Initial phase wall conditioning in KSTAR

International Nuclear Information System (INIS)

Hong, Suk-Ho; Kim, Kwang-Pyo; Kim, Sungwoo; Lee, Dong-Su; Kim, Kyung-Min; Lee, Kun-Su; Kim, Jong-Su; Park, Jae-Min; Kim, Woong-Chae; Kim, Hak-Kun; Park, Kap-Rai; Yang, Hyung-Lyeol; Sun, Jong-Ho; Woo, Hyun-Jong; Lee, Sang-Yong; Lee, Sang-Hwa; Park, Eun-Kyung; Park, Sang-Joon; Kim, Sun-Ho; Wang, Sun-Jung

2011-01-01

The initial phase wall conditioning in KSTAR is depicted. The KSTAR wall conditioning procedure consists of vessel baking, glow discharge cleaning (GDC), ICRH wall conditioning (ICWC) and boronization (Bz). Vessel baking is performed for the initial vacuum conditioning in order to remove various kinds of impurities including H 2 O, carbon and oxygen and for the plasma operation. The total outgassing rates after vessel baking in three successive KSTAR campaigns are compared. GDC is regularly performed as a standard wall cleaning procedure. Another cleaning technique is ICWC, which is useful for inter-shot wall conditioning under a strong magnetic field. In order to optimize the operation time and removal efficiency of ICWC, a parameter scan is performed. Bz is a standard technique to remove oxygen impurity from a vacuum vessel. KSTAR has used carborane powder which is a non-toxic boron-containing material. The KSTAR Bz has been successfully performed through two campaigns: water and oxygen levels in the vacuum vessel are reduced significantly. As a result, KSTAR has achieved its first L-H mode transition, although the input power was marginal for the L-H transition threshold. The characteristics of boron-containing thin films deposited for boronization are investigated.

Measurement of LHCD antenna position in Aditya tokamak

International Nuclear Information System (INIS)

Ambulkar, K K; Sharma, P K; Virani, C G; Parmar, P R; Thakur, A L; Kulkarni, S V

2010-01-01

To drive plasma current non-inductively in ADITYA tokamak, 120 kW pulsed Lower Hybrid Current Drive (LHCD) system at 3.7 GHz has been designed, fabricated and installed on ADITYA tokamak. In this system, the antenna consists of a grill structure, having two rows, each row comprising of four sub-waveguides. The coupling of LHCD power to the plasma strongly depends on the plasma density near the mouth of grill antenna. Thus the grill antenna has to be precisely positioned for efficient coupling. The movement of mechanical bellow, which contracts or expands up to 50mm, governs the movement of antenna. In order to monitor the position of the antenna precisely, the reference position of the antenna with respect to the machine/plasma position has to be accurately determined. Further a mechanical system or an electronic system to measure the relative movement of the antenna with respect to the reference position is also desired. Also due to poor accessibility inside the ADITYA machine, it is impossible to measure physically the reference position of the grill antenna with respect to machine wall, taken as reference position and hence an alternative method has to be adopted to establish these measurements reliably. In this paper we report the design and development of a mechanism, using which the antenna position measurements are made. It also describes a unique method employing which the measurements of the reference position of the antenna with respect to the inner edge of the tokamak wall is carried out, which otherwise was impossible due to poor accessibility and physical constraints. The position of the antenna is monitored using an electronic scale, which is developed and installed on the bellow. Once the reference position is derived, the linear potentiometer, attached to the bellow, measures the linear distance using position transmitter. The accuracy of measurement obtained in our setup is within +/- 0.5 % and the linearity, along with repeatability is excellent.

Fluctuation measurements by Langmuir probes during LHCD on ASDEX tokamak. [LHCD (Lower Hybrid Current Drive)

Energy Technology Data Exchange (ETDEWEB)

Stoeckel, J [Ceskoslovenska Akademie Ved, Prague (Czech Republic). Ustav Fyziky Plazmatu; Soeldner, F; Giannone, L.; Leuterer, F [Max-Planck-Institut fuer Plasmaphysik, Garching (Germany)

1991-01-01

The level of edge electrostatic fluctuations decreases and the global particle/energy confinement improves during lower hybrid current drive (LHCD) regimes on ASDEX, when the total power remains below the initial OH power level. For higher powers, the fluctuations increase noticeably, whereas the global confinement is returning to its OH value. The observed increase of fluctuations is poloidally asymmetric and is caused by local power deposition in front of the grill antenna. (author) 5 refs., 4 figs.

Operator interface programs for KSTAR operation

International Nuclear Information System (INIS)

Lee, Sangil; Park, Mikyung; Park, Jinseop; Na, Hoonkyun; Kwon, M.

2013-01-01

Beginning the first plasma discharging experiment of KSTAR since 2008, KSTAR performed the third plasma discharging experiment by 2010. During the experiment of three times, KSTAR OPerator Interface (OPI) programs have been developed for KSTAR operation by itself. OPI programs used in KSTAR were implemented by KSTAR widget plug-in Toolkit (KWT). The KWT means the plug-in library implemented by Qt-based user interface development software. The main purpose of developing the KWT library is to implement full automation libraries having interface with the automated EPICS channel access (CA) guaranteeing the flexibility for requirements of operators. In addition, it has advantages in minimizing human code error and maximizing utilization of the limited human resource. According to the increasing of control systems, a number of OPI servers connected to one EPICS gateway server caused the connection problem and increased the amount of the network data packets. To solve these problems, an algorithm of “CachedChannelAccess” for shared memory base was implemented into an inner logic of the KWT library. KSTAR control system monitoring (CSM) program is one of applications developed by using KWT library. The function of CSM program is to notify alarm to operators by checking health status of every server's network health status and resource (cpu, memory, network packets, disk usage rate and system/user defined process) usage state. Another application is a post-shot sequencing program which is activated after every shot is completed. This application is to display major plasma parameters and diagnostic data in chart form, to save this data to database, and to transfer a chart image file to a web server. This paper describes the technical details how to develop OPI applications which have high productivity using Qt on the EPICS-based control system

Operator interface programs for KSTAR operation

Energy Technology Data Exchange (ETDEWEB)

Lee, Sangil, E-mail: leesi@nfri.re.kr; Park, Mikyung, E-mail: mkpark@nfri.re.kr; Park, Jinseop, E-mail: linupark@nfri.re.kr; Na, Hoonkyun, E-mail: hkna@nfri.re.kr; Kwon, M., E-mail: kwonm@nfri.re.kr

2013-11-15

Beginning the first plasma discharging experiment of KSTAR since 2008, KSTAR performed the third plasma discharging experiment by 2010. During the experiment of three times, KSTAR OPerator Interface (OPI) programs have been developed for KSTAR operation by itself. OPI programs used in KSTAR were implemented by KSTAR widget plug-in Toolkit (KWT). The KWT means the plug-in library implemented by Qt-based user interface development software. The main purpose of developing the KWT library is to implement full automation libraries having interface with the automated EPICS channel access (CA) guaranteeing the flexibility for requirements of operators. In addition, it has advantages in minimizing human code error and maximizing utilization of the limited human resource. According to the increasing of control systems, a number of OPI servers connected to one EPICS gateway server caused the connection problem and increased the amount of the network data packets. To solve these problems, an algorithm of “CachedChannelAccess” for shared memory base was implemented into an inner logic of the KWT library. KSTAR control system monitoring (CSM) program is one of applications developed by using KWT library. The function of CSM program is to notify alarm to operators by checking health status of every server's network health status and resource (cpu, memory, network packets, disk usage rate and system/user defined process) usage state. Another application is a post-shot sequencing program which is activated after every shot is completed. This application is to display major plasma parameters and diagnostic data in chart form, to save this data to database, and to transfer a chart image file to a web server. This paper describes the technical details how to develop OPI applications which have high productivity using Qt on the EPICS-based control system.

KSTAR RF heating system development

Energy Technology Data Exchange (ETDEWEB)

Kwak, J. G.; Kim, S. K.; Hwang, C. K. (and others)

2007-10-15

Design, high-voltage test, and installation of 6 MW ICRF heating system for KSTAR is completed. The antenna demonstrated satisfactory standoff at high voltages up to 41 kV for 300 sec. The result indicates good power handling capabilities of the antenna as high as 10 MW/m2. This power density is equivalent to RF power coupling of 6 MW into a 4 {omega}/m target plasma, and is typical of advanced tokamak heating scenarios. In addition, vacuum feed through, DC break, and liquid stub developed for 300 sec operation are installed, as well as a 2 MW, 30-60MHz transmitter. The transmitter successfully produced output powers of 600 kW continuously, 1.5{approx}1.8 MW for 300 sec, and 2 MW for 100 msec or shorter pulses. A realtime control system based on DSP and EPICS is developed, installed, and tested on the ICRF system. Initial results from feasibility study indicate that the present antenna and the transmission lines could allow load-resilient operation on KSTAR. Until the KSTAR tokamak start to produce plasmas in 2008, however, hands-on operational experiences are obtained from participating in ICRF heating experiments at ASDEX and DIII-D tokamaks arranged through international cooperation.

First neutral beam injection experiments on KSTAR tokamaka)

Science.gov (United States)

Jeong, S. H.; Chang, D. H.; Kim, T. S.; In, S. R.; Lee, K. W.; Jin, J. T.; Chang, D. S.; Oh, B. H.; Bae, Y. S.; Kim, J. S.; Park, H. T.; Watanabe, K.; Inoue, T.; Kashiwagi, M.; Dairaku, M.; Tobari, H.; Hanada, M.

2012-02-01

The first neutral beam (NB) injection system of the Korea Superconducting Tokamak Advanced Research (KSTAR) tokamak was partially completed in 2010 with only 1/3 of its full design capability, and NB heating experiments were carried out during the 2010 KSTAR operation campaign. The ion source is composed of a JAEA bucket plasma generator and a KAERI large multi-aperture accelerator assembly, which is designed to deliver a 1.5 MW, NB power of deuterium at 95 keV. Before the beam injection experiments, discharge, and beam extraction characteristics of the ion source were investigated. The ion source has good beam optics in a broad range of beam perveance. The optimum perveance is 1.1-1.3 μP, and the minimum beam divergence angle measured by the Doppler shift spectroscopy is 0.8°. The ion species ratio is D+:D2+:D3+ = 75:20:5 at beam current density of 85 mA/cm2. The arc efficiency is more than 1.0 A/kW. In the 2010 KSTAR campaign, a deuterium NB power of 0.7-1.5 MW was successfully injected into the KSTAR plasma with a beam energy of 70-90 keV. L-H transitions were observed within a wide range of beam powers relative to a threshold value. The edge pedestal formation in the Ti and Te profiles was verified through CES and electron cyclotron emission diagnostics. In every deuterium NB injection, a burst of D-D neutrons was recorded, and increases in the ion temperature and plasma stored energy were found.

Experimental measurements of Helicon wave coupling in KSTAR plasmas

Energy Technology Data Exchange (ETDEWEB)

Kim, H. J.; Wi, H. H.; Wang, S. J.; Park, S. Y.; Jeong, J. H.; Han, J. W.; Kwak, J. G.; Oh, Y. K. [National Fusion Research Institute, Daejeon (Korea, Republic of); Chun, M. H.; Yu, I. H. [Pohang Accelerator Laboratory, Pohang (Korea, Republic of)

2016-05-15

KSTAR tokamak can be a good platform to test this current drive concept because it has adequate machine parameters. Furthermore, KSTAR will have high electron beta plasmas in near future with additional ECH power. In 2015 KSTAR experiments, low-power traveling wave antenna has been designed, fabricated and installed for helicon wave coupling tests in KSTAT plasmas. In 2016 KSTAR campaign, 200 kW klystron power will be combined using three coaxial hybrid couplers and three dummy loads. High power RF will be fed into the traveling wave antenna with two coaxial feeders through two dual disk windows and 6 inch coaxial transmission line system. Current status and plan for high power helicon wave current drive system in KSTAR will be presented. Mock-up TWA antenna installed at the KSTAR reveals high couplings in both L- and H-mode plasmas. The coupling can be easily controlled by radial outer gap without degradation of plasma confinement or local gas puffing with slight decrease of plasma confinement.

First neutral beam injection experiments on KSTAR tokamak.

Science.gov (United States)

Jeong, S H; Chang, D H; Kim, T S; In, S R; Lee, K W; Jin, J T; Chang, D S; Oh, B H; Bae, Y S; Kim, J S; Park, H T; Watanabe, K; Inoue, T; Kashiwagi, M; Dairaku, M; Tobari, H; Hanada, M

2012-02-01

The first neutral beam (NB) injection system of the Korea Superconducting Tokamak Advanced Research (KSTAR) tokamak was partially completed in 2010 with only 1∕3 of its full design capability, and NB heating experiments were carried out during the 2010 KSTAR operation campaign. The ion source is composed of a JAEA bucket plasma generator and a KAERI large multi-aperture accelerator assembly, which is designed to deliver a 1.5 MW, NB power of deuterium at 95 keV. Before the beam injection experiments, discharge, and beam extraction characteristics of the ion source were investigated. The ion source has good beam optics in a broad range of beam perveance. The optimum perveance is 1.1-1.3 μP, and the minimum beam divergence angle measured by the Doppler shift spectroscopy is 0.8°. The ion species ratio is D(+):D(2)(+):D(3)(+) = 75:20:5 at beam current density of 85 mA/cm(2). The arc efficiency is more than 1.0 A∕kW. In the 2010 KSTAR campaign, a deuterium NB power of 0.7-1.5 MW was successfully injected into the KSTAR plasma with a beam energy of 70-90 keV. L-H transitions were observed within a wide range of beam powers relative to a threshold value. The edge pedestal formation in the T(i) and T(e) profiles was verified through CES and electron cyclotron emission diagnostics. In every deuterium NB injection, a burst of D-D neutrons was recorded, and increases in the ion temperature and plasma stored energy were found.

Improvement of initial vacuum condition along 2008-2010 KSTAR campaign by vessel baking

Energy Technology Data Exchange (ETDEWEB)

Kim, Kwang Pyo, E-mail: kpkim@nfri.er.ke [National Fusion Research Institute, Gwahagno 113, Daejeon 305-333 (Korea, Republic of); Hong, S.H.; Jung, N.Y.; Kim, S.T.; Kim, H.T.; Lee, K.S.; Kim, K.M.; Bang, E.N.; Chang, Y.B.; Kim, H.K.; Chu, Y.; Kim, Y.O.; Park, S.H.; Woo, I.S.; Hong, J.S.; Kim, S.W.; Park, K.R.; Na, H.K.; Yang, H.L.; Kim, Y.S. [National Fusion Research Institute, Gwahagno 113, Daejeon 305-333 (Korea, Republic of)

2011-10-15

Korea Superconducting Tokamak Advanced Research (KSTAR) is upgraded for its KSTAR 3rd campaign for new target mission to produce the D-shaped plasma with a target plasma current of 500 kA and/or pulse length of 5 s. New Plasma Facing Components (PFCs) are installed which leads to the increase of the surface area of the vessel by a factor of about 5. The vacuum conditioning such as the vessel baking has been performed in order to remove various kinds of impurities including H{sub 2}O, carbon and oxygen for the plasma. The total outgassing rate in the KSTAR 1st campaign was measured as 1.5 x 10{sup -4} mbar l s{sup -1} which is increased by a factor of 3 (6.49 x 10{sup -4} mbar l s{sup -1}) in the KSTAR 3rd campaign. Nevertheless, the outgassing rates per unit area have been decreased from 9.31 x 10{sup -5} mbar l m{sup -2} s{sup -1} to 1.22 x 10{sup -5} mbar l m{sup -2} s{sup -1} due to the upgrade of baking system and series of baking operation.

Improvement of initial vacuum condition along 2008-2010 KSTAR campaign by vessel baking

International Nuclear Information System (INIS)

Kim, Kwang Pyo; Hong, S.H.; Jung, N.Y.; Kim, S.T.; Kim, H.T.; Lee, K.S.; Kim, K.M.; Bang, E.N.; Chang, Y.B.; Kim, H.K.; Chu, Y.; Kim, Y.O.; Park, S.H.; Woo, I.S.; Hong, J.S.; Kim, S.W.; Park, K.R.; Na, H.K.; Yang, H.L.; Kim, Y.S.

2011-01-01

Korea Superconducting Tokamak Advanced Research (KSTAR) is upgraded for its KSTAR 3rd campaign for new target mission to produce the D-shaped plasma with a target plasma current of 500 kA and/or pulse length of 5 s. New Plasma Facing Components (PFCs) are installed which leads to the increase of the surface area of the vessel by a factor of about 5. The vacuum conditioning such as the vessel baking has been performed in order to remove various kinds of impurities including H 2 O, carbon and oxygen for the plasma. The total outgassing rate in the KSTAR 1st campaign was measured as 1.5 x 10 -4 mbar l s -1 which is increased by a factor of 3 (6.49 x 10 -4 mbar l s -1 ) in the KSTAR 3rd campaign. Nevertheless, the outgassing rates per unit area have been decreased from 9.31 x 10 -5 mbar l m -2 s -1 to 1.22 x 10 -5 mbar l m -2 s -1 due to the upgrade of baking system and series of baking operation.

Progress in LHCD: a tool for advanced regimes on ITER

Energy Technology Data Exchange (ETDEWEB)

Tuccillo, A. A.

2005-07-01

for ITER has been designed based on a new concept of launcher, the PAM, consisting of Passive waveguides inserted between every other Active one of a Multijunction. A first successful test of the PAM has been conducted on FTU, one is in preparation on Tore Supra and a possible test on an ITER relevant plasma scenario in JET has also been envisaged. A new carbon mouth is undergoing tests on JT-60U launcher and a new LH system has recently been installed on Alcator C-Mod. Finally a 500kW-CW klystron at 5GHz, the frequency foreseen for ITER, is under development for the LH system of KSTAR in Korea. (Author)

Conceptual design of the KSTAR Motor Generator

Energy Technology Data Exchange (ETDEWEB)

Kim, Chang-Hwan, E-mail: kch2004@nfri.re.kr [National Fusion Research Institute, 169-148 Gwahangno, Yusung-gu, Daejeon 305-333 (Korea, Republic of); Kong, Jong-Dea; Eom, Dae-Young; Joung, Nam-Young; Lee, Woo-Jin; Kim, Yang-Soo; Kwon, Myeun [National Fusion Research Institute, 169-148 Gwahangno, Yusung-gu, Daejeon 305-333 (Korea, Republic of); Han, Chul-Woo; Lee, Sel-Ki [Vitzrotech Co. Ltd, 605-2 Seonggok-dong, Danwon-gu, Ansan, Gyeonggi-do 425-833 (Korea, Republic of); Parker, F.J.; Hopkinson, D.; Le Flem, G.D. [Converteam UK Ltd, Leicester Road, Rugby, Warwickshire CV21 1BD (United Kingdom)

2012-09-15

Highlights: Black-Right-Pointing-Pointer The design of the MG which is required to allow the PF MPS to operate at its full power rating has been completed. Black-Right-Pointing-Pointer This system will increase the supply capability to the MPS to 200 MVA, 1.6 GJ and will supply reactive power to the MPS. Black-Right-Pointing-Pointer A VVVF of 12 MW will control the MG and will supply additional active power to the PF MPS in parallel with the MG. Black-Right-Pointing-Pointer The MG will be installed in August 2012. Black-Right-Pointing-Pointer The dummy coil testing will commence in December 2012 with superconducting coil testing scheduled for 2013. - Abstract: The Korean Superconducting Tokamak Advanced Research (KSTAR) superconducting magnet power supply is composed of a Poloidal Field Magnet Power Supply (PF MPS) and a Toroidal Field Magnet Power Supply (TF MPS). When the PF MPS is operated, it requires a large amount of power instantaneously from the KSTAR electric power system. To achieve the KSTAR operational goal, with a long pulse scenario, a peak power of 200 MVA is required and the total power demand for the KSTAR system can exceed 200 MVA. The available grid power is only 100 MVA at the KSTAR site. Increasing the available grid power was uneconomical and inefficient which is why NFRI are installing a Motor Generator (MG). National Fusion Research Institute (NFRI) has made a contract with Vitzrotech and Converteam to design, manufacture and install the MG. Converteam has designed the electromagnetic and mechanical specification of the MG and Variable Voltage Variable Frequency (VVVF) converter. In this paper we discuss the conceptual design, including energy saving and electrical capacity of the MG system and the performance of the MG to satisfy the KSTAR 300 s operation scenario. In addition, the manufacturing and installation plan for the KSTAR MG is discussed.

Feasibility study of advanced operation scenario in KSTAR using CRONOS

International Nuclear Information System (INIS)

Kim, H.-S.; Na, Y.-S.; Bae, Y.S.; Jeon, Y.M.; Kim, S.H.; Artaud, J.-F.

2014-01-01

We report the results of predictive modelling of advanced operation scenarios in KSTAR. Firstly, the operation windows are produced to explore the KSTAR advanced scenarios in the condition of upgrading H/CD mix. Using METIS code, the rough ranges of operation condition of I_P and B_T to utilize for the development of advanced operation scenario scenario are determined. Secondly, the advanced inductive and the advanced tokamak operation scenario of KSTAR are developing with the scaling based and the physics based transport model by using CRONOS to make a suggestion to on-going KSTAR experiment. Thirdly, the dependency of the time of L-H transition on q_0 an q_m_i_n is investigated for the advanced inductive operation scenario. These reliable results can become the useful database for exploring the advanced regime of KSTAR discharges in the future. (author)

KSTAR Helium Refrigeration System Design and Manufacturing

International Nuclear Information System (INIS)

Dauguet, P.; Briend, P.; Abe, I.; Fauve, E.; Bernhardt, J.-M.; Andrieu, F.; Beauvisage, J.

2006-01-01

The tokamak developed in the KSTAR (Korean Superconducting Tokamak Advanced Research) project makes intensive use of superconducting magnets operated at 4.5 K. The cold components of the KSTAR tokamak require forced flow of supercritical helium for magnets/structure, boiling liquid helium for current leads, and gaseous helium for thermal shields. The cryogenic system will provide stable operation and full automatic control. A three-pressure helium cycle composed of six turbines has been customised design for this project. The '' design '' operating mode results with a system composed of a 9 kW refrigerator (including safety margin) and using gas and liquid storages for mass balancing. During Shot/Standby mode, the heat loads are highly time-dependent. A thermal damper is used to smooth these variations and will allow stable operation. (author)

Functional Analysis of the Distribution Box of the KSTAR Helium Refrigerator

International Nuclear Information System (INIS)

Chang, H. S.; Kim, Y. S.; Bak, J. S.

2005-01-01

KSTAR (Korea Superconducting Tokamak Advanced Research) is a tokamak device with 30 superconducting (SC) magnet coils. The main duty of the KSTAR helium refrigerator is to keep all cold components of KSTAR (SC magnet coils, magnet structures, SC bus-lines, current lead system, and thermal shields) at suitable temperatures in order to operate the SC magnet coils consistent with the operation scenario of KSTAR. A distribution box (D/B) which is equipped with helium-property-measuring sensors, cryogenic valves (CV's), cryogenic circulators, and heat exchangers (HX's) submerged in a huge liquid helium (LHe) bath (thermal damper), intervenes the cryogenic helium via cryogenic transfer lines (TL's) between the refrigerator cold box (C/B) and the KSTAR cold components. The major functions of the D/B can be classified as listed below: i) Supplying the proper cryogen to the respective cold components of KSTAR during various operation modes (including the idle mode). ii) Cool/re-cool down of the KSTAR cold components from any temperature down to their operating cryogenic temperature within the constraints of time and temperature difference between the components. iii) Protection of the KSTAR cold components and refrigerator from damaging in case of probable abnormal events. iv) Simulation of the temporal variation of the thermal load and pressure drops occurring in the KSTAR cold components to pre-commission the refrigerator and test the cryogenic circulators. v) SC coil/bus-line cable-in-conduit conductor (CICC) cleaning. Since the helium flow in the thermal shields (TS's) is rather routine and the current lead (CL) system has its own helium distribution system, in this proceeding mainly the supercritical helium (SHe) circuits of the SC magnets and bus-lines will be discussed

Progress and plan of KSTAR plasma control system upgrade

Energy Technology Data Exchange (ETDEWEB)

Hahn, Sang-hee, E-mail: hahn76@nfri.re.kr [National Fusion Research Institute, Daejeon (Korea, Republic of); Kim, Y.J. [National Fusion Research Institute, Daejeon (Korea, Republic of); Penaflor, B.G. [General Atomics, San Diego, CA (United States); Bak, J.G.; Han, H.; Hong, J.S.; Jeon, Y.M.; Jeong, J.H.; Joung, M.; Juhn, J.W.; Kim, J.S.; Kim, H.S.; Lee, W.R.; Woo, M.H. [National Fusion Research Institute, Daejeon (Korea, Republic of); Eidietis, N.W.; Ferron, J.R.; Humphreys, D.A.; Hyatt, A.; Johnson, R.D.; Piglowski, D.A. [General Atomics, San Diego, CA (United States); and others

2016-11-15

Highlights: • Recent achievements of the KSTAR plasma control system are described. • Requirements and results of the testbed system for the future upgrade of the KSTAR plasma control system are presented. • An overview of the upgrade layout based is given. - Abstract: The plasma control system (PCS) has been one of essential systems in annual KSTAR plasma campaigns: starting from a single-process version in 2008, extensive upgrades are done through the previous 7 years in order to achieve major goals of KSTAR performance enhancement. Major implementations are explained in this paper. In consequences of successive upgrades, the present KSTAR PCS is able to achieve ∼48 s of 500 kA plasma pulses with full real-time shaping controls and real-time NB power controls. It has become a huge system capable of dealing with 8 separate categories of algorithms, 26 actuators directly controllable during the shot, and real-time data communication units consisting of +180 analog channels and +600 digital input/outputs through the reflective memory (RFM) network. The next upgrade of the KSTAR PCS is planned in 2015 before the campaign. An overview of the upgrade layout will be given for this paper. The real-time system box is planned to use the CERN MRG-Realtime OS, an ITER-compatible standard operating system. New hardware is developed for faster real-time streaming system for future installations of actuators/diagnostics.

Engineering Design of KSTAR tokamak main structure

International Nuclear Information System (INIS)

Im, K.H.; Cho, S.; Her, N.I.

2001-01-01

The main components of the KSTAR (Korea Superconducting Tokamak Advanced Research) tokamak including vacuum vessel, plasma facing components, cryostat, thermal shield and magnet supporting structure are in the final stage of engineering design. Hundai Heavy Industries (HHI) has been involved in the engineering design of these components. The current configuration and the final engineering design results for the KSTAR main structure are presented. (author)

Investigation of the Energy Confinement in Ohmic and LHCD Plasmas in HT-7

International Nuclear Information System (INIS)

Zhang Xiaoqing; Wan Baonian; Shen Biao; Hu Xiwei; Qian Jinping; Fan Hengyu; Ding Yonghua

2006-01-01

Investigation of the energy confinement in ohmic and lower hybrid current drive (LHCD) plasmas in HT-7 has been performed. In ohmic discharges at low densities the global energy confinement time τ E increases almost linearly with the density, saturates at a critical density (2.5 x 10 13 /cm 3 for HT-7) and is nearly constant at higher densities. The energy confinement time is in good agreement with the Neo-Alcator scaling law at different densities and currents. In the LHCD plasmas the global energy confinement time similar to that of the L-mode discharges has been observed to be in good agreement with the low confinement mode (L mode) scaling law of ITER89-P in higher electron density and plasma current

LHCD current profile control experiments towards steady state improved confinement on JT-60U

International Nuclear Information System (INIS)

Ide, S.; Naito, O.; Oikawa, T.; Fujita, T.; Kondoh, T.; Seki, M.; Ushigusa, K.

2001-01-01

In JT-60U lower hybrid current drive (LHCD) experiments, a reversed magnetic shear configuration that was accompanied by the internal transport barriers was successfully maintained by means of LHCD almost in the full current drive quasi-steady state for 4.7 s. The normalized beta was kept near 1 and the neutron emission rate was almost steady as well indicating no accumulation of impurities into the plasma. Diagnostics data showed that all the profiles of the electron and ion temperatures, the electron density and the current profile were almost unchanged during the LHCD phase. Moreover, capability of LHCD in H-mode plasmas has been also investigated. It was found that the lower hybrid waves can be coupled to an H-mode edge plasma even with the plasma wall distance of about 14 cm. The maximum coupling distance was found to depend on the edge recycling. (author)

Investigation of intrinsic toroidal rotation scaling in KSTAR

Science.gov (United States)

Yoo, J. W.; Lee, S. G.; Ko, S. H.; Seol, J.; Lee, H. H.; Kim, J. H.

2017-07-01

The behaviors of an intrinsic toroidal rotation without any external momentum sources are investigated in KSTAR. In these experiments, pure ohmic discharges with a wide range of plasma parameters are carefully selected and analyzed to speculate an unrevealed origin of toroidal rotation excluding any unnecessary heating sources, magnetic perturbations, and strong magneto-hydrodynamic activities. The measured core toroidal rotation in KSTAR is mostly in the counter-current direction and its magnitude strongly depends on the ion temperature divided by plasma current (Ti/IP). Especially the core toroidal rotation in the steady-state is well fitted by Ti/IP scaling with a slope of ˜-23, and the possible explanation of the scaling is compared with various candidates. As a result, the calculated offset rotation could not explain the measured core toroidal rotation since KSTAR has an extremely low intrinsic error field. For the stability conditions for ion and electron turbulences, it is hard to determine a dominant turbulence mode in this study. In addition, the intrinsic toroidal rotation level in ITER is estimated based on the KSTAR scaling since the intrinsic rotation plays an important role in stabilizing resistive wall modes for future reference.

Development and operation of fast protection for KSTAR

Energy Technology Data Exchange (ETDEWEB)

Hong, Jaesic, E-mail: hjaesic@nfri.re.kr; Lee, Woongryol; Lee, Taegu; Han, Hyunsun; Han, Sang-Hee; Park, Kaprai

2016-11-15

Highlights: • The evolution of KSTAR machine interlock system. • The evolution of KSTAR fast interlock. • The fast interlock interface. • The operation results of the fast interlock. - Abstract: Protection for the Korea superconducting tokamak advanced research (KSTAR) is somewhat more complicated than for the previous tokomak generation. External reasons for this increased complexity are the initial and maintenance costs, and internal reasons relate to various characteristics of the tokamak and long pulse operation. KSTAR has two protection mechanisms: the device protection system protects damage to superconducting coils etc. from events within the other systems, and the fast protection system protects the internal vacuum vessel components against damage from heating and the long pulse plasma. The fast protection system initially contained the plasma control system (PCS), central control system (CCS), and the heating devices. In 2012, a fast interlock interface was implemented for PCS fail-safe. This detected the absence of plasma current using the diagnostic signals and discharge operation gate windows of the timing synchronized system (TSS), and activates the operation gates and heating stop from the CCS. Additional fast interlock logic was implemented to reduce damage to the plasma facing components (PFC) and other materials by overheating and improper operational state of heating systems after starting the discharge sequence. However, the fast interlock interface system has failed to protect the heating during PCS malfunctions since 2013. This paper introduces the KSTAR protection system, and describes the fast protection interface, with testing and operational results, then discusses future plans for a more effective and safer protection system.

Development of LHCD launcher for next stage tokamak

International Nuclear Information System (INIS)

Seki, M.; Obara, K.; Maebara, S.

1994-01-01

In next stage LHCD experiment, long pulse RF injection is required for studying quasi-steady state tokamaks. The suppression of outgassing from waveguides is one of the main issues for LHCD launchers to transmit RF power in the waveguides continuously and stably. In order to know the parameters which control outgassing rate and to investigate how to reduce outgassing rate, JAERI and CEA have performed outgassing experiment by using four divided waveguides. The experimental setup and the results are reported. Steady state outgassing was observed in long duration up to 1800s when RF heat was removed by water cooling. In next generation LHCD launchers, it should be demanded to launch the high directive and sharp spectra, and to make the structure simple and compact. But these spectra require many waveguides in front of plasma, and this situation is not compatible with the compact structure which is necessary for low cost and easy maintenance. Moreover, the launchers are advantageous if the controllability is wide, and the low RF power density at grill mouth makes power launching easy. In order to realize the above features, a new launcher was devised. The conceptual structure is shown. The main R and D item is to divide RF power into three waveguides lined in poloidal direction. The RF property is discussed. (K.I.)

Design of test kits for the RF characterization of the PAM antenna of LHCD system for Aditya-upgrade Tokamak

International Nuclear Information System (INIS)

Jain, Yogesh M.; Sharma, P.K.; Parmar, P.R.; Ambulkar, K.K.

2017-01-01

The Lower Hybrid Current Drive (LHCD) system of the ADITYA-Upgrade tokamak will employ a Passive Active Multijunction (PAM) antenna to launch 250 kW of RF power at 3.7 GHz to drive plasma current non inductively in the tokamak. To evaluate the RF performance of the designed PAM antenna, it is characterized with the help of VNA measurements. The performance of the PAM antenna is mainly decided by the integrated performance of the entire antenna (with a differential phase shift of 270° and equal power distribution between each of the output waveguides) and the performance of mode converter, which transforms input TE 10 mode to TE 30 mode (with a mode purity of 98.5% at the output). This poster thus reports the design and analysis of these testing kits. Also, the test results of PAM antenna obtained by using these test kits would also be presented and discussed in this poster

Simulations of KSTAR high performance steady state operation scenarios

International Nuclear Information System (INIS)

Na, Yong-Su; Kessel, C.E.; Park, J.M.; Yi, Sumin; Kim, J.Y.; Becoulet, A.; Sips, A.C.C.

2009-01-01

We report the results of predictive modelling of high performance steady state operation scenarios in KSTAR. Firstly, the capabilities of steady state operation are investigated with time-dependent simulations using a free-boundary plasma equilibrium evolution code coupled with transport calculations. Secondly, the reproducibility of high performance steady state operation scenarios developed in the DIII-D tokamak, of similar size to that of KSTAR, is investigated using the experimental data taken from DIII-D. Finally, the capability of ITER-relevant steady state operation is investigated in KSTAR. It is found that KSTAR is able to establish high performance steady state operation scenarios; β N above 3, H 98 (y, 2) up to 2.0, f BS up to 0.76 and f NI equals 1.0. In this work, a realistic density profile is newly introduced for predictive simulations by employing the scaling law of a density peaking factor. The influence of the current ramp-up scenario and the transport model is discussed with respect to the fusion performance and non-inductive current drive fraction in the transport simulations. As observed in the experiments, both the heating and the plasma current waveforms in the current ramp-up phase produce a strong effect on the q-profile, the fusion performance and also on the non-inductive current drive fraction in the current flattop phase. A criterion in terms of q min is found to establish ITER-relevant steady state operation scenarios. This will provide a guideline for designing the current ramp-up phase in KSTAR. It is observed that the transport model also affects the predictive values of fusion performance as well as the non-inductive current drive fraction. The Weiland transport model predicts the highest fusion performance as well as non-inductive current drive fraction in KSTAR. In contrast, the GLF23 model exhibits the lowest ones. ITER-relevant advanced scenarios cannot be obtained with the GLF23 model in the conditions given in this work

Diagnostic development for current density profile control at KSTAR

Energy Technology Data Exchange (ETDEWEB)

Ko, J., E-mail: jinseok@nfri.re.kr [National Fusion Research Institute, Daejeon 34133 (Korea, Republic of); University of Science and Technology, Daejeon 34113 (Korea, Republic of); Chung, J. [National Fusion Research Institute, Daejeon 34133 (Korea, Republic of); Messmer, M.C.C. [Department of Applied Physics, Eindhoven University of Technology, Eindhoven (Netherlands)

2016-11-01

Highlights: • The motional Stark effect (MSE) diagnostic installed at KSTAR. • Engineering challenges and solutions on the design and fabrication of the front optics housing and filter modules. • Characterization of the bandpass filters and the responses to polarized light. - Abstract: The current density profile diagnostics are critical for the control of the steady-state burning plasma operations. A multi-channel motional Stark effect (MSE) diagnostic system has been implemented for the measurements of the internal magnetic field structures that constrain the magnetic equilibrium reconstruction to accurately produce the tokamak safety factor and current density profiles for the Korea Superconducting Tokamak Advanced Research (KSTAR). This work presents the design and fabrication of the front optics and the filter modules and the calibration activities for the MSE diagnostic at KSTAR.

Ramp generator circuit for probe diagnostics using microcontroller for LHCD system

International Nuclear Information System (INIS)

Virani, C G; Sharma, P K

2010-01-01

It is well known that in LHCD system, the rf power coupling between antenna and plasma strongly depends on the edge plasma parameter. Thus it is mandatory to monitor edge plasma parameter to establish proper impedance matching condition when LHCD power is launched into the plasma. For SST1 LHCD system, we intend to monitor the edge plasma parameter employing electric probes, connected to the grill antenna sides for the said purpose. In SST1, initially LHCD system would couple rf power to plasmas lasting for small durations. Gradually the power and pulse length would be increased to eventually get 1000 seconds plasma. To monitor the edge plasma parameter, over such a wide spectrum (say few millisecond to seconds) during the above campaign, a flexible measurement scheme is desired which would cater to entire spectrum of operation. Normally a ramp is utilized to bias the electric probe, which yields various plasma parameters. To cater our requirement, the ramp generator must have facility to change ramp-up rate to meet our pulse length requirement. Further during SST operation, the human access near the machine would not be permitted and ramp circuit might not be accessible for manual settings. Thus remote setting facility to change ramp-up rate is also desired. Keeping these constraints in mind, a ramp circuit has been designed using Analog Device micro-controller ADuC842. The circuit has both manual and remote setting facility. Ramp generator parameters like Ramp-up rate, Trigger mode, number of cycles, etc. can be set from PC through RS-485 serial link. Initially low voltage (0-5V) ramp signal is generated using micro-controller and inbuilt DAC. This low voltage ramp is then amplified with PA-85 op-amp to get desired probe biasing voltage (-110V to +110V). The ramp period can be change form (1ms to 1000 ms) to cater to different plasma pulse length. Programming for micro-controller is done in structured language-C with the help of ''Keil'' IDE. In this paper, a

Ramp generator circuit for probe diagnostics using microcontroller for LHCD system

Energy Technology Data Exchange (ETDEWEB)

Virani, C G; Sharma, P K, E-mail: cgvirani@ipr.res.i [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India)

2010-02-01

It is well known that in LHCD system, the rf power coupling between antenna and plasma strongly depends on the edge plasma parameter. Thus it is mandatory to monitor edge plasma parameter to establish proper impedance matching condition when LHCD power is launched into the plasma. For SST1 LHCD system, we intend to monitor the edge plasma parameter employing electric probes, connected to the grill antenna sides for the said purpose. In SST1, initially LHCD system would couple rf power to plasmas lasting for small durations. Gradually the power and pulse length would be increased to eventually get 1000 seconds plasma. To monitor the edge plasma parameter, over such a wide spectrum (say few millisecond to seconds) during the above campaign, a flexible measurement scheme is desired which would cater to entire spectrum of operation. Normally a ramp is utilized to bias the electric probe, which yields various plasma parameters. To cater our requirement, the ramp generator must have facility to change ramp-up rate to meet our pulse length requirement. Further during SST operation, the human access near the machine would not be permitted and ramp circuit might not be accessible for manual settings. Thus remote setting facility to change ramp-up rate is also desired. Keeping these constraints in mind, a ramp circuit has been designed using Analog Device micro-controller ADuC842. The circuit has both manual and remote setting facility. Ramp generator parameters like Ramp-up rate, Trigger mode, number of cycles, etc. can be set from PC through RS-485 serial link. Initially low voltage (0-5V) ramp signal is generated using micro-controller and inbuilt DAC. This low voltage ramp is then amplified with PA-85 op-amp to get desired probe biasing voltage (-110V to +110V). The ramp period can be change form (1ms to 1000 ms) to cater to different plasma pulse length. Programming for micro-controller is done in structured language-C with the help of ''Keil'' IDE

Intra-shot MSE Calibration Technique For LHCD Experiments

International Nuclear Information System (INIS)

Ko, Jinseok; Scott, Steve; Shiraiwa, Syun'ichi; Greenwald, Martin; Parker, Ronald; Wallace, Gregory

2009-01-01

The spurious drift in pitch angle of order several degrees measured by the Motional Stark Effect (MSE) diagnostic in the Alcator C-Mod tokamak1 over the course of an experimental run day has precluded direct utilization of independent absolute calibrations. Recently, the underlying cause of the drift has been identified as thermal stress-induced birefringence in a set of in-vessel lenses. The shot-to-shot drift can be avoided by using MSE to measure only the change in pitch angle between a reference phase and a phase of physical interest within a single plasma discharge. This intra-shot calibration technique has been applied to the Lower Hybrid Current Drive (LHCD) experiments and the measured current profiles qualitatively demonstrate several predictions of LHCD theory such as an inverse dependence of current drive efficiency on the parallel refractive index and the presence of off-axis current drive.

Thermal and non-thermal particle interaction with the LHCD launchers in Tore Supra

International Nuclear Information System (INIS)

Ekedahl, A.; Goniche, M.; Balorin, C.; Basiuk, V.; Bibet, Ph.; Chantant, M.; Colas, L.; Delpech, L.; Desgranges, C.; Eriksson, L.-G.; Joffrin, E.; Kazarian, F.; Lowry, C.; Moreau, Ph.; Petrzilka, V.; Portafaix, C.; Prou, M.; Roche, H.

2007-01-01

The interaction between the lower hybrid current drive (LHCD) launchers and the plasma has been studied during long pulse, high power operation in the Tore Supra tokamak. The main diagnostics used for characterising the plasma-launcher interaction are calorimetry of the energy extracted by the launchers and infrared (IR) imaging of the launchers and their side limiters. The calorimetry has allowed to identify three different heat sources on the LHCD launchers, namely the RF losses in the waveguides, a fraction (∼0.8%) of the total injected energy and, finally, fast ion losses during ion cyclotron resonance heating (ICRH), accounting for ∼1% of the injected ICRH energy. The interaction by fast ions is identified by infrared imaging of the LHCD launchers as a localised hotspot on the ion drift side, below or at the mid-plane

Transport and stability analyses supporting disruption prediction in high beta KSTAR plasmas

Science.gov (United States)

Ahn, J.-H.; Sabbagh, S. A.; Park, Y. S.; Berkery, J. W.; Jiang, Y.; Riquezes, J.; Lee, H. H.; Terzolo, L.; Scott, S. D.; Wang, Z.; Glasser, A. H.

2017-10-01

KSTAR plasmas have reached high stability parameters in dedicated experiments, with normalized beta βN exceeding 4.3 at relatively low plasma internal inductance li (βN/li>6). Transport and stability analyses have begun on these plasmas to best understand a disruption-free path toward the design target of βN = 5 while aiming to maximize the non-inductive fraction of these plasmas. Initial analysis using the TRANSP code indicates that the non-inductive current fraction in these plasmas has exceeded 50 percent. The advent of KSTAR kinetic equilibrium reconstructions now allows more accurate computation of the MHD stability of these plasmas. Attention is placed on code validation of mode stability using the PEST-3 and resistive DCON codes. Initial evaluation of these analyses for disruption prediction is made using the disruption event characterization and forecasting (DECAF) code. The present global mode kinetic stability model in DECAF developed for low aspect ratio plasmas is evaluated to determine modifications required for successful disruption prediction of KSTAR plasmas. Work supported by U.S. DoE under contract DE-SC0016614.

LHCD experiments on tokamak CASTOR

International Nuclear Information System (INIS)

Zacek, F.; Badalec, J.; Jakubka, J.; Kryska, L.; Preinhaelter, J.; Stoeckel, J.; Valovic, M.; Nanobashvili, S.; Weixelbaum, L.; Wenzel, U.; Spineanu, F.; Vlad, M.

1990-10-01

A short survey is given of the experimental activities at the small Prague tokamak CASTOR. They concern primarily the LH current drive using multijunction waveguide grills as launching antennae. During two last years the, efforts were focused on a study of the electrostatic and magnetic fluctuations under conditions of combined inductive/LHCD regimes and of the relation of the level of these fluctuations to the anomalous particles transport in tokamak CASTOR. Results of the study are discussed in some detail. (author). 24 figs., 51 refs

Experiences on vacuum conditioning in the cryostat of KSTAR tokamak

Energy Technology Data Exchange (ETDEWEB)

Kim, Kwang Pyo, E-mail: kpkim@nfri.er.ke [National Fusion Research Institute, Daejeon (Korea, Republic of); Woo, I.S.; Chang, Y.B.; Kwag, S.W.; Song, N.H.; Bang, E.N.; Hong, J.S.; Chu, Y.; Park, K.R. [National Fusion Research Institute, Daejeon (Korea, Republic of)

2013-10-15

Highlights: ► The vacuum of the cryostat has been stably maintained during the KSTAR operation. ► The detected cold leak at the PF/CS coils and CS structure. ► The present helium leak makes no issue for the cryostat operation. -- Abstract: Korea Superconducting Tokamak Advanced Research (KSTAR) device has been successfully operated for the plasma experiment from KSTAR 1st campaign to 4th campaign. The main pumping system for the cryostat has to maintain the target pressure below 1.0 × 10{sup −4} mbar at room temperature and 1.0 × 10{sup −5} mbar at extremely low temperature for the plasma experiment against the air leak coming from ports of vessel and/or the helium leak from cooling loops in the cryostat. No leak has been detected at room temperature. Unexpectedly, the cold-leak appeared in the cryostat at temperature around 50 K during the cool-down in the KSTAR 2nd campaign. We carefully analyzed the characteristics of detected cold leak because it can cause the increase of the base pressure in the cryostat. After the cool-down, the leak detection was performed to locate the position and size of the leak by the pressurizing the loops. As a result, it is found that the cold leak was located at cooling loops for PF/CS coils and CS structure. Nevertheless, the vacuum inside the cryostat was well maintained below 6.0 × 10{sup −8} mbar during the entire operation period. The impact of the He-leak in present status on the plasma operation is negligible. However, we have found that the leak rate increases as a function of time. Therefore careful monitoring on cold-leak is an important technical issue for the operation of superconducting tokamak.

The design of two color interferometer system for the 3-dimensional analysis of plasma density evolution on KSTAR

Energy Technology Data Exchange (ETDEWEB)

Lee, K.C., E-mail: kclee@nfri.re.kr [National Fusion Research Institute, Daejeon 34133 (Korea, Republic of); Juhn, J.-W.; Nam, Y.U.; Kim, Y.S.; Wi, H.M. [National Fusion Research Institute, Daejeon 34133 (Korea, Republic of); Kim, S.W.; Ghim, Y.-C. [Korea Advanced Institute of Science and Technology, Daejeon 34141 (Korea, Republic of)

2016-12-15

Highlights: • A Two Color Interferometer (TCI) system is designed for 3-D measurement of KSTAR. • TCI is consists of 10.6 μm CO2 laser and 0.63 μm HeNe laser with tangential 5 channels. • 2 channels are installed in 2016 and 5 channel operation is planned in 2017. - Abstract: A 5-channel two color interferometer (TCI) system has been designed on KSTAR. TCI system is designed for tangential beam paths, which will combine with two existing interferometer systems of vertical and radial beam paths, so that it will provide 3-dimensional measurement of electron density evolution. TCI system uses wavelengths of 10.6 μm by a CO{sub 2} laser and 0.633 μm by a HeNe laser. The system compensates the vibrational noise by using two colors and avoids refraction by short wavelengths. The main purpose of the TCI is to generate routine measurement of the line integrated plasma density for the real time density control on KSTAR. The 5-channels will provide profile data for the density. Time resolution of the system is expected to be 500 kHz or higher in order to measure 3-dimensional density fluctuations for ELMs and other MHD activities including TAE modes. The system is planned to be working on KSTAR 2016 campaign with 1–2 channels.

The design of two color interferometer system for the 3-dimensional analysis of plasma density evolution on KSTAR

International Nuclear Information System (INIS)

Lee, K.C.; Juhn, J.-W.; Nam, Y.U.; Kim, Y.S.; Wi, H.M.; Kim, S.W.; Ghim, Y.-C.

2016-01-01

Highlights: • A Two Color Interferometer (TCI) system is designed for 3-D measurement of KSTAR. • TCI is consists of 10.6 μm CO2 laser and 0.63 μm HeNe laser with tangential 5 channels. • 2 channels are installed in 2016 and 5 channel operation is planned in 2017. - Abstract: A 5-channel two color interferometer (TCI) system has been designed on KSTAR. TCI system is designed for tangential beam paths, which will combine with two existing interferometer systems of vertical and radial beam paths, so that it will provide 3-dimensional measurement of electron density evolution. TCI system uses wavelengths of 10.6 μm by a CO 2 laser and 0.633 μm by a HeNe laser. The system compensates the vibrational noise by using two colors and avoids refraction by short wavelengths. The main purpose of the TCI is to generate routine measurement of the line integrated plasma density for the real time density control on KSTAR. The 5-channels will provide profile data for the density. Time resolution of the system is expected to be 500 kHz or higher in order to measure 3-dimensional density fluctuations for ELMs and other MHD activities including TAE modes. The system is planned to be working on KSTAR 2016 campaign with 1–2 channels.

Key features and progress of the KSTAR tokamak engineering

International Nuclear Information System (INIS)

Bak, J.S.; Choi, C.H.; Oh, Y.K.

