying the cavity magnetic field, step tuning through a sequence of TEm,p,1 modes with p = 2,3 and 4 was observed. The highest order mode observed was the TE22,4,1 at 243 GHz, which corresponds to a cavity diameter of 12 free space wavelengths. An output power of 470 kW was measured in this mode at 80 kV and 35 A.","PeriodicalId":399243,"journal":{"name":"1987 Twelth International Conference on Infrared and Millimeter Waves","volume":"86 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":"122403046","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.1987.9126943
S. Marsh, N. Cronin, P. H. Reece
This paper describes the design and optimisation of a rugged, 183 GHz, subharmonic mixer using a novel monolithic integrated circuit. The circuit consists of two, balanced planar GaAs Schottky-Barrier diodes symmetrically opposed together with associated antenna coupling structures.
{"title":"183 GHz monolithic subharmonic mixer","authors":"S. Marsh, N. Cronin, P. H. Reece","doi":"10.1109/irmm.1987.9126943","DOIUrl":"https://doi.org/10.1109/irmm.1987.9126943","url":null,"abstract":"This paper describes the design and optimisation of a rugged, 183 GHz, subharmonic mixer using a novel monolithic integrated circuit. The circuit consists of two, balanced planar GaAs Schottky-Barrier diodes symmetrically opposed together with associated antenna coupling structures.","PeriodicalId":399243,"journal":{"name":"1987 Twelth International Conference on Infrared and Millimeter Waves","volume":"21 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":"124060244","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.1987.9127081
P. Vitello, C. Menyuk
Start oscillation conditions are considered for rectangular slotted gyrotron cavities. It is found that the addition of slots to a cavity lowers the required beam power for oscillation at high harmonics and can lead to a decrease of the start oscillation beam power as the harmonic number is increased. Previous gyrotron cavity designs have consistently shown the start oscillation beam power increasing with harmonic number. Slotted devices thus appear potentially attractive as a means of achieving millimeter wave emission.
{"title":"High Harmonic Emission from Slotted rectangular gyrotron oscillators","authors":"P. Vitello, C. Menyuk","doi":"10.1109/irmm.1987.9127081","DOIUrl":"https://doi.org/10.1109/irmm.1987.9127081","url":null,"abstract":"Start oscillation conditions are considered for rectangular slotted gyrotron cavities. It is found that the addition of slots to a cavity lowers the required beam power for oscillation at high harmonics and can lead to a decrease of the start oscillation beam power as the harmonic number is increased. Previous gyrotron cavity designs have consistently shown the start oscillation beam power increasing with harmonic number. Slotted devices thus appear potentially attractive as a means of achieving millimeter wave emission.","PeriodicalId":399243,"journal":{"name":"1987 Twelth International Conference on Infrared and Millimeter Waves","volume":"3 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":"124161943","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.1987.9126895
A. Ali, M. Alhaider, A. Ahmed
We report the results of scintillation measurement obtained in Riyadh, Saudi Arabia for 40-GHz links. Three types of scintillations viz; dry, semi-wet and wet scintillation were observed and recorded. Statistical analysis as well as a comparison with similar results will be presented.
{"title":"Amplitude scintillations measurement on a 40 GHz, 14 km link in an arid climate","authors":"A. Ali, M. Alhaider, A. Ahmed","doi":"10.1109/irmm.1987.9126895","DOIUrl":"https://doi.org/10.1109/irmm.1987.9126895","url":null,"abstract":"We report the results of scintillation measurement obtained in Riyadh, Saudi Arabia for 40-GHz links. Three types of scintillations viz; dry, semi-wet and wet scintillation were observed and recorded. Statistical analysis as well as a comparison with similar results will be presented.","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":"127921394","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.1987.9127076
M. Rob, J. Izatt
Interference fringes produced by an extra-cavity wedged etalon and recorded with a 128-element pyroelectric detector array have been used to study the mode structure and fine-tuning behavior of a TEA-CO2 laser, which is tuned with a diffraction grating and a temperature controlled intracavity etalon (1). The TEA-CO2 laser can be tuned over a range of about ± 2 GHz centered on each of its strong emission lines, and its longitudinal mode spacing is ∼120 MHz. The wedge and detector array provide an experimental resolution of a few 10's of MHz so that the intermode spacing of the laser can be probed in several well-resolved steps. As the temperature of the intracavity etalon is changed, the fine-scale tuning curve of the laser is a staircase function, with a series of flat (nearly constant frequency) segments separated by sharp jumps to the next longitudinal mode frequency. Oscilloscope traces recorded with a photon drag detector show the laser pulses to alternate, as the frequency scan proceeds, between pure single longitudinal mode structure and a small admixture of a second longitudinal mode. These results will be discussed in the context of the development of a high-power multi-atmosphere continuously-tunable SLM CO2 laser (2).