2003-01-01

Substantial progress of the KSTAR tokamak engineering has been made on major tokamak structures, superconducting magnets, in-vessel components, diagnostic system, heating system, and power supplies. The engineering design has been elaborated to the extent necessary to allow a realistic assessment of its feasibility, performance, and cost. The prototype fabrication has been carried out to establish the reliable fabrication technologies and to confirm the validation of analyses employed for the KSTAR design. The completion of experimental building with beneficial occupancy for machine assembly was accomplished in Sep. 2002. The construction of special utility such as cryo-plant, de-ionized water-cooling system, and main power station will begin upon completion of building construction. The commissioning, construction, fabrication, and assembly of the whole facility will be going on by the end of 2005. This paper describes the main design features and engineering progress of the KSTAR tokamak, and elaborates the work currently underway. (author)

Design of practical alignment device in KSTAR Thomson diagnostic

Energy Technology Data Exchange (ETDEWEB)

Lee, J. H., E-mail: jhlee@nfri.re.kr [National Fusion Research Institute, Daejeon (Korea, Republic of); University of Science and Technology (UST), Daejeon (Korea, Republic of); Lee, S. H. [National Fusion Research Institute, Daejeon (Korea, Republic of); Yamada, I. [National Institute for Fusion Science, Toki (Japan)

2016-11-15

The precise alignment of the laser path and collection optics in Thomson scattering measurements is essential for accurately determining electron temperature and density in tokamak experiments. For the last five years, during the development stage, the KSTAR tokamak’s Thomson diagnostic system has had alignment fibers installed in its optical collection modules, but these lacked a proper alignment detection system. In order to address these difficulties, an alignment verifying detection device between lasers and an object field of collection optics is developed. The alignment detection device utilizes two types of filters: a narrow laser band wavelength for laser, and a broad wavelength filter for Thomson scattering signal. Four such alignment detection devices have been successfully developed for the KSTAR Thomson scattering system in this year, and these will be tested in KSTAR experiments in 2016. In this paper, we present the newly developed alignment detection device for KSTAR’s Thomson scattering diagnostics.

Design and implementation of a standard framework for KSTAR control system

International Nuclear Information System (INIS)

Lee, Woongryol; Park, Mikyung; Lee, Taegu; Lee, Sangil; Yun, Sangwon; Park, Jinseop; Park, Kaprai

2014-01-01

Highlights: • We performed a standardized of control system in KSTAR. • EPICS based software framework is developed for the realization of various control systems. • The applicability of the framework is widened from a simple command dispatcher to the real time application. • Our framework supports the implementation of embedded IOC in FPGA board. - Abstract: Standardization of control system is an important issue in KSTAR which is organized with various heterogeneous systems. Diverse control systems in KSTAR have been adopting new application software since 2010. Development of this software was launched for easy implementation of a data acquisition system but it is extended to as a Standard Framework (SFW) of control system in KSTAR. It is composed with a single library, database, template, and descriptor files. The SFW based controller has common factors. It has non-blocking control command method with a thread. The internal sequence handler makes it can be synchronized with KSTAR experiment. It also has a ring buffer pool mechanism for streaming input data handling. Recently, there are two important functional improvements in the framework. Processor embedded FPGA was proposed as a standard hardware platform for specific application. These are also manipulated by the SFW based embedded application. This approach gives single board system an ability of low level distributed control under the EPICS environments. We also developed a real time monitoring system as a real time network inspection tool in 2012 campaign using the SFW

Fuel retention and recovery in natural and MGI disruptions on KSTAR

International Nuclear Information System (INIS)

Yu, Y.W.; Hong, S.H.; Yoon, S.W.; Kim, K.P.; Kim, W.C.; Seo, D.C.

2013-01-01

Fuel retention and recovery are studied during natural and Massive Gas Injection (MGI) induced disruptions in KSTAR with full graphite wall. The amount of released particles in natural disruptions in 15 s after the discharge is ∼5–10 times higher than that of non-disruption shots, but the difference is only ∼ 2 MGI induced disruptions depends on magnetic field (B t ) and MGI amount. The MGI disruption under a low B t and a medium MGI amount shows shorter thermal quench (TQ) and current quench (CQ), thereby higher fuel recovery. High B t plasma requires higher MGI amount for both disruption mitigation and fuel recovery. A high recovery of 4.2 × 10 22 D (∼0.78 monolayers) is obtained by MGI disruption in KSTAR 2011

Plasma control system for 'Day-One' operation of KSTAR tokamak

International Nuclear Information System (INIS)

Hahn, Sang-hee; Walker, M.L.; Kim, Kukhee; Ahn, H.S.; Penaflor, B.G.; Piglowski, D.A.; Johnson, R.D.; Choi, Jaehoon; Lee, Dong-keun; Kim, Jayhyun; Yoon, S.W.; Seo, Seong-Heon; Kim, H.T.; Kim, K.P.; Lee, T.G.; Park, M.K.; Bak, J.G.; Lee, S.G.; Nam, Y.U.; Eidietis, N.W.

2009-01-01

A complete plasma control system (PCS) has been developed for KSTAR's first plasma campaign as a collaborative project with the DIII-D team. The KSTAR real time plasma control system is based on a conceptual design by Jhang and Choi [Hogun Jhang, I.S. Choi, Fusion Engineering and Design 73 (2005) 35-49] and consists of a fast real-time computer/communication cluster and software derived from the GA-PCS [Penaflor, B.G., et.al., Fusion Engineering and Design, 83 (2) (2008) 176]. The system has been used for simulation testing, poloidal field (PF) coil power supply commissioning and first plasma control. The seven sets of up-down symmetric, superconducting PF coil/power supply systems have been successfully tested. Reflective memory (RFM) is utilized as the primary actuator/PCS real-time communication layer and PCS synchronization with KSTAR timing system and slower control devices is achieved through an EPICS implementation. Consistent feedback loop times of 100 microseconds has been achieved during PF coil power supply testing and first plasma commissioning. Here we present the 'Day-One' plasma control system in its final form for the first plasma experimental campaign of KSTAR and describe how the system has been utilized during magnet commissioning and plasma startup experiments.

Propagation and scattering in Lower Hybrid Current Drive (LHCD)

International Nuclear Information System (INIS)

Horton, W.; Goniche, M.; Peysson, Y.; Decker, J.; Ekedahl, A.; Litaudon, X.

2015-01-01

Full text of publication follows. The propagation and scattering of the 5 GHz RF waves planned for driving and controlling the plasma current in stage 2 of ITER is analyzed with theory, simulations and data from Tore Supra. The internal RF wavenumber spectrum is determined by a combination of elements including the (1) the azimuthal spectrum launched by the antenna, (2) coupling of the radial and azimuthal oscillations of the ray trajectories described the ray Hamiltonian with the radial and the poloidal variation of plasma and scattering from the drift wave turbulence (ref. 1, 2). The scattering of the RF waves from the drift wave turbulence in the plasma is described through a Fokker-Planck equation for the probability density of the rays. The new 4D ray kinetic equation has (1) an edge source from the antenna, (2) a core sink from the electron resonances, and (3) a global scattering rate tensor D ij (k,r,t) derived from the ambient plasma turbulence. The tensor reduces to a parallel and cross-field component with the cross-field component describing side-scatter of the RF waves. The solutions give a spectral distribution for the parallel index of refraction from the antenna to the region of three times the core electron thermal velocity. Strong absorption of the rays occurs where the plateau in the fast electron distribution joins the steeply increasing slope of the thermal electron phase space density (ref. 3). Solutions of the ray kinetic equation with the source, sink and scattering provide the filling of the spectral gap and the efficiency of the LHCD system. The ETG turbulence is modified by the temperature anisotropies and the sharp radial gradients of the LHCD electron distribution function (ref. 3). In the presence of the ETG turbulence projections of the partial differential equations to low-order transport models are derived with dynamical feed-forward/ feedback loops following L-H-ELM modeling (ref. 4). The low-order models may be used with feedback

Design of the klystron filament power supply control system for EAST LHCD

Energy Technology Data Exchange (ETDEWEB)

Wu, Zege; Wang, Mao; Hu, Huaichuan; Ma, Wendong; Zhou, Taian; Zhou, Faxin; Liu, Fukun; Shan, Jiafang [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China)

2016-09-15

A filament is a critical component of the klystron used to heat the cathode. There are totally 44 klystrons in experimental advanced superconducting tokamak (EAST) lower hybrid current drive (LHCD) systems. All klystron filaments are powered by AC power suppliers through isolated transformers. In order to achieve better klystron preheat, a klystron filament power supply control system is designed to obtain the automatic control of all filament power suppliers. Klystron filament current is measured by PLC and the interlock between filament current and klystron high voltage system is also implemented. This design has already been deployed in two LHCD systems and proves feasible completely.

Analysis of the flow imbalance in the KSTAR PF cryo-circuit

International Nuclear Information System (INIS)

Lee, Hyun-Jung; Park, Dong-Seong; Kwag, Sang-Woo; Joo, Jae-Jun; Moon, Kyung-Mo; Kim, Nam-Won; Lee, Young-Joo; Park, Young-Min; Yang, Hyung-Lyeol

2015-01-01

Highlights: • Investigate of flow imbalance trend for the KSTAR PF superconducting magnet. • Flow imbalance is compared with individual magnet test and integration magnet test. • Intensifying of flow imbalance is proven from the flow monitoring in the KSTAR PF circuit. • Flow behavior is analyzed during magnet charging in the circulator circuit. • Variation of magnet outlet temperature is analyzed due to flow imbalance. - Abstract: The KSTAR PF cryo-circuit is a quasi-closed circulation system in which more than 370 g/s of supercritical helium (SHe) is circulated using a SHe circulator. The heated helium from superconducting magnet is cooled through sub cooler (4.3 K). The circulator is operated at 4.5 K and 6.5 bar, and the pressure drop of the circuit is kept at 2 bar in order to maintain the supercritical state and circulator stability. The circuit is connected with helium refrigerator system, distribution system, and supercritical magnet system. It has a hundred branches to supply supercritical helium to the poloidal field superconducting magnet. The branch was designed to optimize the operation conditions and they are grouped for one cryogenic valve has the same length within the cardinal principle of the optimization. Five cryogenic valves are installed to control the mass flow rate, and seven orifice mass flow meters, differential pressure gauges and temperature sensors were installed in front of the magnet in the distribution because upper magnet and lower magnet is symmetric theoretically. The cryogenic pipe line was manufactured with elevation about 10 m between upper magnet and lower magnet. The inlet and outlet helium feed-through were installed at the coil inside in case of KSTAR PF1–PF5 upper magnet and lower magnet. The flow imbalance is caused by void fraction and it could be changed due to manufacturing process even if it has the same length of cooling channel. This creates an imbalance among cooling channels and temperatures are

Effective diagnostic DAQ systems to reduce unnecessary data in KSTAR

Energy Technology Data Exchange (ETDEWEB)

Lee, Taegu, E-mail: glory@nfri.re.kr; Lee, Woongryol; Hong, Jaesic; Park, Kaprai

2016-11-15

Highlights: • When plasma shots do not successfully perform during the intended target time, the diagnostics systems continue to record these unusable data, contributing to increasing data size. • To overcome this problem, some KSTAR’s library were upgraded to monitor the plasma status in real-time. • With the real-time information of plasma status, some of the KSTAR diagnostic systems stop the acquisition process of unnecessary data. • We were able to reduce the refuse data of approximately 698 GByte in the KSTAR 7th campaign. • It was a very effective way to store useful data, and it was helpful to analysts after shot. - Abstract: The plasma status of Korea Superconducting Tokamak Advanced Research (KSTAR) is measured by various diagnostics systems. The measured data size has been increasing every year due to increasing plasma pulse lengths, higher diagnostics operating frequencies, the additions of new diagnostic systems, and an increasing number of diagnostics channels. At times, when plasma shots do not successfully perform during the intended target time, the diagnostics systems continue to record these unusable data, contributing to increasing data size. In addition, the analysis time was affected, as these data need to be separated from the relevant data set. To overcome this problem, KSTAR’s Standard Framework (SFW), Real Time Monitoring (RTMON), and Pulse Automation and Scheduling System (PASS) were upgraded to monitor the plasma status in real-time. When the plasma current is less than 200kA, RTMON sends the plasma status information every second to the SFW via EPICS Channel Access. With the real-time information on plasma status, some of the KSTAR diagnostic systems stop the acquisition process of unnecessary data. This paper describes a method for reducing the storage of unnecessary data and its results in the KSTAR 7th campaign.

Study of runaway current generation following disruptions in KSTAR

International Nuclear Information System (INIS)

Chen, Z Y; Kim, W C; Yu, Y W; England, A C; Yoo, J W; Hahn, S H; Yoon, S W; Lee, K D; Oh, Y K; Kwak, J G; Kwon, M

2013-01-01

The high fraction of runaway current conversion following disruptions has an important effect on the first wall for next-generation tokamaks. Because of the potentially severe consequences of a large full current runaway beam on the first wall in an unmitigated disruption, runaway suppression is given a high priority. The behavior of runaway currents both in spontaneous disruptions and in D 2 massive gas injection (MGI) shutdown experiments is investigated in the KSTAR tokamak. The experiments in KSTAR show that the toroidal magnetic field threshold, B T >2 T, for runaway generation is not absolute. A high fraction of runaway current conversion following spontaneous disruptions is observed at a much lower toroidal magnetic field of B T = 1.3 T. A dedicated fast valve for high-pressure gas injection with 39.7 bar is developed for the study of disruptions. A study of runaway current parameters shows that the conversion efficiency of pre-disruptive plasma currents into runaway current can reach over 80% both in spontaneous disruptions and in D 2 MGI shutdown experiments in KSTAR. (paper)

Experiments on FW-IBW mode conversion heating combined with LHCD on Tore Supra

International Nuclear Information System (INIS)

Basiuk, V.; Becoulet, A.; Imbeaux, F.; Nguyen, F.; Peysson, Y.; Monakhov, I.; Petrov, Y.; Petrov, Y.

1999-01-01

Recent RF heating and current drive investigations revealed a growing interest in a scheme based on mode conversion (MC) of externally excited fast waves (FW) to ion Bernstein waves (IBW). Suitability of MC scheme for on/off axis electron heating has already been reported on Tore Supra. New results, which were obtained during MC experiments combined with Low Hybrid Current Drive (LHCD) are presented in this paper. Application of new experimental tools and numerical techniques provided better insight into the problem of MC power deposition. an outcome of active search for synergistic LHCD-IBW current drive effects is also reported

First mirror deposition/erosion experiment by using multi-purpose manipulators in KSTAR

Energy Technology Data Exchange (ETDEWEB)

Hong, Suk-Ho, E-mail: sukhhong@nfri.re.kr [National Fusion Research Institute, Daejeon (Korea, Republic of); University of Science and Technology, Daejeon (Korea, Republic of); Department of Electrical Engineering, Hanyang University, Seoul (Korea, Republic of); Bang, Eunnam; Son, Soohyun [National Fusion Research Institute, Daejeon (Korea, Republic of); Kogut, Dmitry; Douai, David [CEA, IRFM, Association Euratom-CEA, Paul lez Durance (France)

2016-11-01

First mirrors are essential plasma-facing components (PFCs) for fusion devices. Erosion and redeposition on first mirrors are of interest, since they cause degradation of signal intensity. In order to trace deposition/erosion characteristics of amorphous hydrogenated carbon (a-C:H) films on first mirrors, two manipulators attached at midplane and divertor regions of KSTAR vacuum vessel are utilized. A net deposition rate of 0.3–0.5 nm/s during a discharge and an erosion rates of 0.1 nm/s during He ion cyclotron wall conditioning (ICWC) are obtained. Property of redeposited layers are different depending on the location, varying from soft polymer-like to hard diamond-like a-C:H layers. For the deposition and erosion of metal layers, a plan for a dedicated experimental session has been set at KSTAR.

First mirror deposition/erosion experiment by using multi-purpose manipulators in KSTAR

International Nuclear Information System (INIS)

Hong, Suk-Ho; Bang, Eunnam; Son, Soohyun; Kogut, Dmitry; Douai, David

2016-01-01

First mirrors are essential plasma-facing components (PFCs) for fusion devices. Erosion and redeposition on first mirrors are of interest, since they cause degradation of signal intensity. In order to trace deposition/erosion characteristics of amorphous hydrogenated carbon (a-C:H) films on first mirrors, two manipulators attached at midplane and divertor regions of KSTAR vacuum vessel are utilized. A net deposition rate of 0.3–0.5 nm/s during a discharge and an erosion rates of 0.1 nm/s during He ion cyclotron wall conditioning (ICWC) are obtained. Property of redeposited layers are different depending on the location, varying from soft polymer-like to hard diamond-like a-C:H layers. For the deposition and erosion of metal layers, a plan for a dedicated experimental session has been set at KSTAR.

Control advances for achieving the ITER baseline scenario on KSTAR

Science.gov (United States)

Eidietis, N. W.; Barr, J.; Hahn, S. H.; Humphreys, D. A.; in, Y. K.; Jeon, Y. M.; Lanctot, M. J.; Mueller, D.; Walker, M. L.

2017-10-01

Control methodologies developed to enable successful production of ITER baseline scenario (IBS) plasmas on the superconducting KSTAR tokamak are presented: decoupled vertical control (DVC), real-time feedforward (rtFF) calculation, and multi-input multi-output (MIMO) X-point control. DVC provides fast vertical control with the in-vessel control coils (IVCC) while sharing slow vertical control with the poloidal field (PF) coils to avoid IVCC saturation. rtFF compensates for inaccuracies in offline PF current feedforward programming, allowing reduction or removal of integral gain (and its detrimental phase lag) from the shape controller. Finally, MIMO X-point control provides accurate positioning of the X-point despite low controllability due to the large distance between coils and plasma. Combined, these techniques enabled achievement of IBS parameters (q95 = 3.2, βN = 2) with a scaled ITER shape on KSTAR. n =2 RMP response displays a strong dependence upon this shaping. Work supported by the US DOE under Award DE-SC0010685 and the KSTAR project.

Transport modeling of L- and H-mode discharges with LHCD on EAST

Science.gov (United States)

Li, M. H.; Ding, B. J.; Imbeaux, F.; Decker, J.; Zhang, X. J.; Kong, E. H.; Zhang, L.; Wei, W.; Shan, J. F.; Liu, F. K.; Wang, M.; Xu, H. D.; Yang, Y.; Peysson, Y.; Basiuk, V.; Artaud, J.-F.; Yuynh, P.; Wan, B. N.

2013-04-01

High-confinement (H-mode) discharges with lower hybrid current drive (LHCD) as the only heating source are obtained on EAST. In this paper, an empirical transport model of mixed Bohm/gyro-Bohm for electron and ion heat transport was first calibrated against a database of 3 L-mode shots on EAST. The electron and ion temperature profiles are well reproduced in the predictive modeling with the calibrated model coupled to the suite of codes CRONOS. CRONOS calculations with experimental profiles are also performed for electron power balance analysis. In addition, the time evolutions of LHCD are calculated by the C3PO/LUKE code involving current diffusion, and the results are compared with experimental observations.

ICH/FWCD system design for KSTAR

Energy Technology Data Exchange (ETDEWEB)

Bae, Young Dug; Kwak, J. G.; Han, J. M.; Ju, M. H.; Hong, B. G.

1997-07-01

The ICH/FWCD system for KSTAR shall initially be configured to provide 6 MW power to the plasma with one antenna. The system can be upgraded to provide 12 MW of power to the plasma with the addition of a second system that is duplicate of the first. The initial KSTAR ion cyclotron system consist of one port-mounted antenna that have four current straps. Each strap, using appropriate tuning, matching, and decoupling circuitry will be driven by an independent rf power source. The goal of this ICH/FWCD system is to deliver up to 6 MW of power to the plasma under a variety of plasma conditions. In this report, the plasma loading for various plasma conditions is computed by RANT3D code; electric property of antenna, i.e. inductance, capacitance and mutual coupling are examined; and then a brief description of the overall ICH/FWCD system is given. (author). 3 refs., 4 tabs., 25 figs.

ICH/FWCD system design for KSTAR

International Nuclear Information System (INIS)

Bae, Young Dug; Kwak, J. G.; Han, J. M.; Ju, M. H.; Hong, B. G.

1997-07-01

The ICH/FWCD system for KSTAR shall initially be configured to provide 6 MW power to the plasma with one antenna. The system can be upgraded to provide 12 MW of power to the plasma with the addition of a second system that is duplicate of the first. The initial KSTAR ion cyclotron system consist of one port-mounted antenna that have four current straps. Each strap, using appropriate tuning, matching, and decoupling circuitry will be driven by an independent rf power source. The goal of this ICH/FWCD system is to deliver up to 6 MW of power to the plasma under a variety of plasma conditions. In this report, the plasma loading for various plasma conditions is computed by RANT3D code; electric property of antenna, i.e. inductance, capacitance and mutual coupling are examined; and then a brief description of the overall ICH/FWCD system is given. (author). 3 refs., 4 tabs., 25 figs

Toward Tungsten Plasma-Facing Components in KSTAR: Research on Plasma-Metal Wall Interaction

NARCIS (Netherlands)

Hong, S. H.; Kim, K. M.; Song, J. H.; Bang, E. N.; Kim, H. T.; Lee, K. S.; Litnovsky, A.; Hellwig, M.; Seo, D. C.; van den Berg, M. A.; Lee, H. H.; Kang, C. S.; Lee, H. Y.; Hong, J. H.; Bak, J. G.; Kim, H. S.; Juhn, J. W.; Son, S. H.; Kim, H. K.; Douai, D.; Grisolia, C.; Wu, J.; Luo, G. N.; Choe, W. H.; Komm, M.; De Temmerman, G.; Pitts, R.

2015-01-01

One of the main missions of KSTAR is to develop long-pulse operation capability relevant to the production of fusion energy. After a full metal wall configuration was decided for ITER, a major upgrade for KSTAR was planned, to a tungsten first wall similar to the JET ITER-like wall (coatings and

Time-dependent simulations of feedback stabilization of neoclassical tearing modes in KSTAR plasmas

Energy Technology Data Exchange (ETDEWEB)

Kim, Kyungjin [Department of Nuclear Engineering, Seoul National University, Seoul (Korea, Republic of); Na, Yong-Su, E-mail: ysna@snu.ac.kr [Department of Nuclear Engineering, Seoul National University, Seoul (Korea, Republic of); Kim, Hyun-Seok [Department of Nuclear Engineering, Seoul National University, Seoul (Korea, Republic of); Maraschek, M. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Garching bei München (Germany); Park, Y.S. [Department of Applied Physics and Applied Mathematics, Columbia University, New York (United States); Stober, J. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Garching bei München (Germany); Terzolo, L. [National Fusion Research Institute, Daejeon (Korea, Republic of); Zohm, H. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Garching bei München (Germany)

2014-06-15

A simulation is performed for feedback stabilization of neoclassical tearing mode (NTM) by electron cyclotron current drive (ECCD) for KSTAR in preparation for experiments. An integrated numerical system is constructed by coupling plasma transport, NTM stability, and heating and current drive modules and applied to a KSTAR plasma by assuming similar experimental conditions as ASDEX Upgrade to predict NTM behaviors in KSTAR. System identification is made with database produced by predictive simulations with this integrated numerical system so that three plasma response models are extracted which describe the relation between the EC poloidal launcher angle and the island width in KSTAR. Among them, the P1DI model exhibiting the highest fit accuracy is selected for designing a feedback controller based on the classical Proportional–Integral–Derivative (PID) concept. The controller is coupled with the integrated numerical system and applied to a simulation of NTM stabilization. It is observed that the controller can search and fully stabilize the mode even though the poloidal launch angle is misaligned with the island initially.

Design and construction of the KSTAR tokamak

International Nuclear Information System (INIS)

Lee, G.S.

2001-01-01

The extensive design effort has been focused on two major aspects of the KSTAR project mission, steady-state operation capability and 'advanced tokamak' physics. The steady-state aspect of mission is reflected in the choice of superconducting magnets, provision of actively cooled in-vessel components, and long-pulse current-drive and heating systems. The 'advanced tokamak' aspect of the mission is incorporated in the design features associated with flexible plasma shaping, double-null divertor and passive stabilizers, internal control coils , and a comprehensive set of diagnostics. Substantial progress in engineering has been made on superconducting magnets, vacuum vessel, plasma facing components, and power supplies. The new KSTAR experimental facility with cryogenic system and de-ionized water-cooling and main power systems has been designed, and the construction work has been on-going for completion in year 2004. (author)

Neutral beam injection system design for KSTAR tokamak

Energy Technology Data Exchange (ETDEWEB)

Choi, B.H.; Lee, K.W.; Chung, K.S.; Oh, B.H.; Cho, Y.S.; Bae, Y.D.; Han, J.M. [Korea Atomic Energy Research Institute, Taejon (Korea)

1998-06-01

The NBI system for KSTAR (Korean Superconducting Tokamak Advanced Research) has been designed based on conventional positive ion beam technology. One beam line consists of three ion sources, three neutralizers, one bending magnet, and one drift tube. This system will deliver 8 MW deuterium beam to KSTAR plasma in normal operation to support the advanced experiments on heating, current drive and profile control. The key technical issues in this design were high power ion source(120 kV, 65 A), long pulse operation (300 seconds; world record is 30 sec), and beam rotation from vertical to horizontal direction. The suggested important R and D points on ion source and beam line components are also included. (author). 7 refs., 27 figs., 1 tab.

Multi-purpose mid-plane manipulator for plasma surface interaction research in KSTAR

Energy Technology Data Exchange (ETDEWEB)

Son, S.H., E-mail: ssh0609@nfri.re.kr [National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Hong, S.-H. [National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Department of Electrical Engineering, HanYang University, Seoul 133-791 (Korea, Republic of); Department of Accelerator and Nuclear Fusion Physics and Engineering, Korea University of Science and Technology, Daejeon 305-333 (Korea, Republic of); Kim, Junghee [National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Kim, Jun Young [National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Department of Accelerator and Nuclear Fusion Physics and Engineering, Korea University of Science and Technology, Daejeon 305-333 (Korea, Republic of); Kim, H.S. [National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Ding, F.; Luo, G.-N. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 1126 (China); Németh, J.; Zoletnik, S. [Institute for Particle and Nuclear Physics (RMI), Wigner RCP, Hungarian Academy of Sciences, Budapest (Hungary); Fenyvesi, A. [Institute for Nuclear Physis (MTA Atomki), Hungarian Academy of Sciences, Devrecent (Hungary); Pitts, R. [ITER Organization, Route de Vinon-surVerdon, 13115 Saint Paul-lez-Durance (France)

2016-11-01

Highlights: • A multi-purpose mid-plane manipulator system has been developed and installed at the mid-plane of the KSTAR vacuum vessel. • It presents mechanial structure and function for multi-purpose manipulator system. • The changeable head part allows change the samples and probe during inter-shot/day without breaking vacuum system in KSTAR which gives flexibility for various PSI studies in a campaign. - Abstract: A multi-purpose mid-plane manipulator system has been developed and installed at the mid-plane of the KSTAR vacuum vessel. The system serves as user facility which allows to cover various topics of researches in plasma-surface interaction (PSI) including material sample test and PSI diagnostic. The multi-purpose mid-plane manipulator system has a 4 m long cantilever structure with a 3 m long moving shaft. The system is equipped with a differential pumping system for the independent installation and removal of samples and diagnostic without vacuum break of KSTAR. The sample mounting head at the end of the shaft can reach the position of the outer boundary of ∼10 cm away from the last closed flux surface (LCFS). In this paper, selected PSI related experiments by using the manipulator are introduced.

Multi-purpose mid-plane manipulator for plasma surface interaction research in KSTAR

International Nuclear Information System (INIS)

Son, S.H.; Hong, S.-H.; Kim, Junghee; Kim, Jun Young; Kim, H.S.; Ding, F.; Luo, G.-N.; Németh, J.; Zoletnik, S.; Fenyvesi, A.; Pitts, R.

2016-01-01

Highlights: • A multi-purpose mid-plane manipulator system has been developed and installed at the mid-plane of the KSTAR vacuum vessel. • It presents mechanial structure and function for multi-purpose manipulator system. • The changeable head part allows change the samples and probe during inter-shot/day without breaking vacuum system in KSTAR which gives flexibility for various PSI studies in a campaign. - Abstract: A multi-purpose mid-plane manipulator system has been developed and installed at the mid-plane of the KSTAR vacuum vessel. The system serves as user facility which allows to cover various topics of researches in plasma-surface interaction (PSI) including material sample test and PSI diagnostic. The multi-purpose mid-plane manipulator system has a 4 m long cantilever structure with a 3 m long moving shaft. The system is equipped with a differential pumping system for the independent installation and removal of samples and diagnostic without vacuum break of KSTAR. The sample mounting head at the end of the shaft can reach the position of the outer boundary of ∼10 cm away from the last closed flux surface (LCFS). In this paper, selected PSI related experiments by using the manipulator are introduced.

Heating, current drive and confinement regimes with the JET ICRH and LHCD systems

DEFF Research Database (Denmark)

Jacquinot, J.; Adams, J.M.; Altmann, H.

1991-01-01

by pellet injection. A value of n(d) tau-E T(i) = 7.8 x 10(20) m-3 s keV was obtained in this mode with T(e) approximately T(i) approximately 11 keV. In the L-mode regime, a regime, a record (140 kW) D-He-3 fusion power was generated with 10 - 14 MW of ICRH at the He-3 cyclotron frequency. Experiments were....... Paradoxically, LHCD induces central heating particularly in combination with ICRH. Finally we present the first observations of the synergistic acceleration of fast electrons by Transit Time Magnetic Pumping (TTMP) (from ICRH) and Electron Landau Damping (ELD) (from LHCD). The synergism generates TTMP current...

Design of EAST LHCD high power supply feedback control system based on PLC

International Nuclear Information System (INIS)

Hu Huaichuan; Shan Jiafang

2009-01-01

Design of EAST LHCD -35kV/5.6MW high power supply feedback control system based on PLC is described. Industrial computer and PLC are used to control high power supply in the system. PID arithmetic is adopted to achieve the feedback control of voltage of high power supply. Operating system is base on real-time operating system of QNX. Good controlling properties and reliable protective properties of the feedback control system are proved by the experiment results. (authors)

Enhancement of the power system efficiency using the hybrid-type harmonic filters for a KSTAR nuclear fusion experimental system

International Nuclear Information System (INIS)

Yoon, Dong-Hee; Lee, Hansang; Park, Byungju; Jang, Gilsoo

2011-01-01

Highlights: → The low power factor and power quality problems are occurred by the operation of the PF facility in KSTAR system. We model the power system of KSTAR system including the PF facility. We show a method of the filter insertion to improve the problem and conduct the simulations to verify our method. - Abstract: The KSTAR system, which includes a large amount of nonlinear load, is a relatively high reactive power consumption load which injects harmonic currents into the power system which could result in the possibility for a power system perturbation to occur in the transmission lines, affecting nearby customers. In order to maintain the power quality and power factor in the inner system of the KSTAR system and the adjacent distribution lines, the assessment of the effect of the DC power supply in the KSTAR system is required for appropriate countermeasures to be put in place. In this paper, on the basis of a preliminary inspection of the power system near a KSTAR system, the simulation of a compensating device is performed for the prevention of abnormal voltage variations caused by a large amount of reactive and nonlinear load. In addition, through the comparison of the pre- and post-application of compensation devices in the actual power system, it is verified that a stable operation of the KSTAR nuclear fusion experimental system can be achieved.

Measurement of vertical stability metrics in KSTAR

Science.gov (United States)

Hahn, Sang-Hee; Humphreys, D. A.; Mueller, D.; Bak, J. G.; Eidietis, N. W.; Kim, H.-S.; Ko, J. S.; Walker, M. L.; Kstar Team

2017-10-01

The paper summarizes results of multi-year ITPA experiments regarding measurement of the vertical stabilization capability of KSTAR discharges, including most recent measurements at the highest achievable elongation (κ 2.0 - 2.1). The measurements of the open-loop growth rate of VDE (γz) and the maximum controllable vertical displacement (ΔZmax) are done by the release-and-catch method. The dynamics of the vertical movement of the plasma is verified by both relevant magnetic reconstructions and non-magnetic diagnostics. The measurements of γz and ΔZmax were done for different plasma currents, βp, internal inductances, elongations and different configurations of the vessel conductors that surround the plasma as the first wall. Effects of control design choice and diagnostics noise are discussed, and comparison with the axisymmetric plasma response model is given for partial accounting for the measured control capability. This work supported by Ministry of Science, ICT, and Future Planning under KSTAR project.

Design and simulation for the pulse high-voltage DC power supply (HVPS) of 1.2 MW/2.45 GHz HT-7U lower hybrid current drive system

International Nuclear Information System (INIS)

Huang Yiyun; Kuang Guangli; Xu Weihua; Liu Baohua; Lin Jianan; Wu Junshuan; Zheng Guanghua; Yang Chunshen

2000-01-01

The superconducting tokamak HT-7U has been designed by the Institute of Plasma Physics since 1998 and will be set up before 2003. The 1.2 MW/2.45 GHz HT-7U LHCD (Lower hybrid current drive) system which being the most efficient non-induction device can heat the plasma and drive the plasma current has been efficiently in operation now, and a particular design of the 2.8 MW/-35 kV high-voltage DC power supply has been already completed and will apply to the klystron of LHCD on HT-7 and the future HT-7U, and the project of the power supply has been examined and approved professionally by an authorized group of high-level specialist in the Institute of Plasma Physics. The detailed design of the power supply and the simulation results are referred

Management tools for distributed control system in KSTAR

International Nuclear Information System (INIS)

Sangil Lee; Jinseop Park; Jaesic Hong; Mikyung Park; Sangwon Yun

2012-01-01

The integrated control system of the Korea Superconducting Tokamak Advanced Research (KSTAR) has been developed with distributed control systems based on Experimental Physics and Industrial Control System (EPICS) middle-ware. It has the essential role of remote operation, supervising of tokamak device and conducting of plasma experiments without any interruption. Therefore, the availability of the control system directly impacts on the entire device performance. For the non-interrupted operation of the KSTAR control system, we have developed a tool named as Control System Monitoring (CSM) to monitor the resources of EPICS Input/Output Controller (IOC) servers (utilization of memory, cpu, disk, network, user-defined process and system-defined process), the soundness of storage systems (storage utilization, storage status), the status of network switches using Simple Network Management Protocol (SNMP), the network connection status of every local control sever using Internet Control Message Protocol (ICMP), and the operation environment of the main control room and the computer room (temperature, humidity, electricity) in real time. When abnormal conditions or faults are detected by the CSM, it alerts abnormal or fault alarms to operators. Especially, if critical fault related to the data storage occurs, the CSM sends the simple messages to operator's mobile phone. The operators then quickly restored the problems according to the emergency procedure. As a result of this process, KSTAR was able to perform continuous operation and experiment without interruption for 4 months

The KSTAR integrated control system based on EPICS

International Nuclear Information System (INIS)

Kim, K.H.; Ju, C.J.; Kim, M.K.; Park, M.K.; Choi, J.W.; Kyum, M.C.; Kwon, M.

2006-01-01

The Korea Superconducting Tokamak Advanced Research (KSTAR) control system will be developed with several subsystems, which consist of the central control system (e.g. plasma control, machine control, diagnostic control, time synchronization, and interlock systems) and local control systems for various subsystems. We are planning to connect the entire system with several networks, viz. a reflective-memory-based real-time network, an optical timing network, a gigabit Ethernet network for generic machine control, and a storage network. Then it will evolve into a network-based, distributed real-time control system. Thus, we have to consider the standard communication protocols among the subsystems and how to handle the various kinds of hardware in a homogeneous way. To satisfy these requirements, EPICS has been chosen for the KSTAR control. The EPICS framework provides network-based real-time distributed control, operating system independent programming tools, operator interface tools, archiving tools, and interface tools with other commercial and non-commercial software. The most important advantage of the use of the EPICS framework is in providing homogeneity of the system for the control system developer. The developer does not have to be concerned about the specifics of the local system, but can concentrate on the implementation of the control logic with EPICS tools. We will present the details of the integration issues and also will give a brief summary of the entire KSTAR control system from an integration point of view

High heat flux test of tungsten brazed mock-ups developed for KSTAR divertor

Energy Technology Data Exchange (ETDEWEB)

Song, J.H. [National Fusion Research Institute, Daejeon (Korea, Republic of); Kim, K.M., E-mail: kyungmin@nfri.re.kr [National Fusion Research Institute, Daejeon (Korea, Republic of); Hong, S.H.; Kim, H.T.; Park, S.H.; Park, H.K.; Ahn, H.J. [National Fusion Research Institute, Daejeon (Korea, Republic of); Kim, S.K.; Lee, D.W. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2016-11-01

The tungsten (W) brazed flat type mock-up which consists of W, OFHC-Cu (oxygen-free high conductive copper) and CuCrZr alloy has been designed for KSTAR divertor in preparation for KSTAR upgrade with 17 MW heating power. For verification of the W brazed mock-up, the high heat flux test is performed at KoHLT-EB (Korea High Heat Load Test Facility-Electron Beam) in KAERI (Korea Atomic Energy Research Institute). Three mock-ups are tested for several thousand thermal cycles with absorbed heat flux up to 5 MW/m{sup 2} for 20 s duration. There is no evidence of the failure at the bonding joints of all mock-ups after HHF test. Finite element analysis (FEA) is performed to interpret the result of the test. As a result, it is considered that the local area in the water is in the subcooled boiling regime.

Design and experimental results of feedback control of Ohmic-heating transformer magnetic flux by LHCD power in HT-7 Tokamak

International Nuclear Information System (INIS)

Yiyun Huang

2006-01-01

In order to make a research on long pulse or even steady state operation with non-inductive drive in plasma discharge, a new feedback control scheme instead of the previous one has been designed and operated in HT-7 [HT-7 team presented by J. Li, et al., Plasma Phys. Control. Fusion 42 (2) (2000) 135-146] Tokamak experiment, 2004. Consumption of iron-core transformer magnetic flux (MFT) is feedback controlled for the first time by power of lower hybrid current drive (LHCD) P LH , when the Ohmic-heating circuit current can maintain the plasma current I P constant with another feedback control loop, which make MFT evolve at alternating-change state to avoid flux saturation. Plasma current I P can be maintained steadily up to 120s in this operation mode at reduced plasma parameters (I P ∼50-100KA, average density n-bar e =0.4-0.5x10 19 m -3 , P LH =100-200KW). Design and experimental results are presented in the paper, which including control model analysis, configurations of control system and MFT feedback control experiments in HT-7. The high voltage power supply (HVPS) of LHCD is the main controller that regulates the LHCD power into the plasma to control the MFT

Power supply system for KSTAR neutral beam injector

Energy Technology Data Exchange (ETDEWEB)

Cho, W., E-mail: franciscocho@nfri.re.kr; Bae, Y.S.; Han, W.S.; Jeong, J.H.; Kim, J.S.; Park, H.T.; Yang, H.L.; Oh, Y.K.; Kwak, J.G.

2015-10-15

Highlights: • The power supply system in KSTAR NBI consists of DC power supplies for ion source. • For operation NBI, DC High Voltage based on the low voltage transformer with chopper. • The surge absorber near the ion source limit the energy deposited to accelerator grid. - Abstract: The power supply system in KSTAR neutral beam injector consists of low voltage and high current DC power supplies for plasma generator of ion source and high voltage and high current DC power supply for accelerator grid system. The arc discharge is initiated by an arc power supply supplying the arc voltage between the chamber wall and 12 filaments which are heated by individual filament power supply. The negative output of arc power supply is common to each positive output of 12 filament power supplies. To interrupt the arc discharging for the fault condition of the arc current unbalance, DCCT current monitor is placed at the positive output cable of the filament power supply. The plasma grid (G1) power supply has the maximum capability of 120 kV/70 A which consists of low voltage regulator with IGBT-switched chopper array system for the voltage control in unit of 600 V and the high voltage rectified transformers to supply DC voltage of 20 kV, 30 kV, and 50 kV. The output voltage of the G1 power supply is also connected to the input of the voltage divider system which supplies the gradient voltage to the gradient grid (G2) in the range of 80–90% of G1 voltage by changing tap of winding resistors in unit of 1%. The charged G1 voltage is turned on and off by the high voltage switch (HVS) system consisting of MOSFET fast semiconductor switches which can immediately be opened less than 1 μs when the ion source grid breakdown occurs. The decelerating grid (G3) power supply is inverter system using capacitor-charge power supply to supply maximum −5 kV/5 A. The important component in power supply system is the surge absorber near the ion source to limit the arc energy deposited to

Power supply system for KSTAR neutral beam injector

International Nuclear Information System (INIS)

Cho, W.; Bae, Y.S.; Han, W.S.; Jeong, J.H.; Kim, J.S.; Park, H.T.; Yang, H.L.; Oh, Y.K.; Kwak, J.G.

2015-01-01

Highlights: • The power supply system in KSTAR NBI consists of DC power supplies for ion source. • For operation NBI, DC High Voltage based on the low voltage transformer with chopper. • The surge absorber near the ion source limit the energy deposited to accelerator grid. - Abstract: The power supply system in KSTAR neutral beam injector consists of low voltage and high current DC power supplies for plasma generator of ion source and high voltage and high current DC power supply for accelerator grid system. The arc discharge is initiated by an arc power supply supplying the arc voltage between the chamber wall and 12 filaments which are heated by individual filament power supply. The negative output of arc power supply is common to each positive output of 12 filament power supplies. To interrupt the arc discharging for the fault condition of the arc current unbalance, DCCT current monitor is placed at the positive output cable of the filament power supply. The plasma grid (G1) power supply has the maximum capability of 120 kV/70 A which consists of low voltage regulator with IGBT-switched chopper array system for the voltage control in unit of 600 V and the high voltage rectified transformers to supply DC voltage of 20 kV, 30 kV, and 50 kV. The output voltage of the G1 power supply is also connected to the input of the voltage divider system which supplies the gradient voltage to the gradient grid (G2) in the range of 80–90% of G1 voltage by changing tap of winding resistors in unit of 1%. The charged G1 voltage is turned on and off by the high voltage switch (HVS) system consisting of MOSFET fast semiconductor switches which can immediately be opened less than 1 μs when the ion source grid breakdown occurs. The decelerating grid (G3) power supply is inverter system using capacitor-charge power supply to supply maximum −5 kV/5 A. The important component in power supply system is the surge absorber near the ion source to limit the arc energy deposited to

Baking results of KSTAR vacuum vessel

International Nuclear Information System (INIS)

Kim, S. T.; Kim, Y. J.; Kim, K. M.; Im, D. S.; Joung, N. Y.; Yang, H. L.; Kim, Y. S.; Kwon, M.

2009-01-01

The Korea Superconducting Tokamak Advanced Research (KSTAR) is an advanced superconducting tokamak designed to establish a scientific and technological basis for an attractive fusion reactor. The fusion energy in the tokamak device is released through fusion reactions of light atoms such as deuterium or helium in hot plasma state, of which temperature reaches several hundreds of millions Celsius. The high temperature plasma is created in the vacuum vessel that provides ultra high vacuum status. Accordingly, it is most important for the vacuum condition to keep clean not only inner space but also surface of the vacuum vessel to make high quality plasma. There are two methods planned to clean the wall surface of the KSTAR vacuum vessel. One is surface baking and the other is glow discharge cleaning (GDC). To bake the vacuum vessel, De-Ionized (DI) water is heated to 130 .deg. C and circulated in the passage between double walls of the vacuum vessel (VV) in order to bake the surface. The GDC operation uses hydrogen and inert gas discharges. In this paper, general configuration and brief introduction of the baking result will be reported

Baking results of KSTAR vacuum vessel

Energy Technology Data Exchange (ETDEWEB)

Kim, S. T.; Kim, Y. J.; Kim, K. M.; Im, D. S.; Joung, N. Y.; Yang, H. L.; Kim, Y. S.; Kwon, M. [National Fusion Research Institute, Daejeon (Korea, Republic of)

2009-05-15

The Korea Superconducting Tokamak Advanced Research (KSTAR) is an advanced superconducting tokamak designed to establish a scientific and technological basis for an attractive fusion reactor. The fusion energy in the tokamak device is released through fusion reactions of light atoms such as deuterium or helium in hot plasma state, of which temperature reaches several hundreds of millions Celsius. The high temperature plasma is created in the vacuum vessel that provides ultra high vacuum status. Accordingly, it is most important for the vacuum condition to keep clean not only inner space but also surface of the vacuum vessel to make high quality plasma. There are two methods planned to clean the wall surface of the KSTAR vacuum vessel. One is surface baking and the other is glow discharge cleaning (GDC). To bake the vacuum vessel, De-Ionized (DI) water is heated to 130 .deg. C and circulated in the passage between double walls of the vacuum vessel (VV) in order to bake the surface. The GDC operation uses hydrogen and inert gas discharges. In this paper, general configuration and brief introduction of the baking result will be reported.

Design of 2.5 GHz broad bandwidth microwave bandpass filter at operating frequency of 10 GHz using HFSS

Science.gov (United States)

Jasim, S. E.; Jusoh, M. A.; Mahmud, S. N. S.; Zamani, A. H.

2018-04-01

Development of low losses, small size and broad bandwidth microwave bandpass filter operating at higher frequencies is an active area of research. This paper presents a new route used to design and simulate microwave bandpass filter using finite element modelling and realized broad bandwidth, low losses, small dimension microwave bandpass filter operating at 10 GHz frequency using return loss method. The filter circuit has been carried out using Computer Aid Design (CAD), Ansoft HFSS software and designed with four parallel couple line model and small dimension (10 × 10 mm2) using LaAlO3 substrate. The response of the microwave filter circuit showed high return loss -50 dB at operating frequency at 10.4 GHz and broad bandwidth of 2.5 GHz from 9.5 to 12 GHz. The results indicate the filter design and simulation using HFSS is reliable and have the opportunity to transfer from lab potential experiments to the industry.

Demonstration of real-time control for poloidal beta in KSTAR

Energy Technology Data Exchange (ETDEWEB)

Han, Hyunsun, E-mail: hyunsun@nfri.re.kr [National Fusion Research Institute, Daejeon 305-806 (Korea, Republic of); Hahn, S.H.; Bak, J.G. [National Fusion Research Institute, Daejeon 305-806 (Korea, Republic of); Hyatt, A.; Johnson, R. [General Atomics, San Diego, CA (United States); Woo, M.H.; Kim, J.S.; Bae, Y.S. [National Fusion Research Institute, Daejeon 305-806 (Korea, Republic of)

2015-06-15

Highlights: • Real time control system for poloidal beta has been designed in KSTAR. • Poloidal beta has been calculated based on the diamagnetic loop signals. • The neutral beam Injector plays a role as the actuator. • The control system has been validated in the KSTAR experiments. - Abstract: Sustaining the plasma in a stable and a high performance condition is one of the important control issues for future steady state tokamaks. In the 2014 KSTAR campaign, we have developed a real-time poloidal beta (β{sub p}) control technique and carried out preliminary experiments to identify its feasibility. In the control system, the β{sub p} is calculated in real time using the measured diamagnetic loop signal, and compared with the target value leading to the change of the neutral beam (NB) heating power using a feedback PID control algorithm. To match the requested power of NB which is operated with constant voltage, the on-time periods of the intervals were adjusted as the ratio of the required power to the maximum achievable one. This paper will present the overall procedures of the β{sub p} control, the β{sub p} estimation process and NB operation scheme implemented in the plasma control system (PCS), and the analysis on the preliminary experimental results.

Demonstration of real-time control for poloidal beta in KSTAR

International Nuclear Information System (INIS)

Han, Hyunsun; Hahn, S.H.; Bak, J.G.; Hyatt, A.; Johnson, R.; Woo, M.H.; Kim, J.S.; Bae, Y.S.

2015-01-01

Highlights: • Real time control system for poloidal beta has been designed in KSTAR. • Poloidal beta has been calculated based on the diamagnetic loop signals. • The neutral beam Injector plays a role as the actuator. • The control system has been validated in the KSTAR experiments. - Abstract: Sustaining the plasma in a stable and a high performance condition is one of the important control issues for future steady state tokamaks. In the 2014 KSTAR campaign, we have developed a real-time poloidal beta (β p ) control technique and carried out preliminary experiments to identify its feasibility. In the control system, the β p is calculated in real time using the measured diamagnetic loop signal, and compared with the target value leading to the change of the neutral beam (NB) heating power using a feedback PID control algorithm. To match the requested power of NB which is operated with constant voltage, the on-time periods of the intervals were adjusted as the ratio of the required power to the maximum achievable one. This paper will present the overall procedures of the β p control, the β p estimation process and NB operation scheme implemented in the plasma control system (PCS), and the analysis on the preliminary experimental results

ECH pre-ionization and assisted startup in the fully superconducting KSTAR tokamak using second harmonic

International Nuclear Information System (INIS)

Bae, Y.S.; Joung, M.; Kim, J.H.; Hahn, S.H.; Yoon, S.W.; Yang, H.L.; Kim, W.C.; Oh, Y.K.; England, A.C.; Bak, J.S.; Jeong, J.H.; Park, S.I.; Namkung, W.; Cho, M.H.; Jackson, G.L.

2009-01-01

This letter reports on the successful demonstration of the second harmonic electron cyclotron heating (ECH)-assisted startup in the first plasma experiments recently completed in the fully superconducting Korea Superconducting Tokamak Advanced Research (KSTAR) device whose major and minor radii are 1.8 m and 0.5 m, respectively. For the second harmonic ECH-assisted startup, an 84 GHz EC wave at 0.35 MW was launched before the onset of the toroidal electric field of the Ohmic system. And it was observed that this was sufficient to achieve breakdown in the ECH pre-ionization phase, allow burn-through and sustain the plasma during the current ramp with a low loop voltage of 2.0 V and a corresponding toroidal electric field of 0.24 V m -1 at the innermost vacuum vessel wall (R = 1.3 m). This is a lower value than 0.3 Vm -1 which is the maximum electric field in ITER. Due to the limited volt-seconds and the loop voltage of the Ohmic power system, the extended pulse duration of the ECH power up to 180 ms allowed the plasma current to rise up to more than 100 kA with a ramp-up rate of 0.8 MA s -1 . (letter)

Reconstruction of -35 kV/200 kW HVPS for test of klystron units in LHCD system

International Nuclear Information System (INIS)

Huang Yiyun

2004-01-01

The paper introduces the -35 kV/200 kW high voltage power supply (HVPS) which is specially used to test klystron units in LHCD system. The new klystrons must be tested under high voltage level before operation and the old klystrons which have worked for a longtime must be exercised by HVPS in lower hybrid current drive (LHCD) system. As the former HVPS has some shortages in engineering design and operation design, the HVPS has to be modified and rebuilt by adopting new method and technology to solve existing bottle-neck problems. (author)

Numerical estimation on balance coefficients of central difference averaging method for quench detection of the KSTAR PF coils

International Nuclear Information System (INIS)

Kim, Jin Sub; An, Seok Chan; Ko, Tae Kuk; Chu, Yong

2016-01-01

A quench detection system of KSTAR Poloidal Field (PF) coils is inevitable for stable operation because normal zone generates overheating during quench occurrence. Recently, new voltage quench detection method, combination of Central Difference Averaging (CDA) and Mutual Inductance Compensation (MIK) for compensating mutual inductive voltage more effectively than conventional voltage detection method, has been suggested and studied. For better performance of mutual induction cancellation by adjacent coils of CDA+MIK method for KSTAR coil system, balance coefficients of CDA must be estimated and adjusted preferentially. In this paper, the balance coefficients of CDA for KSTAR PF coils were numerically estimated. The estimated result was adopted and tested by using simulation. The CDA method adopting balance coefficients effectively eliminated mutual inductive voltage, and also it is expected to improve performance of CDA+MIK method for quench detection of KSTAR PF coils

Physics validation for design change of KSTAR passive stabilizer

Science.gov (United States)

Jeon, Y. M.; Kim, J. Y.; Oh, Y. K.; Yang, H. L.; Kim, W. C.; Kim, H. K.; Sabbagh, S. A.; Bialek, J. M.; Humphreys, D. A.; Welander, A. S.; Walker, M. L.

2009-11-01

Recently, the design of the passive stabilizer in KSTAR has been changed to improve controllability of the active control system and reduce the possibility of producing an additional error field. Originally the passive stabilizer in KSTAR was designed for RWM and vertical instability (or VDE) stabilizations and plasma startup efficiency, so that current bridges were designed and combined through 3D saddle-loop connections. Since the key design change is removing the current bridges, it's essential to assure satisfactory control performance for these instabilities under the design change. Control capability for n=1 RWM and achievable βN will be addressed as a primary goal of the passive stabilizer together with vertical instability control and effects on plasma startup. In addition, the changes in electro-magnetic force on conducting structures will be discussed qualitatively as a key engineering issue of the design change.

Exploration of extremely low q_e_d_g_e regime in KSTAR

International Nuclear Information System (INIS)

Kim, Jayhyun; In, Y.; Park, B.H.; Aydemir, A.

2015-01-01

The q_e_d_g_e < 2 regime had long been regarded as an experimentally forbidden regime due to magneto-hydrodynamic instabilities. However, RFX-MOD experiment demonstrated that the control of error field could enable the entrance and sustainment of the discharge even in the forbidden regime. We explored q_e_d_g_e < 2 regime in Korea superconducting tokamak advanced research (KSTAR) without any feedback or feedforward control of error field since the intrinsic level of error field in KSTAR is inherently comparable to the controlled level of other device. The discharge sustained at q_9_5 ∼ 1.9 for 800 ms that is at least one order of magnitude longer than the resistive wall time of the device. Furthermore, simulated error field applied by field error correction coils prevented the passage of q_e_d_g_e = 3 integer rational surface before reaching q_e_d_g_e = 2. The detailed analysis is on-going for revealing the role of error field in the excitation of limiting instability. (author)

The upgrade of KSTAR timing system to support long-pulse operation and high-speed data acquisition

Energy Technology Data Exchange (ETDEWEB)

Park, Mikyung, E-mail: mkpark@nfri.re.kr [National Fusion Research Institute (NFRI), Daejeon (Korea, Republic of); Lee, Woongryol; Na, Hoonkyun [National Fusion Research Institute (NFRI), Daejeon (Korea, Republic of)

2012-12-15

Since the first campaign of KSTAR in 2008, the home-made timing system had run for the synchronized operation of tokamak. The timing board which featured PMC-form factor, giga-bit optical communication, home-made protocol, multi-triggering capability, using GPS time and being integrated to EPICS (Experimental Physics and Industrial Control System), had advantages of compactness, modularity, platform independency and full functionality for the synchronized tokamak operation. However, there was deficiency in timing accuracy resulting from the engagement of software in realization of timing function and timing jitter due to poor isolation in output ports. Moreover, new requirements were on the rise as the plasma pulse length was getting longer and diagnostics operating at the higher frequency were newly installed. In order to meet new requirements and overcome the problems, the new timing board has been developed. As a result, the performance is remarkably enhanced: timing accuracy less than 5 ns, jitter less than 100 ps, 8 configurable multi-triggering sections, provision of maximum 100 MHz sampling clock. The KSTAR timing system upgraded by introducing the new timing board is participating in the 2011 campaign after calibration and consolidating the established timing system. This paper describes design, development and commissioning results of the new KSTAR timing system.

Dynamical back-action at 5.5 GHz in a corrugated optomechanical beam

Energy Technology Data Exchange (ETDEWEB)

Navarro-Urrios, D., E-mail: daniel.navarrourrios@nano.cnr.it [Catalan Institute of Nanoscience and Nanotechnology, Campus UAB, Edifici ICN2, 08193 Bellaterra (Spain); NEST, Istituto Nanoscienze – CNR and Scuola Normale Superiore, Piazza San Silvestro 12, Pisa, I-56127 (Italy); Gomis-Bresco, J.; Alzina, F. [Catalan Institute of Nanoscience and Nanotechnology, Campus UAB, Edifici ICN2, 08193 Bellaterra (Spain); El-Jallal, S. [IEMN, Universite de Lille 1, Villeneuve d’Ascq (France); PRILM, Université Moulay Ismail, Faculté des sciences, Meknès (Morocco); Oudich, M.; Pennec, Y.; Djafari-Rouhani, B. [IEMN, Universite de Lille 1, Villeneuve d’Ascq (France); Pitanti, A. [NEST, Istituto Nanoscienze – CNR and Scuola Normale Superiore, Piazza San Silvestro 12, Pisa, I-56127 (Italy); Capuj, N. [Depto. Física, Universidad de la Laguna, 38206 (Spain); Tredicucci, A. [NEST, Istituto Nanoscienze – CNR and Scuola Normale Superiore, Piazza San Silvestro 12, Pisa, I-56127 (Italy); Dipartimento di Fisica, Universita di Pisa, Largo Pontecorvo 3, I-56127 Pisa (Italy); Griol, A.; Martínez, A. [Nanophotonics Technology Center, Universitat Politècnica de València, Valencia (Spain); Sotomayor Torres, C. M. [Catalan Institute of Nanoscience and Nanotechnology, Campus UAB, Edifici ICN2, 08193 Bellaterra (Spain); Catalan Institution for Research and Advanced Studies (ICREA), 08010 Barcelona (Spain)

2014-12-15

We report on the optomechanical properties of a breathing mechanical mode oscillating at 5.5 GHz in a 1D corrugated Si nanobeam. This mode has an experimental single-particle optomechanical coupling rate of |g{sub o,OM}| = 1.8 MHz (|g{sub o,OM}|/2π = 0.3 MHz) and shows strong dynamical back-action effects at room temperature. The geometrical flexibility of the unit-cell would lend itself to further engineering of the cavity region to localize the mode within the full phononic band-gap present at 4 GHz while keeping high g{sub o,OM} values. This would lead to longer lifetimes at cryogenic temperatures, due to the suppression of acoustic leakage.

LHCD operations in JET and developments for fusion applications

International Nuclear Information System (INIS)

Froissard, P.; Baranov, Y.; Brandon, M.; Brusati, M.; Dobbing, J.A.; Ekedahl, A.; Finburg, P.; Fischer, B.; Gormezano, C.; Haydon, P.; Kaye, A.; Lennholm, M.; McCarthy, T.; Page, R.; Paling, P.; Platt, G.; Pledge, D.; Plancoulaine, J.; Rimini, F.; Schild, P.; Soeldner, F.X.

1995-01-01

The full Lower Hybrid Current Drive (LHCD) launcher in JET has been completed and installed. Up to 6 MW has been coupled to the plasma and 2 MA full current drive was achieved with 4 MW of LH power. Coupling is improved by using active feedback control on the launcher and plasma position. A new launcher design concept, called Hyperguide, has been developed and tested successfully in JET to replace eventually conventional launchers using multijunctions for next step machines like ITER. (orig.)

Steady state plasma operation in RF dominated regimes on EAST

Energy Technology Data Exchange (ETDEWEB)

Zhang, X. J.; Zhao, Y. P.; Gong, X. Z.; Hu, C. D.; Liu, F. K.; Hu, L. Q.; Wan, B. N., E-mail: bnwan@ipp.ac.cn; Li, J. G. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China)

2015-12-10

Significant progress has recently been made on EAST in the 2014 campaign, including the enhanced CW H&CD system over 20MW heating power (LHCD, ICRH and NBI), more than 70 diagnostics, ITER-like W-monoblock on upper divertor, two inner cryo-pumps and RMP coils, enabling EAST to investigate long pulse H mode operation with dominant electron heating and low torque to address the critical issues for ITER. H-mode plasmas were achieved by new H&CD system or 4.6GHz LHCD alone for the first time. Long pulse high performance H mode has been obtained by LHCD alone up to 28s at H{sub 98}∼1.2 or by combing of ICRH and LHCD, no or small ELM was found in RF plasmas, which is essential for steady state operation in the future Tokamak. Plasma operation in low collision regimes were implemented by new 4.6GHz LHCD with core Te∼4.5keV. The non-inductive scenarios with high performance at high bootstrap current fraction have been demonstrated in RF dominated regimes for long pulse operation. Near full non-inductive CD discharges have been achieved. In addition, effective heating and decoupling method under multi-transmitter for ICRF system were developed in this campaign, etc. EAST could be in operation with over 30MW CW heating and current drive power (LHCD ICRH NBI and ECRH), enhanced diagnostic capabilities and full actively-cooled metal wall from 2015. It will therefore allow to access new confinement regimes and to extend these regimes towards to steady state operation.

Triton burnup measurements in KSTAR using a neutron activation system

Energy Technology Data Exchange (ETDEWEB)

Jo, Jungmin; Shi, Yue-Jiang; Chung, Kyoung-Jae, E-mail: jkjlsh1@snu.ac.k; Hwang, Y. S. [Department of Nuclear Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of); Cheon, MunSeong; Rhee, T.; Kim, Junghee [National Fusion Research Institute, Daejeon 34133 (Korea, Republic of); Kim, Jun Young [Korea University of Science and Technology, Daejeon 34133 (Korea, Republic of); Isobe, M.; Ogawa, K. [National Institute for Fusion Science, Toki-shi (Japan); SOKENDAI (The Graduate University for Advanced Studies), Toki-shi (Japan)

2016-11-15

Measurements of the time-integrated triton burnup for deuterium plasma in Korea Superconducting Tokamak Advanced Research (KSTAR) have been performed following the simultaneous detection of the d-d and d-t neutrons. The d-d neutrons were measured using a {sup 3}He proportional counter, fission chamber, and activated indium sample, whereas the d-t neutrons were detected using activated silicon and copper samples. The triton burnup ratio from KSTAR discharges is found to be in the range 0.01%–0.50% depending on the plasma conditions. The measured burnup ratio is compared with the prompt loss fraction of tritons calculated with the Lorentz orbit code and the classical slowing-down time. The burnup ratio is found to increase as plasma current and classical slowing-down time increase.

A comprehensive study on rotation reversal in KSTAR: experimental observations and modelling

Science.gov (United States)

Na, D. H.; Na, Yong-Su; Angioni, C.; Yang, S. M.; Kwon, J. M.; Jhang, Hogun; Camenen, Y.; Lee, S. G.; Shi, Y. J.; Ko, W. H.; Lee, J. A.; Hahm, T. S.; KSTAR Team

2017-12-01

Dedicated experiments have been performed in KSTAR Ohmic plasmas to investigate the detailed physics of the rotation reversal phenomena. Here we adapt the more general definition of rotation reversal, a large change of the intrinsic toroidal rotation gradient produced by minor changes in the control parameters (Camenen et al 2017 Plasma Phys. Control. Fusion 59 034001), which is commonly observed in KSTAR regardless of the operating conditions. The two main phenomenological features of the rotation reversal are the normalized toroidal rotation gradient ({{u}\\prime} ) change in the gradient region and the existence of an anchor point. For the KSTAR Ohmic plasma database including the experiment results up to the 2016 experimental campaign, both features were investigated. First, the observations show that the locations of the gradient and the anchor point region are dependent on {{q}95} . Second, a strong dependence of {{u}\\prime} on {νeff} is clearly observed in the gradient region, whereas the dependence on R/{{L}{{Ti}}} , R/{{L}{{Te}}} , and R/{{L}{{ne}}} is unclear considering the usual variation of the normalized gradient length in KSTAR. The experimental observations were compared against several theoretical models. The rotation reversal might not occur due to the transition of the dominant turbulence from the trapped electron mode to the ion temperature gradient mode or the neoclassical equilibrium effect in KSTAR. Instead, it seems that the profile shearing effects associated with a finite ballooning tilting well reproduce the experimental observations of both the gradient region and the anchor point; the difference seems to be related to the magnetic shear and the q value. Further analysis implies that the increase of {{u}\\prime} in the gradient region with the increase of the collisionality would occur when the reduction of the momentum diffusivity is comparatively larger than the reduction of the residual stress. It is supported by the perturbative

Numerical Study of Equilibrium, Stability, and Advanced Resistive Wall Mode Feedback Algorithms on KSTAR

Science.gov (United States)

Katsuro-Hopkins, Oksana; Sabbagh, S. A.; Bialek, J. M.; Park, H. K.; Kim, J. Y.; You, K.-I.; Glasser, A. H.; Lao, L. L.

2007-11-01

Stability to ideal MHD kink/ballooning modes and the resistive wall mode (RWM) is investigated for the KSTAR tokamak. Free-boundary equilibria that comply with magnetic field coil current constraints are computed for monotonic and reversed shear safety factor profiles and H-mode tokamak pressure profiles. Advanced tokamak operation at moderate to low plasma internal inductance shows that a factor of two improvement in the plasma beta limit over the no-wall beta limit is possible for toroidal mode number of unity. The KSTAR conducting structure, passive stabilizers, and in-vessel control coils are modeled by the VALEN-3D code and the active RWM stabilization performance of the device is evaluated using both standard and advanced feedback algorithms. Steady-state power and voltage requirements for the system are estimated based on the expected noise on the RWM sensor signals. Using NSTX experimental RWM sensors noise data as input, a reduced VALEN state-space LQG controller is designed to realistically assess KSTAR stabilization system performance.

Fluctuation measurements by Langmuir probes during LHCD on ASDEX tokamak

International Nuclear Information System (INIS)

Stoeckel, J.

1991-01-01

The level of edge electrostatic fluctuations decreases and the global particle/energy confinement improves during lower hybrid current drive (LHCD) regimes on ASDEX, when the total power remains below the initial OH power level. For higher powers, the fluctuations increase noticeably, whereas the global confinement is returning to its OH value. The observed increase of fluctuations is poloidally asymmetric and is caused by local power deposition in front of the grill antenna. (orig.)

Sample design and gamma-ray counting strategy of neutron activation system for triton burnup measurements in KSTAR

Energy Technology Data Exchange (ETDEWEB)

Jo, Jungmin [Department of Energy System Engineering, Seoul National University, Seoul (Korea, Republic of); Cheon, Mun Seong [ITER Korea, National Fusion Research Institute, Daejeon (Korea, Republic of); Chung, Kyoung-Jae, E-mail: jkjlsh1@snu.ac.kr [Department of Energy System Engineering, Seoul National University, Seoul (Korea, Republic of); Hwang, Y.S. [Department of Energy System Engineering, Seoul National University, Seoul (Korea, Republic of)

2016-11-01

Highlights: • Sample design for triton burnup ratio measurement is carried out. • Samples for 14.1 MeV neutron measurements are selected for KSTAR. • Si and Cu are the most suitable materials for d-t neutron measurements. • Appropriate γ-ray counting strategies for each selected sample are established. - Abstract: On the purpose of triton burnup measurements in Korea Superconducting Tokamak Advanced Research (KSTAR) deuterium plasmas, appropriate neutron activation system (NAS) samples for 14.1 MeV d-t neutron measurements have been designed and gamma-ray counting strategy is established. Neutronics calculations are performed with the MCNP5 neutron transport code for the KSTAR neutral beam heated deuterium plasma discharges. Based on those calculations and the assumed d-t neutron yield, the activities induced by d-t neutrons are estimated with the inventory code FISPACT-2007 for candidate sample materials: Si, Cu, Al, Fe, Nb, Co, Ti, and Ni. It is found that Si, Cu, Al, and Fe are suitable for the KSATR NAS in terms of the minimum detectable activity (MDA) calculated based on the standard deviation of blank measurements. Considering background gamma-rays radiated from surrounding structures activated by thermalized fusion neutrons, appropriate gamma-ray counting strategy for each selected sample is established.

75 FR 71064 - Allocation and Designation of Spectrum for Fixed-Satellite Services in the 37.5-38.5 GHz, 40.5-41...

Science.gov (United States)

2010-11-22

... prevent harmful interference from FSS operators to terrestrial microwave and to radioastronomy operations... requirements will adequately protect radioastronomy operations in the 42.5-43.5 GHz band. To allow FSS... ensure the protection of radioastronomy operations in the 42.5-43.5 GHz band from interference from...

Operating characteristics of a new ion source for KSTAR neutral beam injection system.

Science.gov (United States)

Kim, Tae-Seong; Jeong, Seung Ho; Chang, Doo-Hee; Lee, Kwang Won; In, Sang-Ryul

2014-02-01

A new positive ion source for the Korea Superconducting Tokamak Advanced Research neutral beam injection (KSTAR NBI-1) system was designed, fabricated, and assembled in 2011. The characteristics of the arc discharge and beam extraction were investigated using hydrogen and helium gas to find the optimum operating parameters of the arc power, filament voltage, gas pressure, extracting voltage, accelerating voltage, and decelerating voltage at the neutral beam test stand at the Korea Atomic Energy Research Institute in 2012. Based on the optimum operating condition, the new ion source was then conditioned, and performance tests were primarily finished. The accelerator system with enlarged apertures can extract a maximum 65 A ion beam with a beam energy of 100 keV. The arc efficiency and optimum beam perveance, at which the beam divergence is at a minimum, are estimated to be 1.0 A/kW and 2.5 uP, respectively. The beam extraction tests show that the design goal of delivering a 2 MW deuterium neutral beam into the KSTAR Tokamak plasma is achievable.

Variability of GPS Radio Sources at 5 GHz

Indian Academy of Sciences (India)

GPS) radio sources at 5 GHz and find that about one-third of them show considerable Inter-Month Variability (IMV), and these IMV phenomena are likely to be caused by interstellar scintillation (ISS). Furthermore, we find that those showing IMV ...

Integration of 128 channels for monitoring, acquisition and control with existing LHCD DAC system

International Nuclear Information System (INIS)

Joshi, Ramesh; Virani, Chetan; Wadhwani, Archana; Sharma, P.K.

2015-01-01

Lower Hybrid Current Drive (LHCD) data acquisition system needs to be upgraded for additional channel requirement. The existing VME based DAC has been used since long with 32 analog input channels for data monitoring and control. Additional 128 channels require integrating with existing DAC. There are four layers of waveguides which deliver final output power into tokamak. Each layer requires 32 channels for power measurement. For the same requirement 128 analog input channels have been integrated with the help of carrier board and IP modules. Acromag IP330 modules have been procured and finally integrated with additional carrier board with existing VME hardware. Each module provides 32 analog input channels. Device driver has been developed for each module and integrated with existing program. LHCD DAC system has been upgraded with additional 128 channels requirement. It has been successfully testing with recent SST-1 campaign. (author)

The design of the KSTAR tokamak

International Nuclear Information System (INIS)

Lee, G.S.; Kim, J.; Hwang, S.M.

1999-01-01

The Korea superconducting tokamak advanced research (KSTAR) project is the major effort of the Korean national fusion program (KNFP) to develop a steady-state-capable advanced superconducting tokamak to establish a scientific and technological basis for an attractive fusion reactor. Major parameters of the tokamak are: major radius 1.8 m, minor radius 0.5 m, toroidal field 3.5 Tesla, and plasma current 2 MA with a strongly shaped plasma cross-section and double-null divertor. The initial pulse length provided by the poloidal magnet system is 20 s, but the pulse length can be increased to 300 s through non-inductive current drive. The plasma heating and current drive system consists of neutral beam, ion cyclotron waves, lower hybrid waves, and electron-cyclotron waves for flexible profile control. A comprehensive set of diagnostics is planned for plasma control and performance evaluation and physics understanding. The project has completed its conceptual design phase and moved to the engineering design phase. The target date of the first plasma is set for year 2002. (orig.)

Reconfigurable antenna options for 2.45/5 GHz wireless body area networks in healthcare applications.

Science.gov (United States)

Abbas, Syed Muzahir; Ranga, Yogesh; Esselle, Karu P

2015-01-01

This paper presents electronically reconfigurable antenna options in healthcare applications. They are suitable for wireless body area network devices operating in the industrial, scientific, and medical (ISM) band at 2.45 GHz and IEEE 802.11 Wireless Local Area Network (WLAN) band at 5 GHz (5.15-5.35 GHz, 5.25-5.35 GHz). Two types of antennas are investigated: Antenna-I has a full ground plane and Antenna-II has a partial ground plane. The proposed antennas provide ISM operation in one mode while in another mode they support 5 GHz WLAN band. Their performance is assessed for body centric wireless communication using a simplified human body model. Antenna sensitivity to the gap between the antenna and the human body is investigated for both modes of each antenna. The proposed antennas exhibit a wide radiation pattern along the body surface to provide wide coverage and their small width (14 mm) makes them suitable for on-body communication in healthcare applications.

Verification of radiation heat transfer analysis in KSTAR PFC and vacuum vessel during baking

Energy Technology Data Exchange (ETDEWEB)

Yoo, S.Y. [Chungnam National University, 79 Daehak-ro, Yuseong-gu, Daejeon 34167 (Korea, Republic of); Kim, Y.J., E-mail: k43689@nfri.re.kr [National Fusion Research Institute, 169-148 Gwahang-ro, Yuseong-gu, Daejeon 34133 (Korea, Republic of); Kim, S.T.; Jung, N.Y.; Im, D.S.; Gong, J.D.; Lee, J.M.; Park, K.R.; Oh, Y.K. [National Fusion Research Institute, 169-148 Gwahang-ro, Yuseong-gu, Daejeon 34133 (Korea, Republic of)

2016-11-01

Highlights: • Thermal network is used to analyze heat transfer from PFC to VV. • Three heat transfer rate equations are derived based on the thermal network. • The equations is verified using Experimental data and design documents. • Most of the heat lost in tokamak is transferred to experimental room air. • The heat loss to the air is 101 kW of the total heat loss of 154 kW in tokamak. - Abstract: KSTAR PFC (Plasma Facing Component) and VV (Vacuum Vessel) were not arrived at the target temperatures in bake-out phase, which are 300 °C and 110 °C, respectively. The purpose of this study is to find out the reason why they have not been reached the target temperature. A thermal network analysis is used to investigate the radiation heat transfer from PFC to VV, and the thermal network is drawn up based on the actual KSTAR tokamak. The analysis model consists of three equations, and is solved using the EES (Engineering Equation Solver). The heat transfer rates obtained with the analysis model is verified using the experimental data at the KSTAR bake-out phase. The analyzed radiation heat transfer rates from PFC to VV agree quite well with those of experiment throughout the bake-out phase. Heat loss from PFC to experimental room air via flange of VV is also calculated and compared, which is found be the main reason of temperature gap between the target temperature and actually attained temperature of KSTAR PFC.

Verification of radiation heat transfer analysis in KSTAR PFC and vacuum vessel during baking

International Nuclear Information System (INIS)

Yoo, S.Y.; Kim, Y.J.; Kim, S.T.; Jung, N.Y.; Im, D.S.; Gong, J.D.; Lee, J.M.; Park, K.R.; Oh, Y.K.

2016-01-01

Highlights: • Thermal network is used to analyze heat transfer from PFC to VV. • Three heat transfer rate equations are derived based on the thermal network. • The equations is verified using Experimental data and design documents. • Most of the heat lost in tokamak is transferred to experimental room air. • The heat loss to the air is 101 kW of the total heat loss of 154 kW in tokamak. - Abstract: KSTAR PFC (Plasma Facing Component) and VV (Vacuum Vessel) were not arrived at the target temperatures in bake-out phase, which are 300 °C and 110 °C, respectively. The purpose of this study is to find out the reason why they have not been reached the target temperature. A thermal network analysis is used to investigate the radiation heat transfer from PFC to VV, and the thermal network is drawn up based on the actual KSTAR tokamak. The analysis model consists of three equations, and is solved using the EES (Engineering Equation Solver). The heat transfer rates obtained with the analysis model is verified using the experimental data at the KSTAR bake-out phase. The analyzed radiation heat transfer rates from PFC to VV agree quite well with those of experiment throughout the bake-out phase. Heat loss from PFC to experimental room air via flange of VV is also calculated and compared, which is found be the main reason of temperature gap between the target temperature and actually attained temperature of KSTAR PFC.

Prompt loss of beam ions in KSTAR plasmas

Directory of Open Access Journals (Sweden)

Jun Young Kim

2016-10-01

Full Text Available For a toroidal plasma facility to realize fusion energy, researching the transport of fast ions is important not only due to its close relation to the heating and current drive efficiencies but also to determine the heat load on the plasma-facing components. We present a theoretical analysis and orbit simulation for the origin of lost fast-ions during neutral beam injection (NBI heating in Korea Superconducting Tokamak Advanced Research (KSTAR device. We adopted a two-dimensional phase diagram of the toroidal momentum and magnetic moment and describe detectable momentums at the fast-ion loss detector (FILD position as a quadratic line. This simple method was used to model birth ions deposited by NBI and drawn as points in the momentum phase space. A Lorentz orbit code was used to calculate the fast-ion orbits and present the prompt loss characteristics of the KSTAR NBI. The scrape-off layer deposition of fast ions produces a significant prompt loss, and the model and experimental results closely agreed on the pitch-angle range of the NBI prompt loss. Our approach can provide wall load information from the fast ion loss.

Condition monitoring of face milling tool using K-star algorithm and histogram features of vibration signal

Directory of Open Access Journals (Sweden)

C.K. Madhusudana

2016-09-01

Full Text Available This paper deals with the fault diagnosis of the face milling tool based on machine learning approach using histogram features and K-star algorithm technique. Vibration signals of the milling tool under healthy and different fault conditions are acquired during machining of steel alloy 42CrMo4. Histogram features are extracted from the acquired signals. The decision tree is used to select the salient features out of all the extracted features and these selected features are used as an input to the classifier. K-star algorithm is used as a classifier and the output of the model is utilised to study and classify the different conditions of the face milling tool. Based on the experimental results, K-star algorithm is provided a better classification accuracy in the range from 94% to 96% with histogram features and is acceptable for fault diagnosis.

Snake perturbations during pellet injection and LHCD in the HL-1M tokamak

International Nuclear Information System (INIS)

Liu Yi; Qiu Xiaoming; Dong Yunbo; Guo Gangcheng; Xiao Zhengui; Zhong Yunzhe; Zheng Yinjia; Fu Bingzhong; Dong Jiafu; Liu Yong; Wang Enyao

2004-01-01

Excitation of snake perturbations has been observed in the core region of pellet-fuelled HL-1M plasmas when the pellets cross the surface with a q value of 1. It is observed that the snake oscillations have an m = 1, n = 1 helicity with quite a long lifetime. A detailed comparison has been made between the locations of the q = 1 surface and the snake oscillation. Through measurements of the plasma q-profile by means of multi-exposures with a CCD camera during pellet ablation, and investigation of the pellet ablation process, possible mechanisms for the formation of the snake oscillation are discussed. In addition, a large, long-lived snake-like oscillation is frequently observed in lower-hybrid current driven (LHCD) discharge in which the sawtooth has been stabilized early in the discharge. There is evidence that such a perturbation is due to impurity accumulation during sawtooth-stabilization, and good performance with peaking profiles after LHCD is limited by magnetohydrodynamic instabilities including sawtooth and snake activities in HL-1M plasmas

Predictions of the poloidal asymmetries and transport frequencies in KSTAR

Energy Technology Data Exchange (ETDEWEB)

Bae, C., E-mail: cbae@nfri.re.kr; Lee, S. G.; Terzolo, L. [National Fusion Research Institute, Gwahak-ro, Yuseong-gu, Daejeon 305-806 (Korea, Republic of); Stacey, W. M. [Fusion Research Center, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States)

2014-01-15

The extended neoclassical rotation theory formulated in Miller flux surface geometry enables unprecedented neoclassical calculations of the poloidal asymmetries in density, rotation velocities, electrostatic potential along the flux surfaces, and of the inertial (Reynolds stress) and gyroviscous transport frequencies, which are strong functions of these asymmetries. This paper presents such calculations of the poloidal asymmetries and non-negligible inertial and gyroviscous transport frequencies in two KSTAR (Korea Superconducting Tokamak Advanced Research) [Kwon et al., Nucl. Fusion 51, 094006 (2011)] Neutral Beam Injection H-mode discharges. The in-out asymmetries in the velocities are an order of magnitude larger than their up-down asymmetries. The magnitudes of the predicted inertial and gyroviscous transport frequencies depend on the magnitudes of the density and velocity asymmetries. The neoclassically predicted density asymmetries are shown to correspond with the reported measurements in tokamaks and the predicted carbon toroidal velocities agree very well with the measurements in KSTAR.

Versatile controllability of non-axisymmetric magnetic perturbations in KSTAR experiments

Science.gov (United States)

Han, Hyunsun; Jeon, Y. M.; in, Y.; Kim, J.; Yoon, S. W.; Hahn, S. H.; Ahn, H. S.; Woo, M. H.; Park, B. H.; Bak, J. G.; Kstar Team

2015-11-01

A newly upgraded IVCC (In-Vessel Control Coil) system equipped with four broadband power supplies, along with current connection patch panel, will be presented and discussed in terms of its capability on various KSTAR experiments. Until the last run-campaign, there were impressive experimental results on ELM(Edge Localized Mode) control experiments using the 3D magnetic field, but the non-axisymmetric field configuration could not be changed in a shot, let alone the limited number of accessible configurations. Introducing the new power supplies, such restrictions have been greatly reduced. Based on the preliminary commissioning results for 2015 KSTAR run-campaign, this new system has been confirmed to easily cope with various dynamic demands for toroidal and poloidal phases of 3D magnetic field in a shot. This enables us to diagnose the plasma response in more detail and to address the 3-D field impacts on the ELM behaviors better than ever.

Impact of cell load on 5GHz IEEE 802.11 WLAN

OpenAIRE

Abu-Tair, Mamoun; Bhatti, Saleem Noel

2017-01-01

We have conducted an empirical study of the latest 5GHz IEEE 802.11 wireless LAN (WLAN) variants of 802.11n (5GHz) and 802.11ac (Wave 1), under different cell load conditions. We have considered typical configurations of both protocols on a Linux testbed. Under light load,there is no clear difference between 802.11n and 802.11ac in terms of performance and energy consumption. However, in some cases of high cell load, we have found that there may be a small advantage with 802.11ac. Overall, we...

Modelling ion cyclotron emission from KSTAR tokamak and LHD helical device plasmas

Science.gov (United States)

Dendy, Richard; Chapman, Ben; Reman, Bernard; Chapman, Sandra; Akiyama, Tsuyoshi; Yun, Gunsu

2017-10-01

New high quality measurements of ion cyclotron emission (ICE) from KSTAR and LHD greatly extend the scope and diversity of plasma conditions under which ICE is observed. Variables include the origin (fusion reactions or neutral beam injection) and energy (sub- or super-Alfvénic) of the minority energetic ions that drive ICE; the composition of the bulk plasma (hydrogen or deuterium) which supports the modes excited; plasma density in the emitting region, and the timescale on which it changes; and toroidal magnetic field geometry (tokamak or helical device). Future exploitation of ICE as a diagnostic for energetic ion populations in JET D-T plasmas and in ITER rests on quantitative understanding of the physics of the emission. This is tested and extended by current KSTAR and LHD measurements of ICE. We report progress on direct numerical simulation using full orbit ion kinetic codes that solve the Maxwell-Lorentz equations for hundreds of millions of particles. In the saturated regime, these simulations yield excited field spectra that correspond directly to the measured ICE spectra under diverse KSTAR and LHD regimes. At early times, comparison of simulation outputs with linear analytical theory confirms the magnetoacoustic cyclotron instability as the basic driver of ICE. Supported by RCUK Energy Programme Grant EP/P012450/1, NRF Korea Grant 2014M1A7A1A03029881, NIFS budget ULHH029 and Euratom.

The baking analysis for vacuum vessel and plasma facing components of the KSTAR tokamak

International Nuclear Information System (INIS)

Lee, K. H.; Woo, H. K.; Im, K. H.; Cho, S. Y.; Kim, J. B.

2000-01-01

The base pressure of vacuum vessel of the KSTAR (Korea Superconducting Tokamak Advanced Research) Tokamak is to be a ultra high vacuum, 10 -6 ∼10 -7 Pa, to produce clean plasma with low impurity containments. For this purpose, the KSTAR vacuum vessel and plasma facing components need to be baked up to at least 250 .deg. C, 350 .deg. C respectively, within 24 hours by hot nitrogen gas from a separate baking/cooling line system to remove impurities from the plasma-material interaction surfaces before plasma operation. Here by applying the implicit numerical method to the heat balance equations of the system, overall temperature distributions of the KSTAR vacuum vessel and plasma facing components are obtained during the whole baking process. The model for 2-dimensional baking analysis are segmented into 9 imaginary sectors corresponding to each plasma facing component and has up-down symmetry. Under the resulting combined loads including dead weight, baking gas pressure, vacuum pressure and thermal loads, thermal stresses in the vacuum vessel during bakeout are calculated by using the ANSYS code. It is found that the vacuum vessel and its supports are structurally rigid based on the thermal stress analyses

The baking analysis for vacuum vessel and plasma facing components of the KSTAR tokamak

Energy Technology Data Exchange (ETDEWEB)

Lee, K. H.; Woo, H. K. [Chungnam National Univ., Taejon (Korea, Republic of); Im, K. H.; Cho, S. Y. [korea Basic Science Institute, Taejon (Korea, Republic of); Kim, J. B. [Hyundai Heavy Industries Co., Ltd., Ulsan (Korea, Republic of)

2000-07-01

The base pressure of vacuum vessel of the KSTAR (Korea Superconducting Tokamak Advanced Research) Tokamak is to be a ultra high vacuum, 10{sup -6}{approx}10{sup -7}Pa, to produce clean plasma with low impurity containments. For this purpose, the KSTAR vacuum vessel and plasma facing components need to be baked up to at least 250 .deg. C, 350 .deg. C respectively, within 24 hours by hot nitrogen gas from a separate baking/cooling line system to remove impurities from the plasma-material interaction surfaces before plasma operation. Here by applying the implicit numerical method to the heat balance equations of the system, overall temperature distributions of the KSTAR vacuum vessel and plasma facing components are obtained during the whole baking process. The model for 2-dimensional baking analysis are segmented into 9 imaginary sectors corresponding to each plasma facing component and has up-down symmetry. Under the resulting combined loads including dead weight, baking gas pressure, vacuum pressure and thermal loads, thermal stresses in the vacuum vessel during bakeout are calculated by using the ANSYS code. It is found that the vacuum vessel and its supports are structurally rigid based on the thermal stress analyses.

Integration of -70kV, 22A high voltage power supply with solid state crowbar and the LHCD system of SST-1

International Nuclear Information System (INIS)

Rajan Babu, N.; Virani, C.G.; Dalakoti, S.; Sharma, P.K.; Ambulkar, K.K.; Parmar, P.R.; Thakur, A.L.; Dhorajiya, Pragnesh

2015-01-01

LHCD system is a important system for the steady state operation of the SST-1 machine. Four numbers of klystrons of 3.7 GHz are used as a microwave source to produce 2 MW of microwave power. This power is launched into the machine to achieve the steady state operation of the SST-1 Machine. A -70kV, 22A high voltage power supply and a solid-state crowbar are procured and tested and validated for its performance separately. Both of the system are integrated and tested for its integrated performance for the safe and reliable test of the klystron tube. A 10J wire test is conducted for the optimum value of the series resistor. This test will validate the integrated performance of power supply, Crowbar and the interlocking circuit. This paper details the optimization of the ballast resistor from 150 ohms to 40 ohms and its successful integration with the klystron tube for its 500kW CW operation. Some operational experience is also shared

Control of the current density profile with lower hybrid current drive on PBX-M

International Nuclear Information System (INIS)

Bell, R.E.; Bernabei, S.; Chu, T.K.; Gettelfinger, G.; Greenough, N.; Hatcher, R.; Ignat, D.; Jardin, S.; Kaita, R.; Kaye, S.; Kozub, T.; Kugel, H.; LeBlanc, B.; Okabayashi, M.; Paul, S.; Sauthoff, N.; Sesnic, S.; Sun, Y.; Takahashi, H.; Tighe, W.; Valeo, E.; von Goeler, S.; Jones, S.; Kesner, J.; Luckhardt, S.; Paoletti, F.; Levinton, F.; Timini, F.

1993-07-01

Lower hybrid current drive (LHCD) is being explored as a means to control the current density profile on PBX-M with the goal of raising the central safety factor q(O) to values of 1.5-2 to facilitate access to a full-volume second stable regime. Initial experiments have been conducted with up to 400 kW of 4.6 GHz LH power in circular and indented plasmas with modest parameters. A tangential-viewing two-dimensional hard x-ray imaging diagnostic has been used to observe the bremsstrahlung emission from the suprathermal electrons generated during LHCD. Hollow hard x-ray images have indicated off-axis localization of the driven current. A serious obstacle to the control of the current density profile with LHCD is the concomitant generation of MHD activity, which can seriously degrade the confinement of suprathermal electrons. By combining neutral beam injection with LHCD, an MHD-free condition has been obtained where q(O) is raised above 1

A 5-GHz survey of bright southern elliptical and SO galaxies

International Nuclear Information System (INIS)

Disney, M.J.; Wall, J.V.

1977-01-01

The Parkes 64-m telescope has been used in a 5.0 GHz survey of 181 Southern E and SO galaxies from the Reference catalogue of bright galaxies. Of the 39 detections above the nominal limit of 12 mJy, 15 are new, several have radio spectra indicating membership in the active class, and two have shown intensity variations at centimetre wavelengths. The results of this survey combined with results from earlier surveys of lower sensitivity suggest that only about 40 per cent of the E/SO galaxies in the Reference catalogue have Ssub(5GHz)>1 mJy. (author)

Software development of the KSTAR Tokamak Monitoring System

International Nuclear Information System (INIS)

Kim, K.H.; Lee, T.G.; Baek, S.; Lee, S.I.; Chu, Y.; Kim, Y.O.; Kim, J.S.; Park, M.K.; Oh, Y.K.

2008-01-01

The Korea Superconducting Tokamak Advanced Research (KSTAR) project, which is constructing a superconducting Tokamak, was launched in 1996. Much progress in instrumentation and control has been made since then and the construction phase will be finished in August 2007. The Tokamak Monitoring System (TMS) measures the temperatures of the superconducting magnets, bus-lines, and structures and hence monitors the superconducting conditions during the operation of the KSTAR Tokamak. The TMS also measures the strains and displacements on the structures in order to monitor the mechanical safety. There are around 400 temperature sensors, more than 240 strain gauges, 10 displacement gauges and 10 Hall sensors. The TMS utilizes Cernox sensors for low temperature measurement and each sensor has its own characteristic curve. In addition, the TMS needs to perform complex arithmetic operations to convert the measurements into temperatures for each Cernox sensor for this large number of monitoring channels. A special software development effort was required to reduce the temperature conversion time and multi-threading to achieve the higher performance needed to handle the large number of channels. We have developed the TMS with PXI hardware and with EPICS software. We will describe the details of the implementations in this paper

A Compact 5.5 GHz Band-Rejected UWB Antenna Using Complementary Split Ring Resonators

Directory of Open Access Journals (Sweden)

M. M. Islam

2014-01-01

Full Text Available A band-removal property employing microwave frequencies using complementary split ring resonators (CSRRs is applied to design a compact UWB antenna wishing for the rejection of some frequency band, which is meanwhile exercised by the existing wireless applications. The reported antenna comprises optimization of a circular radiating patch, in which slotted complementary SRRs are implanted. It is printed on low dielectric FR4 substrate material fed by a partial ground plane and a microstrip line. Validated results exhibit that the reported antenna shows a wide bandwidth covering from 3.45 to more than 12 GHz, with a compact dimension of 22 × 26 mm2, and VSWR < 2, observing band elimination of 5.5 GHz WLAN band.

Logo Antenna for 5.8 GHz Wireless Communications

DEFF Research Database (Denmark)

Jørgensen, Kasper Lüthje; Jakobsen, Kaj Bjarne

2016-01-01

A logo antenna for the 5.8 GHz ISM band is presented. The idea behind the logo antenna is to use the company or university logo as part of the antenna. When disguised as a logo, it may be more acceptable to place the antenna at optimal locations to obtain good coverage. In the present work...

Electron Heating of LHCD Plasma in HT-7 Tokamak

International Nuclear Information System (INIS)

Ding Yonghua; Wan Baonian; Lin Shiyao; Chen Zhongyong; Hu Xiwei; Shi Yuejiang; Hu Liqun; Kong Wei; Zhang Xiaoqing

2006-01-01

Electron heating via lower hybrid current drive (LHCD) has been investigated in HT-7 superconducting tokamak. Experiments show that the central electron temperature T e0 , the volume averaged electron temperature e > and the peaking factor of the electron temperature Q Te = T e0 / e > increase with the lower hybrid wave (LHW) power. Simultaneously the electron heating efficiency and the electron temperature as the function of the central line-averaged electron density (n e ) and the plasma current (I p ) have also been investigated. The experimental results are in a good agreement with those of the classical collision theory and the LHW power deposition theory

Compact Planar Ultrawideband Antennas with 3.5/5.2/5.8 GHz Triple Band-Notched Characteristics for Internet of Things Applications.

Science.gov (United States)

Dong, Jian; Li, Qianqian; Deng, Lianwen

2017-02-10

Ultrawideband (UWB) antennas, as core devices in high-speed wireless communication, are widely applied to mobile handsets, wireless sensor networks, and Internet of Things (IoT). A compact printed monopole antenna for UWB applications with triple band-notched characteristics is proposed in this paper. The antenna has a very compact size of 10 x 16 mm2 and is composed of a square slotted radiation patch and a narrow rectangular ground plane on the back of the substrate. First, by etching a pair of inverted T-shaped slots at the bottom of the radiation patch, one notched band at 5-6 GHz for rejecting the Wireless Local Area Network (WLAN) is generated. Then, by cutting a comb-shaped slot on the top of the radiation patch, a second notched band for rejecting 3.5 GHz Worldwide Interoperability for Microwave Access (WiMAX) is obtained. Further, by cutting a pair of rectangular slots and a C-shaped slot as well as adding a pair of small square parasitic patches at the center of the radiating patch, two separate notched bands for rejecting 5.2 GHz lower WLAN and 5.8 GHz upper WLAN are realized, respectively. Additionally, by integrating the slotted radiation patch with the narrow rectangular ground plane, an enhanced impedance bandwidth can be achieved, especially at the higher band. The antenna consists of linear symmetrical sections only and is easy for fabrication and fine-tuning. The measured results show that the designed antenna provides a wide impedance bandwidth of 150% from 2.12 to 14.80 GHz for VSWR applications.

Engineering design and fabrication of ICH antenna on KSTAR

Energy Technology Data Exchange (ETDEWEB)

Bae, Y.D.; Hong, B.G.; Hwang, C.K. [Korea Atomic Energy Research Institute, Taejon (Korea)

1999-08-01

Engineering design of 6MW ICH(Ion Cyclotron Heating) system for the plasma heating and current drive in KSTAR (Korea Superconducting Tokamak Advanced Research) tokamak is carried out and a proto-type antenna is domestically fabricated. The proto-type antenna is installed on RF test chamber, and its mutual coupling and vacuum impedance will be measured. Furthermore, high voltage and current behavior under no-plasma load conditions will be studied using 100 kW of 30 MHz RF power. A vacuum feedthrough is designed and fabricated using two ceramic cylinder, which has power rating of 1.5 MW and pulse length of 300 sec. Its RF characteristics will be tested using 100 kW RF transmitter. 19 refs., 46 figs., 8 tabs. (Author)

Thermographic studies of outer target heat fluxes on KSTAR

Directory of Open Access Journals (Sweden)

H.H. Lee

2017-08-01

Full Text Available A new infra-red (IR thermography system with high spatial resolution has been installed on KSTAR and is now mainly applied to measure the outer divertor heat load profile. The first measurement results of the outer divertor heat load profiles between ELMs have been applied to characterize the inter-ELMs outer divertor heat loads in KSTAR H-mode plasmas. In particular, the power decay length (λq of the divertor heat load profile has been determined by fitting the profile to a convolution of an exponential decay and a Gaussian function. The analysis on the power decay length shows a good agreement with the recent multi-machine λq scaling, which predicts λq of the inter-ELMs divertor heat load to be ∼1 mm under the standard H-mode scenario in ITER. The divertor IR thermography system has also successfully measured the strike point splitting of the outer divertor heat flux during the application of resonant magnetic perturbation (RMP fields. In addition, it has provided a clear evidence that the strike point splitting pattern depends on the RMP fields configuration.

Design features of the KSTAR in-vessel control coils

Energy Technology Data Exchange (ETDEWEB)

Kim, H.K. [National Fusion Research Institute (NFRI), 52 Yeoeun-dong, Yusung-ku, Daejeon, 305-333 (Korea, Republic of)], E-mail: hkkim@nfri.re.kr; Yang, H.L.; Kim, G.H.; Kim, Jin-Yong; Jhang, Hogun; Bak, J.S.; Lee, G.S. [National Fusion Research Institute (NFRI), 52 Yeoeun-dong, Yusung-ku, Daejeon, 305-333 (Korea, Republic of)

2009-06-15

In-vessel control coils (IVCCs) are to be used for the fast plasma position control, field error correction (FEC), and resistive wall mode (RWM) stabilization for the Korea Superconducting Tokamak Advanced Research (KSTAR) device. The IVCC system comprises 16 segments to be unified into a single set to achieve following remarkable engineering advantages; (1) enhancement of the coil system reliability with no welding or brazing works inside the vacuum vessel, (2) simplification in fabrication and installation owing to coils being fabricated outside the vacuum vessel and installed after device assembly, and (3) easy repair and maintenance of the coil system. Each segment is designed in 8 turns coil of 32 mm x 15 mm rectangular oxygen free high conductive copper with a 7 mm diameter internal coolant hole. The conductors are enclosed in 2 mm thick Inconel 625 rectangular welded vacuum jacket with epoxy/glass insulation. Structural analyses were implemented to evaluate structural safety against electromagnetic loads acting on the IVCC for the various operation scenarios using finite element analysis. This paper describes the design features and structural analysis results of the KSTAR in-vessel control coils.

Investigation on synergy of IBW and LHCD for integrated high performance operation in HT-7 tokamak

International Nuclear Information System (INIS)

Wan Baonian

2002-01-01

Control of the current density profile has been realized with off-axis current drive by LHW in the HT-7 tokamak predicted by a 2D FP code simulation and supported by measurements of a vertical HX array. IBW is explored to improve performance through heating electrons in the selected region. Strong synergy effect on driven current profile and increased driven efficiency was observed. Electron temperature shows an ITB-like profile with a significantly improved performance. Operation of IBW and LHCD synergetic discharges was optimized through moving the IBW resonant layer to maximize the plasma performance and to avoid the MHD activities. A variety of high performance discharges indicated by β N *H89=1∼ 4 was produced for several tens energy confinement times. This operation mode utilizing synergy effect of IBW and LHCD provide a new way to obtain steady-state operation in advanced tokamak scenario. (author)

Ion cyclotron system design for KSTAR tokamak

International Nuclear Information System (INIS)

Hong, B. G.; Hwang, C. K.; Jeong, S. H.; Yoony, J. S.; Bae, Y. D.; Kwak, J. G.; Ju, M. H.