{"title":"Intermodal tuning behavior of an etalon tuned slm tea-co2 laser","authors":"M. Rob, J. Izatt","doi":"10.1109/irmm.1987.9127076","DOIUrl":"https://doi.org/10.1109/irmm.1987.9127076","url":null,"abstract":"Interference fringes produced by an extra-cavity wedged etalon and recorded with a 128-element pyroelectric detector array have been used to study the mode structure and fine-tuning behavior of a TEA-CO2 laser, which is tuned with a diffraction grating and a temperature controlled intracavity etalon (1). The TEA-CO2 laser can be tuned over a range of about ± 2 GHz centered on each of its strong emission lines, and its longitudinal mode spacing is ∼120 MHz. The wedge and detector array provide an experimental resolution of a few 10's of MHz so that the intermode spacing of the laser can be probed in several well-resolved steps. As the temperature of the intracavity etalon is changed, the fine-scale tuning curve of the laser is a staircase function, with a series of flat (nearly constant frequency) segments separated by sharp jumps to the next longitudinal mode frequency. Oscilloscope traces recorded with a photon drag detector show the laser pulses to alternate, as the frequency scan proceeds, between pure single longitudinal mode structure and a small admixture of a second longitudinal mode. These results will be discussed in the context of the development of a high-power multi-atmosphere continuously-tunable SLM CO2 laser (2).","PeriodicalId":399243,"journal":{"name":"1987 Twelth International Conference on Infrared and Millimeter Waves","volume":"40 5 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":"129114963","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.1987.9127004
Y. Komine, Y. Yoshida, M. Hibino, Y. Hisa, R. Ohkata, K. Ikeda, W. Susaki, K. Yasumura, K. Sato
High quality n-type Cd0.2Hg 0.8Te epi-layers doped with In below 0.1 ppm, whose carrier concentration and mobility at 77 K are below 4×1014 cm−3 and over 2× 105 cm2/V·S, respectively, have been grown by LPE on CdTe (111) B substrates with EPDs below 105 cm−2. A new result obtained is that long carrier diffusion length is essentially important for realizing a high performance detector, whose detectivity reaches to D∗BLIP.
{"title":"Cd0.2hg0.8te epi—layer for a high detectivity pc—type ir detector","authors":"Y. Komine, Y. Yoshida, M. Hibino, Y. Hisa, R. Ohkata, K. Ikeda, W. Susaki, K. Yasumura, K. Sato","doi":"10.1109/IRMM.1987.9127004","DOIUrl":"https://doi.org/10.1109/IRMM.1987.9127004","url":null,"abstract":"High quality n-type Cd<inf>0.2</inf>Hg <inf>0.8</inf>Te epi-layers doped with In below 0.1 ppm, whose carrier concentration and mobility at 77 K are below 4×10<sup>14</sup> cm<sup>−3</sup> and over 2× 10<sup>5</sup> cm<sup>2</sup>/V·S, respectively, have been grown by LPE on CdTe (111) B substrates with EPDs below 10<sup>5</sup> cm<sup>−2</sup>. A new result obtained is that long carrier diffusion length is essentially important for realizing a high performance detector, whose detectivity reaches to D∗BLIP.","PeriodicalId":399243,"journal":{"name":"1987 Twelth International Conference on Infrared and Millimeter Waves","volume":"4 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":"116922125","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.1987.9126996
W. Chew, H. Fetterman
Planar twin-dipole microstrip antennas with FET detectors have been constructed and found to provide antenna patterns suitable for millimeter-wave quasioptical applications. The circuits are suitable as individual elements of an imaging array.
{"title":"Printed circuit antennas and fet detectors for millimeter-wave imaging","authors":"W. Chew, H. Fetterman","doi":"10.1109/irmm.1987.9126996","DOIUrl":"https://doi.org/10.1109/irmm.1987.9126996","url":null,"abstract":"Planar twin-dipole microstrip antennas with FET detectors have been constructed and found to provide antenna patterns suitable for millimeter-wave quasioptical applications. The circuits are suitable as individual elements of an imaging array.","PeriodicalId":399243,"journal":{"name":"1987 Twelth International Conference on Infrared and Millimeter Waves","volume":"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":"117018662","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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