1998-05-01

The KSTAR (Korean Superconducting Tokamak Advanced Research) tokamak (R=1.8 m, a=0.5 m, k=2, b=3.5T, I=2MA, t=300 s) is being constructed to do long-pulse, high-b, advanced-operating-mode fusion physics experiments. The ion cyclotron (IC) system (in conjunction with an 8-MW neutral beam and a 1.5-MW lower hybrid system) will provide heating and current drive capability for the machine. The IC system will deliver 6 MW of RF power to the plasma in the 25 to 60 MHz frequency range, using a single four-strap antenna mounted in a midplane port. It will be used for ion heating, fast-wave current drive (FWCD), and mode-conversion current drive (MCCD). The phasing between current straps in the antenna will be adjustable quickly during operation to provide the capability of changing the current-drive efficiency. This report describes the design of the IC system hardware: the electrical characteristics of the antenna and the matching system, the requirements on the power sources, and electrical analyses of the launcher. (author). 7 refs., 2 tabs., 40 figs

Ion cyclotron system design for KSTAR tokamak

Energy Technology Data Exchange (ETDEWEB)

Hong, B. G.; Hwang, C. K.; Jeong, S. H.; Yoony, J. S.; Bae, Y. D.; Kwak, J. G.; Ju, M. H

1998-05-01

The KSTAR (Korean Superconducting Tokamak Advanced Research) tokamak (R=1.8 m, a=0.5 m, k=2, b=3.5T, I=2MA, t=300 s) is being constructed to do long-pulse, high-b, advanced-operating-mode fusion physics experiments. The ion cyclotron (IC) system (in conjunction with an 8-MW neutral beam and a 1.5-MW lower hybrid system) will provide heating and current drive capability for the machine. The IC system will deliver 6 MW of RF power to the plasma in the 25 to 60 MHz frequency range, using a single four-strap antenna mounted in a midplane port. It will be used for ion heating, fast-wave current drive (FWCD), and mode-conversion current drive (MCCD). The phasing between current straps in the antenna will be adjustable quickly during operation to provide the capability of changing the current-drive efficiency. This report describes the design of the IC system hardware: the electrical characteristics of the antenna and the matching system, the requirements on the power sources, and electrical analyses of the launcher. (author). 7 refs., 2 tabs., 40 figs.

Preliminary test results on tungsten tile with castellation structures in KSTAR

NARCIS (Netherlands)

Hong, S. H.; Bang, E. N.; Lim, S. T.; Lee, J. Y.; Yang, S. J.; Litnovsky, A.; Hellwig, M.; Matveev, D.; Komm, M.; van den Berg, M. A.; Lho, T.; Park, C. R.; Kim, G. H.

2014-01-01

A bulk tungsten tile with conventional and shaped castellation structures was exposed to various plasmas in KSTAR during 2012 campaign, in order to verify the functions of the shaped castellation designed for ITER divertor. The thermal response of the tile during the campaign was measured by

First Trial of Real-time Poloidal Beta Control in KSTAR

Science.gov (United States)

Han, Hyunsun; Hahn, S. H.; Bak, J. G.; Walker, M. L.; Woo, M. H.; Kim, J. S.; Kim, Y. J.; Bae, Y. S.; KSTAR Team

2014-10-01

Sustaining the plasma in a stable and a high performance condition is one of the important control issues for future steady state tokamaks. In the 2014 KSTAR campaign, we have developed a real-time poloidal beta (βp) control technique and carried out preliminary experiments to identify its feasibility. In the control system, the βp is calculated in real time using the measured diamagnetic loop signal (DLM03) with coil pickup corrections, and compared with the target value leading to the change of the neutral beam (NB) heating power using a feedback PID control algorithm. To match the required power of NB which is operated with constant voltage, the duty cycles of the modulation were adjusted as the ratio of the required power to the maximum achievable one. This paper will present the overall procedures of the βp control, the βp estimation process implemented in the plasma control system, and the analysis on the preliminary experimental results. This work is supported by the KSTAR research project funded by the Ministry of Science, ICT & Future Planning of Korea.

The baking analysis for vacuum vessel and plasma facing components of the KSTAR tokamak

Energy Technology Data Exchange (ETDEWEB)

Lee, K.H. [Chungnam National University Graduate School, Taejeon (Korea); Im, K.H.; Cho, S.Y. [Korea Basic Science Institute, Taejeon (Korea); Kim, J.B. [Hyundai Heavy Industries Co., Ltd. (Korea); Woo, H.K. [Chungnam National University, Taejeon (Korea)

2000-11-01

The base pressure of vacuum vessel of the KSTAR (Korea Superconducting Tokamak Advanced Research) Tokamak is to be a ultra high vacuum, 10{sup -6} {approx} 10{sup -7} Pa, to produce clean plasma with low impurity containments. for this purpose, the KSTAR vacuum vessel and plasma facing components need to be baked up to at least 250 deg.C, 350 deg.C respectively, within 24 hours by hot nitrogen gas from a separate baking/cooling line system to remove impurities from the plasma-material interaction surfaces before plasma operation. Here by applying the implicit numerical method to the heat balance equations of the system, overall temperature distributions of the KSTAR vacuum vessel and plasma facing components are obtained during the whole baking process. The model for 2-dimensional baking analysis are segmented into 9 imaginary sectors corresponding to each plasma facing component and has up-down symmetry. Under the resulting combined loads including dead weight, baking gas pressure, vacuum pressure and thermal loads, thermal stresses in the vacuum vessel during bakeout are calculated by using the ANSYS code. It is found that the vacuum vessel and its supports are structurally rigid based on the thermal stress analyses. (author). 9 refs., 11 figs., 1 tab.

Compact Planar Ultrawideband Antennas with 3.5/5.2/5.8 GHz Triple Band-Notched Characteristics for Internet of Things Applications

Directory of Open Access Journals (Sweden)

Jian Dong

2017-02-01

Full Text Available Ultrawideband (UWB antennas, as core devices in high-speed wireless communication, are widely applied to mobile handsets, wireless sensor networks, and Internet of Things (IoT. A compact printed monopole antenna for UWB applications with triple band-notched characteristics is proposed in this paper. The antenna has a very compact size of 10 x 16 mm2 and is composed of a square slotted radiation patch and a narrow rectangular ground plane on the back of the substrate. First, by etching a pair of inverted T-shaped slots at the bottom of the radiation patch, one notched band at 5-6 GHz for rejecting the Wireless Local Area Network (WLAN is generated. Then, by cutting a comb-shaped slot on the top of the radiation patch, a second notched band for rejecting 3.5 GHz Worldwide Interoperability for Microwave Access (WiMAX is obtained. Further, by cutting a pair of rectangular slots and a C-shaped slot as well as adding a pair of small square parasitic patches at the center of the radiating patch, two separate notched bands for rejecting 5.2 GHz lower WLAN and 5.8 GHz upper WLAN are realized, respectively. Additionally, by integrating the slotted radiation patch with the narrow rectangular ground plane, an enhanced impedance bandwidth can be achieved, especially at the higher band. The antenna consists of linear symmetrical sections only and is easy for fabrication and fine-tuning. The measured results show that the designed antenna provides a wide impedance bandwidth of 150% from 2.12 to 14.80 GHz for VSWR < 2, except for three notched bands of 3.36–4.16, 4.92–5.36, and 5.68–6.0 GHz. Additionally, the antenna exhibits nearly omnidirectional radiation characteristics, low gain at the stopbands, and flat group delay over the whole UWB except at the stopbands. Simulated and experimental results show that the proposed antenna can provide good frequency-domain and time-domain performances at desired UWB frequencies and be an attractive candidate for

Development of KSTAR Neutral Beam Heating System

Energy Technology Data Exchange (ETDEWEB)

Oh, B. H.; Song, W. S.; Yoon, B. J. (and others)

2007-10-15

The prototype components of a neutral beam injection (NBI) system have been developed for the KSTAR, and a capability of the manufactured components has been tested. High power ion source, acceleration power supply, other ion source power supplies, neutralizer, bending magnet for ion beam separation, calorimeter, and cryo-sorption pump have been developed by using the domestic technologies and tested for a neutral beam injection of 8 MW per beamline with a pulse duration of 300 seconds. The developed components have been continuously upgraded to achieve the design requirements. The development technology of high power and long pulse neutral beam injection system has been proved with the achievement of 5.2 MW output for a short pulse length and 1.6 MW output for a pulse length of 300 seconds. Using these development technologies, the domestic NB technology has been stabilized under the development of high power ion source, NB beamline components, high voltage and current power supplies, NB diagnostics, NB system operation and control.

Examination of a duo-collection optics design for the Korea superconducting tokamak advanced research (KSTAR) Thomson scattering system

International Nuclear Information System (INIS)

Oh, Seungtae; Lee, Jong Ha

2011-01-01

The comparison of collective optic designs is described for the Thomson scattering system of the Korea superconducting tokamak advanced research (KSTAR) device. The optical systems collecting the light emission induced through the interaction between the plasma electrons and a laser beam are the key components for the Thomson scattering system. In the first conceptual design of the collection optics for the KSTAR Thomson scattering system, a duo-lens system covering individually the core and the edge regions of the KSTAR plasma with two optical lens modules was proposed. In optical designs, the number of optical modules is a great concern in the case of limited system space. Here, the duo-lens system is evaluated through a comparison with a uni-lens system covering the whole region of the plasma with a single optical module. The duo-lens system turned out to have 2.0 times and 4.73 times higher light collections of the plasma core and edge compared with the uni-lens system

Dual Band a-Si:H Solar-Slot Antenna for 2.4/5.2GHz WLAN Applications

Directory of Open Access Journals (Sweden)

S. V. Shynu

2009-12-01

Full Text Available A simple and compact design of solar-slot antenna for dual band 2.4/5.2GHz wireless local area networks (WLAN applications is proposed. The design employs amorphous silicon (a-Si:H solar cells in polyimide substrate with an embedded twin strip slot structure to generate dual resonant frequencies. A T-shaped microstripline feed is used to excite the twin slot in the a-Si:H solar cell. The measured impedance bandwidths for the proposed solar antenna are 25.9% (642 MHz centered at 2.482 GHz and 8.2% (420 MHz centered at 5.098 GHz. The measured gain at 2.4 and 5.2 GHz are 3.1 dBi and 2.1 dBi respectively.

Indoor Corridor Wideband Radio Propagation Measurements and Channel Models for 5G Millimeter Wave Wireless Communications at 19 GHz, 28 GHz, and 38 GHz Bands

Directory of Open Access Journals (Sweden)

Ahmed M. Al-samman

2018-01-01

Full Text Available This paper presents millimeter wave (mmWave measurements in an indoor environment. The high demands for the future applications in the 5G system require more capacity. In the microwave band below 6 GHz, most of the available bands are occupied; hence, the microwave band above 6 GHz and mmWave band can be used for the 5G system to cover the bandwidth required for all 5G applications. In this paper, the propagation characteristics at three different bands above 6 GHz (19, 28, and 38 GHz are investigated in an indoor corridor environment for line of sight (LOS and non-LOS (NLOS scenarios. Five different path loss models are studied for this environment, namely, close-in (CI free space path loss, floating-intercept (FI, frequency attenuation (FA path loss, alpha-beta-gamma (ABG, and close-in free space reference distance with frequency weighting (CIF models. Important statistical properties, such as power delay profile (PDP, root mean square (RMS delay spread, and azimuth angle spread, are obtained and compared for different bands. The results for the path loss model found that the path loss exponent (PLE and line slope values for all models are less than the free space path loss exponent of 2. The RMS delay spread for all bands is low for the LOS scenario, and only the directed path is contributed in some spatial locations. For the NLOS scenario, the angle of arrival (AOA is extensively investigated, and the results indicated that the channel propagation for 5G using high directional antenna should be used in the beamforming technique to receive the signal and collect all multipath components from different angles in a particular mobile location.

A low power 3-5 GHz CMOS UWB receiver front-end

International Nuclear Information System (INIS)

Li Weinan; Huang Yumei; Hong Zhiliang

2009-01-01

A novel low power RF receiver front-end for 3-5 GHz UWB is presented. Designed in the 0.13 μm CMOS process, the direct conversion receiver features a wideband balun-coupled noise cancelling transconductance input stage, followed by quadrature passive mixers and transimpedance loading amplifiers. Measurement results show that the receiver achieves an input return loss below -8.5 dB across the 3.1-4.7 GHz frequency range, maximum voltage conversion gain of 27 dB, minimum noise figure of 4 dB, IIP3 of -11.5 dBm, and IIP2 of 33 dBm. Working under 1.2 V supply voltage, the receiver consumes total current of 18 mA including 10 mA by on-chip quadrature LO signal generation and buffer circuits. The chip area with pads is 1.1 x 1.5 mm 2 .

Features and applications of RMP in KSTAR

International Nuclear Information System (INIS)

Jeon, Youngmu

2014-01-01

Recent RMP ELM experiments in KSTAR have successfully demonstrated that ELMs can be controlled and avoided by utilizing low n RMPs, where n is a toroidal mode number being 1 or 2. Unlike DIII-D, it is shown that the effect of RMPs on particle and thermal confinement is directly related to the state of ELMs, otherwise it is proportional to applied field strength. Most importantly, it is observed that the global particle and thermal confinement are improved significantly by suppressing ELMs, so that the typical large degradation of confinement in ELM control by using RMPs can be minimized. (author)

Logo Antenna for 5.8 GHz Wireless Communications (invited)

DEFF Research Database (Denmark)

Jørgensen, Kasper Lüthje; Jakobsen, Kaj Bjarne

2016-01-01

A logo antenna for the 5.8 GHz ISM band is presented. The idea behind the logo antenna is to use the company or university logo as part of the antenna. When disguised as a logo, it may be more acceptable to place the antenna at optimal locations to obtain good coverage. In the present work...

24-71 GHz PCB Array for 5G ISM

Science.gov (United States)

Novak, Markus H.; Volakis, John L.; Miranda, Felix A.

2017-01-01

Millimeter-wave 5G mobile architectures need to consolidate disparate frequency bands into a single, multifunctional array. Existing arrays are either narrow-band, prohibitively expensive or cannot be scaled to these frequencies. In this paper, we present the first ultra-wideband millimeter wave array to operate across six 5G and ISM bands spanning 24-71 GHz. Importantly, the array is realized using low-cost PCB. The paper presents the design and optimized layout, and discusses fabrication and measurements.

Conceptual design and implementation of Pulse Automation and Scheduling System for KSTAR

International Nuclear Information System (INIS)

Lee, Woongryol; Lee, Taegu; Park, Jinseop; Hong, Jaesic; Hahn, Sanghee; Han, Hyunsun; Woo, Minho; Park, Kaprai

2015-01-01

Highlights: • The world clock based automatic sequential operation manipulator. • Configuration of the Pulse Automation System (PAS) and the Pulse Scheduling System (PSS) • Providing of operational information in voice through an Ethernet interface. • A perceptional operation status, easy time manipulator, and intuitive man machine interface for the purpose of the Tokamak operation. • Generation of the plasma disruption information. - Abstract: The world clock based automatic sequential operation manipulator has been developed and begin to work on the 7th campaign in KSTAR Tokamak. The Pulse Automation and Scheduling System (PASS) divided into Pulse Automation System (PAS) and Pulse Scheduling System (PSS). The PAS is on the online control system and it has communicated with many other local control systems. Before PASS, the plasma experiment was performed manually by using Central Control System (CCS). However the PASS currently manipulates the sequential operation of KSTAR with the programmed shot interval time. It provides readiness check routine, shot time handler, and local system monitoring functions. The PASS has no hardware dependency and it was configured with EPICS extensions. The Real Time Monitoring System, PCS-GATE, Automatic Reporting System, Central Control System, and Timing Synchronization System are well organized and they communicate to each other. The PASS provides perceptual operation status, easy time manipulator, and intuitive man machine interface. The plasma disruption information which is used in the KSTAR standard software framework also comes from the PASS. We describe the functions and system architecture of the Pulse Automation System in this paper. The PSS will be specified inside PASS for the purpose of intelligent system parameterization.

Conceptual design and implementation of Pulse Automation and Scheduling System for KSTAR

Energy Technology Data Exchange (ETDEWEB)

Lee, Woongryol, E-mail: wrlee@nfri.re.kr; Lee, Taegu; Park, Jinseop; Hong, Jaesic; Hahn, Sanghee; Han, Hyunsun; Woo, Minho; Park, Kaprai

2015-10-15

Highlights: • The world clock based automatic sequential operation manipulator. • Configuration of the Pulse Automation System (PAS) and the Pulse Scheduling System (PSS) • Providing of operational information in voice through an Ethernet interface. • A perceptional operation status, easy time manipulator, and intuitive man machine interface for the purpose of the Tokamak operation. • Generation of the plasma disruption information. - Abstract: The world clock based automatic sequential operation manipulator has been developed and begin to work on the 7th campaign in KSTAR Tokamak. The Pulse Automation and Scheduling System (PASS) divided into Pulse Automation System (PAS) and Pulse Scheduling System (PSS). The PAS is on the online control system and it has communicated with many other local control systems. Before PASS, the plasma experiment was performed manually by using Central Control System (CCS). However the PASS currently manipulates the sequential operation of KSTAR with the programmed shot interval time. It provides readiness check routine, shot time handler, and local system monitoring functions. The PASS has no hardware dependency and it was configured with EPICS extensions. The Real Time Monitoring System, PCS-GATE, Automatic Reporting System, Central Control System, and Timing Synchronization System are well organized and they communicate to each other. The PASS provides perceptual operation status, easy time manipulator, and intuitive man machine interface. The plasma disruption information which is used in the KSTAR standard software framework also comes from the PASS. We describe the functions and system architecture of the Pulse Automation System in this paper. The PSS will be specified inside PASS for the purpose of intelligent system parameterization.

5-GHz passively mode-locked quantum dot ring laser diode at 1.5 μm

NARCIS (Netherlands)

Heck, M.J.R.; Renault, A.; Bente, E.A.J.M.; Oei, Y.S.; Smit, M.K.; Eikema, K.S.E.; Ubachs, W.; Anantathanasarn, S.; Nötzel, R.

2008-01-01

In this paper we present the first observation of passive mode-locking in a quantum dot (QD) ring laser operating at wavelengths around 1.5 µm. The device consists of an 18-mm long (electrically pumped) ring cavity, corresponding to a 5-GHz roundtrip frequency. The waveguide width is 2 µm. A

Gyrokinetic simulation study of magnetic island effects on neoclassical physics and micro-instabilities in a realistic KSTAR plasma

Science.gov (United States)

Kwon, Jae-Min; Ku, S.; Choi, M. J.; Chang, C. S.; Hager, R.; Yoon, E. S.; Lee, H. H.; Kim, H. S.

2018-05-01

We perform gyrokinetic simulations to study the effects of a stationary magnetic island on neoclassical flow and micro-instability in a realistic KSTAR plasma condition. Through the simulations, we aim to analyze a recent KSTAR experiment, which was to measure the details of poloidal flow and fluctuation around a stationary (2, 1) magnetic island [M. J. Choi et al., Nucl. Fusion 57, 126058 (2017)]. From the simulations, it is found that the magnetic island can significantly enhance the equilibrium E × B flow. The corresponding flow shearing is strong enough to suppress a substantial portion of ambient micro-instabilities, particularly ∇Te -driven trapped electron modes. This implies that the enhanced E × B flow can sustain a quasi-internal transport barrier for Te in an inner region neighboring the magnetic island. The enhanced E × B flow has a (2, 1) mode structure with a finite phase shift from the mode structure of the magnetic island. It is shown that the flow shear and the fluctuation suppression patterns implied from the simulations are consistent with the observations on the KSTAR experiment.

Measurement of LHCD edge power deposition through modulation techniques on Alcator C-Mod

Energy Technology Data Exchange (ETDEWEB)

Faust, I. C.; Brunner, D.; LaBombard, B.; Parker, R. R.; Baek, S. G.; Chilenksi, M. A.; Hubbard, A.; Hughes, J. W.; Terry, J. L.; Shiraiwa, S.; Walk, J. R.; Wallace, G. M.; Whyte, D. G. [MIT Plasma Science and Fusion Center, Cambridge, MA USA (United States); Edlund, E. [Princeton Plasma Physics Laboratory, Princeton, NJ USA (United States)

2015-12-10

The efficiency of LHCD on Alcator C-Mod drops exponentially with line average density. At reactor relevant densities (> 1 · 1020 [m{sup −3}]) no measurable current is driven. While a number of causes have been suggested, no specific mechanism has been shown to be responsible for the loss of current drive at high density. Fast modulation of the LH power was used to isolate and quantify the LHCD deposition within the plasma. Measurements from these plasmas provide unique evidence for determining a root cause. Modulation of LH power in steady plasmas exhibited no correlated change in the core temperature. A correlated, prompt response in the edge suggests that the loss in efficiency is related to a edge absorption mechanism. This follows previous results which found the generation of n{sub ||}-independent SOL currents. Multiple Langmuir probe array measurements of the conducted heat conclude that the lost power is deposited near the last closed flux surface. The heat flux induced by LH waves onto the outer divertor is calculated. Changes in the neutral pressure, ionization and hard X-ray emission at high density highlight the importance of the active divertor in the loss of efficiency. Results of this study implicate a mechanism which may occur over multiple passes, leading to power absorption near the LCFS.

A 6-9 GHz 5-band CMOS synthesizer for MB-OFDM UWB

International Nuclear Information System (INIS)

Chen Pufeng; Li Zhiqiang; Wang Xiaosong; Zhang Haiying; Ye Tianchun

2010-01-01

An ultra-wideband frequency synthesizer is designed to generate carrier frequencies for 5 bands distributed from 6 to 9 GHz with less than 3 ns switching time. It incorporates two phase-locked loops and one single-sideband (SSB) mixer. A 2-to-1 multiplexer with high linearity is proposed. A modified wideband SSB mixer, quadrature VCO, and layout techniques are also employed. The synthesizer is fabricated in a 0.18 μm CMOS process and operates at 1.5-1.8 V while consuming 40 mA current. The measured phase noise is -128 dBc/Hz at 10 MHz offset, and the sideband rejection is -22 dBc at 7.656 GHz.

A 6-9 GHz 5-band CMOS synthesizer for MB-OFDM UWB

Energy Technology Data Exchange (ETDEWEB)

Chen Pufeng; Li Zhiqiang; Wang Xiaosong; Zhang Haiying; Ye Tianchun, E-mail: chenpufeng@ime.ac.c [Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029 (China)

2010-07-15

An ultra-wideband frequency synthesizer is designed to generate carrier frequencies for 5 bands distributed from 6 to 9 GHz with less than 3 ns switching time. It incorporates two phase-locked loops and one single-sideband (SSB) mixer. A 2-to-1 multiplexer with high linearity is proposed. A modified wideband SSB mixer, quadrature VCO, and layout techniques are also employed. The synthesizer is fabricated in a 0.18 {mu}m CMOS process and operates at 1.5-1.8 V while consuming 40 mA current. The measured phase noise is -128 dBc/Hz at 10 MHz offset, and the sideband rejection is -22 dBc at 7.656 GHz.

Investigation of a novel x-ray tube for the calibration of the x-ray crystal spectrometer in the KSTAR machine

International Nuclear Information System (INIS)

Bak, J.G.; Lee, S.G.

2007-01-01

A novel x-ray tube with a line filament has been developed for the in-situ calibration of the x-ray crystal spectrometer (XCS) in the KSTAR machine. The characteristics of the x-ray tube are investigated from the x-ray images obtained by using a pinhole and a CCD detector. It is found that the image has the width of about 0.1 mm, which is much improved as compared with the previous experimental results. In addition, there is a uniform region around the center of the image within its full length of 13.5 mm. This work may lead to the development of a novel x-ray tube with a line focus, which is required for the calibration of the XCS. Experimental results from the investigation of the x-ray tube are presented and the technical issues in a design of the in-situ calibration system using the x-ray tube for the KSTAR XCS are discussed. (author)

Transport barrier formation by LHCD on TRIAM-1M

International Nuclear Information System (INIS)

Hanada, K.; Iyomasa, A.; Zushi, H.; Hasegawa, M.; Nakamura, K.; Sakamoto, M.; Sato, K.N.; Idei, H.; Kawasaki, S.; Nakashima, H.; Higashijima, A.; Sasaki, K.; Hoshika, H.

2004-01-01

Internal transport barrier (ITB) has been obtained in full lower hybrid current driven (LHCD) plasmas on a superconducting tokamak, TRIMA-1M (R 0.84 m, a x b = 0.12 m x 0.18 m, B T L/R . ITB is terminated by the reduction of current drive efficiency caused by metal impurities accumulation. In some condition, self organized slow sawtooth oscillations (SSSO) of plasma current, density, temperature, and so on with the period comparable to the current diffusion time have been also observed during ITB discharge. The oscillation has the capability of particle exhaust, as the result, it may play an role in the avoidance of the impurity accumulation and the dilution in the future steady state fusion plasma with ITB, as the edge-localized mode in H-mode. (authors)

Design and operation results of nitrogen gas baking system for KSTAR plasma facing components

Energy Technology Data Exchange (ETDEWEB)

Kim, Sang-Tae [National Fusion Research Institute, 113 Gwahang-ro, Yuseong-gu, Daejeon 305-806 (Korea, Republic of); Kim, Young-Jin, E-mail: k43689@nfri.re.kr [National Fusion Research Institute, 113 Gwahang-ro, Yuseong-gu, Daejeon 305-806 (Korea, Republic of); Joung, Nam-Yong; Im, Dong-Seok; Kim, Kang-Pyo; Kim, Kyung-Min; Bang, Eun-Nam; Kim, Yaung-Soo [National Fusion Research Institute, 113 Gwahang-ro, Yuseong-gu, Daejeon 305-806 (Korea, Republic of); Yoo, Seong-Yeon [Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon 305-764 (Korea, Republic of)

2013-11-15

Highlights: • Vacuum pressure in a vacuum vessel arrived at 7.24 × 10{sup −8} mbar. • PFC temperature was reached maximum 250 °C by gas temperature at 300 °C. • PFC inlet gas temperature was changed 5 °C per hour during rising and falling. • PFC gas balancing was made temperature difference among them below 8.3 °C. • System has a pre-cooler and a three-way valve to save operation energy. -- Abstract: A baking system for the Korea Superconducting Tokamak Advanced Research (KSTAR) plasma facing components (PFCs) is designed and operated to achieve vacuum pressure below 5 × 10{sup −7} mbar in vacuum vessel with removing impurities. The purpose of this research is to prevent the fracture of PFC because of thermal stress during baking the PFC, and to accomplish stable operation of the baking system with the minimum life cycle cost. The uniformity of PFC temperature in each sector was investigated, when the supply gas temperature was varied by 5 °C per hour using a heater and the three-way valve at the outlet of a compressor. The alternative of the pipe expansion owing to hot gas and the cage configuration of the three-way valve were also studied. During the fourth campaign of the KSTAR in 2011, nitrogen gas temperature rose up to 300 °C, PFC temperature reached at 250 °C, the temperature difference among PFCs was maintained at below 8.3 °C, and vacuum pressure of up to 7.24 × 10{sup −8} mbar was achieved inside the vacuum vessel.

A 30 GHz 5-TeV Linear Collider

International Nuclear Information System (INIS)

Wilson, Perry B

2003-01-01

We present parameters for a linear collider with a 3 to 5 TeV center-of-mass energy that utilizes conventional rf technology operating at a frequency around 30 GHz. We discuss the scaling laws and assumed limitations that lead to the parameters described and we compare the merits and liabilities of different technological options including rf power source, accelerator structure, and final focus system design. Finally, we outline the components of the collider while specifying the required alignment and construction tolerances

47 CFR 25.250 - Sharing between NGSO MSS Feeder links Earth Stations in the 19.3-19.7 GHz and 29.1-29.5 GHz Bands.

Science.gov (United States)

2010-10-01

... 47 Telecommunication 2 2010-10-01 2010-10-01 false Sharing between NGSO MSS Feeder links Earth Stations in the 19.3-19.7 GHz and 29.1-29.5 GHz Bands. 25.250 Section 25.250 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Technical Standards § 25...

Surveys of radio sources at 5 GHz

International Nuclear Information System (INIS)

Pauliny-Toth, I.I.K.

1977-01-01

A number of surveys have been carried out at a frequency of 5 GHz at the National Radio Astronomy Observatory (NRAO) and at the Max-Planck-Institut fuer Radioastronomy (MPIFR) with the aim of determining the number-flux density relation for the sources detected and also of obtaining their radio spectra and optical identifications. The surveys fall into two categories: first, the strong source (S) surveys which are intended in due course to cover the whole northern sky and to be complete above a flux density of about 0.6 Jy; second, surveys of limited areas of sky down to lower levels of the flux density. (Auth.)

Design of a 5.8 GHz Multi-Modulus Prescaler

OpenAIRE

Myklebust, Vidar

2006-01-01

A 64-modulus prescaler operating at 5.8 GHz has been designed in a 0.18 μm CMOS process. The prescaler uses a four-phase high-speed ÷4 circuit at the input, composed of two identical cascaded ÷2 circuits implemented in pseudo-NMOS. The high-speed divider is followed by a two-bits phase switching stage, which together with the input divider forms a ÷4/5/6/7 circuit. The phase switching stage is mostly implemented in complementary CMOS. After this follows four identical ÷2/3 cells with local fe...

Modeling of lower hybrid current drive (LHCD) and parametric instability (PI) for high performance internal transport barriers (ITBs)

International Nuclear Information System (INIS)

Cesario, R.; Cardinali, A.; Castaldo, C.; Paoletti, F.; Challis, C.; Mailloux, J.; Mazon, D.

2003-01-01

ITBs (internal transport barrier) with high performance in time duration (4 seconds) were produced at Jet in plasma discharges operating at the plasma current of 2,4 MA and toroidal magnetic field of 3,45 T using lower hybrid (LH) radiofrequency power (2,3 MW) for heating and current drive. The first results of the modeling devoted to calculate the LH power deposition and current density profiles for ITB plasmas are presented. The LH power density profile was first calculated considering the nominal LH power n / spectrum launched by the antenna, a substantially centrally deposition is obtained, many passes (> 10) are necessary for producing a significant fraction of the coupled LH power to be absorbed. In a second step some broadening (20%) of the launched n / power spectrum was considered to simulate the effect of a non-linear wave scattering. Most of the LH power is deposited at the first pass, mainly in the outer half of plasma. The simulation gives a moderate amount (60%) of non-inductive current, including 30% of LHCD fraction. The q-profiles from polarization and from MSE (motional Stark effect) at the beginning and during the main heating phase were analysed. Non-linear plasma edge phenomena allow propagation of some LH power with large n / . Such effect should be retained for a realistic LHCD modeling of ITB plasmas. The consequent enhanced off-axis LHCD is consistent with the observed large ITBs and the obtained large region with low magnetic shear. The LH power might provide a powerful tool for controlling the q-profile for ITB at high plasma current, for potential application to the advanced tokamak regimes

Modeling of lower hybrid current drive (LHCD) and parametric instability (PI) for high performance internal transport barriers (ITBs)

Energy Technology Data Exchange (ETDEWEB)

Cesario, R.; Cardinali, A.; Castaldo, C. [Associazione Euratom-ENEA sulla Fusione, Centro Ricerche Frascadi (Italy); Paoletti, F. [PPPL Pinceton (United States); Challis, C.; Mailloux, J. [Euratom-UKAEA fusion association, Culham Science Centre, Abingdon, Oxfordshire, OX (United Kingdom); Mazon, D. [Association Euratom-CEA Cadarache, 13 - Saint-Paul-lez-Durance (France)

2003-07-01

ITBs (internal transport barrier) with high performance in time duration (4 seconds) were produced at Jet in plasma discharges operating at the plasma current of 2,4 MA and toroidal magnetic field of 3,45 T using lower hybrid (LH) radiofrequency power (2,3 MW) for heating and current drive. The first results of the modeling devoted to calculate the LH power deposition and current density profiles for ITB plasmas are presented. The LH power density profile was first calculated considering the nominal LH power n{sub /} spectrum launched by the antenna, a substantially centrally deposition is obtained, many passes (> 10) are necessary for producing a significant fraction of the coupled LH power to be absorbed. In a second step some broadening (20%) of the launched n{sub /} power spectrum was considered to simulate the effect of a non-linear wave scattering. Most of the LH power is deposited at the first pass, mainly in the outer half of plasma. The simulation gives a moderate amount (60%) of non-inductive current, including 30% of LHCD fraction. The q-profiles from polarization and from MSE (motional Stark effect) at the beginning and during the main heating phase were analysed. Non-linear plasma edge phenomena allow propagation of some LH power with large n{sub /}. Such effect should be retained for a realistic LHCD modeling of ITB plasmas. The consequent enhanced off-axis LHCD is consistent with the observed large ITBs and the obtained large region with low magnetic shear. The LH power might provide a powerful tool for controlling the q-profile for ITB at high plasma current, for potential application to the advanced tokamak regimes.

A mechanism for tuning 5 GHz HTS filters

Energy Technology Data Exchange (ETDEWEB)

Ohsaka, M.; Takeuchi, S.; Ono, S.; Lee, J.H.; Saito, A. [Department of Electrical Engineering, Yamagata University, 4-3-16 Johnan, Yonezawa 992-8510 (Japan); Akasegawa, A.; Yamanaka, K.; Kurihara, K. [Fujitsu LTD., 10-1 Wakamiya, Morinosato, Atsugi, Kanagawa 243-0197 (Japan); Ohshima, S. [Department of Electrical Engineering, Yamagata University, 4-3-16 Johnan, Yonezawa 992-8510 (Japan)], E-mail: ohshima@yz.yamagata-u.ac.jp

2008-09-15

We developed a tuning mechanism of HTS filter with a dielectric tuning plate, dielectric trimming rods, and conducting trimming rods. The tuning plate has windows through which the dielectric and conducting trimming rods pass. The tuning plate was designed for a 3-pole filter with 5 GHz center frequency (f{sub c}) and 100 MHz bandwidth (BW) using a 3-dimensional electromagnetic simulator. We were able to shift the f{sub c} to frequencies below 500 MHz using the tuning plate with a dielectric constant of 45. However, the insertion loss (IL) and the pass-band ripple of the filter became more severe and the BW of the filter was narrower after tuning. We tried to improve the filter properties after tuning using the dielectric and conducting trimming rods. We decreased the IL and the pass-band ripple by adjusting the height of the dielectric trimming rods to above the resonators. Also, the BW was improved by using copper (Cu) trimming rods above the spaces between the resonators. The tuning plate and the trimming rods did not affect the IL. So, we simulated 500 MHz tuning without the filter properties deteriorating at f{sub c} = 5 GHz. Also, we experimentally evaluated that the f{sub c} could be shifted to 340 MHz using the dielectric plate, the pass-band ripple could be decreased by ripple trimming using the dielectric rods, and the BW could be increased 31 MHz by BW trimming using the Cu rods.

Pramana – Journal of Physics | Indian Academy of Sciences

Indian Academy of Sciences (India)

A 3.7 GHz system, which is meant for LHCD experiments on ADITYA tokamak, is used for producing ECR discharge. The ECR discharge is produced by setting the appropriate resonance magnetic field of 0.13 T, with hydrogen at a fill pressure of about 5 × 10-5 Torr. The RF powe r, up to 10 kW (of which ∼ 50% is reflected ...

Development of multi-channel high power rectangular RF window for LHCD system employing high temperature vacuum brazing technique

International Nuclear Information System (INIS)

Sharma, P K; Ambulkar, K K; Parmar, P R; Virani, C G; Thakur, A L; Joshi, L M; Nangru, S C

2010-01-01

A 3.7 GHz., 120 kW (pulsed), lower hybrid current drive (LHCD) system is employed to drive non-inductive plasma current in ADITYA tokamak. The rf power is coupled to the plasma through grill antenna and is placed in vacuum environment. A vacuum break between the pressurized transmission line and the grill antenna is achieved with the help of a multi (eight) channel rectangular RF vacuum window. The phasing between adjacent channels of 8-channel window (arranged in two rows) is important for launching lower hybrid waves and each channel should have independent vacuum window so that phase information is retained. The geometrical parameter of the grill antenna, like periodicity (9mm), channel dimensions (cross sectional dimension of 76mm x 7mm), etc. is to be maintained. These design constraint demanded a development of a multi channel rectangular RF vacuum window. To handle rf losses and thermal effects, high temperature vacuum brazing techniques is desired. Based on the above requirements we have successfully developed a multi channel rectangular rf vacuum window employing high temperature vacuum brazing technique. During the development process we could optimize the chemical processing parameters, brazing process parameters, jigs and fixtures for high temperature brazing and leak testing, etc. Finally the window is tested for low power rf performance using VNA. In this paper we would present the development of the said window in detail along with its mechanical, vacuum and rf performances.

Development of multi-channel high power rectangular RF window for LHCD system employing high temperature vacuum brazing technique

Energy Technology Data Exchange (ETDEWEB)

Sharma, P K; Ambulkar, K K; Parmar, P R; Virani, C G; Thakur, A L [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India); Joshi, L M; Nangru, S C, E-mail: pramod@ipr.res.i [Central Electronics Engineering Research Institute, Pilani, Rajasthan 333 031 (India)

2010-02-01

A 3.7 GHz., 120 kW (pulsed), lower hybrid current drive (LHCD) system is employed to drive non-inductive plasma current in ADITYA tokamak. The rf power is coupled to the plasma through grill antenna and is placed in vacuum environment. A vacuum break between the pressurized transmission line and the grill antenna is achieved with the help of a multi (eight) channel rectangular RF vacuum window. The phasing between adjacent channels of 8-channel window (arranged in two rows) is important for launching lower hybrid waves and each channel should have independent vacuum window so that phase information is retained. The geometrical parameter of the grill antenna, like periodicity (9mm), channel dimensions (cross sectional dimension of 76mm x 7mm), etc. is to be maintained. These design constraint demanded a development of a multi channel rectangular RF vacuum window. To handle rf losses and thermal effects, high temperature vacuum brazing techniques is desired. Based on the above requirements we have successfully developed a multi channel rectangular rf vacuum window employing high temperature vacuum brazing technique. During the development process we could optimize the chemical processing parameters, brazing process parameters, jigs and fixtures for high temperature brazing and leak testing, etc. Finally the window is tested for low power rf performance using VNA. In this paper we would present the development of the said window in detail along with its mechanical, vacuum and rf performances.

2D scrape-off layer turbulence measurement using Deuterium beam emission spectroscopy on KSTAR

Science.gov (United States)

Lampert, M.; Zoletnik, S.; Bak, J. G.; Nam, Y. U.; Kstar Team

2018-04-01

Intermittent events in the scrape-off layer (SOL) of magnetically confined plasmas, often called blobs and holes, contribute significantly to the particle and heat loss across the magnetic field lines. In this article, the results of the scrape-off layer and edge turbulence measurements are presented with the two-dimensional Deuterium Beam Emission Spectroscopy system (DBES) at KSTAR (Korea Superconducting Tokamak Advanced Research). The properties of blobs and holes are determined in an L-mode and an H-mode shot with statistical tools and conditional averaging. These results show the capabilities and limitations of the SOL turbulence measurement of a 2D BES system. The results from the BES study were compared with the analysis of probe measurements. It was found that while probes offer a better signal-to-noise ratio and can measure blobs down to 3 mm size, BES can monitor the two-dimensional dynamics of larger events continuously during full discharges, and the measurement is not limited to the SOL on KSTAR.

A 3-5GHz UWB CMOS Receiver with Digital Control Technique

DEFF Research Database (Denmark)

Han, Bo; Liu, Mengmeng; Ge, Ning

2010-01-01

This article presents a CMOS receiver that works for 3-5GHz low band SC-UWB. The receiver contains PLL, Mixer, and VGA. Double down conversion is adopted in the receiver to overcome the orthogonal clock design difficulty; digital assisted RF control method is used to increase the stability...

Design of ITER divertor VUV spectrometer and prototype test at KSTAR tokamak

Science.gov (United States)

Seon, Changrae; Hong, Joohwan; Song, Inwoo; Jang, Juhyeok; Lee, Hyeonyong; An, Younghwa; Kim, Bosung; Jeon, Taemin; Park, Jaesun; Choe, Wonho; Lee, Hyeongon; Pak, Sunil; Cheon, MunSeong; Choi, Jihyeon; Kim, Hyeonseok; Biel, Wolfgang; Bernascolle, Philippe; Barnsley, Robin; O'Mullane, Martin

2017-12-01

Design and development of the ITER divertor VUV spectrometer have been performed from the year 1998, and it is planned to be installed in the year 2027. Currently, the design of the ITER divertor VUV spectrometer is in the phase of detail design. It is optimized for monitoring of chord-integrated VUV signals from divertor plasmas, chosen to contain representative lines emission from the tungsten as the divertor material, and other impurities. Impurity emission from overall divertor plasmas is collimated through the relay optics onto the entrance slit of a VUV spectrometer with working wavelength range of 14.6-32 nm. To validate the design of the ITER divertor VUV spectrometer, two sets of VUV spectrometers have been developed and tested at KSTAR tokamak. One set of spectrometer without the field mirror employs a survey spectrometer with the wavelength ranging from 14.6 nm to 32 nm, and it provides the same optical specification as the spectrometer part of the ITER divertor VUV spectrometer system. The other spectrometer with the wavelength range of 5-25 nm consists of a commercial spectrometer with a concave grating, and the relay mirrors with the same geometry as the relay mirrors of the ITER divertor VUV spectrometer. From test of these prototypes, alignment method using backward laser illumination could be verified. To validate the feasibility of tungsten emission measurement, furthermore, the tungsten powder was injected in KSTAR plasmas, and the preliminary result could be obtained successfully with regard to the evaluation of photon throughput. Contribution to the Topical Issue "Atomic and Molecular Data and their Applications", edited by Gordon W.F. Drake, Jung-Sik Yoon, Daiji Kato, Grzegorz Karwasz.

A Compact UWB Antenna with a Quarter-Wavelength Strip in a Rectangular Slot for 5.5 GHz Band Notch

Directory of Open Access Journals (Sweden)

Pichet Moeikham

2013-01-01

Full Text Available The limitation of the electromagnetic interferences (EMIs caused by UWB radiating sources into WLAN/WiMAX communication systems operating in the frequency band located around 5.5 GHz requires the adoption of appropriate design features. To this purpose, a notch filter integrated into an UWB antenna, which is able to ensure a better electrical insulation between the two mentioned communication systems with respect to that already presented by the authors Moeikham et al. (2011, is proposed in this paper. The proposed filter, consisting in a rectangular slot including a quarter-wavelength strip integrated on the lower inner edge of the UWB radiating patch, is capable of reducing the energy emission in the frequency range between 5.1 and 5.75 GHz resulting in lower EMIs with sensible electronic equipments working in this frequency band. The antenna structure has no need to be tuned after inserting the rectangle slot with a quarter-wavelength strip. The proposed antenna has potential to minimize the EMIs at a frequency range from 5.1 to 5.75 GHz. The radiation patterns are given nearly omnidirectional in plane and likely bidirectional in plane at all frequencies by the proposed antenna. Therefore, this antenna is suitable to apply for various UWB applications.

A 5.2/5.8 GHz Dual Band On-Off Keying Transmitter Design for Bio-Signal Transmission

Science.gov (United States)

Wu, Chang-Hsi; You, Hong-Cheng; Huang, Shun-Zhao

2018-02-01

An architecture of 5.2/5.8-GHz dual-band on-off keying (DBOOK) modulated transmitter is designed in a 0.18-μm CMOS technology. The proposed DBOOK transmitter is used in the biosignal transmission system with high power efficiency and small area. To reduce power consumption and enhance output swing, two pairs of center-tapped transformers are used as both LC tank and source grounding choke for the designed voltage controlled oscillator (VCO). Switching capacitances are used to achieve dual band operations, and a complemented power combiner is used to merge the differential output power of VCO to a single-ended output. Besides, the linearizer circuits are used in the proposed power amplifier with wideband output matching to improve the linearity both at 5.2/5.8-GHz bands. The designed DBOOK transmitter is implemented by dividing it into two chips. One chip implements the dual-band switching VCO and power combiner, and the other chip implements a linear power amplifier including dual-band operation. The first chip drives an output power of 2.2mW with consuming power of 5.13 mW from 1.1 V supply voltage. With the chip size including pad of 0.61 × 0.91 m2, the measured data rate and transmission efficiency attained are 100 Mb/s and 51 pJ/bit, respectively. The second chip, for power enhanced mode, exhibits P1 dB of -9 dBm, IIP3 of 1 dBm, the output power 1 dB compression point of 12.42 dBm, OIP3 of about 21 dBm, maximum output power of 17.02/16.18 dBm, and power added efficiency of 17.13/16.95% for 5.2/ 5.8 GHz. The chip size including pads is 0:693 × 1:084mm2.

Design and analysis of the vacuum vessel supports and limiting structure on EAST 4.6 GHz LHCD system

International Nuclear Information System (INIS)

Li Bo; Wu Jiefeng; Zhu Wenhua; Liu Liang

2013-01-01

Presently, a remote steering antenna is building for 4.6 GHz lower hybrid wave system on EAST, which needs 100 mm movable distance and very strong basis as well as absolutely reliable limiting stroke. For reliable structure strength better than any section bar, this paper presents 3 kinds of different high-strength welding holder and support, which are named as support frame, fixed foundation, limiting stroke. All of them are made of 316L stainless steel. Three types of welding structures are employed designed as frame structure, plug-welding structure and portal strengthened square steel welding component. Result computed by ANSYS shows that structure strengthen of 3 supports is stable and firmly reliable. (authors)

THE 5 GHz ARECIBO SEARCH FOR RADIO FLARES FROM ULTRACOOL DWARFS

Energy Technology Data Exchange (ETDEWEB)

Route, Matthew; Wolszczan, Alexander, E-mail: mroute@astro.psu.edu, E-mail: alex@astro.psu.edu [Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States)

2013-08-10

We present the results of a 4.75 GHz survey of 33 brown dwarfs and one young exoplanetary system for flaring radio emission, conducted with the 305 m Arecibo radio telescope. The goal of this program was to detect and characterize the magnetic fields of objects cooler than spectral type L3.5, the coolest brown dwarf detected prior to our survey. We have also attempted to detect flaring radio emission from the HR 8799 planetary system, guided by theoretical work indicating that hot, massive exoplanets may have strong magnetic fields capable of generating radio emission at GHz frequencies. We have detected and confirmed radio flares from the T6.5 dwarf 2MASS J10475385+2124234. This detection dramatically extends the temperature range over which brown dwarfs appear to be at least sporadic radio-emitters, from 1900 K (L3.5) down to 900 K (T6.5). It also demonstrates that the utility of radio detection as a unique tool to study the magnetic fields of substellar objects extends to the coolest dwarfs, and, plausibly to hot, massive exoplanets. We have also identified a single, 3.6{sigma} flare from the L1 dwarf, 2MASS J1439284+192915. This detection is tentative and requires confirmation by additional monitoring observations.

Characteristic of slide away discharges in the KSTAR tokamak

Energy Technology Data Exchange (ETDEWEB)

Chen, Z.Y., E-mail: zychen@mail.hust.edu.cn [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, College of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan, 430074 (China); National Fusion Research Institute, Daejeon, 305-333 (Korea, Republic of); Kim, W.C.; Yoon, S.W.; England, A.C.; Lee, K.D.; Yoo, J.W.; Oh, Y.K.; Kwak, J.G.; Kwon, M. [National Fusion Research Institute, Daejeon, 305-333 (Korea, Republic of)

2012-11-01

Low density slide away discharges with anomalous Doppler resonance (ADR) effects have been observed in the KSTAR tokamak. When the line averaged electron density was lower than 0.6×10{sup 19} m{sup −3}, the discharges went into the slide-away regime with relaxations in the electron cyclotron emission due to the ADR effects which transferred the runaway electron energy from parallel to perpendicular motion. The suppression of the ADR effects has been achieved by electron cyclotron resonance heating which enhanced the perpendicular energy of electrons and led to an isotropization of the electron distribution function.

Development of novel low-voltage free-electron lasers in the 5-500GHz region

International Nuclear Information System (INIS)

Zhong, Xiehe

2002-01-01

The electromagnetic spectrum from 5GHz to 500GHz is important for many industrial, commercial, and scientific applications. In particular for the 100 - 500GHz region, free electron lasers (FELs) are usually the only viable radiation sources with sizeable output power and as such are an attractive enabling technology for many applications. One major issue for widespread application of free electron lasers is to reduce their cost and size. This is particularly challenging because of the expensive electron accelerator system they employ. To make it significantly more attractive economically for many important applications, the electron energy has to be reduced to below 300keV. In this thesis two novel electron-energy-reduction techniques are investigated for FEL systems operated in the spectrum from 5GHz to 500GHz with the development of a suite of suitable FEL codes. In the microwave to millimetre-wave region, a novel energy reduction technique based on second harmonic waveguide FELs is studied. It is shown that the required electron voltage is approximately half of what is normally required for comparable conventional waveguide FELs. Effect of electron energy spread is studied for second harmonic waveguide FELs both in microwave and millimetre-wave regions. It is shown that strong wiggler field enhances electron hunching thereby increasing the small-signal gain as well as the insusceptibility to electron voltage spread. Saturation behaviour of second harmonic waveguide FELs is also studied because it is important for evaluation of output power. For FEL generation above 300GHz, it is found that second harmonic waveguide FELs need to increase electron energy above 300keV. To this end, a second energy reduction technique is considered based on a novel quasiperiodic wiggler. It is established that by changing the initial phase angle between the two component wigglers, strong radiation can be generated near 1THz with electron energy below 300keV. (author)

VUV spectroscopy in impurity injection experiments at KSTAR using prototype ITER VUV spectrometer

Science.gov (United States)

Seon, C. R.; Hong, J. H.; Song, I.; Jang, J.; Lee, H. Y.; An, Y. H.; Kim, B. S.; Jeon, T. M.; Park, J. S.; Choe, W.; Lee, H. G.; Pak, S.; Cheon, M. S.; Choi, J. H.; Kim, H. S.; Biel, W.; Bernascolle, P.; Barnsley, R.

2017-08-01

The ITER vacuum ultra-violet (VUV) core survey spectrometer has been designed as a 5-channel spectral system so that the high spectral resolving power of 200-500 could be achieved in the wavelength range of 2.4-160 nm. To verify the design of the ITER VUV core survey spectrometer, a two-channel prototype spectrometer was developed. As a subsequent step of the prototype test, the prototype VUV spectrometer has been operated at KSTAR since the 2012 experimental campaign. From impurity injection experiments in the years 2015 and 2016, strong emission lines, such as Kr xxv 15.8 nm, Kr xxvi 17.9 nm, Ne vii 46.5 nm, Ne vi 40.2 nm, and an array of largely unresolved tungsten lines (14-32 nm) could be measured successfully, showing the typical photon number of 1013-1015 photons/cm2 s.

Precise Absolute Astrometry from the VLBA Imaging and Polarimetry Survey at 5 GHz

Science.gov (United States)

Petrov, L.; Taylor, G. B.

2011-01-01

We present accurate positions for 857 sources derived from the astrometric analysis of 16 eleven-hour experiments from the Very Long Baseline Array imaging and polarimetry survey at 5 GHz (VIPS). Among the observed sources, positions of 430 objects were not previously determined at milliarcsecond-level accuracy. For 95% of the sources the uncertainty of their positions ranges from 0.3 to 0.9 mas, with a median value of 0.5 mas. This estimate of accuracy is substantiated by the comparison of positions of 386 sources that were previously observed in astrometric programs simultaneously at 2.3/8.6 GHz. Surprisingly, the ionosphere contribution to group delay was adequately modeled with the use of the total electron content maps derived from GPS observations and only marginally affected estimates of source coordinates.

PRECISE ABSOLUTE ASTROMETRY FROM THE VLBA IMAGING AND POLARIMETRY SURVEY AT 5 GHz

International Nuclear Information System (INIS)

Petrov, L.; Taylor, G. B.

2011-01-01

We present accurate positions for 857 sources derived from the astrometric analysis of 16 eleven-hour experiments from the Very Long Baseline Array imaging and polarimetry survey at 5 GHz (VIPS). Among the observed sources, positions of 430 objects were not previously determined at milliarcsecond-level accuracy. For 95% of the sources the uncertainty of their positions ranges from 0.3 to 0.9 mas, with a median value of 0.5 mas. This estimate of accuracy is substantiated by the comparison of positions of 386 sources that were previously observed in astrometric programs simultaneously at 2.3/8.6 GHz. Surprisingly, the ionosphere contribution to group delay was adequately modeled with the use of the total electron content maps derived from GPS observations and only marginally affected estimates of source coordinates.

Measurement of the ratio of hydrogen to deuterium at the KSTAR 2009 experimental campaign

International Nuclear Information System (INIS)

Kwak, Jong-Gu; Wang, Son Jong; Kim, Sun Ho; Park, Jae Min; Na, Hoon Kyun

2010-01-01

The control of the ratio of hydrogen to the deuterium is one of the very important issues for ion cyclotron range of frequency (ICRF) minority heating as well as the plasma wall interaction in the tokamak. The ratio of hydrogen to deuterium during the tokamak shot was deduced from the emission spectroscopy measurements during the KSTAR 2009 experimental campaign. Graphite tiles were used for the plasma facing components (PFCs) at KSTAR and its surface area exposed to the plasma was about 11 m 2 . The data showed that it remained as high as around 50% during the campaign period because graphite tiles were exposed to the air for about two months and the hydrogen contents at the tiles are not fully pumped out due to the lack of baking on the PFC in the 2009 campaign. The validation of the spectroscopy method was checked by using the Zeeman effects and the ratio of hydrogen to the deuterium is compared with results from the residual gas analysis. During the tokamak shot, the ratio is low below 10% initially and saturated after around 1 s. When there is a hydrogen injection to the vessel via ion cyclotron wall conditioning and the boronization process where the carbone is used, the ratio of the hydrogen to the deuterium is increased by up to 100% and it recovers to around 50% after one day of operation. However it does not decrease below 50% at the end of the experimental campaign. It was found that the full baking on the PFC (with a high temperature and sufficient vacuum pumping) is required for the ratio control which guarantees the efficient ICRF heating at the KSTAR 2010 experimental campaign.

Enabling LTE and WiFi Coexisting in 5 GHz for Efficient Spectrum Utilization

Directory of Open Access Journals (Sweden)

Hongyu Sun

2017-01-01

Full Text Available Due to the increasing mobile traffic demands in cellular network, researchers have proposed the coexistence of LTE and WiFi technologies in 5 GHz unlicensed bands. Therefore, how to efficiently utilize the spectrum in 5 GHz becomes extremely important. To avoid the channel access conflicts, current LTE Unlicensed (LTE-U technology introduces the duty cycle of LTE, while License-Assisted Access (LAA technology introduces Listen-Before-Talk (LBT mechanism. While these two technologies improve the spectrum utilization by using time division access schema, we believe that more efficient spectrum utilization can be achieved by enabling simultaneous transmissions from LTE and WiFi. In this paper, we propose a novel method (i.e., Low Amplitude Stream Injection (LASI method to enable the simultaneous transmissions of WiFi and LTE frames in the same channel and recover the data from the conflicts. To further utilize the LASI method, we introduce the Conflict-Tolerant Channel Allocation (CTCA algorithm to optimize the channel allocation and achieve more efficient spectrum utilization in 5 GHz. Extensive simulation results show that our approach achieves lower latency and higher throughput. Compared with the state-of-the-art LTE-U and LAA technologies, our approach can improve the spectrum efficiency 2.9 times.

Propagation Characteristics in an Underground Shopping Area for 5GHz-band Wireless Access Systems

Science.gov (United States)

Itokawa, Kiyohiko; Kita, Naoki; Sato, Akio; Matsue, Hideaki; Mori, Daisuke; Watanabe, Hironobu

5-GHz band wireless access systems, such as the RLAN (Radio Local Area Network) system of IEEE802.11a, HiperLAN/2, HiSWANa and AWA, are developed and provide transmission rates over 20 Mbps for indoor use. Those 5-GHz access systems are expected to extend service areas from the office to the so-called “hot-spot" in public areas. Underground shopping malls are one of the anticipated service areas for such a nomadic wireless access service. Broadband propagation characteristics are required for radio zone design in an underground mall environment despite previous results obtained by narrow band measurements. This paper presents results of an experimental study on the propagation characteristics for broadband wireless access systems in an underground mall environment. First, broadband propagation path loss is measured and formulated considering human body shadowing. A ray trace simulation is used to clarify the basic propagation mechanism in such a closed environment. Next, a distance dependency of the delay spread during a crowded time period, rush hour, is found to be at most 65 nsec, which is under the permitted maximum value of the present 5-GHz systems. Finally, above propagation characteristics support the result of transmission test carried out by using AWA equipment.

Progress in the RAMI analysis of a conceptual LHCD system for DEMO

Science.gov (United States)

Mirizzi, F.

2014-02-01

Reliability, Availability, Maintainability and Inspectability (RAMI) concepts and techniques, that acquired great importance during the first manned space missions, have been progressively extended to industrial, scientific and consumer equipments to assure them satisfactory performances and lifetimes. In the design of experimental facilities, like tokamaks, mainly aimed at demonstrating validity and feasibility of scientific theories, RAMI analysis has been often left aside. DEMO, the future prototype fusion reactors, will be instead designed for steadily delivering electrical energy to commercial grids, so that the RAMI aspects will assume an absolute relevance since their initial design phases. A preliminary RAMI analysis of the LHCD system for the conceptual EU DEMO reactor is given in the paper.

Progress in the RAMI analysis of a conceptual LHCD system for DEMO

International Nuclear Information System (INIS)

Mirizzi, F.

2014-01-01

Reliability, Availability, Maintainability and Inspectability (RAMI) concepts and techniques, that acquired great importance during the first manned space missions, have been progressively extended to industrial, scientific and consumer equipments to assure them satisfactory performances and lifetimes. In the design of experimental facilities, like tokamaks, mainly aimed at demonstrating validity and feasibility of scientific theories, RAMI analysis has been often left aside. DEMO, the future prototype fusion reactors, will be instead designed for steadily delivering electrical energy to commercial grids, so that the RAMI aspects will assume an absolute relevance since their initial design phases. A preliminary RAMI analysis of the LHCD system for the conceptual EU DEMO reactor is given in the paper

Superconducting ECR ion source: From 24-28 GHz SECRAL to 45 GHz fourth generation ECR

Science.gov (United States)

Zhao, H. W.; Sun, L. T.; Guo, J. W.; Zhang, W. H.; Lu, W.; Wu, W.; Wu, B. M.; Sabbi, G.; Juchno, M.; Hafalia, A.; Ravaioli, E.; Xie, D. Z.

2018-05-01

The development of superconducting ECR source with higher magnetic fields and higher microwave frequency is the most straight forward path to achieve higher beam intensity and higher charge state performance. SECRAL, a superconducting third generation ECR ion source, is designed for 24-28 GHz microwave frequency operation with an innovative magnet configuration of sextupole coils located outside the three solenoids. SECRAL at 24 GHz has already produced a number of record beam intensities, such as 40Ar12+ 1.4 emA, 129Xe26+ 1.1 emA, 129Xe30+ 0.36 emA, and 209Bi31+ 0.68 emA. SECRAL-II, an upgraded version of SECRAL, was built successfully in less than 3 years and has recently been commissioned at full power of a 28 GHz gyrotron and three-frequency heating (28 + 45 + 18 GHz). New record beam intensities for highly charged ion production have been achieved, such as 620 eμA 40Ar16+, 15 eμA 40Ar18+, 146 eμA 86Kr28+, 0.5 eμA 86Kr33+, 53 eμA 129Xe38+, and 17 eμA 129Xe42+. Recent beam test results at SECRAL and SECRAL II have demonstrated that the production of more intense highly charged heavy ion beams needs higher microwave power and higher frequency, as the scaling law predicted. A 45 GHz superconducting ECR ion source FECR (a first fourth generation ECR ion source) is being built at IMP. FECR will be the world's first Nb3Sn superconducting-magnet-based ECR ion source with 6.5 T axial mirror field, 3.5 T sextupole field on the plasma chamber inner wall, and 20 kW at a 45 GHz microwave coupling system. This paper will focus on SECRAL performance studies at 24-28 GHz and technical design of 45 GHz FECR, which demonstrates a technical path for highly charged ion beam production from 24 to 28 GHz SECRAL to 45 GHz FECR.

First tests os a Micro-TCA-Based downconverter electronic for 5GHz higher order modes in third harmonic accelerating cavities at the XFEL

CERN Document Server

Wamsat, T

2014-01-01

converter RTMs (5GHz and 9GHz) and a third RTM with two phase locked loop synthesizers on board for LO generation. Presently the 5GHz and the PLL RTMs are under construction. The first measurements with these cards will be presented.

Dielectric relaxation studies in 5CB nematic liquid crystal at 9 GHz ...

Indian Academy of Sciences (India)

Resonance width, shift in resonance frequency, relaxation time and activation energy of 5CB nematic liquid crystal are measured using microwave cavity technique under the influence of an external magnetic field at 9 GHz and at different temperatures. The dielectric response in liquid crystal at different temperatures and ...

Experiments on a 14.5 GHz ECR source

International Nuclear Information System (INIS)

Hill, C.E.; Langbein, K.

1996-01-01

The 14.5 GHz ECR4 source supplied to CERN in the framework of the Heavy Ion Facility collaboration provided Pb 27+ operational beams to a new custom built linac in 1994. This source, which operates in the pulsed 'afterglow' mode, quickly met its design specification of 80 eμA and now provides currents >100 eμA regularly. Early source tests showed the existence of extremely stable modes of operation. In the search for higher intensities a number of experiments have been performed on plasma gas composition, RF power matching, extraction, beam pulse compression and a biased dynode. The results of these tests will be presented along with further ideas to improve source performance. (author)

Edge electron density profiles and fluctuations measured by two-dimensional beam emission spectroscopy in the KSTAR

Energy Technology Data Exchange (ETDEWEB)

Nam, Y. U., E-mail: yunam@nfri.re.kr; Wi, H. M. [National Fusion Research Institute, Daejeon (Korea, Republic of); Zoletnik, S.; Lampert, M. [Wigner RCP Institute for Particle and Nuclear Physics, Budapest (Hungary); Kovácsik, Ákos [Institute of Nuclear Techniques, Budapest Technical University, Budapest (Hungary)

2014-11-15

Beam emission spectroscopy (BES) system in Korea Superconducting Tokamak Advanced Research (KSTAR) has recently been upgraded. The background intensity was reduced from 30% to 2% by suppressing the stray lights. This allows acquisition of the relative electron density profiles on the plasma edge without background subtraction from the beam power modulation signals. The KSTAR BES system has its spatial resolution of 1 cm, the temporal resolution of 2 MHz, and a total 32 channel (8 radial × 4 poloidal) avalanche photo diode array. Most measurements were done on the plasma edge, r/a ∼ 0.9, with 8 cm radial measurement width that covers the pedestal range. High speed density profile measurements reveal temporal behaviors of fast transient events, such as the precursors of edge localized modes and the transitions between confinement modes. Low background level also allows analysis of the edge density fluctuation patterns with reduced background fluctuations. Propagation of the density structures can be investigated by comparing the phase delays between the spatially distributed channels.

Study on quench detection of the KSTAR CS coil with CDA+MIK compensation of inductive voltages

Energy Technology Data Exchange (ETDEWEB)

An, Seok Chan; Kim, Jin Sub [Yonsei University, Seoul (Korea, Republic of); Chu, Yong [National Fusion Research Institute(NFRI), Daejeon (Korea, Republic of)

2016-03-15

Quench Detection System (QDS) is essential to guarantee the stable operation of the Korea Superconducting Tokamak Advanced Research (KSTAR) Poloidal Field (PF) magnet system because the stored energy in the magnet system is very large. For the fast response, voltage-based QDS has been used. Co-wound voltage sensors and balanced bridge circuits were applied to eliminate the inductive voltages generated during the plasma operation. However, as the inductive voltages are hundreds times higher than the quench detection voltage during the pulse-current operation, Central Difference Averaging (CDA) and MIK, where I and K stand for mutual coupling indexes of different circuits, which is an active cancellation of mutually generated voltages have been suggested and studied. In this paper, the CDA and MIK technique were applied to the KSTAR magnet for PF magnet quench detection. The calculated inductive voltages from the MIK and measured voltages from the CDA circuits were compared to eliminate the inductive voltages at result signals.

Study on quench detection of the KSTAR CS coil with CDA+MIK compensation of inductive voltages

International Nuclear Information System (INIS)

An, Seok Chan; Kim, Jin Sub; Chu, Yong

2016-01-01

Quench Detection System (QDS) is essential to guarantee the stable operation of the Korea Superconducting Tokamak Advanced Research (KSTAR) Poloidal Field (PF) magnet system because the stored energy in the magnet system is very large. For the fast response, voltage-based QDS has been used. Co-wound voltage sensors and balanced bridge circuits were applied to eliminate the inductive voltages generated during the plasma operation. However, as the inductive voltages are hundreds times higher than the quench detection voltage during the pulse-current operation, Central Difference Averaging (CDA) and MIK, where I and K stand for mutual coupling indexes of different circuits, which is an active cancellation of mutually generated voltages have been suggested and studied. In this paper, the CDA and MIK technique were applied to the KSTAR magnet for PF magnet quench detection. The calculated inductive voltages from the MIK and measured voltages from the CDA circuits were compared to eliminate the inductive voltages at result signals

Variability of GPS Radio Sources at 5 GHz Lang Cui , Xiang Liu ...

Indian Academy of Sciences (India)

2010-02-07

Feb 7, 2010 ... Abstract. We carry out flux monitoring on a sample of 169 Gigahertz. Peaked Spectrum (GPS) radio sources at 5 GHz and find that about one- third of them show considerable Inter-Month Variability (IMV), and these. IMV phenomena are likely to be caused by interstellar scintillation (ISS). Furthermore, we ...

Mitigation of current quench by runaway electrons in LHCD discharges in the HT-7 tokamak

International Nuclear Information System (INIS)

Lu, H.W.; Hu, L.Q.; Lin, S.Y.; Zhong, G.Q.

2009-01-01

Production of runaway electrons during a major disruption has been observed in HT-7 Tokamak. The runaway current plateaus, which can carry part of the pre-disruptive current, are observed in lower-hybrid current drive (LHCD) limiter discharges. It is found that the runaway current can mitigate the disruptions effectively. Detailed observations are presented on the runaway electrons generated following disruptions in the HT-7 tokamak with carbon limited discharges. The results indicate that the magnetic oscillations play an important role in the activity of runaway electrons in disruption. (author)

Design and Fabrication of the KSTAR Poloidal Field Coil Structure

International Nuclear Information System (INIS)

Park, H. K.; Choi, C. H.; Sa, J. W.

2005-01-01

The KSTAR magnet system consists of 16 toroidal field(TF) coils. 4 pairs of central solenoid(CS) coils, and 3 pairs of outer poloidal field(PF) coils. The TF coils are encased in a structure to enhance mechanical stability. The CS coil structure is supported on top of the TF coil structure and supplies a vertical compression of 15 MN to prevent lateral movement due to a repulsive force between the CS coils. The PF coil system is vertically symmetry to the machine mid-plane and consists of 6 coils and 80 support structures(i.e, 16 for PF5, 32 for PF6 and 32 fort PF7). All PF coil structures should absorb the thermal contraction difference between TF coil structure and PF coils due to cool down and endure the vertical and radial magnetic forces due to current charging. In order to satisfy these structural requirements. the PF5 coil structure is designed base on hinges and both of PF6 and PF7 coil structures based on flexible plates. The PF coil structures are assembled on the TF coil structure with an individual basement that is welded on the TF coil structure

Performance Comparison Of Triangle Antenna of 60 GHz for 5G Wireless Communication Network

Directory of Open Access Journals (Sweden)

Aishah A.S.

2017-01-01

Full Text Available In this paper microstrip triangle with slot antenna for 5G wireless communication network are proposed. The microstip triangle antenna is design and operating 60 GHz milimeter-wave frequency band and it's suitable for 5G wireless communication. The substrates are chosen in the design, which are RogerRT5880 with copper thickness 0.035 mm to analyze their effect toward milimeter-wave performance on the designed. The designed and analysis is performed by using CST Microwave Studio. The lowest return loss of the antenna is -24.75dB which is triangle with slot and the maximum gain obtained is 6.82 db at the 59.68GHz for this antenna. The antenna is considering the gain, return loss and size, the microstrip antenna can be a suitable candidate for the 5G wireless application for short range high speed communication.

Characteristics of 6.5 GHz ECR ion source for polarized H- ion source

International Nuclear Information System (INIS)

Ikegami, Kiyoshi; Mori, Yoshiharu; Takagi, Akira; Fukumoto, Sadayoshi.

1983-04-01

A 6.5 GHz ECR (electron cyclotron resonance) ion source has been developed for optically pumped polarized H - ion source at KEK. The properties of this ECR ion source such as beam intensities, proton ratios, plasma electron temperatures and beam emittances were measured. (author)

Modification of boundary fluctuations by LHCD in the HT-7 tokamak

International Nuclear Information System (INIS)

Song Mei; Wan Baonian; Xu Guosheng; Ling Bili

2003-01-01

Measurements of boundary fluctuations and fluctuation driven electron fluxes have been performed in ohmic and lower hybrid current drive enhanced confinement plasma using a graphite Langmuir probe array on HT-7 tokamak. The fluctuations are significantly suppressed and the turbulent fluxes are remarkably depressed in the enhanced plasma. We characterized the statistical properties of fluctuations and the particle flux and found a non-Gaussian character in the whole scrape-off layer with minimum deviations from Gaussian in the proximity of the velocity shear layer in ohmic plasma. In the enhanced plasma the deviations in the boundary region are all reduces obviously. The fluctuations and induced electron fluxes show sporadic bursts asymmetric in time and the asymmetry is remarkably weakened in the lower hybrid current driving (LHCD) phase. The results suggest a coupling between the statistical behaviour of fluctuations and the turbulent flow

CONTEMPORANEOUS VLBA 5 GHz OBSERVATIONS OF LARGE AREA TELESCOPE DETECTED BLAZARS

Energy Technology Data Exchange (ETDEWEB)

Linford, J. D.; Taylor, G. B. [Department of Physics and Astronomy, University of New Mexico, MSC07 4220, Albuquerque, NM 87131-0001 (United States); Romani, R. W. [Department of Physics, Stanford University, Stanford, CA 94305 (United States); Helmboldt, J. F. [Naval Research Laboratory, Code 7213, 4555 Overlook Avenue SW, Washington, DC 20375 (United States); Readhead, A. C. S.; Reeves, R.; Richards, J. L. [Astronomy Department, California Institute of Technology, Mail Code 247-17, 1200 East California Boulevard, Pasadena, CA 91125 (United States)

2012-01-10

The radio properties of blazars detected by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope have been observed contemporaneously by the Very Long Baseline Array (VLBA). In total, 232 sources were observed with the VLBA. Ninety sources that were previously observed as part of the VLBA Imaging and Polarimetry Survey (VIPS) have been included in the sample, as well as 142 sources not found in VIPS. This very large, 5 GHz flux-limited sample of active galactic nuclei (AGNs) provides insights into the mechanism that produces strong {gamma}-ray emission. In particular, we see that {gamma}-ray emission is related to strong, uniform magnetic fields in the cores of the host AGN. Included in this sample are non-blazar AGNs such as 3C84, M82, and NGC 6251. For the blazars, the total VLBA radio flux density at 5 GHz correlates strongly with {gamma}-ray flux. The LAT BL Lac objects tend to be similar to the non-LAT BL Lac objects, but the LAT flat-spectrum radio quasars (FSRQs) are significantly different from the non-LAT FSRQs. Strong core polarization is significantly more common among the LAT sources, and core fractional polarization appears to increase during LAT detection.

CONTEMPORANEOUS VLBA 5 GHz OBSERVATIONS OF LARGE AREA TELESCOPE DETECTED BLAZARS

International Nuclear Information System (INIS)

Linford, J. D.; Taylor, G. B.; Romani, R. W.; Helmboldt, J. F.; Readhead, A. C. S.; Reeves, R.; Richards, J. L.

2012-01-01

The radio properties of blazars detected by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope have been observed contemporaneously by the Very Long Baseline Array (VLBA). In total, 232 sources were observed with the VLBA. Ninety sources that were previously observed as part of the VLBA Imaging and Polarimetry Survey (VIPS) have been included in the sample, as well as 142 sources not found in VIPS. This very large, 5 GHz flux-limited sample of active galactic nuclei (AGNs) provides insights into the mechanism that produces strong γ-ray emission. In particular, we see that γ-ray emission is related to strong, uniform magnetic fields in the cores of the host AGN. Included in this sample are non-blazar AGNs such as 3C84, M82, and NGC 6251. For the blazars, the total VLBA radio flux density at 5 GHz correlates strongly with γ-ray flux. The LAT BL Lac objects tend to be similar to the non-LAT BL Lac objects, but the LAT flat-spectrum radio quasars (FSRQs) are significantly different from the non-LAT FSRQs. Strong core polarization is significantly more common among the LAT sources, and core fractional polarization appears to increase during LAT detection.

Contemporaneous VLBA 5 GHz Observations of Large Area Telescope Detected Blazars

Science.gov (United States)

Linford, J. D.; Taylor, G. B.; Romani, R. W.; Helmboldt, J. F.; Readhead, A. C. S.; Reeves, R.; Richards, J. L.

2012-01-01

The radio properties of blazars detected by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope have been observed contemporaneously by the Very Long Baseline Array (VLBA). In total, 232 sources were observed with the VLBA. Ninety sources that were previously observed as part of the VLBA Imaging and Polarimetry Survey (VIPS) have been included in the sample, as well as 142 sources not found in VIPS. This very large, 5 GHz flux-limited sample of active galactic nuclei (AGNs) provides insights into the mechanism that produces strong γ-ray emission. In particular, we see that γ-ray emission is related to strong, uniform magnetic fields in the cores of the host AGN. Included in this sample are non-blazar AGNs such as 3C84, M82, and NGC 6251. For the blazars, the total VLBA radio flux density at 5 GHz correlates strongly with γ-ray flux. The LAT BL Lac objects tend to be similar to the non-LAT BL Lac objects, but the LAT flat-spectrum radio quasars (FSRQs) are significantly different from the non-LAT FSRQs. Strong core polarization is significantly more common among the LAT sources, and core fractional polarization appears to increase during LAT detection.

Recent advancement in research and planning toward high beta steady state operation in KSTAR

International Nuclear Information System (INIS)

Park, Hyeon Keo; Hong, S.; Humphreys, D.

2015-01-01

The goal of Korean Superconducting Tokamak Advanced Research (KSTAR) research is to explore stable improved confinement regimes and technical challenge for superconducting tokamak operation and thus, to establish the basis for predictable high beta steady state tokamak plasma operation. To fulfil the goal, the current KSTAR research program is composed of three elements: 1) Exploration of anticipated engineering and technology for a stable long pulse operation of high beta plasmas including Edge Localized Mode (ELM) control with the low n (=1, 2) Resonant Magnetic Perturbation (RMP) using in-vessel control coils and innovative non-inductive current drives. The achieved long pulse operation up to ∼50s and fully non-inductive current drive will be combined in the future. Study of efficient heat exhaust will be combined with an innovative divertor design/operation. 2) Exploration of the operation boundary through establishment of true stability limits of the harmful MagnetoHydroDynamic (MHD) instabilities and confinement of the tokamak plasmas in KSTAR, making use of the lowest error field and magnetic ripple simultaneously achieved among all tokamaks ever built. The intrinsic machine error field has a long history of research as the source of MHD instabilities and magnetic ripple is known to be a cause of energy loss in the plasma. The achieved high beta discharges at β N ∼4 and stable discharges at q 95 (∼2) will be further improved. 3) Validation of theoretical modeling of MHD instabilities and turbulence toward predictive capability of stable high beta plasmas. In support of these research goals, the state of the art diagnostic systems, such as Electron Cyclotron Emission Imaging (ECEI) system in addition to accurate profile diagnostics, are deployed not only to provide precise 2D/3D information of the MHD instabilities and turbulence but also to challenge unresolved physics problems such as the nature of ELMs, ELM-crash dynamics and the role of the core

Welding distortion control in double walled KSTAR vacuum vessel fabrication

International Nuclear Information System (INIS)

Oh, D. W.; Lee, G. T.; Kim, H. K.; Yang, H. L.; Bak, J. S.

2004-01-01

The KSTAR(Korea Superconducting Tokamak Advanced Research) vacuum vessel is designed to be a double walled structure made of 12mm thick 316LN stainless steel with a D shaped cross-section about 4 m height. Vacuum vessel was pre-fabricated in two parts, 180 degree and 157.5 degree sectors in toroidal direction to meet the transportation purpose. These two parts have to be welded on site with ±2mm allowable fabrication tolerances. 1/3 scaled mock-up model was used to estimate the welding distortion and to ensure the weld quality of vacuum vessel. Gas Tungsten Arc Welding(GTAW), which has been approved by procedure qualification test, was used during mock-up test and vacuum vessel site fabrication. Welding distortion could be managed by allowing for distortion in opposite direction, by applying high restraint using lots of strong backs, by controlling the welding heat input with symmetrical welding sequence. The integrity of the site welding joint was assured by radiographic test, ultrasonic test and leak test with helium detecting method

ASTEROID SIZING BY RADIOGALAXY OCCULTATION AT 5 GHZ

Energy Technology Data Exchange (ETDEWEB)

Lehtinen, K.; Muinonen, K.; Poutanen, M. [Finnish Geospatial Research Institute FGI, Geodeetinrinne 2, FI-02430 Masala (Finland); Bach, U. [Max-Planck-Institut für Radioastronomie, Radioobservatorium Effelsberg, Max-Planck-Str. 28, D-53902 Bad Münstereifel-Effelsberg (Germany); Petrov, L., E-mail: kimmo.lehtinen@nls.fi [Astrogeo Center, Falls Church, VA 22043 (United States)

2016-05-10

Stellar occultations by asteroids observed at visual wavelengths have been an important tool for studying the size and shape of asteroids and for revising the orbital parameters of asteroids. At radio frequencies, a shadow of an asteroid on the Earth is dominated by diffraction effects. Here, we show, for the first time, that a single observation of an occultation of a compact radio source at a frequency of 5 GHz can be used to derive the effective size of the occulting object and to derive the distance between the observer and the center of the occultation path on the Earth. The derived diameter of the occulting object, asteroid (115) Thyra, is 75 ± 6 km. The observed occultation profile shows features that cannot be explained by diffraction of a single asteroid.

Physical Models of Layered Polar Firn Brightness Temperatures from 0.5 to 2 GHz

Science.gov (United States)

Tan, Shurun; Aksoy, Mustafa; Brogioni, Marco; Macelloni, Giovanni; Durand, Michael; Jezek, Kenneth C.; Wang, Tian-Lin; Tsang, Leung; Johnson, Joel T.; Drinkwater, Mark R.;

Wideband Circularly Polarized Printed Ring Slot Antenna for 5 GHz – 6 GHz

Science.gov (United States)

Nasrun Osman, Mohamed; Rahim, Mohamad Helmi A.; Jusoh, Muzammil; Sabapathy, Thennarasan; Rahim, Mohamad Kamal A.; Norlyana Azemi, Saidatul

2018-03-01

This paper presents the design of circularly polarized printed slot antenna operating at 5 – 6 GHz. The proposed antenna consists of L-shaped feedline on the top of structure and circular ring slot positioned at the ground plane underneath the substrate as a radiator. A radial and narrow slot in the ground plane provides coupling between the L-shaped feedline and circular ring slot. The circular polarization is realized by implementing the slits perturbation located diagonally to perturb the current flow on the slot structure. The antenna prototype is fabricated on FR4 substrate. The simulated and measured results are compared and analyzed to demonstrate the performance of the antenna. Good measured of simulated results are obtained at the targeted operating frequency. The simulated -10dB reflection coefficient bandwidths and axial ratio are 750 MHz and 165 MHz, respectively. The investigation on the affect of the important parameters towards the reflection coefficient and axial are also presented. The proposed antenna is highly potential to be used for wireless local area network (WLAN) and wireless power transfer (WPT).

Contactless Investigations of Yeast Cell Cultivation in the 7 GHz and 240 GHz Ranges

International Nuclear Information System (INIS)

Wessel, J; Schmalz, K; Meliani, C; Gastrock, G; Cahill, B P

2013-01-01

Using a microfluidic system based on PTFE tubes, experimental results of contactless and label-free characterization techniques of yeast cell cultivation are presented. The PTFE tube has an inner diameter of 0.5 mm resulting in a sample volume of 2 μ1 for 1 cm sample length. Two approaches (at frequencies around 7 GHz and 240 GHz) are presented and compared in terms of sensitivity and applicability. These frequency bands are particularly interesting to gain information on the permittivity of yeast cells in Glucose solution. Measurements from 240 GHz to 300 GHz were conducted with a continuous wave spectrometer from Toptica. At 7 GHz band, measurements have been performed using a rat-race based characterizing system realized on a printed circuit board. The conducted experiments demonstrate that by selecting the phase as characterization parameter, the presented contactless and label-free techniques are suitable for cell cultivation monitoring in a PTFE pipe based microfluidic system.

Fabrication of the KSTAR toroidal field coil structure

International Nuclear Information System (INIS)

Choi, C.H.; Sa, J.W.; Park, H.K.; Hong, K.H.; Shin, H.; Kim, H.T.; Bak, J.S.; Lee, G.S.; Kwak, J.H.; Moon, H.G.; Yoon, H.H.; Lee, J.W.; Lee, S.K.; Song, J.Y.; Nam, K.M.; Byun, S.E.; Kim, H.C.; Ha, E.T.; Ahn, H.J.; Kim, D.S.; Lee, J.S.; Park, K.H.; Hong, C.D.

2005-01-01

The KSTAR toroidal field (TF) coil structure is under fabrication upon completion of engineering design and prototype construction. The prototype TF coil structure has been fabricated within allowable tolerances. Encasing of the prototype TF coil (TF00) in the prototype structure has been carried out through major processes involving a coil encasing, an enclosing weld, a vacuum pressure impregnation, and an outer surface machining. During the enclosing weld of the TF00 coil structure, we have measured temperatures and stresses on the coil surface. Assembly test had been performed with the TF00 coil structure. We have chosen Type 316LN as material of the TF coil structure. We used the narrow-gap TIG welding method. Doosan Heavy Industries and Construction Company (DHI) will complete the fabrication of the TF coil structure in Feb. 2006. (author)

ICRF experiments and synergy with LHCD on HT-6M tokamak

International Nuclear Information System (INIS)

Li, J.; Yin, F.X.; Wan, B.N.

1997-01-01

The successful ion cyclotron heating (ICRH) experiment with high power density of nearly 1MW/m 3 was carried out in HT-6M tokamak. The good heating efficiency was achieved by using different wall conditioning techniques, such as He GDC, Ti gettering and boronization. With 300kW injected RF power, the ion temperature reach about 750eV and Te increases from 700eV to about 1keV. Synergy effects between lower hybrid current drive (LHCD) and ICRH have some unique features. The current driven efficiency improved in full current drive case from 0.8x10 19 AW -1 M -2 (without ICRH) to 1.75x10 19 AW -1 M -2 (with ICRH). The reason for this high current driven efficiency may because the mode conversion at ion-ion hybrid resonance to an Ion Bernstein Wave (IBW) which is damped on the fast electron. (author)

Resistive wall mode active control physics design for KSTAR

International Nuclear Information System (INIS)

Park, Y. S.; Sabbagh, S. A.; Bialek, J. M.; Berkery, J. W.; Bak, J. G.; Lee, S. G.; Oh, Y. K.

2014-01-01

As KSTAR H-mode operation approaches the region where the resistive wall mode (RWM) can be unstable, an important issue for future long pulse, high beta plasma operation is to evaluate RWM active feedback control performance using a planned active/passive RWM stabilization system on the device. In particular, an optimal design of feedback sensors allows mode stabilization up to the highest achievable β N close to the ideal with-wall limit, β N wall , with reduced control power requirements. The computed ideal n = 1 mode structure from the DCON code has been input to the VALEN-3D code to calculate the projected performance of an active RWM control system in the KSTAR three-dimensional conducting structure device geometry. Control performance with the midplane locked mode detection sensors, off-midplane saddle loops, and magnetic pickup coils is examined. The midplane sensors measuring the radial component of the mode perturbation is found to be strongly affected by the wall eddy current. The off-axis saddle loops with proper compensation of the prompt applied field are computed to provide stabilization at β N up to 86% of β N wall but the low RWM amplitude computed in the off-axis regions near the sensors can produce a low signal-to-noise ratio. The required control power and bandwidth are also estimated with varied noise levels in the feedback sensors. Further improvements have been explored by examining a new RWM sensor design motivated by the off-midplane poloidal magnetic field sensors in NSTX. The new sensors mounted off of the copper passive stabilizer plates near the device midplane show a clear advantage in control performance corresponding to achieving 99% of β N wall without the need of compensation of the prompt field. The result shows a significant improvement of RWM feedback stabilization using the new sensor set which motivates a future feedback sensor upgrade

Design of a Hardware-Implemented Phase Calculating System for Feedback Control in the LHCD Experiments on EAST

International Nuclear Information System (INIS)

Liu Qiang; Liang Hao; Zhou Yongzhao

2009-01-01

A fully hardware-implemented phase calculating system for the feedback control in the lower-hybrid current drive (LHCD) experiments is presented in this paper. By taking advantages of field programmable gate array (FPGA) chips with embedded digital signal processing (DSP) cores and the Matlab-aided design method, the phase calculating algorithm with a square root operation and parallel process are efficiently implemented in a single FPGA chip to complete the calculation of phase differences fast and accurately in the lower-hybrid wave (LHW) system on EAST. (fusion engineering)

5.2 GHz variable-gain amplifier and power amplifier driver for WLAN IEEE 802.11a transmitter front-end

Energy Technology Data Exchange (ETDEWEB)

Zhang Xuelian; Yan Jun; Shi Yin [Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China); Foster, Dai Fa, E-mail: xlzhang@semi.ac.c [Department of Electrical and Computer Engineering, Auburn University, Auburn, AL 36849-5201 (United States)

2009-01-15

A 5.2 GHz variable-gain amplifier (VGA) and a power amplifier (PA) driver are designed for WLAN IEEE 802.11a monolithic RFIC. The VGA and the PA driver are implemented in a 50 GHz 0.35 mum SiGe BiCMOS technology and occupy 1.12 x 1.25 mm{sup 2} die area. The VGA with effective temperature compensation is controlled by 5 bits and has a gain range of 34 dB. The PA driver with tuned loads utilizes a differential input, single-ended output topology, and the tuned loads resonate at 5.2 GHz. The maximum overall gain of the VGA and the PA driver is 29 dB with the output third-order intercept point (OIP3) of 11 dBm. The gain drift over the temperature varying from -30 to 85 deg. C converges within +-3 dB. The total current consumption is 45 mA under a 2.85 V power supply.

Snake perturbations during pellet injection and LHCD in the HL-1M tokamak

International Nuclear Information System (INIS)

Liu Yi; Qiu Xiaoming; Dong Yunbo; Zhong Yunzhe; Fu Bingzhong; Jiafu Dong Yong Liu

2005-01-01

Excitation of snake perturbations has been observed in the core region of pellet-fuelled HL-1M plasmas when the pellets cross surface with q value 1. Through measurements of plasma q profile by means of multi-exposures with CCD camera during pellet ablation, and investigation on pellet ablation process, possible mechanisms for the formation of snake oscillation are discussed. In addition, a large, long-lived snake-like oscillation is frequently observed in lower hybrid current driven discharge in which the sawtooth has been stabilized at early times. There is evidence that such a perturbation is due to impurity accumulation during sawtooth-stabilization, and the good performance with peaking profiles after LHCD is limited by magnetohydrodynamic (MHD) instabilities including sawtooth and snake activities in HL-1M plasma. (author)

Development of 16.5 GHz ECR ion source in KEK

International Nuclear Information System (INIS)

Mori, Yoshiharu; Kinsho, Michikazu; Ikegami, Kiyoshi; Takagi, Akira

1992-01-01

An electron cyclotron resonance (ECR) ion source is useful for generating not only highly charged heavy ions but intense protons. We have developed the 16.5 GHz ECR ion source for the optically pumped polarized ion source (OPPIS). Recently, we have modified it to extract highly charged heavy ions and succeeded in producting highly charged argon ions of which charge-states were from 2 to 8. When we introduced electrons into the plasma with a LaB 6 filament, the argon ion beam whose charge-state up to 11 could be extracted. The intensity was also enhanced in factor 2 to 6 for each charge-state ions. (author)

Progress and improvement of KSTAR plasma control using model-based control simulators

Energy Technology Data Exchange (ETDEWEB)

Hahn, Sang-hee, E-mail: hahn76@nfri.re.kr [National Fusion Research Institute, 169-148 Gwahak-ro, yuseong-gu, Daejeon (Korea, Republic of); Welander, A.S. [General Atomics, San Diego, CA (United States); Yoon, S.W.; Bak, J.G. [National Fusion Research Institute, 169-148 Gwahak-ro, yuseong-gu, Daejeon (Korea, Republic of); Eidietis, N.W. [General Atomics, San Diego, CA (United States); Han, H.S. [National Fusion Research Institute, 169-148 Gwahak-ro, yuseong-gu, Daejeon (Korea, Republic of); Humphreys, D.A.; Hyatt, A. [General Atomics, San Diego, CA (United States); Jeon, Y.M. [National Fusion Research Institute, 169-148 Gwahak-ro, yuseong-gu, Daejeon (Korea, Republic of); Johnson, R.D. [General Atomics, San Diego, CA (United States); Kim, H.S.; Kim, J. [National Fusion Research Institute, 169-148 Gwahak-ro, yuseong-gu, Daejeon (Korea, Republic of); Kolemen, E.; Mueller, D. [Princeton Plasma Physics Laboratory, Princeton, NJ (United States); Penaflor, B.G.; Piglowski, D.A. [General Atomics, San Diego, CA (United States); Shin, G.W. [University of Science and Technology, Daejeon (Korea, Republic of); Walker, M.L. [General Atomics, San Diego, CA (United States); Woo, M.H. [National Fusion Research Institute, 169-148 Gwahak-ro, yuseong-gu, Daejeon (Korea, Republic of)

2014-05-15

Superconducting tokamaks like KSTAR, EAST and ITER need elaborate magnetic controls mainly due to either the demanding experiment schedule or tighter hardware limitations caused by the superconducting coils. In order to reduce the operation runtime requirements, two types of plasma simulators for the KSTAR plasma control system (PCS) have been developed for improving axisymmetric magnetic controls. The first one is an open-loop type, which can reproduce the control done in an old shot by loading the corresponding diagnostics data and PCS setup. The other one, a closed-loop simulator based on a linear nonrigid plasma model, is designed to simulate dynamic responses of the plasma equilibrium and plasma current (I{sub p}) due to changes of the axisymmetric poloidal field (PF) coil currents, poloidal beta, and internal inductance. The closed-loop simulator is the one that actually can test and enable alteration of the feedback control setup for the next shot. The simulators have been used routinely in 2012 plasma campaign, and the experimental performances of the axisymmetric shape control algorithm are enhanced. Quality of the real-time EFIT has been enhanced by utilizations of the open-loop type. Using the closed-loop type, the decoupling scheme of the plasma current control and axisymmetric shape controls are verified through both the simulations and experiments. By combining with the relay feedback tuning algorithm, the improved controls helped to maintain the shape suitable for longer H-mode (10–16 s) with the number of required commissioning shots largely reduced.

Development of a processor embedded timing unit for the synchronized operation in KSTAR

Energy Technology Data Exchange (ETDEWEB)

Lee, Woongryol, E-mail: wrlee@nfri.re.kr; Lee, Taegu; Hong, Jaesic

2016-11-15

Highlights: • Timing board for the synchronized tokamak operation. • Processor embedded distributed control system. • Single clock source and multiple trigger signal for the plasma diagnostics. • Delay compensation among the distributed timing boards. - Abstract: The Local Timing Unit (LTU) in KSTAR provides a single clock source and multiple trigger signals with flexible configuration. Over the past seven years, the LTU had a mechanical redesign and several firmware updates for the purpose of provision of a robust operation and precision timing signal. Now we have developed a third version of a local timing unit which has a standalone operation capability. The LTU is built in a cabinet mountable 1U PIZZA box and provides twelve signal output ports, a packet mirroring interface, and an LCD interface panel. The core functions of the LTU are implemented in a Field Programmable Gate Array (FPGA) which has an internal hardcore processor. The internal processor allows the use of Linux Operating System (OS) and the Experimental Physics and Industrial Control System (EPICS). All user level application functions are controllable through the EPICS, however the time critical internal functions are performed by the FPGA logic blocks same as the previous version. The new LTU provides pluggable output module so that we can easily extend the signal output port. The easy installation and effective replacement reduce the efforts of maintenance. This paper describes design, development, and commissioning results of the new KSTAR LTU.

Development of a processor embedded timing unit for the synchronized operation in KSTAR

International Nuclear Information System (INIS)

Lee, Woongryol; Lee, Taegu; Hong, Jaesic

2016-01-01

Highlights: • Timing board for the synchronized tokamak operation. • Processor embedded distributed control system. • Single clock source and multiple trigger signal for the plasma diagnostics. • Delay compensation among the distributed timing boards. - Abstract: The Local Timing Unit (LTU) in KSTAR provides a single clock source and multiple trigger signals with flexible configuration. Over the past seven years, the LTU had a mechanical redesign and several firmware updates for the purpose of provision of a robust operation and precision timing signal. Now we have developed a third version of a local timing unit which has a standalone operation capability. The LTU is built in a cabinet mountable 1U PIZZA box and provides twelve signal output ports, a packet mirroring interface, and an LCD interface panel. The core functions of the LTU are implemented in a Field Programmable Gate Array (FPGA) which has an internal hardcore processor. The internal processor allows the use of Linux Operating System (OS) and the Experimental Physics and Industrial Control System (EPICS). All user level application functions are controllable through the EPICS, however the time critical internal functions are performed by the FPGA logic blocks same as the previous version. The new LTU provides pluggable output module so that we can easily extend the signal output port. The easy installation and effective replacement reduce the efforts of maintenance. This paper describes design, development, and commissioning results of the new KSTAR LTU.

Statistical analysis of temporal and spatial evolution of in-vessel dust particles in KSTAR

International Nuclear Information System (INIS)

Kim, Kyung-Rae; Hong, Suk-Ho; Nam, Yong-Un; Jung, Jinil; Kim, Woong-Chae

2013-01-01

Images of wide-angle visible standard CCD cameras contain information on in-vessel dusts such as dust creation events (DCEs) that occur during plasma operations, and their velocity. Analyzing the straight line-like dust traces in the shallow cylindrical shell-structured scrape-off layer along the vacuum vessel, a database on the short/long term temporal evolutions, spatial locations of DCEs caused by plasma–dust interaction, and the dust velocity distribution are built. We have studied DCEs of 2010 and 2011 KSTAR campaign

Discharge cleaning on KSTAR 1st plasma events

Energy Technology Data Exchange (ETDEWEB)

Kwak, J. G.; Wang, J. S. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Kim, J. S.; Yang, H. L.; Kim, K. P.; Kim, K. M. [National Fusion Research Institute, Daejeon (Korea, Republic of)

2008-10-15

A discharge cleaning of a vacuum vessel was conducted with a GDC (Glow discharge cleaning) and a ICRF-DC(ICRF assisted discharge cleaning) for the KSTAR first plasma event period. The base pressure of the vessel was kept below 10-7 mbar via a cool down of the cryo-vessel, a 100C baking, and a GDC. (Partial pressure of hydrogen and nitrogen is below 10-8 mbar). The diagnostics for a discharge cleaning is a differential pumped RGA attached to a pumping duct and a cold cathode and a hot cathode gauge attached to the vessel and the pumping duct respectively. To analyze the discharge characteristics, a microwave interferometer, Bremsstahlung, H-alphas and a TV camera were used. Two straps among the four straps of the ICRF antenna are used for the ICRF-DC and ICRF heating experiments. The phase difference between the adjacent straps was 0 degree and the operating frequency was 30-33MHz.

Completed installations and the individual commissioning of the KSTAR MG system

Energy Technology Data Exchange (ETDEWEB)

Kim, Chang-Hwan, E-mail: kch2004@nfri.re.kr [National Fusion Research Institute, 169-148 Gwahangno, Yusung-gu, Daejeon 305-333 (Korea, Republic of); Eom, Dae-young; Lee, Woo-Jin; Kong, Jong-Dea; Joung, Nam-Young; Kim, Yang-Soo; Kwon, Myeun [National Fusion Research Institute, 169-148 Gwahangno, Yusung-gu, Daejeon 305-333 (Korea, Republic of); Jang, Eun; Han, Chul-Woo; Lee, Sel-Ki; Kim, Gwang-Seon; Maeng, Jae-Hoon [Vitzrotech Co., Ltd, 605-2 Seonggok-dong, Danwon-gu, Ansan, Gyeonggi-do 425-833 (Korea, Republic of)

2014-04-15

Highlights: • All components of the MG system were made from each professional supplier and installed completely in the NFRI site. • The building and the overhead crane which need to install the MG system, were built in two sections. One is for the bearing, rotor and stator and the other section is for the VVVF and excitation system. • The dummy coil testing will commence in July 2013 and the comprehensive performance test of MG will be tested from August when the MPS commissioning is processing with superconducting coil. - Abstract: Peak power of 200 MVA is required in order to achieve the goal within a long pulse scenario for the final operation of the Korean Superconducting Tokamak Advanced Research (KSTAR). The available grid power is only 100 MVA at the National Fusion Research Institute (NFRI) site. Motor generator (MG) was considered as a method of resolving such problems. The design of the KSTAR MG system was completed in July 2010 and individual devices were produced by relevant manufacturers. The installation of individual devices was completed in December 2012. Specifically, the stator and rotor were assembled at the site due to their large size and weight. The bearings, variable voltage variable frequency (VVVF) and excitation systems were transported and installed on site after being manufactured externally. The building used for MG installation was built in 2011. With the building designed for ease of installation, an overhead crane was designed to allow access to the loading bay. In this paper, we discuss the installation of the MG system and the construction of the building suitable for installation of individual devices. In addition, performance on the test results of individual devices is also discussed.

The comparison of heat flux pattern on lower divertor in KSTAR

International Nuclear Information System (INIS)

Bang, Eunnam; Hong, Suk-Ho; Bak, JunGyo; Kim, Kyungmin; Kim, Hongtack; Kim, Hakkun; Yang, H.L.

2015-01-01

Highlights: • The heat flux on the lower divertor is higher than upper divertor. • The heat flux on OD is decreased with IVCP. • The heat flux on CD is decreased with RMP, but that on OD is increased. • Because the strike point was shifted from CD toward OD due to the RMP. - Abstract: The heat flux in KSTAR is estimated for various discharge conditions by using thermocouple arrays. The heat flux on the divertor is higher than that on inboard limiter or passive stabilizer by a factor of 2. Although the plasma configuration in KSTAR has been set to a double-null configuration, the heat flux on lower divertor is higher than that on upper divertor by 3–8 times, indicating a lower-single-null-like configuration. It is observed that the operation of the in-vessel cryo-pump (IVCP) changes the heat flux pattern significantly: When the IVCP was not operated, the heat fluxes on inboard divertor (ID), central divertor (CD) and outboard divertor (OD) were similar, but when the IVCP was operated, the heat fluxes on ID and CD were increased slightly and that on OD was decreased by 2–3 times. The heat flux on divertor was decreased from 35 to 26 kW/m"2 with the use of the resonant magnetic perturbation (RMP), especially that on CD was decreased by 2–4 times, while that on OD is increased by 2–3 times than without RMP. For the longest H-mode pulse of 22 s shot, the heat flux on lower OD was 73 kW/m"2, which is the maximum heat flux among the shots obtained in 2013 campaign.

Design of a magnetron injection gun for a 17.5-GHz

International Nuclear Information System (INIS)

Ha, H. J.; Kim, J. E.; Park, G. S.

1996-01-01

A gyrotwystron which is composed of cavities (gyro-klystron) and waveguides (gyro-TWT) is under investigation for broader bandwidth with high efficiency. A magnetron injection gun (MIG) for the gyrotwystron is designed with the trade-off equation for the MIG and optimized by computer simulation using the e-gun code. A 300-kW, 60-kV MIG with α ≡ υ t /υ z = 1.2 and Δυ z ≤ 5% designed for a 17.5-GHz gyrotwystron is discussed in this paper. Also, the effect of various MIG parameters, such as the beam voltage, the beam current, the magnetic field, the cathode radius and angle, and the MIG dimensions, on the characteristics of the beam (α, Δυ z ) is studied. (author)

A 1.5 V 7.656 GHz PLL with I/Q outputs for a UWB synthesizer

International Nuclear Information System (INIS)

Chen Pufeng; Zhang Haiying; Ye Tianchun

2010-01-01

A fully integrated CMOS phase-locked loop (PLL) which can synthesize a quadrature output frequency of 7.656 GHz is presented. The proposed PLL can be employed as a building block for an MB-OFDM UWB frequency synthesizer. To achieve fast loop settling, integer- N architecture operating with 66 MHz reference frequency and wideband QVCO are implemented. I/Q carriers are generated by two bottom-series cross-coupled LC VCOs. Realized in 0.18 μm CMOS technology, this PLL consumes 16 mA current (including buffers) from a 1.5 V supply and the phase noise is -109.6 dBc/Hz at 1 MHz offset. The measured oscillation frequency shows that the QVCO has a range of 6.95 to 8.73 GHz. The core circuit occupies an area of 1 x 0.5 mm 2 . (semiconductor integrated circuits)

A 1.5 V 7.656 GHz PLL with I/Q outputs for a UWB synthesizer

Energy Technology Data Exchange (ETDEWEB)

Chen Pufeng; Zhang Haiying; Ye Tianchun, E-mail: chenpufeng@ime.ac.c [Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029 (China)

2010-06-15

A fully integrated CMOS phase-locked loop (PLL) which can synthesize a quadrature output frequency of 7.656 GHz is presented. The proposed PLL can be employed as a building block for an MB-OFDM UWB frequency synthesizer. To achieve fast loop settling, integer- N architecture operating with 66 MHz reference frequency and wideband QVCO are implemented. I/Q carriers are generated by two bottom-series cross-coupled LC VCOs. Realized in 0.18 {mu}m CMOS technology, this PLL consumes 16 mA current (including buffers) from a 1.5 V supply and the phase noise is -109.6 dBc/Hz at 1 MHz offset. The measured oscillation frequency shows that the QVCO has a range of 6.95 to 8.73 GHz. The core circuit occupies an area of 1 x 0.5 mm{sup 2}. (semiconductor integrated circuits)

Spectrally-Precoded OFDM for 5G Wideband Operation in Fragmented sub-6GHz Spectrum

OpenAIRE

Pitaval, Renaud-Alexandre; Popović, Branislav M.; Mohamad, Medhat; Nilsson, Rickard; van de Beek, Jaap

2016-01-01

We consider spectrally-precoded OFDM waveforms for 5G wideband transmission in sub-6GHz band. In this densely packed spectrum, a low out-of-band (OOB) waveform is a critical 5G component to achieve the promised high spectral efficiency. By precoding data symbols before OFDM modulation, it is possible to achieve extremely low out-of-band emission with very sharp spectrum transition enabling an efficient and flexible usage of frequency resources. Spectrally-precoded OFDM shows promising results...

A 28 GHz FR-4 Compatible Phased Array Antenna for 5G Mobile Phone Applications

DEFF Research Database (Denmark)

Ojaroudiparchin, Naser; Shen, Ming; Pedersen, Gert F.

2015-01-01

The design of a 28 GHz phased array antenna for future fifth generation (5G) mobile-phone applications has been presented in this paper. The proposed antenna can be implemented using low cost FR-4 substrates, while maintaining good performance in terms of gain and efficiency. This is achieved...

Design and commissioning of the TdeV launcher

International Nuclear Information System (INIS)

Mireault, R.; Demers, Y.; Bagdoo, J.; Brooker, P.; Chaudron, G.A.; Decoste, R.; Dube, A.; Glaude, V.; Guerdain, F.; Hubbard, A.; Jacquet, P.; Robert, A.; St-Onge, M.; Theriault, J.F.; Vachon, L.

1995-01-01

The launcher of TdeV's newly installed LHCD system (P = 1.0 MW at 3.7 GHz for 30 s) consists of 16 identical 4-way multijunction modules. It is bakable up to 350 C and is electrically insulated from the tokamak vacuum vessel. The modules are made of Glidcop (dispersion strengthened copper) which has thermal and electrical properties similar to those of OF copper and good mechanical strength at high temperature. Although brazing Glidcop is difficult, high quality antenna modules were produced using this technique. Since mid-December 1993, LHCD experiments have been carried out on TdeV and operation at power densities of up to 41 MW/m 2 was achieved with a minimum of RF conditioning. The operational experience gained so far with a Glidcop launcher on TdeV indicates that this material would be a good choice for the next generation of LHCD couplers. (orig.)

Study on ECH-assisted start-up using trapped particle configuration in KSTAR and application to ITER

Science.gov (United States)

Lee, Jeongwon; Kim, Jayhyun; An, YoungHwa; Yoo, Min-Gu; Hwang, Y. S.; Na, Yong-Su

2017-12-01

ECH-assisted start-up using trapped particle configuration (TPC) is firstly studied in a superconducting, conventional tokamak, KSTAR. First, improved and efficient start-up using TPC than conventional field null configuration (FNC) is achieved by enhanced pre-ionization plasma quality. TPC shows the broader operation window in terms of the poloidal field quality and the deuterium prefill pressure than that of FNC. Surprisingly the particle trapping enhances the plasma start-up performance even with much lower particle trapping ratio than that of spherical torus. Reliability of TPC with low trapping ratio is investigated by 0D plasma evolution code, TECHP0D. Second, the characteristics of TPC start-up are explored with experiments and modellings. Two kind of start-up failure conditions are identified by the magnetic pitch and prefill pressure scan experiments: (i) low ionization rate; and (ii) low density condition. These experimental observation has consistency with TECHP0D modeling result. Finally, reliable ITER-relevant low toroidal electric field start-up using TPC is achieved with drastically improved success rate of start-up in KSTAR. In this experiments, validity of the ITER-like toroidally inclined ECH/ECCD injection is also expected. Time dependent ITER start-up scenario using TPC is proposed and the superiority of it than FNC is discussed.

Commissioning result of the KSTAR in-vessel cryo-pump

Energy Technology Data Exchange (ETDEWEB)

Chang, Y. B.; Lee, H. J.; Park, Y.M. [National Fusion Research Institute, Daejeon (Korea, Republic of); and others

2013-12-15

KSTAR in-vessel cryo-pump has been installed in the vacuum vessel top and bottom side with up-down symmetry for the better plasma density control in the D-shape H-mode. The cryogenic helium lines of the in-vessel cryo-pump are located at the vertical positions from the vacuum vessel torus center 2,000 mm. The inductive electrical potential has been optimized to reduce risk of electrical breakdown during plasma disruption. In-vessel cryo-pump consists of three parts of coaxial circular shape components; cryo-panel, thermal shield and particle shield. The cryo-panel is cooled down to below 4.5 K. The cryo-panel and thermal shields were made by Inconel 625 tube for higher mechanical strength. The thermal shields and their cooling tubes were annealed in air environment to improve the thermal radiation emissivity on the surface. Surface of cryo-panel was electro-polished to minimize the thermal radiation heat load. The in-vessel cryo-pump was pre-assembled on a test bed in 180 degree segment base. The leak test was carried out after the thermal shock between room temperature to LN2 one before installing them into vacuum vessel. Two segments were welded together in the vacuum vessel and final leak test was performed after the thermal shock. Commissioning of the in-vessel cryo-pump was carried out using a temporary liquid helium supply system.

60 Gbit/s 400 GHz Wireless Transmission

DEFF Research Database (Denmark)

Yu, Xianbin; Asif, Rameez; Piels, Molly

2015-01-01

We experimentally demonstrate a 400 GHz carrier wireless transmission system with real-time capable detection and demonstrate transmission of a 60 Gbit/s signal derived from optical Nyquist channels in a 12.5 GHz ultra-dense wavelength division multiplexing (UD-WDM) grid and carrying QPSK...

Impurity diagnosis of a KSTAR graphite divertor tile using laser induced breakdown spectroscopy technique

Energy Technology Data Exchange (ETDEWEB)

Kim, Minju; Cho, Min Sang; Cho, Byoung Ick, E-mail: bicho@gist.ac.kr

2017-04-15

Laser induced breakdown spectroscopy (LIBS) has been tested to diagnose impurity elements on a Korea Superconducting Tokamak Advanced Research (KSTAR) divertor tile. Spectral lines of various impurity elements such as iron, chromium, and nickel were detected from the divertor surface. The variation of spectra with consecutive laser pulses demonstrates the potential for depth profiling analysis for the deposited impurity layer. The LIBS plasma parameters have been qualitatively determined from analysis of the relative line intensities and linewidths for each element. The validity of this analysis has been checked with atomic spectral simulations.

Performance Analysis of OFDM 60GHz System and SC-FDE 60GHz System

Directory of Open Access Journals (Sweden)

Han Xueyan

2016-01-01

Full Text Available In this paper, the performance of 60GHz wireless communication system with SC and OFDM is studied, the models of OFDM 60GHz system and SC 60GHz frequency domain equalization (SC-FDE system are established, and the bit error rate (BER performance of OFDM 60GHz system and SC-FDE 60GHz system in 802.15.3c channels is compared. The simulation results show that SC-FDE 60GHz system has a slight advantage over OFDM system in line-of-sight (LOS channels, while OFDM 60GHz system has a slight advantage over SC-FDE system in non-line-of-sight (NLOS channels. For 60GHz system, OFDM 60GHz system has a slight advantage over SC-FDE system in overcoming multipath fading, but the performance of both is close whether in the LOS or NLOS case.

60 GHz Milimeter-Wave Antennas for Point-to-Point 5G Communication System

Directory of Open Access Journals (Sweden)

Aishah A.S.

2017-01-01

Full Text Available In this paper microstrip patch antenna for millimeter-wave is proposed. Evolution of shape microstrip antenna are designed which is from rectangular antenna to triangle antenna and changed to triangle with slot. The proposed antenna configuration achieved for covering 5G wireless system. The lowest return loss of the antenna is -29.23dB which is triangle with slot and the maximum gain obtained is 8 db at the 61.93 GHz for the triangle antenna. This antenna are suitable for the 5G wireless application for short range and high rate communication system.

Use of the 37-38 GHz and 40-40.5 GHz Ka-bands for Deep Space Communications

Science.gov (United States)

Morabito, David; Hastrup, Rolf

2004-01-01

This paper covers a wide variety of issues associated with the implementation and use of these frequency bands for deep space communications. Performance issues, such as ground station pointing stability, ground antenna gain, antenna pattern, and propagation effects such as due to atmospheric, charged-particle and space loss at 37 GHz, will be addressed in comparison to the 32 GHz Ka-band deep space allocation. Issues with the use of and competition for this spectrum also will be covered. The state of the hardware developed (or proposed) for operating in this frequency band will be covered from the standpoint of the prospects for achieving higher data rates that could be accommodated in the available bandwidth. Hardware areas to be explored include modulators, digital-to-analog converters, filters, power amplifiers, receivers, and antennas. The potential users of the frequency band will be explored as well as their anticipated methods to achieve the potential high data rates and the implications of the competition for bandwidth.

Structural analysis of the KSTAR vacuum vessel

Energy Technology Data Exchange (ETDEWEB)

In, Sang Ryul; Yoon, Byeong Joo [Korea Atomic Energy Research Institute, Taejon (Korea)

1998-10-01

Structure analysis of the vacuum vessel for the KSTAR tokamak which, is in the end phase of the conceptual design have been performed. Mechanical stresses and deformations of the vessel produced by constant forces due to atmospheric pressure, dead weight, fluid pressure, etc and various transient electromagnetic forces induced during tokamak operations were calculated as well as modal characteristics and buckling properties were investigated. Influences of the temperature gradient and the constraint condition of the support on the thermal stress and deformation of the vessel were analyzed. The thermal stress due to the temperature distribution on the vessel as supplying the N{sub 2} gas of 400 deg C through poloidal channels according to the recent baking concept were calculated. No severe problem in the robustness of the vessel was found when applying the constant pressures on the vessel. However the mechanical stress due to the EM force induced by halo currents flowing on the vessel and the plasma facing components (PFCs) far exceeded the allowable limit. Some reinforcing components should be added on the boundary of the PFC support and the vessel, and that of the vessel support and the vessel. A steep temperature gradient in the vicinity of the inlet and oulet of the heating gas produced a thermal stress much higher than allowable. It is necessary to make the temperature of the vessel as uniform as possible and to develop a new support concept which is flexible enough to accommodate a thermal expansion of a few cm while sufficiently strong to resist mechanical impacts. (author). 5 refs., 41 figs., 9 tabs.

Entanglement swapping of a GHZ state via a GHZ-like state

Energy Technology Data Exchange (ETDEWEB)

Tsai, Chia-Wei; Hwang, Tzonelih, E-mail: hwangtl@ismail.csie.ncku.edu.t [National Cheng Kung University, Department of Computer Science and Information Engineering, No. 1 Ta-Hsueh Road, Tainan City 701, Taiwan (China)

2011-10-15

This study uses the Greenberger-Horne-Zeilinger (GHZ)-like state |G>= 1/2 (|001>+|010>+|100>+|111>) to establish an entanglement swapping protocol on a pure GHZ state. A quantum circuit is proposed to assist in teleporting the entanglement of the pure GHZ state. Furthermore, on the basis of the generation of the GHZ-like state, an improved protocol to reduce the number of transmitted photons required in the process of entanglement swapping is proposed.

A Prediction Study of Path Loss Models from 2-73.5 GHz in an Urban-Macro Environment

DEFF Research Database (Denmark)

Thomas, Timothy; Rybakowski, Marcin; Sun, Shu

2016-01-01

can roughly be broken into two categories, ones that have some anchor in physics, and ones that curve-match only over the data set without any physical anchor. In this paper we use both real-world measurements from 2.0 to 28 GHz and ray-tracing studies from 2.0 to 73.5 GHz, both in an urban-macro...... environment, to assess the prediction performance of the two PL modeling techniques. In other words we look at how the two different PL modeling techniques perform when the PL model is applied to a prediction set which is different in distance, frequency, or environment from a measurement set where...

Spatial and Temporal Characterization of Indoor Millimeter Wave Propagation at 24 GHz

Directory of Open Access Journals (Sweden)

Seok-hwan Min

2016-01-01

Full Text Available Indoor millimeter wave propagation at the frequency of 24 GHz is studied by experimental methods. Measurements are performed to obtain temporal and spatial channel model using a channel sounder and rotating antennas in a corridor. The measured impulse responses are processed to obtain compact channel model following Saleh-Valenzuela’s model. The responses are compared with those of 5.3 GHz for the same test sites. Angular spread of 24 GHz is found to be smaller than that of 5.3 GHz, while echoes of 24 GHz are found to be longer than those of 5.3 GHz.

Performance evaluation of a real time OFDM radio over fiber system at 2.5 GHz using software defined radio SDR

DEFF Research Database (Denmark)

David Cepeda, Juan; Rodriguez, Santiago Isaac; Rico-Martinez, Monica

2017-01-01

This paper presents the implementation of an OFDM radio over fiber (RoF) system at 2.5 GHz using software defined radio (SDR). In this work, first we present an introduction of the main concepts about radio over fiber and an orthogonal frequency-division multiplexing (OFDM) system at 2.5 GHz......, then we present a comparison of an OFDM RoF system in three scenarios, modifying the wireless distances and the optical fiber distance in order to evaluate the performance of the system taking into account the symbol error rate (SER) vs signal to noise ratio (SNR) curves....

Note: Radio frequency surface impedance characterization system for superconducting samples at 7.5 GHz.

Science.gov (United States)

Xiao, B P; Reece, C E; Phillips, H L; Geng, R L; Wang, H; Marhauser, F; Kelley, M J

2011-05-01

A radio frequency (RF) surface impedance characterization (SIC) system that uses a novel sapphire-loaded niobium cavity operating at 7.5 GHz has been developed as a tool to measure the RF surface impedance of flat superconducting material samples. The SIC system can presently make direct calorimetric RF surface impedance measurements on the central 0.8 cm(2) area of 5 cm diameter disk samples from 2 to 20 K exposed to RF magnetic fields up to 14 mT. To illustrate system utility, we present first measurement results for a bulk niobium sample.

Measurement of inner wall limiter SOL widths in KSTAR tokamak

Directory of Open Access Journals (Sweden)

J.G. Bak

2017-08-01

Full Text Available Scrape-off layer (SOL widths λq are presented from the KSTAR tokamak using fast reciprocating Langmuir probe assembly (FRLPA measurements at the outboard mid-plane (OMP and the infra-Red (IR thermography at inboard limiter tiles in moderately elongated (κ = 1.45 – 1.55 L-mode inner wall-limited (IWL plasmas under experimental conditions such as BT = 2.0 T, PNBI = 1.4 – 1.5 MW, line averaged densities 2.5 – 5.1 × 1019 m−3 and plasma current Ip = 0.4 − 0.7 MA. There is clear evidence for a double exponential structure in q||(r from the FRLPA such that, for example at Ip = 0.6 MA, a narrow feature, λq,near (=3.5 mm is found close to the LFCS, followed by a broader width, λq,main (=57.0 mm. Double exponential profiles (λq,near = 1.5 – 2.8 mm, λq,main = 17.0 – 35.0 mm can be also observed in the IR heat flux mapped to the OMP throughout the range of Ip investigated. In addition, analysis of SOL turbulence statistics obtained with the FRLPA shows high relative fluctuation levels and positively skewed distributions in electron temperature and ion particle flux across the SOL, with both properties increasing for longer distance from the LCFS, as often previously observed in the tokamaks. Interestingly, the fluctuation character expressed in terms of spectral distributions remains unchanged in passing from the narrow to the broad SOL heat flux channel.

Proposed high voltage power supply for the ITER relevant lower hybrid current drive system

International Nuclear Information System (INIS)

Sharma, P.K.; Kazarian, F.; Garibaldi, P.; Gassman, T.; Artaud, J.F.; Bae, Y.S.; Belo, J.; Berger-By, G.; Bernard, J.M.; Cara, Ph.; Cardinali, A.; Castaldo, C.; Ceccuzzi, S.; Cesario, R.; Decker, J.; Delpech, L.; Ekedahl, A.; Garcia, J.; Goniche, M.; Guilhem, D.

2011-01-01

In the framework of the EFDA task HCD-08-03-01, the ITER lower hybrid current drive (LHCD) system design has been reviewed. The system aims to generate 24 MW of RF power at 5 GHz, of which 20 MW would be coupled to the plasmas. The present state of the art does not allow envisaging a unitary output of the klystrons exceeding 500 kW, so the project is based on 48 klystron units, leaving some margin when the transmission lines losses are taken into account. A high voltage power supply (HVPS), required to operate the klystrons, is proposed. A single HVPS would be used to feed and operate four klystrons in parallel configuration. Based on the above considerations, it is proposed to design and develop twelve HVPS, based on pulse step modulator (PSM) technology, each rated for 90 kV/90 A. This paper describes in details, the typical electrical requirements and the conceptual design of the proposed HVPS for the ITER LHCD system.

A wideband (3 to 5 GHz) wide-scan connected array of dipoles with low cross polarization

NARCIS (Netherlands)

Cavallo, D.; Neto, A.; Gerini, G.

2012-01-01

A wideband, wide-scan prototype phased array of connected dipoles has been manufactured and tested from 3 to 5 GHz. The array comprises 7 × 7 elements, each fed by a loop-shaped transformer to avoid common-mode resonances. Such resonances typically affect this type of arrays, with consequent

Fuel retention under elevated wall temperature in KSTAR with a carbon wall

Science.gov (United States)

Cao, B.; Hong, S. H.

2018-03-01

The fuel retention during KSTAR discharges with elevated wall temperature (150 °C) has been studied by using the method of global particle balance. The results show that the elevated wall temperature could reduce the dynamic retention via implantation and absorption, especially for the short pulse shots with large injected fuel particles. There is no signature changing of long-term retention, which related to co-deposition, under elevated wall temperature. For soft-landing shots (normal shots), the exhausted fuel particles during discharges is larger with elevated wall temperature than without, but the exhausted particles after discharges within 90 s looks similar. The outgassing particles because of disruption could be exhausted within 15 s.

Development of frequency step tunable 1 MW gyrotron at 131 to 146.5 GHz

Energy Technology Data Exchange (ETDEWEB)

Samartsev, A.; Gantenbein, G.; Dammertz, G.; Illy, S.; Kern, S.; Leonhardt, W.; Schlaich, A.; Schmid, M.; Thumm, M., E-mail: andrey.samartsev@kit.edu [Karlsruhe Institute of Technology, Association EURATOM-KIT, Karlsruhe (Germany)

2011-07-01

Effective control of power absorption in tokamaks and stellarators could be achieved by the frequency tuning of ECH and CD power delivered by high-power gyrotrons. In this report some results of the development of a frequency tunable gyrotron with fused-silica Brewster window are presented. Excitation of several modes at 1 MW power level in the range of frequencies from 131 to 146.5 GHz is achieved. (author)

LTE/Wi-Fi Coexistence in 5 GHz ISM Spectrum: Issues, Solutions and Perspectives

DEFF Research Database (Denmark)

Abinader, Fuad; A. de Sousa Jr., Vicente; Choudhurry, Sayantan

2018-01-01

solutions is the aggregation of ISM unlicensed spectrum to licensed bands, using wireless networks defined by IEEE and 3GPP. While Wi-Fi networks are aggregated to LTE small cells via LTE/WLAN Aggregation (LWA), in proposals like LTE-U and LAA-LTE, the LTE air interface itself is used for transmission...... on the unlicensed band. Wi-Fi technology is widespread and also operates in the 5 GHz ISM spectrum bands, which may bring performance issues due to the coexistence of both technologies in the same spectrum band. This work is dedicated to the study of coexistence between LTE and Wi-Fi access systems operating in 5...

38-GHz millimeter wave beam steered fiber wireless systems for 5G indoor coverage: architectures, devices, and links

NARCIS (Netherlands)

Cao, Z.; Zhao, X.; Soares, F.M.; Tessema, N.M.; Koonen, A.M.J.

2017-01-01

Millimeter wave (mm-wave) beam steering is a key technique for the next generation (5G) wireless communication. The 28 and 38-GHz bands are widely considered as the candidates for 5G. In the context of indoor coverage, fiber-wireless systems with multiple simplified remote antenna sites are

Recovery process of wall condition in KSTAR vacuum vessel after temporal machine-vent for repair

Energy Technology Data Exchange (ETDEWEB)

Kim, Kwang Pyo, E-mail: kpkim@nfri.er.ke; Hong, Suk-Ho; Lee, Hyunmyung; Song, Jae-in; Jung, Nam-Yong; Lee, Kunsu; Chu, Yong; Kim, Hakkun; Park, Kaprai; Oh, Yeong-Kook

2015-10-15

Highlights: • Efforts have been made to obtain vacuum condition that is essential for the plasma experiments. • For example, the vacuum vessel should be vented to repair in-vessel components such as diagnostic shutter, and PFC damaged by high energy plasma. • Here, we present the recovery process of wall condition in KSTAR after temporal machine-vent for repair. • It is found that an acceptable vacuum condition has been achieved only by plasma based wall conditioning techniques such as baking, GDC, and boronization. • This study was that the proper recovering method of the vacuum condition should be developed according to the severity of the accident. - Abstract: Efforts have been made to obtain vacuum condition that is essential for the plasma experiments. Under certain situations, for example, the vacuum vessel should be vented to repair in-vessel components such as diagnostic shutter, exchange of window for diagnostic equipment, and PFC damaged by high energy plasma. For the quick restart of the campaign, a recovery process was established to make the vacuum condition acceptable for the plasma experiment. In this paper, we present the recovery process of wall condition in KSTAR after temporal machine-vent for repair. It is found that an acceptable vacuum condition has been achieved only by plasma based wall conditioning techniques such as baking, GDC, and boronization. This study was that the proper recovering method of the vacuum condition should be developed according to the severity of the accident.

Tearing modes induced by perpendicular electron cyclotron resonance heating in the KSTAR tokamak

Science.gov (United States)

Lee, H. H.; Lee, S. G.; Seol, J.; Aydemir, A. Y.; Bae, C.; Yoo, J. W.; Na, Y. S.; Kim, H. S.; Woo, M. H.; Kim, J.; Joung, M.; You, K. I.; Park, B. H.

2014-10-01

This paper reports on experimental evidence that shows perpendicular electron cyclotron resonance heating (ECRH) can trigger classical tearing modes when deposited near a rational flux surface. The complex evolution of an m = 2 island is followed during current ramp-up in KSTAR plasmas, from its initial onset as the rational surface enters the ECRH resonance layer to its eventual lock on the wall after the rational surface leaves the layer. Stability analysis coupled to a transport calculation of the current profile with ECRH shows that the perpendicular ECRH may play a significant role in triggering and destabilizing classical m = 2 tearing modes, in agreement with our experimental observation.

Recent operating experience with Varian 70 GHz and 140 GHz gyrotrons

International Nuclear Information System (INIS)

Felch, K.; Bier, R.; Fox, L.; Huey, H.; Ives, L.; Jory, H.; Lopez, N.; Shively, J.; Spang, S.

1985-01-01

The design features and initial test results of Varian 70 GHz and 140 GHz CW gyrotrons are presented. The first experimental 140 GHz tube has achieved an output power of 102 kW at 24% efficiency under pulsed conditions in the desired TE 031 0 cavity mode. Further tests aimed at achieving the design goal of 100 kW CW are currently underway. The 70 GHz tube has achieved an output power of 200 kW under pulsed conditions and possesses a wide dynamic range for output power variations. 6 refs., 8 figs

Earth-satellite propagation above GHz: Papers from the 1972 spring URSI session on experiments utilizing the ATS-5 satellite

Science.gov (United States)

Ippolito, L. J. (Compiler)

1972-01-01

Papers are reported from the Special Session on Earth-Satellite Propagation Above 10 GHz, presented at The 1972 Spring Meeting of the United States National Committee, International Union of Radio Science, April 1972, Washington, D. C. This session was devoted to propagation measurements associated with the Applications Technology Satellite (ATS-5), which provided the first operational earth-space links at frequencies above 15 GHz. A comprehensive summary is presented of the major results of the ATS-5 experiment measurements and related radiometric, radar and meteorological studies. The papers are organized around seven selected areas of interest, with the results of the various investigators combined into a single paper presented by a principal author for that area. A comprehensive report is provided on the results of the ATS-5 satellite to earth transmissions. A complete list of published reports and presentations related to the ATS-5 Millimeter Wave Experiment is included.

Progress of the KSTAR experiments and perspective for ITER scientific researches

International Nuclear Information System (INIS)

Oh, Yeong-Kook

2013-01-01

KSTAR is a superconducting tokamak aiming to explore the long-pulse high beta confinement. In the 2012 experimental campaign, the duration of the H-mode flattop has been extended up to 16 s at 0.6 MA and plasma current level in H-mode reached at 0.9 MA by adopting the real-time plasma shape control and 3.5 MW neutral beam injection. The equilibrium operating space could be extended surpassing the n=1 ideal no wall limit with betaN and betaN/li up to 2.9 and 4.1, respectively. The pedestal formation and characteristics were investigated according to L- and H-mode transition and during the edge localized mode (ELM). As one of the ITER high priority research topics, exploring the ELM mitigation or suppression by applying n=1 or n=2 resonance magnetic perturbation (RMP) field or by injecting the supersonic molecular beam. The toroidal rotation changes were inspected for the ohmic and H-mode plasma by applying the ECH or 3D magnetic field. Various experimental researches were conducted according to the proposals including the disruption mitigation by using massive gas injection, fast ion loss detection under the edge perturbation, plasma wall interaction and others. (author)

45-GHz and 60-GHz 90 nm CMOS power amplifiers with a fully symmetrical 8-way transformer power combiner

Institute of Scientific and Technical Information of China (English)

Zhengdong JIANG; Kaizhe GUO; Peng HUANG; Yiming FAN; Chenxi ZHAO; Yongling BAN; Jun LIU; Kai KANG

2017-01-01

In this paper,45 GHz and 60 GHz power amplifiers (PAs) with high output power have been successfully designed by using 90 nm CMOS process.The 45 GHz (60 GHz) PA consists of two (four) differential stages.The sizes of transistors have been designed in an appropriate way so as to trade-off gain,efficiency and stability.Due to limited supply voltage and low breakdown voltage of CMOS MOSFET compared with the traditional Ⅲ-Ⅴ technologies,the technique of power combining has been applied to achieve a high output power.In particular,a novel 8-way distributed active transformer power combiner has been proposed for realizing such mm-wave PA.The proposed transformer combiner with a fully symmetrical layout can improve its input impedance balance at mm-wave frequency regime significantly.Taking its advantages of this novel transformer based power combiner,our realized 45 GHz (60 GHz) mm-wave PA has achieved the gain of 20.3 dB (16.8 dB),the maximum PAE of 14.5％ (13.4％) and the saturated output power of 21 dBm (21 dBm) with the 1.2 V supply voltage.

Propagation Dynamics Associated with Resonant Magnetic Perturbation Fields in High-Confinement Mode Plasmas inside the KSTAR Tokamak.

Science.gov (United States)

Xiao, W W; Evans, T E; Tynan, G R; Yoon, S W; Jeon, Y M; Ko, W H; Nam, Y U; Oh, Y K

2017-11-17

The propagation dynamics of resonant magnetic perturbation fields in KSTAR H-mode plasmas with injection of small edge perturbations produced by a supersonic molecular beam injection is reported for the first time. The results show that the perturbation field first excites a plasma response on the q=3 magnetic surface and then propagates inward to the q=2 surface with a radially averaged propagation velocity of resonant magnetic perturbations field equal to 32.5  m/ s. As a result, the perturbation field brakes the toroidal rotation on the q=3 surface first causing a momentum transport perturbation that propagates both inward and outward. A higher density fluctuation level is observed. The propagation velocity of the resonant magnetic perturbations field is larger than the radial propagation velocity of the perturbation in the toroidal rotation.

Korea Superconducting tokamak advanced research project - Development of heating system

Energy Technology Data Exchange (ETDEWEB)

Choi, Byung Ho [Korea Atomic Energy Research Institute, Taejon (Korea)

1998-10-01

The heating and current drive systems for KSTAR based on multiple technologies (neutral beam, ion cyclotron, lower hybrid and electron cyclotron) have been designed to provide heating and current drive capabilities as well as flexibility in the control of current density and pressure profiles needed to meet the mission and research objectives of the machine. They are designed to operate for long-pulse lengths of up to 300 s. The NBI system initially delivers 8 MW of neutral beam power to the plasma from one co-directed beam line and shall be upgraded to provide 20 MW of neutral beam power with two co-directed beam lines plus one counter-directed beam line. It will be capable of being reconfigured such that the source arrangement is changed from horizontal to vertical stacking, with 6 MW beam power to the plasmas per beam line, in order to facilitate profile control. The RF system initially delivers 6 MW of rf power to the plasma, using a single four-strap antenna mounted in a midplane port. The system will be upgraded to proved 12 MW of rf power through 2 adjacent ports. In the first phase, we completed the basic design of RF system and the system have the capabilities to be operationable for pulse length up to 300 sec and in the 25-60 MHz frequency range. Lower hybrid system initially provides 1.5 MW LH rf power to the plasma at 3.7 GHz through a horizontal port, which has a capability to be operated for pulse length up to 300 sec, and shall be upgraded to provide 4.5 MW of LH rf power to the plasma. In the first phase, we completed the basic design of LHCD system which incorporate the TPX-type launcher and independently phase-changeable transmission system for the fully phased coupler. The ECH system will deliver up to 0.5 MW of power to the plasma for up to 0.5 sec. In the first phase, we completed the basic design of ECH system which includes an 84 GHz gyrotron system, a transmission system, and a launcher. The basic design of the low loss transmission system

Direct measurements of safety factor profiles with motional Stark effect for KSTAR tokamak discharges with internal transport barriers

Science.gov (United States)

Ko, J.; Chung, J.

2017-06-01

The safety factor profile evolutions have been measured from the plasma discharges with the external current drive mechanism such as the multi-ion-source neutral beam injection for the Korea Superconducting Tokamak Advanced Research (KSTAR) for the first time. This measurement has been possible by the newly installed motional Stark effect (MSE) diagnostic system that utilizes the polarized Balmer-alpha emission from the energetic neutral deuterium atoms induced by the Stark effect under the Lorentz electric field. The 25-channel KSTAR MSE diagnostic is based on the conventional photoelastic modulator approach with the spatial and temporal resolutions less than 2 cm (for the most of the channels except 2 to 3 channels inside the magnetic axis) and about 10 ms, respectively. The strong Faraday rotation imposed on the optical elements in the diagnostic system is calibrated out from a separate and well-designed polarization measurement procedure using an in-vessel reference polarizer during the toroidal-field ramp-up phase before the plasma experiment starts. The combination of the non-inductive current drive during the ramp-up and shape control enables the formation of the internal transport barrier where the pitch angle profiles indicate flat or slightly hollow profiles in the safety factor.

Spectrographic observations of solar microwave bursts in the 5.3-7.4 GHz range

International Nuclear Information System (INIS)

Kaverin, N.S.; Korshunov, A.I.; Shushunov, V.V.; Aurass, H.; Detlefs, H.; Hartmann, H.; Krueger, A.; Kurths, J.

1983-01-01

The first results of the Gorky-type microwave spectrograph of Tremsdorf solar radioastronomy observatory are given, observed after the reconstruction of the instrument to get a higher time resolution for the spectral observations. Two 5.3-7.4 GHz microwave burst spectral diagrams are shown having 20 s time resolution. Broad-bond spectral structures of the microwave burst development have been observed. Explanation of a 'pseudo-drift' phenomenon due to individual peaks is given. (D.Gy.)

REMAINING LIFE TIME PREDICTION OF BEARINGS USING K-STAR ALGORITHM – A STATISTICAL APPROACH

Directory of Open Access Journals (Sweden)

R. SATISHKUMAR

2017-01-01

Full Text Available The role of bearings is significant in reducing the down time of all rotating machineries. The increasing trend of bearing failures in recent times has triggered the need and importance of deployment of condition monitoring. There are multiple factors associated to a bearing failure while it is in operation. Hence, a predictive strategy is required to evaluate the current state of the bearings in operation. In past, predictive models with regression techniques were widely used for bearing lifetime estimations. The Objective of this paper is to estimate the remaining useful life of bearings through a machine learning approach. The ultimate objective of this study is to strengthen the predictive maintenance. The present study was done using classification approach following the concepts of machine learning and a predictive model was built to calculate the residual lifetime of bearings in operation. Vibration signals were acquired on a continuous basis from an experiment wherein the bearings are made to run till it fails naturally. It should be noted that the experiment was carried out with new bearings at pre-defined load and speed conditions until the bearing fails on its own. In the present work, statistical features were deployed and feature selection process was carried out using J48 decision tree and selected features were used to develop the prognostic model. The K-Star classification algorithm, a supervised machine learning technique is made use of in building a predictive model to estimate the lifetime of bearings. The performance of classifier was cross validated with distinct data. The result shows that the K-Star classification model gives 98.56% classification accuracy with selected features.

Tearing modes induced by perpendicular electron cyclotron resonance heating in the KSTAR tokamak

International Nuclear Information System (INIS)

Lee, H.H.; Lee, S.G.; Seol, J.; Aydemir, A.Y.; Bae, C.; Woo, M.H.; Kim, J.; Joung, M.; You, K.I.; Park, B.H.; Yoo, J.W.; Na, Y.S.; Kim, H.S.

2014-01-01

This paper reports on experimental evidence that shows perpendicular electron cyclotron resonance heating (ECRH) can trigger classical tearing modes when deposited near a rational flux surface. The complex evolution of an m = 2 island is followed during current ramp-up in KSTAR plasmas, from its initial onset as the rational surface enters the ECRH resonance layer to its eventual lock on the wall after the rational surface leaves the layer. Stability analysis coupled to a transport calculation of the current profile with ECRH shows that the perpendicular ECRH may play a significant role in triggering and destabilizing classical m = 2 tearing modes, in agreement with our experimental observation. (paper)

Polarization of hard X-rays, a contribution to the measurement of the non-thermal electron distribution function (L.H.C.D.)

International Nuclear Information System (INIS)

Hesse, M.; Platz, P.

1990-01-01

The hard X-ray spectrum emitted by a plasma containing non-thermal electrons generated during Lower Hybrid Current Drive experiments has already been measured on several tokamaks, but the properties of the bremsstrahlung have not yet been studied. The present study starts with the comparison of tractable analytical expressions of cross-sections with more precise computer-calculated values; then an evaluation of the polarization is carried out under real tokamak current drive situations and finally a proposal of a new diagnostic for the Tore Supra LHCD experiment is presented. (author) 6 refs., 6 figs

Design Feature and Result of PFCs Baking System for the KSTAR

International Nuclear Information System (INIS)

Bang, Eun Nam; Kim, Kyung Min; Kim, Hong Tack; Kim, Hak Kun; Lee, Kun Su; Kim, Sang Tae; Yang, Hyung Lyeol; Kwon, Myeun

2010-01-01

The Korea Superconducting Tokamak Advanced Research (KSTAR) is being majorly updated for 2010's operation which mainly aims to achieve the plasma shaping and diverted plasmas. The Plasma Facing Components (PFCs) such as inboard and outboard limiters, divertors, and passive stabilizers have been finally installed in the vacuum vessel (VV) by middle of June 2010. The baking and cooling (B and C) pipe system for all the PFCs were installed inside of the vacuum vessel to fulfill baking and active cooling of each PFC components. The PFCs are to be baked by circulating hot nitrogen gas through internal tubes of back-plates of the PFCs. While VV is baked-out, the PFCs temperature was raised from room temperature to 120 .deg. C, and the baking temperature was raised again to 200 .deg. C in spite of the VV being maintained at room temperature

47 CFR 25.136 - Licensing provisions for user transceivers in the 1.6/2.4 GHz, 1.5/1.6 GHz, and 2 GHz Mobile...

Science.gov (United States)

2010-10-01

...) Incorporation of ancillary terrestrial component base station into an L-band mobile-satellite service system... ancillary terrestrial component (ATC) base stations as defined in § 25.201 at its own risk and subject to... Applications and Licenses Earth Stations § 25.136 Licensing provisions for user transceivers in the 1.6/2.4 GHz...

2 ~ 5 times tunable repetition-rate multiplication of a 10 GHz pulse source using a linearly tunable, chirped fiber Bragg grating.

Science.gov (United States)

Lee, Ju Han; Chang, You; Han, Young-Geun; Kim, Sang; Lee, Sang

2004-08-23

We experimentally demonstrate a simple scheme for the tunable pulse repetition-rate multiplication based on the fractional Talbot effect in a linearly tunable, chirped fiber Bragg grating (FBG). The key component in this scheme is our linearly tunable, chirped FBG with no center wavelength shift, which was fabricated with the S-bending method using a uniform FBG. By simply tuning the group velocity dispersion of the chirped FBG, we readily multiply an original 8.5 ps, 10 GHz soliton pulse train by a factor of 2 ~ 5 to obtain high quality pulses at repetition-rates of 20 ~ 50 GHz without significantly changing the system configuration.

Investigation of MHD instabilities and control in KSTAR preparing for high beta operation

Science.gov (United States)

Park, Y. S.; Sabbagh, S. A.; Bialek, J. M.; Berkery, J. W.; Lee, S. G.; Ko, W. H.; Bak, J. G.; Jeon, Y. M.; Park, J. K.; Kim, J.; Hahn, S. H.; Ahn, J.-W.; Yoon, S. W.; Lee, K. D.; Choi, M. J.; Yun, G. S.; Park, H. K.; You, K.-I.; Bae, Y. S.; Oh, Y. K.; Kim, W.-C.; Kwak, J. G.

2013-08-01

Initial H-mode operation of the Korea Superconducting Tokamak Advanced Research (KSTAR) is expanded to higher normalized beta and lower plasma internal inductance moving towards design target operation. As a key supporting device for ITER, an important goal for KSTAR is to produce physics understanding of MHD instabilities at long pulse with steady-state profiles, at high normalized beta, and over a wide range of plasma rotation profiles. An advance from initial plasma operation is a significant increase in plasma stored energy and normalized beta, with Wtot = 340 kJ, βN = 1.9, which is 75% of the level required to reach the computed ideal n = 1 no-wall stability limit. The internal inductance was lowered to 0.9 at sustained H-mode duration up to 5 s. In ohmically heated plasmas, the plasma current reached 1 MA with prolonged pulse length up to 12 s. Rotating MHD modes are observed in the device with perturbations having tearing rather than ideal parity. Modes with m/n = 3/2 are triggered during the H-mode phase but are relatively weak and do not substantially reduce Wtot. In contrast, 2/1 modes to date only appear when the plasma rotation profiles are lowered after H-L back-transition. Subsequent 2/1 mode locking creates a repetitive collapse of βN by more than 50%. Onset behaviour suggests the 3/2 mode is close to being neoclassically unstable. A correlation between the 2/1 mode amplitude and local rotation shear from an x-ray imaging crystal spectrometer suggests that the rotation shear at the mode rational surface is stabilizing. As a method to access the ITER-relevant low plasma rotation regime, plasma rotation alteration by n = 1, 2 applied fields and associated neoclassical toroidal viscosity (NTV) induced torque is presently investigated. The net rotation profile change measured by a charge exchange recombination diagnostic with proper compensation of plasma boundary movement shows initial evidence of non-resonant rotation damping by the n = 1, 2 applied

Investigation of MHD instabilities and control in KSTAR preparing for high beta operation

International Nuclear Information System (INIS)

Park, Y.S.; Sabbagh, S.A.; Bialek, J.M.; Berkery, J.W.; Lee, S.G.; Ko, W.H.; Bak, J.G.; Jeon, Y.M.; Kim, J.; Hahn, S.H.; Yoon, S.W.; Lee, K.D.; You, K.-I.; Bae, Y.S.; Oh, Y.K.; Park, J.K.; Ahn, J.-W.; Choi, M.J.; Yun, G.S.; Park, H.K.

2013-01-01

Initial H-mode operation of the Korea Superconducting Tokamak Advanced Research (KSTAR) is expanded to higher normalized beta and lower plasma internal inductance moving towards design target operation. As a key supporting device for ITER, an important goal for KSTAR is to produce physics understanding of MHD instabilities at long pulse with steady-state profiles, at high normalized beta, and over a wide range of plasma rotation profiles. An advance from initial plasma operation is a significant increase in plasma stored energy and normalized beta, with W tot = 340 kJ, β N = 1.9, which is 75% of the level required to reach the computed ideal n = 1 no-wall stability limit. The internal inductance was lowered to 0.9 at sustained H-mode duration up to 5 s. In ohmically heated plasmas, the plasma current reached 1 MA with prolonged pulse length up to 12 s. Rotating MHD modes are observed in the device with perturbations having tearing rather than ideal parity. Modes with m/n = 3/2 are triggered during the H-mode phase but are relatively weak and do not substantially reduce W tot . In contrast, 2/1 modes to date only appear when the plasma rotation profiles are lowered after H–L back-transition. Subsequent 2/1 mode locking creates a repetitive collapse of β N by more than 50%. Onset behaviour suggests the 3/2 mode is close to being neoclassically unstable. A correlation between the 2/1 mode amplitude and local rotation shear from an x-ray imaging crystal spectrometer suggests that the rotation shear at the mode rational surface is stabilizing. As a method to access the ITER-relevant low plasma rotation regime, plasma rotation alteration by n = 1, 2 applied fields and associated neoclassical toroidal viscosity (NTV) induced torque is presently investigated. The net rotation profile change measured by a charge exchange recombination diagnostic with proper compensation of plasma boundary movement shows initial evidence of non-resonant rotation damping by the n = 1, 2

Development of 14.5 GHz electron cyclotron resonance ion source at KAERI

International Nuclear Information System (INIS)

Byung-Hoon, Oh; Sang-Ryul, In; Kwang-Won, Lee; Chang Seog, Seo; Jung-Tae, Jin; Dae-Sik, Chang; Seong Ho, Jeong; Chul-Kew Hwang

2012-01-01

A 14.5 GHz ECRIS has been designed and fabricated at KAERI (Korea Atomic Energy Research Institute) to produce multi-charged ion beam (especially for C 6+ ion beam) for medical application. The magnet system has copper conductor solenoid coils and a permanent magnet hexapole. A welded tube with aluminium and stainless steel is used for an ECR plasma chamber to improve the production of secondary electron. A klystron supplies microwave energy to the plasma. A movable beam extractor with 8 mm aperture covers different species and different charge numbers of the beam. Fabrication and initial experimental results on ECR plasma are discussed in this paper. The paper is followed by the slides of the presentation. (authors)

High linearity 5.2-GHz power amplifier MMIC using CPW structure technology with a linearizer circuit

International Nuclear Information System (INIS)

Wu Chiasong; Lin Tah-Yeong; Wu Hsien-Ming

2010-01-01

A built-in linearizer was applied to improve the linearity in a 5.2-GHz power amplifier microwave monolithic integrated circuit (MMIC), which was undertaken with 0.15-μm AlGaAs/InGaAs D-mode PHEMT technology. The power amplifier (PA) was studied taking into account the linearizer circuit and the coplanar waveguide (CPW) structures. Based on these technologies, the power amplifier, which has a chip size of 1.44 x 1.10 mm 2 , obtained an output power of 13.3 dBm and a power gain of 14 dB in the saturation region. An input third-order intercept point (HP 3 ) of -3 dBm, an output third-order intercept point (OIP 3 ) of 21.1 dBm and a power added efficiency (PAE) of 22% were attained, respectively. Finally, the overall power characterization exhibited high gain and high linearity, which illustrates that the power amplifier has a compact circuit size and exhibits favorable RF characteristics. This power circuit demonstrated high RF characterization and could be used for microwave power circuit applications at 5.2 GHz. (semiconductor integrated circuits)

Computational dosimetry in embryos exposed to electromagnetic plane waves over the frequency range of 10 MHz-1.5 GHz

International Nuclear Information System (INIS)

Kawai, Hiroki; Nagaoka, Tomoaki; Watanabe, Soichi; Saito, Kazuyuki; Takahashi, Masaharu; Ito, Koichi

2010-01-01

This paper presents calculated specific absorption rate (SAR) dosimetry in 4 and 8 week Japanese pregnant-woman models exposed to plane waves over the frequency range of 10 MHz-1.5 GHz. Two types of 2 mm spatial-resolution pregnant-woman models comprised a woman model, which is similar to the average-sized Japanese adult female in height and weight, with a cubic (4 week) embryo or spheroidal (8 week) one. The averaged SAR in the embryos exposed to vertically and horizontally polarized plane waves at four kinds of propagation directions are calculated from 10 MHz to 1.5 GHz. The results indicate that the maximum average SAR in the embryos exposed to plane waves is lower than 0.08 W kg -1 when the incident power density is at the reference level of ICNIRP guideline for general public environment. (note)

Design Feature and Result of PFCs Baking System for the KSTAR

Energy Technology Data Exchange (ETDEWEB)

Bang, Eun Nam; Kim, Kyung Min; Kim, Hong Tack; Kim, Hak Kun; Lee, Kun Su; Kim, Sang Tae; Yang, Hyung Lyeol; Kwon, Myeun [National Fusion Research Institute, Daejeon (Korea, Republic of)

2010-10-15

The Korea Superconducting Tokamak Advanced Research (KSTAR) is being majorly updated for 2010's operation which mainly aims to achieve the plasma shaping and diverted plasmas. The Plasma Facing Components (PFCs) such as inboard and outboard limiters, divertors, and passive stabilizers have been finally installed in the vacuum vessel (VV) by middle of June 2010. The baking and cooling (B and C) pipe system for all the PFCs were installed inside of the vacuum vessel to fulfill baking and active cooling of each PFC components. The PFCs are to be baked by circulating hot nitrogen gas through internal tubes of back-plates of the PFCs. While VV is baked-out, the PFCs temperature was raised from room temperature to 120 .deg. C, and the baking temperature was raised again to 200 .deg. C in spite of the VV being maintained at room temperature

Simulation of W dust transport in the KSTAR tokamak, comparison with fast camera data

Directory of Open Access Journals (Sweden)

A. Autricque

2017-08-01

Full Text Available In this paper, dust transport in tokamak plasmas is studied through both experimental and modeling aspects. Image processing routines allowing dust tracking on CCD camera videos are presented. The DUMPRO (DUst Movie PROcessing code features a dust detection method and a trajectory reconstruction algorithm. In addition, a dust transport code named DUMBO (DUst Migration in a plasma BOundary is briefly described. It has been developed at CEA in order to simulate dust grains transport in tokamaks and to evaluate the contribution of dust to the impurity inventory of the plasma. Like other dust transport codes, DUMBO integrates the Orbital Motion Limited (OML approach for dust/plasma interactions modeling. OML gives direct expressions for plasma ions and electrons currents, forces and heat fluxes on a dust grain. The equation of motion is solved, giving access to the dust trajectory. An attempt of model validation is made through comparison of simulated and measured trajectories on the 2015 KSTAR dust injection experiment, where W dust grains were successfully injected in the plasma using a gun-type injector. The trajectories of the injected particles, estimated using the DUMPRO routines applied on videos from the fast CCD camera in KSTAR, show two distinct general dust behaviors, due to different dust sizes. Simulations were made with DUMBO to match the measurements. Plasma parameters were estimated using different diagnostics during the dust injection experiment plasma discharge. The experimental trajectories show longer lifetimes than the simulated ones. This can be due to the substitution of a boiling/sublimation point to the usual vaporization/sublimation cooling, OML limitations (eventual potential barriers in the vicinity of a dust grain are neglected and/or to the lack of a vapor shielding model in DUMBO.

A 5.2GHz, 0.5mW RF powered wireless sensor with dual on-chip antennas for implantable intraocular pressure monitoring

KAUST Repository

Arsalan, Muhammad; Ouda, Mahmoud H.; Marnat, Loic; Ahmad, Talha Jamal; Shamim, Atif; Salama, Khaled N.

2013-01-01

For the first time a single chip implantable wireless sensor system for Intraocular Pressure Monitoring (IOPM) is presented. This system-on-chip (SoC) is battery-free and harvests energy from incoming RF signals. The chip is self-contained and does not require external components or bond wires to function. This 1.4mm3 SoC has separate 2.4GHz-transmit and 5.2GHz-receive antennas, an energy harvesting module, a temperature sensor, a 7-bit TIQ Flash ADC, a 4-bit RFID, a power management and control unit, and a VCO transmitter. The chip is fabricated in a standard 6-metal 0.18μm CMOS process and is designed to work with a post-processed MEMS pressure sensor. It consumes 513μW of peak power and when implanted inside the eye, it is designed to communicate with an external reader using on-off keying (OOK). © 2013 IEEE.

A 5.2GHz, 0.5mW RF powered wireless sensor with dual on-chip antennas for implantable intraocular pressure monitoring

KAUST Repository

Arsalan, Muhammad

2013-06-01

For the first time a single chip implantable wireless sensor system for Intraocular Pressure Monitoring (IOPM) is presented. This system-on-chip (SoC) is battery-free and harvests energy from incoming RF signals. The chip is self-contained and does not require external components or bond wires to function. This 1.4mm3 SoC has separate 2.4GHz-transmit and 5.2GHz-receive antennas, an energy harvesting module, a temperature sensor, a 7-bit TIQ Flash ADC, a 4-bit RFID, a power management and control unit, and a VCO transmitter. The chip is fabricated in a standard 6-metal 0.18μm CMOS process and is designed to work with a post-processed MEMS pressure sensor. It consumes 513μW of peak power and when implanted inside the eye, it is designed to communicate with an external reader using on-off keying (OOK). © 2013 IEEE.

Electric probe diagnostics for measuring SOL parameters, wall and divertor fluxes in KSTAR

Energy Technology Data Exchange (ETDEWEB)

Kim, Heung-Su, E-mail: kimhs@nfri.re.kr [National Fusion Research Institute, Daejeon (Korea, Republic of); Bak, Jun-Gyo [National Fusion Research Institute, Daejeon (Korea, Republic of); Bae, Min-Keun; Chung, Kyu-Sun [Hanyang University, Seoul (Korea, Republic of); Hong, Suk-Ho [National Fusion Research Institute, Daejeon (Korea, Republic of)

2016-11-01

Highlights: • Some components in EPDs were improved to investigate characteristics of the SOL plasmas and to measure wall and divertor fluxes in the KSTAR tokamak plasmas. From the upgrades in the EPDs, the measured error of the elapsed distance for the evaluation of the SOL profiles can be reduced up to 1%. • In the SOL parameter measurement during IWL plasma, the e-folding lengths in the main SOL region lTe and lne were evaluated as 3.5 cm and 2.1 cm, respectively. • From flux measurement at the far SOL during a diverted ELMy H-mode, peaked heat flux toward to outboard wall during ELMs might be less than 1% of the peaked divertor heat flux. • The movement of an OSP during a diverted H-mode can be detected from the divertor probe measurement, and the peaked heat flux near the OSP was estimated as few MW m-2. - Abstract: Some components in electric probe diagnostics (EPDs) are improved in order to investigate characteristics of edge plasmas in the upstream scrape-off-layer (SOL) region and to measure wall and divertor fluxes during L-mode and H-mode plasma discharges in the Korea Superconducting Tokamak Advanced Research (KSTAR). From the upgrades in the EPDs, the measured error of the elapsed distance for the evaluation of the SOL profiles can be reduced up to 1% and the ion saturation current of up to 1.0 A near an outer strike point (OSP) can be measured at the divertor region. In the SOL profile measurements during L-mode and inner wall limited plasma (B{sub T} = 2.0 T, I{sub p} = 0.4 MA), the e-folding lengths in the main SOL region λ{sub Te} and λ{sub ne} are evaluated as 3.5 cm and 2.1 cm, respectively. From particle flux measurement at the far SOL region during a diverted ELMy H-mode discharge (B{sub T} = 1.8 T, I{sub p} = 0.65 MA), peaked heat flux toward to outboard wall during ELM bursts is estimated up to ∼20 k Wm{sup −2}, which may be less than 1% of the peaked divertor heat flux expected for the neutral beam (NB) heating power P{sub NB

A measurement of the cosmic microwave background temperature at 7.5 GHz

Science.gov (United States)

Levin, S.; Bensadoun, M.; Bersanelli, M.; De Amici, G.; Kogut, A.; Limon, M.; Smoot, G.

1992-01-01

The temperature of the cosmic microwave background (CMB) radiation at a frequency of 7.5 GHz (4 cm wavelength) is measured, obtaining a brightness temperature of T(CMB) = 2.70 +/- 0.08 K (68 percent confidence level). The measurement was made from a site near the geographical South Pole during the austral spring of 1989 and was part of an international collaboration to measure the CMB spectrum at low frequencies with a variety of radiometers from several different sites. This recent result is in agreement with the 1988 measurement at the same frequency, which was made from a different site with significantly different systematic errors. The combined result of the 1988 and 1989 measurements is 2.64 +/- 0.06 K.

Feasibility study of direct spectra measurements for Thomson scattered signals for KSTAR fusion-grade plasmas

Science.gov (United States)

Park, K.-R.; Kim, K.-h.; Kwak, S.; Svensson, J.; Lee, J.; Ghim, Y.-c.

2017-11-01

Feasibility study of direct spectra measurements of Thomson scattered photons for fusion-grade plasmas is performed based on a forward model of the KSTAR Thomson scattering system. Expected spectra in the forward model are calculated based on Selden function including the relativistic polarization correction. Noise in the signal is modeled with photon noise and Gaussian electrical noise. Electron temperature and density are inferred using Bayesian probability theory. Based on bias error, full width at half maximum and entropy of posterior distributions, spectral measurements are found to be feasible. Comparisons between spectrometer-based and polychromator-based Thomson scattering systems are performed with varying quantum efficiency and electrical noise levels.

Packaging of microwave integrated circuits operating beyond 100 GHz

Science.gov (United States)

Samoska, L.; Daniel, E.; Sokolov, V.; Sommerfeldt, S.; Bublitz, J.; Olson, K.; Gilbert, B.; Chow, D.

2002-01-01

Several methods of packaging high speed (75-330 GHz) InP HEMT MMIC devices are discussed. Coplanar wirebonding is presented with measured insertion loss of less than 0.5dB and return loss better than -17 dB from DC to 110 GHz. A motherboard/daughterboard packaging scheme is presented which supports minimum loss chains of MMICs using this coplanar wirebonding method. Split waveguide block packaging approaches are presented in G-band (140-220 GHz) with two types of MMIC-waveguide transitions: E-plane probe andantipodal finline.

Molecular astronomy using heterodyne detection at 691 GHz

International Nuclear Information System (INIS)

Fetterman, H.R.; Buhl, D.

1984-01-01

Observations of the CO J 6 - 5 transition at 691 GHz in new interstellar and planetary sources have been made. The heterodyne receiver uses an optically pumped laser local oscillator and a quasi-optical Schottky diode mixer, with measured noise temperatures consistently under 4000 K (double sideband). Continued improvements in system performance and antenna coupling have made possible the mapping of 691 GHz emission from W3, and the detection of CO J 5 - 6 absorption in the atmosphere of Venus. A detailed description of the instrumentation and recent observational data are provided. 14 references

Characteristics of ocular temperature elevations after exposure to quasi- and millimeter waves (18-40 GHz)

Science.gov (United States)

Kojima, Masami; Suzuki, Yukihisa; Tsai, Cheng-Yu; Sasaki, Kensuke; Wake, Kanako; Watanabe, Soichi; Taki, Masao; Kamimura, Yoshitsugu; Hirata, Akimasa; Sasaki, Kazuyuki; Sasaki, Hiroshi

2015-04-01

In order to investigate changes in ocular temperature in rabbit eyes exposed to different frequencies (18 to 40 GHz) of quasi-millimeter waves, and millimeter waves (MMW). Pigmented rabbits were anesthetized with both general and topical anesthesia, and thermometer probes (0.5 mm in diameter) were inserted into their cornea (stroma), lens (nucleus) and vitreous (center of vitreous). The eyes were exposed unilaterally to 200 mW/cm2 by horn antenna for 3 min at 18, 22 and 26.5 GHz using a K band exposure system or 26.5, 35 and 40 GHz using a Ka band exposure system. Changes in temperature of the cornea, lens and vitreous were measured with a fluoroptic thermometer. Since the ocular temperatures after exposure to 26.5 GHz generated by the K band and Ka band systems were similar, we assumed that experimental data from these 2 exposure systems were comparable. The highest ocular temperature was induced by 40 GHz MMW, followed by 35 GHz. The 26.5 and 22 GHz corneal temperatures were almost the same. The lowest temperature was recorded at 18 GHz. The elevation in ocular temperature in response to exposure to 200 mW/cm2 MMW is dependent on MMW frequency. MMW exposure induced heat is conveyed not only to the cornea but also the crystalline lens.

60 GHz 5-bit digital controlled phase shifter in a digital 40 nm CMOS technology without ultra-thick metals

NARCIS (Netherlands)

Gao, H.; Ying, K.; Matters-Kammerer, M.K.; Harpe, P.; Wang, B.; Liu, B.; Serdijn, W.A.; Baltus, P.G.M.

2016-01-01

A 5-bit digital controlled switch-type passive phase shifter realised in a 40 nm digital CMOS technology without ultra-thick metals for the 60 GHz Industrial, Scientific and Medical (ISM) band is presented. A patterned shielding with electromagnetic bandgap structure and a stacked metals method to

Predictive modeling of pedestal structure in KSTAR using EPED model

Energy Technology Data Exchange (ETDEWEB)

Han, Hyunsun; Kim, J. Y. [National Fusion Research Institute, Daejeon 305-806 (Korea, Republic of); Kwon, Ohjin [Department of Physics, Daegu University, Gyeongbuk 712-714 (Korea, Republic of)

2013-10-15

A predictive calculation is given for the structure of edge pedestal in the H-mode plasma of the KSTAR (Korea Superconducting Tokamak Advanced Research) device using the EPED model. Particularly, the dependence of pedestal width and height on various plasma parameters is studied in detail. The two codes, ELITE and HELENA, are utilized for the stability analysis of the peeling-ballooning and kinetic ballooning modes, respectively. Summarizing the main results, the pedestal slope and height have a strong dependence on plasma current, rapidly increasing with it, while the pedestal width is almost independent of it. The plasma density or collisionality gives initially a mild stabilization, increasing the pedestal slope and height, but above some threshold value its effect turns to a destabilization, reducing the pedestal width and height. Among several plasma shape parameters, the triangularity gives the most dominant effect, rapidly increasing the pedestal width and height, while the effect of elongation and squareness appears to be relatively weak. Implication of these edge results, particularly in relation to the global plasma performance, is discussed.

Antenne Design for 24 GHz and 60 GHz Emerging Microwave Applications

NARCIS (Netherlands)

Jansen, F.; Dolmans, W.M.C.

2006-01-01

In this project integrated antennas on a LAMP3 substrate for automotive radar systems at 24 GHz and wireless networks at 60 GHz have been designed. The most severe requirements on the antennas were the large bandwidth, which can not be met with conventional patch antennas. A tapered slot antenna and

Handoff Management in Radio over Fiber 60 GHz Indoor Networks

NARCIS (Netherlands)

Bien, V.Q.

2014-01-01

Because of high data rate multimedia applications such as HD and UHDTV, online games, etc., the future home networks are expected to support short-range gigabit transmission. With the worldwide availability of 5 GHz spectrum at the 60 GHz band, it creates the opportunity for a promising air

Multi-gigabit wireless data transfer at 60 GHz

International Nuclear Information System (INIS)

Soltveit, H K; Schöning, A; Wiedner, D; Brenner, R

2012-01-01

In this paper we describe the status of the first prototype of the 60 GHz wireless Multi-gigabit data transfer topology currently under development at University of Heidelberg using IBM 130 nm SiGe HBT BiCMOS technology. The 60 GHz band is very suitable for high data rate and short distance applications. One application can be a wireless multi Gbps radial data transmission inside the ATLAS silicon strip detector, making a first level track trigger feasible. The wireless transceiver consists of a transmitter and a receiver. The transmitter includes an On-Off Keying (OOK) modulator, a Local Oscillator (LO), a Power Amplifier (PA) and a Band-pass Filter (BPF). The receiver part is composed of a Band-pass Filter (BPF), a Low Noise Amplifier (LNA), a double balanced down-convert Gilbert mixer, a Local Oscillator (LO), then a BPF to remove the mixer introduced noise, an Intermediate Amplifier (IF), an On-Off Keying demodulator and a limiting amplifier. The first prototype would be able to handle a data-rate of about 3.5 Gbps over a link distance of 1 m. The first simulations of the LNA show that a Noise figure (NF) of 5 dB, a power gain of 21 dB at 60 GHz with a 3 dB bandwidth of more than 20 GHz with a power consumption 11 mW are achieved. Simulations of the PA show an output referred compression point P1dB of 19.7 dB at 60 GHz.

THE SECOND ARECIBO SEARCH FOR 5 GHz RADIO FLARES FROM ULTRACOOL DWARFS

Energy Technology Data Exchange (ETDEWEB)

Route, Matthew; Wolszczan, Alexander, E-mail: alex@astro.psu.edu, E-mail: mroute@purdue.edu [Department of Astronomy and Astrophysics, the Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States)

2016-10-20

We describe our second installment of the 4.75 GHz survey of ultracool dwarfs (UCDs) conducted with the Arecibo radio telescope, which has observed 27 such objects and resulted in the detection of sporadic flaring from the T6 dwarf, WISEPC J112254.73+255021.5. We also present follow-up observations of the first radio-emitting T dwarf, 2MASS J10475385+2124234, a tentatively identified radio-emitting L1 dwarf, 2MASS J1439284+192915, and the known radio-flaring source, 2MASS J13142039+132011 AB. Our new data indicate that 2MASS J1439284+192915 is not a radio-flaring source. The overall detection rate of our unbiased survey for radio-flaring UCDs is ∼5% for new sources, with a detection rate for each spectral class of ∼5%–10%. Evidently, radio luminosity of the UCDs does not appear to monotonically decline with spectral type from M7 dwarfs to giant planets, contradictory to theories of the magnetic field generation and the internal structure of these objects. Along with other, recently published results, our data exemplify the unique value of using radio surveys to reveal and study properties of substellar magnetic activity.

Passive mode-locking dynamics in a 3.1GHz quantum dot laser diode operating around 1.5μm

NARCIS (Netherlands)

Tahvili, M.S.; Heck, M.J.R.; Nötzel, R.; Smit, M.K.; Bente, E.A.J.M.

2010-01-01

We report on passive mode-locking in a 3.1GHz InAs/InP(100) quantum dot laser diode operating around 1.5µm. The range of stable passive mode-locking, detailed measurements of the linewidth of the optical modes and the phase modulation in output pulses are presented.

Design of 5.8 GHz Integrated Antenna on 180nm Complementary Metal Oxide Semiconductor (CMOS) Technology

Science.gov (United States)

Razak, A. H. A.; Shamsuddin, M. I. A.; Idros, M. F. M.; Halim, A. K.; Ahmad, A.; Junid, S. A. M. Al

2018-03-01

This project discusses the design and simulation performances of integrated loop antenna. Antenna is one of the main parts in any wireless radio frequency integrated circuit (RFIC). Naturally, antenna is the bulk in any RFIC design. Thus, this project aims to implement an integrated antenna on a single chip making the end product more compact. This project targets 5.8 GHz as the operating frequency of the integrated antenna for a transceiver module based on Silterra CMOS 180nm technology. The simulation of the antenna was done by using High Frequency Structure Simulator (HFSS). This software is industrial standard software that been used to simulate all electromagnetic effect including antenna simulation. This software has ability to simulate frequency at range of 100 MHz to 4 THz. The simulation set up in 3 dimension structure with driven terminal. The designed antenna has 1400um of diameter and placed on top metal layer. Loop configuration of the antenna has been chosen as the antenna design. From the configuration, it is able to make the chip more compact. The simulation shows that the antenna has single frequency band at center frequency 5.8 GHz with -48.93dB. The antenna radiation patterns shows, the antenna radiate at omnidirectional. From the simulation result, it could be concluded that the antenna have a good radiation pattern and propagation for wireless communication.

RADIO SOURCES FROM A 31 GHz SKY SURVEY WITH THE SUNYAEV-ZEL'DOVICH ARRAY

International Nuclear Information System (INIS)

Muchovej, Stephen; Hawkins, David; Lamb, James; Woody, David; Leitch, Erik; Carlstrom, John E.; Culverhouse, Thomas; Greer, Chris; Hennessy, Ryan; Loh, Michael; Marrone, Daniel P.; Pryke, Clem; Sharp, Matthew; Joy, Marshall; Miller, Amber; Mroczkowski, Tony

2010-01-01

We present the first sample of 31 GHz selected sources to flux levels of 1 mJy. From late 2005 to mid-2007, the Sunyaev-Zel'dovich Array observed 7.7 deg 2 of the sky at 31 GHz to a median rms of 0.18 mJy beam -1 . We identify 209 sources at greater than 5σ significance in the 31 GHz maps, ranging in flux from 0.7 mJy to ∼200 mJy. Archival NVSS data at 1.4 GHz and observations at 5 GHz with the Very Large Array are used to characterize the sources. We determine the maximum-likelihood integrated source count to be N(>S) = (27.2 ± 2.5)deg -2 x (S mJy ) -1.18±0.12 over the flux range 0.7-15 mJy. This result is significantly higher than predictions based on 1.4 GHz selected samples, a discrepancy which can be explained by a small shift in the spectral index distribution for faint 1.4 GHz sources. From comparison with previous measurements of sources within the central arcminute of massive clusters, we derive an overdensity of 6.8 ± 4.4, relative to field sources.

Design of the Local Instrument for KSTAR Gravity Support

International Nuclear Information System (INIS)

Her, N. I.; Kim, H. K.; Kim, Y. O.; Sa, J. W.; Kim, G. H.; Kim, K. M.; Park, Y. M.; Hong, G. H.; Choi, C. H.; Bak, J. S.

2005-01-01

The gravity support installed between the lower toroidal field (TF) coil cooled by 4.5 K supercritical helium and the cryostat base is the main support structure for the Korea Superconducting Tokamak Advanced Research (KSTAR) superconducting magnet system. This structure should be flexible to absorb thermal shrink of the magnet and also should be rigid to support the magnet weight and the plasma disruptions loads. The gravity support was designed with stainless steel 316LN and Carbon fiber Reinforced Plastics (CFRP) that has low thermal conductivity and high structural strength at low temperature. The fabrication of the support has been completed after engineering design. The gravity support is composed of one toroidal ring and eight supporting posts as shown in Figure 1. The toroidal ring and post are cooled by 4.5 K supercritical helium and 77 K gaseous helium, respectively. The overall dimension of the post is 1 m height and 0.8 m width and depth, respectively. The post is composed of upper block, inner CFRP plate, lower block, flexible plate, thermal anchor block, outer CFRP plate, base block, and strengthen plate. Inner CFRP plate is connected to the upper and lower block using the pin. And the outer CFRP plate is connected to the thermal anchor block and the base block. Inner and outer CFRP plates consist of four and two 20 mm thin plates, respectively. Flexible plates consist of four 8 mm thin stainless steel plates to absorb the magnet shrinkage. These plates are assembled into the thermal anchor block and lower block. The fabrication of the gravity support initiated October 2002 has been completed in October 2003. The supporting post and toroidal ring were fabricated at shop individually and assembled at site. Various of static and dynamic loads will increase the stress level of the structure during the cool-down and plasma operation. After fabrication of the structure, we designed an instrumentation system to monitoring the structural safety. This system

Design of a 5 GHz window in a lower hybrid r.f. system

International Nuclear Information System (INIS)

Maebara, S.; Ikeda, Y.; Seki, M.; Imai, T.

1995-01-01

A new pill-box window at a frequency of 5GHz, which has an oversized length in both the axial and the radial direction, has been designed to reduce the r.f. power density and the electric field strength at the ceramics. The dimension of the new pill-box is optimized from the numerical calculation and a voltage standing-wave ratio of less than 1.02 is obtained. The r.f. power density and the maximum electric field strength are reduced to about 40% and 66% of the standard pill-box window respectively. It is evaluated that the power capability of the new oversized pill-box window by cooling edge of ceramics is more than 500kW with continuous-wave operation. ((orig.))

Design of 20-44 GHz broadband doubler MMIC

International Nuclear Information System (INIS)

Li Qin; Wang Zhigong; Li Wei

2010-01-01

This paper presents the design and performance of a broadband millimeter-wave frequency doubler MMIC using active 0.15 μm GaAs PHEMT and operating at output frequencies from 20 to 44 GHz. This chip is composed of a single ended-into differential-out active Balun, balanced FETs in push-push configuration, and a distributed amplifier. The MMIC doubler exhibits more than 4 dB conversion gain with 12 dBm of output power, and the fundamental frequency suppression is typically -20 dBc up to 44 GHz. The MMIC works at V DD = 3.5 V, V SS = -3.5 V, I d = 200 mA and the chip size is 1.5 x 1.8 mm 2 . (semiconductor integrated circuits)

FRB121102: First detection across 5 - 8 GHz and spectral properties from the Breakthrough Listen instrument

Science.gov (United States)

Gajjar, Vishal; Siemion, Andrew; MacMohan, David; Croft, Steve; Hellbourg, Greg; Isaacson, Howard; Enriquez, J. Emilio; Price, Daniel; Lebofsky, Matt; De Boer, David; Werthimer, Dan; Hickish, Jack; Brinkman, Casey; Chatterjee, Shami; Ransom, Scott M.; Law, Casey; Hessels, Jason W. T.; Cordes, Jim; Spitler, Laura; Lynch, Ryan; McLaughlin, Maura; Scholz, Paul; Marcote, Benito; Bower, Geoffrey C.; Tendulkar, Shriharsh

2018-01-01

Fast Radio Bursts (FRBs) are some of the most energetic and enigmatic events in the Universe. The origin of these sources is among the most challenging questions of modern-day astrophysics. Thus, it is imperative to understand the properties of these bursts across a range of radio frequencies. Among the known FRBs, FRB121102 is the only source known to show repeated bursts [Spitler et al., Nature, 531, 7593 202-205, 2016], which can allow a detailed investigation of various origin models. In August 2017, we initiated a campaign observing FRB 121102 using the Breakthrough Listen Digital Backend with the C-band receiver at the Robert C. Byrd Green Bank Telescope (GBT). We recorded baseband voltage data across 5.4 GHz of bandwidth, completely covering the C-band receiver's nominal 4-8 GHz band [MacMahon et al. arXiv:1707.06024v2]. The recorded data were searched for dispersed pulses consistent with the known dispersion measure of FRB 121102 (557 pc cm-3) using high-speed GPU software tools. We detected 21 bursts above our detection threshold of 6 sigmas in the first 60-minutes, out of which 18 occurred in the first 30-minutes only. To our knowledge, this is the highest event rate seen for FRB121102 at any observing frequency. These observations are the highest frequency and widest bandwidth detection of bursts from FRB 121102 (or any other FRB) obtained to-date. We note that individual bursts show marked changes in spectral extent ranging from hundreds of MHz to several GHz. We have used high frequency dynamic spectra of these bursts to estimate the characteristic scintillation bandwidth and correlation time-scale. We also found distinctive temporal structures, separated by a few milliseconds, in three of the strongest bursts, with each sub-structure exhibiting varied spectral features. We will discuss our findings and how these detections of FRB 121102 around 8 GHz opens up a new regime in scrutinizing various origin models. We will also highlight the unique

Chip design of a 5.8-GHz fractional-N frequency synthesizer with a tunable Gm−C loop filter

International Nuclear Information System (INIS)

Huang Jhin-Fang; Lai Wen-Cheng; Shin Chun-Wei; Hsu Chien-Ming; Liu Ron-Yi

2012-01-01

This paper proposes a novel G m −C loop filter instead of a conventional passive loop filter used in a phase-locked loop. The innovative advantage of the proposed architecture is tunable loop filter bandwidth and hence the process variations of passive elements of resistance R and capacitance C can be overcome and the chip area is greatly reduced. Furthermore, the MASH 1-1-1 sigma-delta (ΣΔ) modulator is adopted for performing the fractional division number and hence improves the phase noise as well. Measured results show that the locked phase noise is −114.1 dBc/Hz with lower G m −C bandwidth and −111.7 dBm/C with higher G m −C bandwidth at 1 MHz offset from carrier of 5.68 GHz. Including pads and built-in G m −C filter, the chip area of the proposed frequency synthesizer is 1.06 mm 2 . The output power is −8.69 dBm at 5.68 GHz and consumes 56 mW with an off-chip buffer from 1.8-V supply voltage. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

Low conversion loss 94 GHz and 188 GHz doublers in InP DHBT technology

DEFF Research Database (Denmark)

Zhurbenko, Vitaliy; Johansen, Tom Keinicke; Squartecchia, Michele

2017-01-01

An Indium Phosphide (InP) Double Heterojunction Bipolar Transistor (DHBT) process has been utilized to design two doublers to cover the 94 GHz and 188 GHz bands. The 94 GHz doubler employs 4-finger DHBTs and provides conversion loss of 2 dB. A maximum output power of nearly 3 dBm is measured whil...... operate over a broad bandwidth. The total circuit area of each chip is 1.41 mm2....

Linearizing of Low Noise Power Amplifier Using 5.8GHz Double Loop Feedforward Linearization Technique

Directory of Open Access Journals (Sweden)

Abdulkareem Mokif Obais

2017-05-01

Full Text Available In this paper, a double loop feedforward linearization technique is analyzed and built with a MMIC low noise amplifier “HMC753” as main amplifier and a two-stage class-A power amplifier as error amplifier. The system is operated with 5V DC supply at a center frequency of 5.8GHz and a bandwidth of 500MHz. The proposed technique, increases the linearity of the MMIC amplifier from 18dBm at 1dB compression point to more than 26dBm. In addition, the proposed system is tested with OFDM signal and it reveals good response in maximizing the linearity region and eliminating distortions. The proposed system is designed and simulated onAdvanced Wave Research-Microwave Office (AWR-MWO.

GHz band frequency hopping PLL-based frequency synthesizers

Institute of Scientific and Technical Information of China (English)

XU Yong; WANG Zhi-gong; GUAN Yu; XU Zhi-jun; QIAO Lu-feng

2005-01-01

In this paper we describe a full-integrated circuit containing all building blocks of a completed PLL-based synthesizer except for low pass filter(LPF).The frequency synthesizer is designed for a frequency hopping (FH) transceiver operating up to 1.5 GHz as a local oscillator. The architecture of Voltage Controlled Oscillator (VCO) is optimized to get better performance, and a phase noise of -111.85-dBc/Hz @ 1 MHz and a tuning range of 250 MHz are gained at a centre frequency of 1.35 GHz.A novel Dual-Modulus Prescaler(DMP) is designed to achieve a very low jitter and a lower power.The settling time of PLL is 80 μs while the reference frequency is 400 KHz.This monolithic frequency synthesizer is to integrate all main building blocks of PLL except for the low pass filter,with a maximum VCO output frequency of 1.5 GHz,and is fabricated with a 0.18 μm mixed signal CMOS process. Low power dissipation, low phase noise, large tuning range and fast settling time are gained in this design.

Limits on Arcminute-Scale Cosmic Microwave Background Anisotropy at 28.5 GHz

Science.gov (United States)

Holzapfel, W. L.; Carlstrom, J. E.; Grego, L.; Holder, G.; Joy, M.; Reese, E. D.

2000-01-01

We have used the Berkeley-Illinois-Maryland Association (BIMA) millimeter array outfitted with sensitive centimeter-wave receivers to search for cosmic microwave background (CMB) anisotropies on arcminute scales. The interferometer was placed in a compact configuration that produces high brightness sensitivity, while providing discrimination against point sources. Operating at a frequency of 28.5 GHz, the FWHM primary beam of the instrument is approximately 6'.6. We have made sensitive images of seven fields, four of which where chosen specifically to have low infrared dust contrast and to be free of bright radio sources. Additional observations with the Owens Valley Radio Observatory (OVRO) millimeter array were used to assist in the location and removal of radio point sources. Applying a Bayesian analysis to the raw visibility data, we place limits on CMB anisotropy flat-band power of Q(sub flat) = 5.6(sub -5.6)(exp 3.0) microK and Q(sub flat) < 14.1 microK at 68% and 95% confidence, respectively. The sensitivity of this experiment to flat-band power peaks at a multipole of I = 5470, which corresponds to an angular scale of approximately 2'. The most likely value of Q(sub flat) is similar to the level of the expected secondary anisotropies.

Construction of a resonant loop with the ICRF antenna for KSTAR

International Nuclear Information System (INIS)

Bae, Young Dug; Jeong, Sung Un; Yoon, Jae Sung; Hong, Bong Geon

2003-01-01

The antenna of the KSTAR ICRF heating system consists of four current straps, each of which is grounded at the center, and has two coaxial ports, one at each end. The top and bottom ports of each strap are fed by one transmitter. The two ports are connected at tee connector to form a resonant loop, and the coaxial feed line from the transmitter is connected to the tee. One resonant loop with the proto-type antenna is built at the RF test stand in KAERI. It is composed with one current strap, one tee connector and two arms connecting them. Each arm consists of a 6-inch vacuum transmission line, a vacuum feed through, a part of pressurized 9-inch coaxial line, and an adjustable phase shifter to cover wide frequency range of 25-60 MHz. Total electrical length is changeable from 45 to 51 m. Many voltage probes and directional couplers are installed to measure RF voltage of the standing wave, power flow and phase difference. Resonant and matching conditions are investigated for various frequencies

Cellular responses to 836 MHz and 1,765 GHz CDMA radiations

International Nuclear Information System (INIS)

Park, Woong Yang; Seo, Jeong Sun; Paik, Jung Ki; Lim, Kye Jae; Yoon, Hyun Bo

2002-01-01

The effect of radiofrequency (RF) radiation in the cellular phone communication range (836.5 MHz and 1.765 GHz code division multiple access, CDMA) on tumorigenesis and other health effect was measured using the in vitro cell culture system. To determine whether 836.5 MHz or 1.765 GHz CDMA radiations have any genotoxic effects to induce neoplastic transformation, C3H 10T1/2 cells were exposed to either of the above radiations at a specific absorption rate (SAR) of 35.6W/Kg (836.5 MHz) and 38.2 W/kg(1.765 GHz) or sham- exposed at the same time for 7 days. Cells were maintained in incubators and refed with fresh growth medium every 3 days. At this SAR, radiofrequency radiation did not induce neoplastic transformation in vitro. The extent of alteration in the kinetics of cell proliferation indicated no significant differences between RF-radiation- and sham-exposed cells with respect to MTS assay and 8-OHdG. Under this experimental conditions tested, there is no evidence for the induction of genotoxic indices in human and mouse cells exposed in vitro for 7 days to 836.5 MHz or 1.765 GHz RF radiation at SARs of up to 35.6 or 38.2 W/kg

A 31 GHz Survey of Low-Frequency Selected Radio Sources

Science.gov (United States)

Mason, B. S.; Weintraub, L.; Sievers, J.; Bond, J. R.; Myers, S. T.; Pearson, T. J.; Readhead, A. C. S.; Shepherd, M. C.

2009-10-01

The 100 m Robert C. Byrd Green Bank Telescope and the 40 m Owens Valley Radio Observatory telescope have been used to conduct a 31 GHz survey of 3165 known extragalactic radio sources over 143 deg2 of the sky. Target sources were selected from the NRAO VLA Sky Survey in fields observed by the Cosmic Background Imager (CBI); most are extragalactic active galactic nuclei (AGNs) with 1.4 GHz flux densities of 3-10 mJy. The resulting 31 GHz catalogs are presented in full online. Using a maximum-likelihood analysis to obtain an unbiased estimate of the distribution of the 1.4-31 GHz spectral indices of these sources, we find a mean 31-1.4 GHz flux ratio of 0.110 ± 0.003 corresponding to a spectral index of α = -0.71 ± 0.01 (S ν vprop να) 9.0% ± 0.8% of sources have α > - 0.5 and 1.2% ± 0.2% have α > 0. By combining this spectral-index distribution with 1.4 GHz source counts, we predict 31 GHz source counts in the range 1 mJy S 31) = (16.7 ± 1.7) deg-2(S 31/1 mJy)-0.80±0.07. We also assess the contribution of mJy-level (S 1.4 GHz < 3.4 mJy) radio sources to the 31 GHz cosmic microwave background power spectrum, finding a mean power of ell(ell + 1)C src ell/(2π) = 44 ± 14 μK2 and a 95% upper limit of 80 μK2 at ell = 2500. Including an estimated contribution of 12 μK2 from the population of sources responsible for the turn-up in counts below S 1.4 GHz = 1 mJy, this amounts to 21% ± 7% of what is needed to explain the CBI high-ell excess signal, 275 ± 63 μK2. These results are consistent with other measurements of the 31 GHz point-source foreground.

Study of lower hybrid current drive system in tokamak fusion devices

International Nuclear Information System (INIS)

Maebara, Sunao

2001-01-01

This report describes R and D of a high-power klystron, RF vacuum window, low-outgassing antenna and a front module for a plasma-facing antenna aiming the 5 GHz Lower Hybrid Current Drive (LHCD) system for the next Tokamak Fusion Device. 5 GHz klystron with a low-perveances of 0.7 μP is designed for a high-power and a high-efficiency, the output-power of 715 kW and the efficiency of 63%, which are beyond the conventional design scaling of 450 kW-45%, are performed using the prototype klystron which operates at the pulse duration of 15 μsec. A new pillbox window, which has an oversized length in both the axial and the radial direction, are designed to reduce the RF power density and the electric field strength at the ceramics. It is evaluated that the power capability by cooling edge of ceramics is 1 MW with continuous-wave operation. The antenna module using Dispersion Strengthened Copper which combines high mechanical property up to 500degC with high thermal conductivity, are developed for a low-outgassing antenna in a steady state operation. It is found that the outgassing rate is in the lower range of 4x10 -6 Pam 3 /sm 2 at the module temperature of 300degC, which requires no active vacuum pumping of the LHCD antenna. A front module using Carbon Fiber Composite (CFC) are fabricated and tested for a plasma facing antenna which has a high heat-resistive. Stationary operation of the CFC module with water cooling is performed at the RF power of 46 MWm -2 (about 2 times higher than the design value) during 1000 sec, it is found that the outgassing rate is less than 10 -5 Pam 3 /sm 2 which is low enough for an antenna material. (author)

Data acquisition and processing system of the electron cyclotron emission imaging system of the KSTAR tokamak

International Nuclear Information System (INIS)

Kim, J. B.; Lee, W.; Yun, G. S.; Park, H. K.; Domier, C. W.; Luhmann, N. C. Jr.

2010-01-01

A new innovative electron cyclotron emission imaging (ECEI) diagnostic system for the Korean Superconducting Tokamak Advanced Research (KSTAR) produces a large amount of data. The design of the data acquisition and processing system of the ECEI diagnostic system should consider covering the large data production and flow. The system design is based on the layered structure scalable to the future extension to accommodate increasing data demands. Software architecture that allows a web-based monitoring of the operation status, remote experiment, and data analysis is discussed. The operating software will help machine operators and users validate the acquired data promptly, prepare next discharge, and enhance the experiment performance and data analysis in a distributed environment.

Lower-hybrid counter current drive for edge current density modification in DIII-D

International Nuclear Information System (INIS)

Fenstermacher, M.E.; Nevins, W.M.; Porkolab, M.; Bonoli, P.T.; Harvey, R.W.

1994-01-01

Each of the Advanced Tokamak operating modes in DIII-D is thought to have a distinctive current density profile. So far these modes have only been achieved transiently through experiments which ramp the plasma current and shape. Extension of these modes to steady state requires non-inductive current profile control, e.g., with lower hybrid current drive (LHCD). Calculations of LHCD have been done for DIII-D using the ACCOME and CQL3D codes, showing that counter driven current at the plasma edge can cancel some of the undesirable edge bootstrap current and potentially extend the VH-mode. Results will be presented for scenarios using 2.45 GHz LH waves launched from both the midplane and off-axis ports. The sensitivity of the results to injected power, n e and T e , and launched wave spectrum will also be shown

High power tests of beryllium oxide windows to the lower hybrid current drive launcher in JET

International Nuclear Information System (INIS)

Ekedahl, A.; Brandon, M.; Finburg, P.

1999-01-01

The vacuum windows to the 3.70 GHz Lower Hybrid Current Drive (LHCD) system in JET were originally designed to withstand 350 kW for 20 s with VSWR ≤ 1.8. High power RF tests of the windows have been carried out in the LHCD test facility at JET. All windows that were tested could operate at 500 kW for 10 s in a matched load. Two windows passed an endurance test at 250 kW for 20 s with the windows terminated in a short circuit. One window also passed this endurance test without active cooling. The results show that this type of window can be used in a new advanced launcher, as proposed for ITER, in which the output power from each klystron (P ≤ 500 kW) will be transmitted through one waveguide and one vacuum window. (author)

Left-handed compact MIMO antenna array based on wire spiral resonator for 5-GHz wireless applications

Science.gov (United States)

Alqadami, Abdulrahman Shueai Mohsen; Jamlos, Mohd Faizal; Soh, Ping Jack; Rahim, Sharul Kamal Abdul; Narbudowicz, Adam

2017-01-01

A compact coplanar waveguide-fed multiple-input multiple-output antenna array based on the left-handed wire loaded spiral resonators (SR) is presented. The proposed antenna consists of a 2 × 2 wire SR with two symmetrical microstrip feed lines, each line exciting a 1 × 2 wire SR. Left-handed metamaterial unit cells are placed on its reverse side and arranged in a 2 × 3 array. A reflection coefficient of less than -16 dB and mutual coupling of less than -28 dB are achieved at 5.15 GHz WLAN band.

InP MMIC Chip Set for Power Sources Covering 80-170 GHz

Science.gov (United States)

Ngo, Catherine

2001-01-01

We will present a Monolithic Millimeter-wave Integrated Circuit (MMIC) chip set which provides high output-power sources for driving diode frequency multipliers into the terahertz range. The chip set was fabricated at HRL Laboratories using a 0.1-micrometer gate-length InAlAs/InGaAs/InP high electron mobility transistor (HEMT) process, and features transistors with an f(sub max) above 600 GHz. The HRL InP HEMT process has already demonstrated amplifiers in the 60-200 GHz range. In this paper, these high frequency HEMTs form the basis for power sources up to 170 GHz. A number of state-of-the-art InP HEMT MMICs will be presented. These include voltage-controlled and fixed-tuned oscillators, power amplifiers, and an active doubler. We will first discuss an 80 GHz voltage-controlled oscillator with 5 GHz of tunability and at least 17 mW of output power, as well as a 120 GHz oscillator providing 7 mW of output power. In addition, we will present results of a power amplifier which covers the full WRIO waveguide band (75-110 GHz), and provides 40-50 mW of output power. Furthermore, we will present an active doubler at 164 GHz providing 8% bandwidth, 3 mW of output power, and an unprecedented 2 dB of conversion loss for an InP HEMT MMIC at this frequency. Finally, we will demonstrate a power amplifier to cover 140-170 GHz with 15-25 mW of output power and 8 dB gain. These components can form a power source in the 155-165 GHz range by cascading the 80 GHz oscillator, W-band power amplifier, 164 GHz active doubler and final 140-170 GHz power amplifier for a stable, compact local oscillator subsystem, which could be used for atmospheric science or astrophysics radiometers.

An Empirical Outdoor-to-Indoor Path Loss Model from below 6 GHz to cm-Wave Frequency Bands

DEFF Research Database (Denmark)

Rodriguez Larrad, Ignacio; Nguyen, Huan Cong; Kovács, István Z.

2017-01-01

This letter presents an empirical multi-frequency outdoor-to-indoor path loss model. The model is based on measurements performed on the exact same set of scenarios for different frequency bands ranging from traditional cellular allocations below 6 GHz (0.8, 2, 3.5 and 5.2 GHz), up to cm-wave fre......This letter presents an empirical multi-frequency outdoor-to-indoor path loss model. The model is based on measurements performed on the exact same set of scenarios for different frequency bands ranging from traditional cellular allocations below 6 GHz (0.8, 2, 3.5 and 5.2 GHz), up to cm...

154 GHz collective Thomson scattering in LHD

Science.gov (United States)

Tanaka, K.; Nishiura, M.; Kubo, S.; Shimozuma, T.; Saito, T.; Moseev, D.; Abramovic, I.

2018-01-01

Collective Thomson scattering (CTS) was developed by using a 154 GHz gyrotron, and the first data has been obtained. Already, 77 GHz CTS has worked successfully. However, in order to access higher density region, 154 GHz option enhances the usability that reduces the refraction effect, which deteriorates in the local measurements. The system in the down converted frequency was almost identical to the system for 77 GHz. Probing beam, a notch filter, a mixer, and a local oscillator in the receiver system for 77 GHz option were replaced to those for the 154 GHz option. 154 GHz gyrotron was originally prepared for the second harmonic electron cyclotron heating (ECRH) at 2.75 T. However, scattering signal was masked by the second harmonic electron cyclotron emission (ECE) at 2.75 T. Therefore, 154 GHz CTS was operated at 1.375 T with fourth harmonic ECE, and an acceptable signal to noise ratio was obtained. There is a signature of fast ion components with neutral beam (NB) injection. In addition, the CTS spectrum became broader in hydrogen discharge than in deuterium discharge, as the theoretical CTS spectrum expects. This observation indicates a possibility to identify ion species ratio by the 154 GHz CTS diagnostic.

An applicable 5.8 GHz wireless power transmission system with rough beamforming to Project Loon

Directory of Open Access Journals (Sweden)

Chang-Jun Ahn

2016-06-01

Full Text Available In recent, Google proposed the Project Loon being developed with the mission of providing internet access to rural and remote areas using high-altitude balloons. In this paper, we describe an applicable prototype of 5.8 GHz wireless power transmission system with rough beamforming method to Project Loon. From the measurement results, transmit beamforming phased array antenna can transmit power more efficiently compared to a horn antenna and array antenna without beamforming with increasing the transmission distance. For the transmission distance of 1000 mm, transmit beamforming phased array antenna can obtain higher received power about 1.46 times compared to array antenna without transmit beamforming.

Integrated 60GHz RF beamforming in CMOS

CERN Document Server

Yu, Yikun; van Roermund, Arthur H M

2011-01-01

""Integrated 60GHz RF Beamforming in CMOS"" describes new concepts and design techniques that can be used for 60GHz phased array systems. First, general trends and challenges in low-cost high data-rate 60GHz wireless system are studied, and the phased array technique is introduced to improve the system performance. Second, the system requirements of phase shifters are analyzed, and different phased array architectures are compared. Third, the design and implementation of 60GHz passive and active phase shifters in a CMOS technology are presented. Fourth, the integration of 60GHz phase shifters

Thermal and mechanical analysis of ITER-relevant LHCD antenna elements

International Nuclear Information System (INIS)

Marfisi, L.; Goniche, M.; Hamlyn-Harris, C.; Hillairet, J.; Artaud, J.F.; Bae, Y.S.; Belo, J.; Berger-By, G.; Bernard, J.M.; Cara, Ph.; Cardinali, A.; Castaldo, C.; Ceccuzzi, S.; Cesario, R.; Decker, J.; Delpech, L.; Ekedahl, A.; Garcia, J.; Garibaldi, P.; Guilhem, D.

2011-01-01

A 20 MW Lower Hybrid Current Drive system using an antenna based on the Passive-Active Multijunction (PAM) concept is envisaged on ITER. This paper gives an overview of the mechanical analysis, modeling and design carried out on two major elements of the antenna: the grill front face, and the RF feed-through or windows. The front face will have to withstand high heat and fast neutrons fluxes directly from the plasma. It will be actively cooled and present a beryllium coating upon ITER requirement. The RF window being a critical safety importance class component (SIC) because of its tritium confinement function, two of them will be put in series on each line to achieve a double barrier. A design of a water cooled 5 GHz CW RF 'pillbox' window capable of sustaining 500 kW of transmitted power is proposed. Both studies allow to move forward, and focus on critical issues, such as manufacturing processes and R and D associated programs including tests of mock-ups.

Fluxon induced surface resistance and field emission in niobium films at 1.5 GHz

CERN Document Server

Benvenuti, Cristoforo; Darriulat, Pierre; Peck, M A; Valente, A M; Van't Hof, C A

2001-01-01

The surface resistance of superconducting niobium films induced by the presence of trapped magnetic flux, presumably in the form of a pinned fluxon lattice, is shown to be modified by the presence of a field emitting impurity or defect. The modification takes the form of an additional surface resistance proportional to the density of the fluxon lattice and increasing linearly with the amplitude of the microwave above a threshold significantly lower than the field emission threshold. Such an effect, a precursor of electron emission, is observed for the first time in a study using radiofrequency cavities operating at their fundamental 1.5 GHz frequency. The measured properties of the additional surface resistance severely constrain possible explanations of the observed effect. (23 refs).

Conceptual Design Studies of the KSTAR Bay-Nm Cassette and Thomson Scattering Optics

International Nuclear Information System (INIS)

Feder, R.; Ellis, R.; Johnson, D.; Park, H.; Lee, H.G.

2005-01-01

A Multi-Channel Thomson Scattering System viewing the edge and core of the KSTAR plasma will be installed at the mid-plane port Bay-N. An engineering design study was undertaken at PPPL in collaboration with the Korea Basic Science Institute (KBSI) to determine the optimal optics and cassette design. Design criteria included environmental, mechanical and optical factors. All of the optical design options have common design features; the Thomson Scattering laser, an in-vacuum shutter, a quartz heat shield and primary vacuum window, a set of optical elements and a fiber optic bundle. Neutron radiation damage was a major factor in the choice of competing lens-based and mirror-based optical designs. Both the mirror based design and the lens design are constrained by physical limits of the Bay-N cassette and interference with the Bay-N micro-wave launcher. The cassette will contain the optics and a rail system for maintenance of the optics

Modulation of electromagnetic and absorption properties in 18-26.5 GHz frequency range of strontium hexaferrites with doping of cobalt-zirconium

Science.gov (United States)

Pubby, Kunal; Narang, Sukhleen Bindra; Kaur, Prabhjyot; Chawla, S. K.

2017-05-01

Hexaferrite nano-particles of stoichiometric composition {{Sr}}{({{CoZr}})_x}{{F}}{{{e}}_{12 - 2x}}{{{O}}_{19}}, with x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0 were prepared using sol-gel auto-combustion route owing to its advantages such as low sintering temperature requirement, homogeneity and uniformity of grains. Tartaric acid as a fuel was utilized to complete the chemical reaction. The goal of this study is to analyse the effect of co-substitution of cobalt and zirconium on the electromagnetic and absorption properties of pure {{SrF}}{{{e}}_{12}}{{{O}}_{19}} hexaferrite. The properties were measured on the rectangular pellets of thickness 2.5 mm for K-frequency band using Vector Network Analyzer. The doping of Co-Zr has resulted in increase in real as well as imaginary parts of permittivity. The values of real permittivity lie in the range 3.6-7.0 for all the composition. The real part of permeability remains in range 0.7-1.6 in the studied frequency band for all the samples and shows slightly increasing trend with frequency. The maximum values of dielectric loss tangent peak (3.04) and magnetic loss tangent peak (2.34), among all the prepared compositions, have been observed for composition x = 0.2. Compositions with x = 0.6 and x = 0.0 also have high dielectric and magnetic loss peaks. Dielectric loss peaks are attributed to dielectric resonance and magnetic loss peaks are attributed to natural resonance. Experimentally determined reflection loss results show that all six compositions of prepared series have high values of absorption to propose them as single-layer absorbers in 18-26.5 GHz frequency range. The composition with x = 0.2 has maximum absorption capacity with reflection loss peak of -37.2 dB at 24.3 GHz frequency. The undoped composition also has high absorption peak (-25.46 dB), but -10 dB absorption bandwidth is minimum (2.2 GHz) out of the present series. Maximum absorption bandwidth is obtained for x = 1.0 (4.1 GHz). Other doped compositions also

Modulation of electromagnetic and absorption properties in 18-26.5 GHz frequency range of strontium hexaferrites with doping of cobalt-zirconium

Energy Technology Data Exchange (ETDEWEB)

Pubby, Kunal; Narang, Sukhleen Bindra [Guru Nanak Dev University, Department of Electronics Technology, Amritsar (India); Kaur, Prabhjyot; Chawla, S.K. [Guru Nanak Dev University, Department of Chemistry, Centre for Advanced Studies-I, Amritsar (India)

2017-05-15

Hexaferrite nano-particles of stoichiometric composition Sr(CoZr){sub x}Fe{sub 12-2x}O{sub 19}, with x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0 were prepared using sol-gel auto-combustion route owing to its advantages such as low sintering temperature requirement, homogeneity and uniformity of grains. Tartaric acid as a fuel was utilized to complete the chemical reaction. The goal of this study is to analyse the effect of co-substitution of cobalt and zirconium on the electromagnetic and absorption properties of pure SrFe{sub 12}O{sub 19} hexaferrite. The properties were measured on the rectangular pellets of thickness 2.5 mm for K-frequency band using Vector Network Analyzer. The doping of Co-Zr has resulted in increase in real as well as imaginary parts of permittivity. The values of real permittivity lie in the range 3.6-7.0 for all the composition. The real part of permeability remains in range 0.7-1.6 in the studied frequency band for all the samples and shows slightly increasing trend with frequency. The maximum values of dielectric loss tangent peak (3.04) and magnetic loss tangent peak (2.34), among all the prepared compositions, have been observed for composition x = 0.2. Compositions with x = 0.6 and x = 0.0 also have high dielectric and magnetic loss peaks. Dielectric loss peaks are attributed to dielectric resonance and magnetic loss peaks are attributed to natural resonance. Experimentally determined reflection loss results show that all six compositions of prepared series have high values of absorption to propose them as single-layer absorbers in 18-26.5 GHz frequency range. The composition with x = 0.2 has maximum absorption capacity with reflection loss peak of -37.2 dB at 24.3 GHz frequency. The undoped composition also has high absorption peak (-25.46 dB), but -10 dB absorption bandwidth is minimum (2.2 GHz) out of the present series. Maximum absorption bandwidth is obtained for x = 1.0 (4.1 GHz). Other doped compositions also have high absorption bandwidth

A compact 5.5 GHz band-rejected UWB antenna using complementary split ring resonators.

Science.gov (United States)

Islam, M M; Faruque, M R I; Islam, M T

2014-01-01

A band-removal property employing microwave frequencies using complementary split ring resonators (CSRRs) is applied to design a compact UWB antenna wishing for the rejection of some frequency band, which is meanwhile exercised by the existing wireless applications. The reported antenna comprises optimization of a circular radiating patch, in which slotted complementary SRRs are implanted. It is printed on low dielectric FR4 substrate material fed by a partial ground plane and a microstrip line. Validated results exhibit that the reported antenna shows a wide bandwidth covering from 3.45 to more than 12 GHz, with a compact dimension of 22 × 26 mm(2), and VSWR WLAN band.

Analysis of the effect of imbalanced flow on the KSTAR's superconducting magnet

International Nuclear Information System (INIS)

Lee, H. J.; Park, Y. M.; Park, D. S.

2014-01-01

The KSTAR superconducting (SC) magnets are cable-in-conduit-conductor (CICC) type magnets, which have a hundred parallel and twisted SC strands in a square conduit with a porosity of 0.36. They are cooled by the forced flow of supercritical helium with a 2 bar pressure drop. A flow imbalance test of the magnet cooling channels, one of the quality assurance processes, was conducted using Ar gas at room temperature during the magnet's manufacture, and was carried out again after assembly. In those tests, the flow imbalance was measured to be within at most ±10% for the all cooling channels, which satisfied the criterion (±20%). During individual tests of the magnets, the tendency of the flow imbalance showed that the mass flow rate of the upper (U) magnets PF1, PF2, PF5, PF6, and PF7 was higher than that of the lower (L) magnets. On the other hand, the mass flow rate of the upper magnets PF3 and PF4 was lower than that of the lower magnets. After assembly, this imbalance became more serious, and the measured mass flow rate of the upper magnets was higher than that of lower magnet at the PF2, PF3 PF4, and PF5 magnets. This imbalance can influence the temperature and the pressure of supercritical helium, as well as accelerate reversal flow and limit operating performance. In this paper, the helium behavior is analyzed and is explained to be due to the flow imbalance in the PF magnet.

LHCD and coupling experiments with an ITER-like PAM launcher on the FTU tokamak

International Nuclear Information System (INIS)

Pericoli Ridolfini, V.; Apicella, M.L.; Barbato, E.; Buratti, P.; Calabro, G.; Cardinali, A.; Mirizzi, F.; Panaccione, L.; Podda, S.; Tuccillo, A.A.; Bibet, Ph.; Granucci, G.; Sozzi, C.

2005-01-01

Successful experimental tests on a PAM (passive active multijunction) prototype antenna for the Lower Hybrid (LH) waves similar to that foreseen for ITER have been carried out on FTU. The power level routinely achieved without any fault in the transmission lines for the maximum time allowed by the LH power plant, i.e. 0.9 s, is 250 kW versus a design value of 270. It corresponds to 50 MW/m 2 through the ITER antenna active area if it is scaled for the different LH frequencies (5 GHz in ITER, 8 GHz in FTU) and it is more than 1.4 times the goal of the ITER design (33 MW/m 2 ). The test results validate the main features indicated by the simulation codes, concerning the power handling, the coupling and the launched N parallel spectrum. The power reflection coefficient R c is always ≤ 2.5%, once the PAM launcher has been properly conditioned, even with the grill mouth retracted 2 mm inside the port shadow, with density in front of the launcher very close or even lower than the cut-off value. The current drive efficiency is comparable to a conventional grill in similar conditions, once the lower directivity is taken into account. The flexibility in the N parallel spectrum is confirmed by the HXR and ECE spectra. Conditioning the PAM to operate at the ITER equivalent power level has required only one day of RF operation, without a previous baking of the waveguides. (author)

Design and Characterization of a 5.2 GHz/2.4 GHz Fractional- Frequency Synthesizer for Low-Phase Noise Performance

Directory of Open Access Journals (Sweden)

Dai Foster F

2006-01-01

Full Text Available This paper presents a complete noise analysis of a -based fractional- phase-locked loop (PLL based frequency synthesizer. Rigorous analytical and empirical formulas have been given to model various phase noise sources and spurious components and to predict their impact on the overall synthesizer noise performance. These formulas have been applied to an integrated multiband WLAN frequency synthesizer RFIC to demonstrate noise minimization through judicious choice of loop parameters. Finally, predicted and measured phase jitter showed good agreement. For an LO frequency of 4.3 GHz, predicted and measured phase noise was rms and rms, respectively.

Recent progresses on high performance steady-state plasmas in the superconducting tokamak TRIAM-1M

International Nuclear Information System (INIS)

Itoh, Satoshi; Sato, Kohnosuke; Nakamura, Kazuo

1999-01-01

The overview of TRIAM-1M experiments is described. The up-to-date issues for steady-state operation are presented through the experience of the achievement of super ultra long tokamak discharges (SULD) sustained by lower hybrid current drive (LHCD) over 2 hours. The importance of the control of an initial phase of plasma, the avoidance of the concentration of huge heat load, the wall conditioning, and abrupt stop of the long discharges are proposed as the indispensable issues for the achievement of the steady-state operation of tokamak. A high ion temperature (HIT) discharge fully sustained by 2.45 GHz LHCD with both high ion temperature and steep temperature gradient is successfully demonstrated for longer than 1 min in the limiter configuration. The HIT discharges can be obtained in the narrow window of density and position. Moreover, the avoidance of the concentration of heat load on a limiter is the key point for the achievement and its long sustainment. As the effective thermal insulation between the wall and the plasma is improved on the single null configuration, HIT discharges with peak ion temperature > 5keV and steeper gradient up to 85 keV/m can be achieved by the exquisite control of density and position. The plasmas with high κ ∼1.5 can be also demonstrated for longer than 1 min. The current profile is also well-controlled for about 2 orders in magnitude longer than the current diffusion time using combined LHCD. The serious damage to the material of the first wall caused by energetic neutral particles produced via charge exchange process is also described. As the neutral particles cannot be affected by magnetic field, this damage by neutral particles must be avoided by the new technique. (author)

Analysis of a prototype of a novel 1.5 MW, 170 GHz coaxial cavity gyrotron

International Nuclear Information System (INIS)

Rzesnicki, T.

2007-06-01

A 170 GHz, 2 MW coaxial cavity gyrotron is under development at the Institut fuer Hochleistungsimpuls- und Mikrowellentechnik (IHM) at Forschungszentrum Karlsruhe (FZK) which will be used as a high power microwave source for heating, current drive and stability control of plasmas in the International Thermonuclear Experimental Reactor (ITER). At frequencies above about 100 GHz the output power of conventional gyrotrons with cylindrical hollow waveguide cavities is limited to 1 MW in CW operation mainly due to the high Ohmic losses and the space charge voltage depression of the electron beam. The coaxial geometry enables a reduction of the mode competition in the gyrotron resonator and decreases also the influence of the beam voltage depression. As result a very high order operating mode (for example TE34,19 at 170 GHz) can be chosen which ultimately allows to increase the output power of the gyrotron in CW operation to a value as high as 2 MW. A first prototype of the 170 GHz, 2 MW coaxial cavity gyrotron has been designed, built and experimentally tested in short pulse operation at FZK. The main goal of this work was to investigate experimentally the design of the critical gyrotron components such as electron gun, resonator and a quasi-optical RF system. Those components are same as used in the first industrial coaxial prototype gyrotron for ITER. During the experiments a strong instability was observed inside the gyrotron tube due to the excitation of parasitic low frequency oscillations. The mechanism of the oscillations has been studied and possibilities for their suppression of these oscillations are proposed and experimentally verified. The RF output system is one of the most critical components. It is responsible for the coupling of the gyrotron power out of the gyrotron by converting the microwave power generated in the TE 34,19 -mode into a fundamental free space TEM 0,0 ''Gaussian'' mode. The performance of the RF output system has been tested in low

Measurement Results of the Caltech Submillimeter Observatory 230 GHz and 460 GHz Balanced Receivers

Science.gov (United States)

Kooi, J. W.; Monje, R. R.; Force, B. L.; Rice, F.; Miller, D.; Phillips, T. G.

2010-03-01

The Caltech Submillimeter observatory (CSO) is located on top of Mauna Kea, Hawaii, at an altitude of 4.2km. The existing suite of heterodyne receivers covering the submillimeter band is rapidly aging, and in need of replacement. To this extend we have developed a family of balanced receivers covering the astrophysical important 180-720 GHz atmospheric windows. For the CSO, wide IF bandwidth receivers are implemented in a balanced receiver configuration with dual frequency observation capability. This arrangement was opted to be an optimal compromise between scientific merit and finite funding. In principle, the balanced receiver configuration has the advantage that common mode amplitude noise in the LO system is canceled, while at the same time utilizing all available LO power. Both of these features facilitate the use of commercially available synthesized LO system. In combination with a 4 GHz IF bandwidth, the described receiver layout allows for rapid high resolution spectral line surveys. Dual frequency observation is another important mode of operation offered by the new facility instrumentation. Two band observations are accomplished by separating the H and V polarizations of the incoming signal and routing them via folded optics to the appropriate polarization sensitive balanced mixer. Scientifically this observation mode facilitates pointing for the higher receiver band under mediocre weather conditions and a doubling of scientific throughput (2 x 4 GHz) under good weather conditions. Not only do these changes greatly enhance the spectroscopic capabilities of the CSO, they also enable the observatory to be integrated into the Harvard-Smithsonian Submillimeter Array (eSMA) as an additional baseline. The upgrade of the 345 GHz/650 GHz dual band balanced receivers is not far behind. All the needed hardware has been procured, and commissioning is expected the summer of 2010. The SIS junctions are capable of a 2-12 GHz bandwidth.

Observations Of Gamma-ray Loud Blazars With The VLBA At 5 GHz

Science.gov (United States)

Linford, Justin; Taylor, G. B.; Romani, R.; Readhead, A. C. S.; Reeves, R.; Richards, J. L.; Helmboldt, J. F.

2011-01-01

The Fermi Gamma-ray Space Telescope has been scanning the sky for more than a year. About half of the sources detected by Fermi's Large Area Telesope (LAT) are active galactic nuclei (AGN). Nearly all of these gamma-ray loud AGN are blazars; strong, compact radio emitters that exhibit variability in their flux and apparent superluminal motion in their jets. Several groups are currently monitoring the radio properties of these gamma-ray loud blazars. We present results from both archival and contemporaneous observations of 200 LAT-detected blazars using the Very Long Baseline Array (VLBA) at a frequency of 5 GHz (wavelength of 6 cm). Our large, flux-limited sample provides unique insights into the mechanism that produces strong gamma-ray emissions. We explore the parsec-scale properties of the cores and jets of these highly energetic objects, including core polarization. We compare the gamma-ray loud blazars to their gamma-ray quiet counterparts in the VLBA Imaging and Polarimetry Survey (VIPS). We also investigate the differences between the BL Lacertae objects (BL Lacs) and flat-spectrum radio quasars (FSRQs).

The Rainfall Intensity Effects on 1–13 GHz UWB-Based 5G System for Outdoor Applications

Directory of Open Access Journals (Sweden)

Joko Suryana

2017-01-01

Full Text Available This paper reports a research contribution on tropical outdoor channel characterization in 1–13 GHz band for 5G systems. This 1–13 GHz ultra-wideband (UWB channel characterization is formulated with rain intensity as the most important variable, from 20 mm/h to 200 mm/h. Tropical rain will cause pulse broadening and distorts the transmitted symbols, so the probability of symbol errors will increase. In this research, the bit error rate (BER performance evaluation is done using both matched filtering or correlator-based receivers. At no rain conditions, BER 10−6 will be attained at signal to noise ratio (SNR 5 dB, but at rainfall intensity 200 mm/h, the BER will fall to 10−2 for matched filter and 5×10-2 for correlator-based receivers. For improving the BER performance, an adaptive nonlinear phase equalizer is proposed which adopts multiple allpass biquad infinite impulse response (IIR filters combined with low-order finite impulse response (FIR filter to mitigate the nonlinearity phase and differential attenuation of magnitude responses due to antenna and tropical outdoor UWB channel effects. Our simulation results show that the proposed equalizer has worked successfully with BER 10−6 on the rain rate that is exceeded for 0.01% of the time (R0.01 rain intensity or 99.99% availability. In addition, at rainfall rate 120 mm/h, the proposed nonlinear phase equalizer can give 9 dB signal improvement.

110GHz ECH on DIII-D

International Nuclear Information System (INIS)

Cary, W.P.; Allen, J.C.; Callis, R.W.; Doane, J.L.; Harris, T.E.; Moetler, C.P.; Neren, A.; Prater, P.; Rensen, D.

1992-01-01

This paper reports on a new high power electron cyclotron heating (ECH) system which has been introduced on DIII-D. This system is designed to operate at 110 GHz with a total output power of 2 MW. The system consists of four Varian VGT-8011 gyrotrons (output power of 500 kW), and their associated support equipment. All components have been designed for up to a 10 second pulse duration. The 110 GHz system is intended to further progress in rf current drive experiments on DIII-D when used in conjunction with the existing 60 GHz ECH (1. 6 MW) , and the 30-60 MHz ICH (2MW) systems. H-mode physics, plasma stabilization experiments and transport studies are also to be conducted at 110 GHz

37 GHz METHANOL MASERS : HORSEMEN OF THE APOCALYPSE FOR THE CLASS II METHANOL MASER PHASE?

International Nuclear Information System (INIS)

Ellingsen, S. P.; Breen, S. L.; Sobolev, A. M.; Voronkov, M. A.; Caswell, J. L.; Lo, N.

2011-01-01

We report the results of a search for class II methanol masers at 37.7, 38.3, and 38.5 GHz toward a sample of 70 high-mass star formation regions. We primarily searched toward regions known to show emission either from the 107 GHz class II methanol maser transition, or from the 6.035 GHz excited OH transition. We detected maser emission from 13 sources in the 37.7 GHz transition, eight of these being new detections. We detected maser emission from three sources in the 38 GHz transitions, one of which is a new detection. We find that 37.7 GHz methanol masers are only associated with the most luminous 6.7 and 12.2 GHz methanol maser sources, which in turn are hypothesized to be the oldest class II methanol sources. We suggest that the 37.7 GHz methanol masers are associated with a brief evolutionary phase (of 1000-4000 years) prior to the cessation of class II methanol maser activity in the associated high-mass star formation region.

A 60 GHz Frequency Generator Based on a 20 GHz Oscillator and an Implicit Multiplier

NARCIS (Netherlands)

Zong, Z.; Babaie, M.; Staszewski, R.B.

2016-01-01

This paper proposes a mm-wave frequency generation technique that improves its phase noise (PN) performance and power efficiency. The main idea is that a fundamental 20 GHz signal and its sufficiently strong third harmonic at 60 GHz are generated simultaneously in a single oscillator. The desired 60

Study of the surface resistance of superconducting niobium films at 1.5 GHz

CERN Document Server

Benvenuti, Cristoforo; Campisi, I E; Darriulat, Pierre; Peck, M A; Russo, R; Valente, A M

1999-01-01

A systematic study of superconducting properties of niobium films sputtered on the inner wall of radiofrequency cavities is presented. The measured quantities include in particular the response to 1.5 GHz microwaves, the critical temperature, the penetration depth and the magnetic penetration field. In addition to films grown in different gas discharges (Xe, Kr, Ar and Ar/Ne mixtures) and to films grown on substrates prepared under different conditions, the study also includes bulk niobium cavities. The surface resistance is analysed in terms of its dependence on temperature, on RF field and, when relevant, on the density of trapped fluxons. A simple parameterisation is found to give a good fit to the data. Once allowance for the presence of impurities and defects is made by means of a single parameter, the electron mean free path, good agreement with BCS theory is observed. The fluxon-induced losses are studied in detail and their dependence on RF field, on temperature and on the density of trapped fluxons i...

Laboratory Heterodyne Spectrometers Operating at 100 and 300 GHZ

Science.gov (United States)

Maßen, Jakob; Wehres, Nadine; Hermanns, Marius; Lewen, Frank; Heyne, Bettina; Endres, Christian; Graf, Urs; Honingh, Netty; Schlemmer, Stephan

2017-06-01

Two new laboratory heterodyne emission spectrometers are presented that are currently used for high-resolution rotational spectroscopy of complex organic molecules. The room temperature heterodyne receiver operating between 80-110 GHz, as well as the SIS heterodyne receiver operating between 270-370 GHz allow access to two very important frequency regimes, coinciding with Bands 3 and 7 of the ALMA (Atacama Large Millimeter Array) telescope. Taking advantage of recent progresses in the field of mm/submm technology, we build these two spectrometers using an XFFFTS (eXtended Fast Fourier Transform Spectrometer) for spectral acquisition. The instantaneous bandwidth is 2.5 GHz in a single sideband, spread over 32768 channels. Thus, the spectral resolution is about 76 kHz per channel and thus comparable to high resolution spectra from telescopes. Both receivers are operated in double sideband mode resulting in a total instantaneous bandwidth of 5 GHz. The system performances, in particular the noise temperatures and stabilities are presented. Proof-of-concept is demonstrated by showing spectra of methyl cyanide obtained with both spectrometers. While the transition frequencies for this molecule are very well known, intensities of those transitions can also be determined with high accuracy using our new instruments. This additional information shall be exploited in future measurements to improve spectral predictions for astronomical observations. Other future prospects concern the study of more complex organic species, such as ethyl cyanide. These aspects of the new instruments as well as limitations of the two distinct receivers will be discussed.

95 GHz methanol masers near DR 21 and DR 21(OH)

International Nuclear Information System (INIS)

Plambeck, R.L.; Menten, K.M.

1990-01-01

The BIMA array is used to map the 95-GHz 8(0) to 7 1A(+) transition of methanol and the 98-GHz J = 2-1 transition of CS toward the DR 21(OH) and DR 21 star-forming regions. Several strong methanol masers were found. The positions of the two brightest masers were measured with an accuracy of about + or - 0.3 arcsec. Toward DR 21(OH), the positions, velocities, and line shapes of the 95 GHz masers are in excellent agreement with those of the 84-GHz 5(-1) to 4 () methanol masers previously mapped by Batrla and Menten (1988), demonstrating that maser emission in both transitions originates from the same clumps of gas. The methanol masers are offset from CS emission peaks and from other known infrared and maser sources; they may possibly be clustered along the interface between outflows, traced by shock-excited H2 emission, and dense ambient gas, traced by CS emission. 25 refs

Valve-like behavior of the magnetoimpedance in the GHz range

International Nuclear Information System (INIS)

Sandacci, S.I.; Makhnovskiy, D.P.; Panina, L.V.

2004-01-01

High-frequency modification in magneto-impedance (MI) characteristics in the frequency range of 0.5-3 GHz has been investigated in 10 μm diameter amorphous microwires with a circumferential anisotropy. As frequency is increased, the peaks in the MI behavior observed at the anisotropy field reduce and become less sharp, disappearing completely at frequencies higher than 1.6 GHz. This 'valve-like' behavior can be explained by considering the dispersion properties of the effective permeability of the AC linear response combined with the rotational DC magnetization

The Atacama Cosmology Telescope: Extragalactic Sources at 148 GHz in the 2008 Survey

Science.gov (United States)

Marriage, T. A.; Juin, J. B.; Lin, Y. T.; Marsden, D.; Nolta, M. R.; Partridge, B.; Ade, P. A. R.; Aguirre, P.; Amiri, M.; Appel, J. W.;

Micro-pulses generation in ECR breakdown stimulated by gyrotron radiation at 37,5 GHz

International Nuclear Information System (INIS)

Skalyga, V.; Zorin, V.; Izotov, I.; Golubev, S.; Razin, S.; Sidorov, A.; Vodopyanov, A.

2012-01-01

The present work is devoted to experimental and theoretical investigation of the creation of short pulsed (< 100 μs) multicharged ion beams. The possibility of quasi-stationary generation of short pulsed beams under conditions of quasi-gasdynamic plasma confinement was shown in recent experiments. Later another way of such beams creation based on the Pre-glow effect was proposed. In present work it was demonstrated that in the case when duration of microwave (MW) pulse is less than formation time of Pre-glow peak, realization of a regime when ion current is negligible during MW pulse and intense multicharged ions flux appears only when MW ends could be possible. Such pulses after the end of MW were called micro-pulses. In the present work the generation of micro-pulses was observed in experiments with ECR discharge stimulated by gyrotron radiation at 37,5 GHz, 100 kW. In this case pulses with duration less than 30 μs were obtained. Probably the same effect was observed in GANIL where 14 GHz radiation was used and pulses with duration about 2 ms were registered. In present work it was shown that the intensity of such micro-pulse could be higher than intensity of Pre-glow peak at the same conditions but with longer MW pulse. The generation of micro-pulses of nitrogen and argon multicharged ions with current of a few mA and length about 30 μs after MW pulse with duration of 30-100 μs was demonstrated. The low level of impurities, high current density and rather high average charge make possible to consider such micro-pulse regime as a possibility for the creation of a short pulsed ion source. The paper is followed by the slides of the presentation. (authors)

47 CFR 25.258 - Sharing between NGSO MSS Feeder links Stations and GSO FSS services in the 29.25-29.5 GHz Bands.

Science.gov (United States)

2010-10-01

... 47 Telecommunication 2 2010-10-01 2010-10-01 false Sharing between NGSO MSS Feeder links Stations and GSO FSS services in the 29.25-29.5 GHz Bands. 25.258 Section 25.258 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Technical Standards § 25...

Rectenna Technology Program: Ultra light 2.45 GHz rectenna 20 GHz rectenna

Science.gov (United States)

Brown, William C.

1987-01-01

The program had two general objectives. The first objective was to develop the two plane rectenna format for space application at 2.45 GHz. The resultant foreplane was a thin-film, etched-circuit format fabricated from a laminate composed of 2 mil Kapton F sandwiched between sheets of 1 oz copper. The thin-film foreplane contains half wave dipoles, filter circuits, rectifying Schottky diode, and dc bussing lead. It weighs 160 grams per square meter. Efficiency and dc power output density were measured at 85% and 1 kw/sq m, respectively. Special testing techniques to measure temperature of circuit and diode without perturbing microwave operation using the fluoroptic thermometer were developed. A second objective was to investigate rectenna technology for use at 20 GHz and higher frequencies. Several fabrication formats including the thin-film scaled from 2.45 GHz, ceramic substrate and silk-screening, and monolithic were investigated, with the conclusion that the monolithic approach was the best. A preliminary design of the monolithic rectenna structure and the integrated Schottky diode were made.

Channel Characteristics and User Body Effects in an Outdoor Urban Scenario at 15 and 28 GHz

DEFF Research Database (Denmark)

Zhao, Kun; Gustafson, Carl; Liao, Qingbi

2017-01-01

The effect of a user’s body on channel characteristics for single user downlink transmission in an urban scenario for the 5th generation (5G) systems is investigated with ray-tracing at 15 GHz and 28 GHz. Three different designs of user equipment (UE) antennas are fabricated and integrated into a...

10C survey of radio sources at 15.7 GHz - II. First results

Science.gov (United States)

AMI Consortium; Davies, Mathhew L.; Franzen, Thomas M. O.; Waldram, Elizabeth M.; Grainge, Keith J. B.; Hobson, Michael P.; Hurley-Walker, Natasha; Lasenby, Anthony; Olamaie, Malak; Pooley, Guy G.; Riley, Julia M.; Rodríguez-Gonzálvez, Carmen; Saunders, Richard D. E.; Scaife, Anna M. M.; Schammel, Michel P.; Scott, Paul F.; Shimwell, Timothy W.; Titterington, David J.; Zwart, Jonathan T. L.

2011-08-01

In a previous paper (Paper I), the observational, mapping and source-extraction techniques used for the Tenth Cambridge (10C) Survey of Radio Sources were described. Here, the first results from the survey, carried out using the Arcminute Microkelvin Imager Large Array (LA) at an observing frequency of 15.7 GHz, are presented. The survey fields cover an area of ≈27 deg2 to a flux-density completeness of 1 mJy. Results for some deeper areas, covering ≈12 deg2, wholly contained within the total areas and complete to 0.5 mJy, are also presented. The completeness for both areas is estimated to be at least 93 per cent. The 10C survey is the deepest radio survey of any significant extent (≳0.2 deg2) above 1.4 GHz. The 10C source catalogue contains 1897 entries and is available online. The source catalogue has been combined with that of the Ninth Cambridge Survey to calculate the 15.7-GHz source counts. A broken power law is found to provide a good parametrization of the differential count between 0.5 mJy and 1 Jy. The measured source count has been compared with that predicted by de Zotti et al. - the model is found to display good agreement with the data at the highest flux densities. However, over the entire flux-density range of the measured count (0.5 mJy to 1 Jy), the model is found to underpredict the integrated count by ≈30 per cent. Entries from the source catalogue have been matched with those contained in the catalogues of the NRAO VLA Sky Survey and the Faint Images of the Radio Sky at Twenty-cm survey (both of which have observing frequencies of 1.4 GHz). This matching provides evidence for a shift in the typical 1.4-GHz spectral index to 15.7-GHz spectral index of the 15.7-GHz-selected source population with decreasing flux density towards sub-mJy levels - the spectra tend to become less steep. Automated methods for detecting extended sources, developed in Paper I, have been applied to the data; ≈5 per cent of the sources are found to be extended

60-GHz Millimeter-Wave Radio: Principle, Technology, and New Results

Directory of Open Access Journals (Sweden)

Nan Guo

2006-12-01

Full Text Available The worldwide opening of a massive amount of unlicensed spectra around 60 GHz has triggered great interest in developing affordable 60-GHz radios. This interest has been catalyzed by recent advance of 60-GHz front-end technologies. This paper briefly reports recent work in the 60-GHz radio. Aspects addressed in this paper include global regulatory and standardization, justification of using the 60-GHz bands, 60-GHz consumer electronics applications, radio system concept, 60-GHz propagation and antennas, and key issues in system design. Some new simulation results are also given. Potentials and problems are explained in detail.

A Wideband High-Gain Dual-Polarized Slot Array Patch Antenna for WiMAX Applications in 5.8 GHz

Directory of Open Access Journals (Sweden)

Amir Reza Dastkhosh

2012-01-01

Full Text Available A low-cost, easy-to-fabricate, wideband and high-gain dual-polarized array antenna employing an innovative microstrip slot patch antenna element is designed and fabricated. The design parameters of the antenna are optimized using commercial softwares (Microwave Office and Zeland IE3D to get the suitable -parameters and radiation patterns. Finally, the simulation results are compared to the experimental ones and a good agreement is demonstrated. The antenna has an approximately bandwidth of 14% (5.15–5.9 GHz which covers Worldwide Interoperability Microwave Access (WiMAX/5.8. It also has the peak gain of 26 dBi for both polarizations and high isolation between two ports over a wide bandwidth.

Design of a 300 GHZ broadband coupler and RF-structure

International Nuclear Information System (INIS)

Krawczyk, F.L.; Carlsten, B.E.; Earley, L.M.; Sigler, F.E.; Potter, J.M.; Schulze, M.E.

2004-01-01

Recent LANL activities in millimeter wave structures focus on 95 and 300 GHz structures. They aim at power generation from low power (100W-2kW) with a round electron beam (120kV, 0.1-1.0 A) to high power (2-100 kW) with a sheet beam structure (120 kV, 20 A). Applications cover basic research, radar and secure communications and remote sensing of biological and chemical agents. In this presentation the design of a 300 GHz RF-structure with a broadband (> 6% bandwidth) power coupler is presented. The choice of two input/output waveguides, a special coupling region and the structure parameters are presented. As a benchmark also a scaled up version at 10 GHz was designed and measured. These results will also be presented. We are investigating planar micro-fabricated traveling-wave tube amplifiers as sources for the generation of millimeter waves from 95 to 300 GHz. While for low energy applications narrow structures with pencil beams are proposed, for high energy operation flat, thin sheet beams are required. For the latter vane-loaded rectangular waveguides that operate in a slow-wave mode matched to the velocity of the electron beam are especially well suited. The 300 GHz effort initially is limited to narrow structures for pencil beams. The main emphasis for this work are the study of fabrication issues and the understanding of features that allow a broadband operation (5-10% bandwidth).

Experimental measurements on a 100 GHz frequency tunable quasioptical gyrotron

International Nuclear Information System (INIS)

Alberti, S.; Tran, M.Q.; Hogge, J.P.; Tran, T.M.; Bondeson, A.; Muggli, P.; Perrenoud, A.; Joedicke, B.; Mathews, H.G.

1990-01-01

Experiments on a 100 GHz quasioptical (QO) gyrotron operating at the fundamental (ω=Ω ce ) are described. Powers larger than 90 kW at an efficiency of about 12% were achieved. Depending on the electron beam parameters, the frequency spectrum of the output can be either single moded or multimoded. One of the main advantages of the QO gyrotron over the conventional gyrotron is its continuous frequency tunability. Various techniques to tune the output frequency have been tested, such as changing the mirror separation, the beam voltage, or the main magnetic field. Within the limitations of the present setup, 5% tunability was achieved. The QO gyrotron designed for operation at the fundamental frequency exhibits simultaneous emission at 100 GHz (fundamental) and 200 GHz (second harmonic). For a beam current of 4 A, 20% of the total rf power is emitted at the second harmonic

10–25 GHz frequency reconfigurable MEMS 5-bit phase shifter using push–pull actuator based toggle mechanism

International Nuclear Information System (INIS)

Dey, Sukomal; Koul, Shiban K

2015-01-01

This paper presents a frequency tunable 5-bit true-time-delay digital phase shifter using radio frequency microelectromechanical system (RF MEMS) technology. The phase shifter is based on the distributed MEMS transmission line (DMTL) concept utilizing a MEMS varactor. The main source of frequency tuning in this work is a bridge actuation mechanism followed by capacitance variation. Two stages of actuation mechanisms (push and pull) are used to achieve a 2:1 tuning ratio. Accurate control of the actuation voltage between the pull to push stages contributes differential phase shift over the band of interest. The functional behavior of the push–pull actuation over the phase shifter application is theoretically established, experimentally investigated and validated with simulation. The phase shifter is fabricated monolithically using a gold based surface micromachining process on an alumina substrate. The individual primary phase-bits (11.25°/22.5°/45°/90°/180°) that are the fundamental building blocks of the complete 5-bit phase shifter are designed, fabricated and experimentally characterized from 10–25 GHz for specific applications. Finally, the complete 5-bit phase shifter demonstrates an average phase error of 4.32°, 2.8°, 1° and 1.58°, an average insertion loss of 3.76, 4.1, 4.2 and 4.84 dB and an average return loss of 11.7, 12, 14 and 11.8 dB at 10, 12, 17.2 and 25 GHz, respectively. To the best of the authors’ knowledge, this is the first reported band tunable stand alone 5-bit phase shifter in the literature which can work over the large spectrum for different applications. The total area of the 5-bit phase shifter is 15.6 mm 2 . Furthermore, the cold-switched reliability of the unit cell and the complete 5-bit MEMS phase shifter are extensively investigated and presented. (paper)

Experimental results for a 1.5 MW, 110 GHz gyrotron oscillator with reduced mode competition

Science.gov (United States)

Choi, E. M.; Marchewka, C. D.; Mastovsky, I.; Sirigiri, J. R.; Shapiro, M. A.; Temkin, R. J.

2006-02-01

A new result from a 110GHz gyrotron at MIT is reported with an output power of 1.67MW and an efficiency of 42% when operated at 97kV and 41A for 3μs pulses in the TE22,6 mode. These results are a major improvement over results obtained with an earlier cavity design, which produced 1.43MW of power at 37% efficiency. These new results were obtained using a cavity with a reduced output taper angle and a lower ohmic loss when compared with the earlier cavity. The improved operation is shown experimentally to be the result of reduced mode competition from the nearby TE19,7 mode. The reduced mode competition agrees well with an analysis of the startup scenario based on starting current simulations. The present results should prove useful in planning long pulse and CW versions of the 110GHz gyrotron.

Experimental results for a 1.5 MW, 110 GHz gyrotron oscillator with reduced mode competition

International Nuclear Information System (INIS)

Choi, E.M.; Marchewka, C.D.; Mastovsky, I.; Sirigiri, J.R.; Shapiro, M.A.; Temkin, R.J.

2006-01-01

A new result from a 110 GHz gyrotron at MIT is reported with an output power of 1.67 MW and an efficiency of 42% when operated at 97 kV and 41 A for 3 μs pulses in the TE 22,6 mode. These results are a major improvement over results obtained with an earlier cavity design, which produced 1.43 MW of power at 37% efficiency. These new results were obtained using a cavity with a reduced output taper angle and a lower ohmic loss when compared with the earlier cavity. The improved operation is shown experimentally to be the result of reduced mode competition from the nearby TE 19,7 mode. The reduced mode competition agrees well with an analysis of the startup scenario based on starting current simulations. The present results should prove useful in planning long pulse and CW versions of the 110 GHz gyrotron

Study of lower hybrid current drive system in tokamak fusion devices

Energy Technology Data Exchange (ETDEWEB)

Maebara, Sunao [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

2001-01-01

This report describes R and D of a high-power klystron, RF vacuum window, low-outgassing antenna and a front module for a plasma-facing antenna aiming the 5 GHz Lower Hybrid Current Drive (LHCD) system for the next Tokamak Fusion Device. 5 GHz klystron with a low-perveances of 0.7 {mu}P is designed for a high-power and a high-efficiency, the output-power of 715 kW and the efficiency of 63%, which are beyond the conventional design scaling of 450 kW-45%, are performed using the prototype klystron which operates at the pulse duration of 15 {mu}sec. A new pillbox window, which has an oversized length in both the axial and the radial direction, are designed to reduce the RF power density and the electric field strength at the ceramics. It is evaluated that the power capability by cooling edge of ceramics is 1 MW with continuous-wave operation. The antenna module using Dispersion Strengthened Copper which combines high mechanical property up to 500degC with high thermal conductivity, are developed for a low-outgassing antenna in a steady state operation. It is found that the outgassing rate is in the lower range of 4x10{sup -6} Pam{sup 3}/sm{sup 2} at the module temperature of 300degC, which requires no active vacuum pumping of the LHCD antenna. A front module using Carbon Fiber Composite (CFC) are fabricated and tested for a plasma facing antenna which has a high heat-resistive. Stationary operation of the CFC module with water cooling is performed at the RF power of 46 MWm{sup -2} (about 2 times higher than the design value) during 1000 sec, it is found that the outgassing rate is less than 10{sup -5} Pam{sup 3}/sm{sup 2} which is low enough for an antenna material. (author)

Research on nuclear fusion reactor - Development of mm-wve (Electron cyclotron) heating device

Energy Technology Data Exchange (ETDEWEB)

Ahn, Sae Young; Myung, Jung Su; Lee, Keun Ho; Lee, Myung Jae; Kim, Hyung Suk; Hur, Jin Woo; Song, Ho Young [Institute for Advanced Engineering, Seoul (Korea, Republic of)

1996-08-01

To establish cooperating system with foreign relevant research institutes, consultation has been given to IAE by Dr. T. V. George regarding ECRH and gyrotron development plan. Discussions with Prof. Temkin and Dr. Kreisher at MIT, who are working for ITER gyrotron development, were made and those helped IAE to collect necessary information for fundamental parameters of ECCD. Also, Prof. Vic Granatstein, U. of Maryland, and Dr. Baruch Levush, NRL, were consulted for computer codes of the gyrotron R and D. It will also be prepared for cooperation in ECCD and mm-wave heating with device research teams of General Atomics and Russia. By visiting various University labs and research institutes and investigating the up-to-date research results, the basic operating parameters of gyrotron for KSTAR project has been determined. By cooperation with MIT, a conceptual design has been made for the KSTAR gyrotron that should generate 1 MW and 110 GHz CW waves. The simulation result of EGUN using self-consistent theory shows that 1.2 MW power with the efficiency of 42.8% can be obtained for TE22,6,1 mode where the average ohmic loss is 0.54 kW/cm{sup 2} assuming 77 kV cathode voltage, 34 A beam current, velocity ratio of 1.62 and perpendicular velocity spread of 6.5%. 9 refs., 5 figs., 3 tabs. (author)

Numerical Simulation of Single-anode and Double-anode Magnetron Injection Guns for 127.5 GHz 1 MW Gyrotron

Science.gov (United States)

Singh, Udaybir; Kumar, Nitin; Kumar, Anil; Purohit, Laxmi Prasad; Sinha, Ashok Kumar

2011-07-01

This paper presents the design of two types of magnetron injection guns (MIG's) for 1 MW, 127.5 GHz gyrotron. TE24,8 mode has been chosen as the operating mode. In-house developed code MIGSYN has been used to estimate the initial gun parameters. The electron trajectory tracing program EGUN and in-house developed code MIGANS have been used to optimize the single-anode and the double-anode design for 80 kV, 40 A MIG. The parametric analysis of MIG has also been presented. The advantages and the disadvantages of each kind of configuration have been critically examined.

An 8–18 GHz broadband high power amplifier

International Nuclear Information System (INIS)

Wang Lifa; Yang Ruixia; Li Yanlei; Wu Jingfeng

2011-01-01

An 8–18 GHz broadband high power amplifier (HPA) with a hybrid integrated circuit (HIC) is designed and fabricated. This HPA is achieved with the use of a 4-fingered micro-strip Lange coupler in a GaAs MMIC process. In order to decrease electromagnetic interference, a multilayer AlN material with good heat dissipation is adopted as the carrier of the power amplifier. When the input power is 25 dBm, the saturated power of the continuous wave (CW) outputted by the power amplifier is more than 39 dBm within the frequency range of 8–13 GHz, while it is more than 38.6 dBm within other frequency ranges. We obtain the peak power output, 39.4 dBm, at the frequency of 11.9 GHz. In the whole frequency band, the power-added efficiency is more than 18%. When the input power is 18 dBm, the small signal gain is 15.7 ± 0.7 dB. The dimensions of the HPA are 25 × 15 × 1.5 mm 3 . (semiconductor integrated circuits)

CARM and harmonic gyro-amplifier experiments at 17 GHz

International Nuclear Information System (INIS)

Menninger, W.L.; Danly, B.G.; Alberti, S.; Chen, C.; Rullier, J.L.; Temkin, R.J.

1993-01-01

Cyclotron resonance maser amplifiers are possible sources for applications such as electron cyclotron resonance heating of fusion plasmas and driving high-gradient rf linear accelerators. For accelerator drivers, amplifiers or phase locked-oscillators are required. A 17 GHz cyclotron autoresonance maser (CARM) amplifier experiment and a 17 GHz third harmonic gyro-amplifier experiment are presently underway at the MIT Plasma Fusion Center. Using the SRL/MIT SNOMAD II introduction accelerator to provide a 380 kV, 180 A, 30 ns flat top electron beam, the gyro-amplifier experiment has produced 5 MW of rf power with over 50 dB of gain at 17 GHz. The gyro-amplifier operates in the TE 31 mode using a third harmonic interaction. Because of its high power output, the gyro-amplifier will be used as the rf source for a photocathode rf electron gun experiment also taking place at MIT. Preliminary gyro-amplifier results are presented, including measurement of rf power, gain versus interaction length, and the far-field pattern. A CARM experiment designed to operate in the TE 11 mode is also discussed

Design of 340 GHz 2× and 4× Sub-Harmonic Mixers Using Schottky Barrier Diodes in Silicon-Based Technology

Directory of Open Access Journals (Sweden)

Chao Liu

2015-05-01

Full Text Available This paper presents the design of terahertz 2× and 4× sub-harmonic down-mixers using Schottky Barrier Diodes fabricated in standard 0.13 μm SiGe BiCMOS technology. The 340 GHz sub-harmonic mixers (SHMs are designed based on anti-parallel-diode-pairs (APDPs. With the 2nd and 4th harmonic, local oscillator (LO frequencies of 170 GHz and 85 GHz are used to pump the two 340 GHz SHMs. With LO power of 7 dBm, the 2× SHM exhibits a conversion loss of 34.5–37 dB in the lower band (320–340 GHz and 35.5–41 dB in the upper band (340–360 GHz; with LO power of 9 dBm, the 4× SHM exhibits a conversion loss of 39–43 dB in the lower band (320–340 GHz and 40–48 dB in the upper band (340–360 GHz. The measured input 1-dB conversion gain compression point for the 2× and 4× SHMs are −8 dBm and −10 dBm at 325 GHz, respectively. The simulated LO-IF (intermediate frequency isolation of the 2× SHM is 21.5 dB, and the measured LO-IF isolation of the 4× SHM is 32 dB. The chip areas of the 2× and 4× SHMs are 330 μm × 580 μm and 550 μm × 610 μm, respectively, including the testing pads.

MSE measurements for sawtooth and non-inductive current drive studies in KSTAR

Science.gov (United States)

Ko, J.; Park, H.; Bea, Y. S.; Chung, J.; Jeon, Y. M.

2016-10-01

Two major topics where the measurement of the magnetic-field-line rotational transform profiles in toroidal plasma systems include the long-standing issue of complete versus incomplete reconnection model of the sawtooth instability and the issue with future reactor-relevant tokamak devices in which non-inductive steady state current sustainment is essential. The motional Stark effect (MSE) diagnostic based on the photoelastic-modulator (PEM) approach is one of the most reliable means to measure the internal magnetic pitch, and thus the rotational transform, or its reciprocal (q), profiles. The MSE system has been commissioned for the Korea Superconducting Tokamak Advanced Research (KSTAR) along with the development of various techniques to minimize systematic offset errors such as Faraday rotation and mis-alignment of the bandpass filters. The diagnostic has revealed the central q is well correlated with the sawtooth oscillation, maintaining its value above unity during the MHD quiescent period and that the response of the q profile to external current drive such as electron cyclotron wave injection not only involves the local change of the pitch angle gradient but also a significant shift of the magnetic topology due to the wave energy transport. Work supported by the Ministry of Science, ICT and Future Planning, Korea.

Bi-directional 35-Gbit/s 2D beam steered optical wireless downlink and 5-Gbit/s localized 60-GHz communication uplink for hybrid indoor wireless systems

NARCIS (Netherlands)

Khalid, A.M.; Baltus, P.G.M.; Dommele, A.R.; Mekonnen, K.A.; Cao, Z.; Oh, C.W.; Matters, M.K.; Koonen, A.M.J.

2017-01-01

We present a full-duplex dynamic indoor optical wireless system using 2D passive optical beam steering for downlink and 60-GHz communication for upstream transmission. We demonstrate 35-Gb/s NRZ-OOK downstream multicasting and 5-Gb/s NRZ-ASK upstream communication.

Experimental study of a 1 MW, 170 GHz gyrotron oscillator

Science.gov (United States)

Kimura, Takuji

A detailed experimental study is presented of a 1 MW, 170 GHz gyrotron oscillator whose design is consistent with the ECH requirements of the International Thermonuclear Experimental Reactor (ITER) for bulk heating and current drive. This work is the first to demonstrate that megawatt power level at 170 GHz can be achieved in a gyrotron with high efficiency for plasma heating applications. Maximum output power of 1.5 MW is obtained at 170.1 GHz in 85 kV, 50A operation for an efficiency of 35%. Although the experiment at MIT is conducted with short pulses (3 μs), the gyrotron is designed to be suitable for development by industry for continuous wave operation. The peak ohmic loss on the cavity wall for 1 MW of output power is calculated to be 2.3 kW/cm2, which can be handled using present cooling technology. Mode competition problems in a highly over-moded cavity are studied to maximize the efficiency. Various aspects of electron gun design are examined to obtain high quality electron beams with very low velocity spread. A triode magnetron injection gun is designed using the EGUN simulation code. A total perpendicular velocity spread of less than 8% is realized by designing a low- sensitivity, non-adiabatic gun. The RF power is generated in a short tapered cavity with an iris step. The operating mode is the TE28,8,1 mode. A mode converter is designed to convert the RF output to a Gaussian beam. Power and efficiency are measured in the design TE28,8,1 mode at 170.1 GHz as well as the TE27,8,1 mode at 166.6 GHz and TE29,8,1 mode at 173.5 GHz. Efficiencies between 34%-36% are consistently obtained over a wide range of operating parameters. These efficiencies agree with the highest values predicted by the multimode simulations. The startup scenario is investigated and observed to agree with the linear theory. The measured beam velocity ratio is consistent with EGUN simulation. Interception of reflected beam by the mod-anode is measured as a function of velocity ratio

Current ramp-up experiments in full current drive plasmas on TRIAM-1M

International Nuclear Information System (INIS)

Hanada, K.; Nakamura, K.; Hasegawa, M.

2003-01-01

Four types of plasma current ramp-up experiments were executed on TRIAM-1M in full lower hybrid current drive plasmas (LHCD: 8.2GHz, up to 0.4 MW, 8 x 2 grill antenna); 1) the current start up by the combination between electron cyclotron resonance heating (ECH: 170GHz, up to 0.2 MW, O-mode launching) and LHCD at the density of ∼2x10 19 m -3 at B t =6.7T, 2) the tail heating by the additional LHCD, 3) the bulk heating by ECH, 4) the spontaneous ramp up by the transition to enhanced current drive (ECD) mode. The time evolutions of plasma current during four types of ramp-up phase were investigated and an exponential type and a tangent-hyperbolic one were observed. The time evolutions of plasma current during the tail and the bulk heating show the exponential type except the tail heating with high n parallel and it has a tangent-hyperbolic one during the ECD mode and the current start-up. A simple model with two different time constants, which are a time defined by L/R, τ L/R , and a time caused by change of the effective refractive index along the magnetic field, τ, is proposed to explain two types of the time evolution of the plasma current. The estimated τ L/R is consistent with the calculated one from the plasma parameter. It is found that τ are less than τ L/R in the cases of the tail and the bulk heating, and comparable in the cases of the ECD mode, and more than τ L/R in the cases of the plasma start-up. This indicates that the value of the effective refractive index along the magnetic field, parallel >, develops during the ECD mode and the current start-up. The value of τ depends on the RF power. The estimated is close to the expected up-shifted n parallel due to the toroidal effect and the magnetic shear. (author)

A fully-differential phase-locked loop frequency synthesizer for 60-GHz wireless communication

International Nuclear Information System (INIS)

Kuang Lixue; Chi Baoyong; Chen Lei; Wang Zhihua; Jia Wen

2014-01-01

A 40-GHz phase-locked loop (PLL) frequency synthesizer for 60-GHz wireless communication applications is presented. The electrical characteristics of the passive components in the VCO and LO buffers are accurately extracted with an electromagnetic simulator HFSS. A differential tuning technique is utilized in the voltage controlled oscillator (VCO) to achieve higher common-mode noise rejection and better phase noise performance. The VCO and the divider chain are powered by a 1.0 V supply while the phase-frequency detector (PFD) and the charge pump (CP) are powered by a 2.5 V supply to improve the linearity. The measurement results show that the total frequency locking range of the frequency synthesizer is from 37 to 41 GHz, and the phase noise from a 40 GHz carrier is −97.2 dBc/Hz at 1 MHz offset. Implemented in 65 nm CMOS, the synthesizer consumes a DC power of 62 mW, including all the buffers. (semiconductor integrated circuits)

A fully-differential phase-locked loop frequency synthesizer for 60-GHz wireless communication

Science.gov (United States)

Lixue, Kuang; Baoyong, Chi; Lei, Chen; Wen, Jia; Zhihua, Wang

2014-12-01

A 40-GHz phase-locked loop (PLL) frequency synthesizer for 60-GHz wireless communication applications is presented. The electrical characteristics of the passive components in the VCO and LO buffers are accurately extracted with an electromagnetic simulator HFSS. A differential tuning technique is utilized in the voltage controlled oscillator (VCO) to achieve higher common-mode noise rejection and better phase noise performance. The VCO and the divider chain are powered by a 1.0 V supply while the phase-frequency detector (PFD) and the charge pump (CP) are powered by a 2.5 V supply to improve the linearity. The measurement results show that the total frequency locking range of the frequency synthesizer is from 37 to 41 GHz, and the phase noise from a 40 GHz carrier is -97.2 dBc/Hz at 1 MHz offset. Implemented in 65 nm CMOS, the synthesizer consumes a DC power of 62 mW, including all the buffers.

Results of a new ''OCTOPUS'' ECR ion source at 6.4 GHz

International Nuclear Information System (INIS)

Dupont, C.; Jongen, Y.; Arakawa, K.; Yokota, W.; Satoh, T.; Tachikawa, T.

1990-01-01

The first OCTOPUS electron cyclstron resonance (ECR) multicharged heavy ion source was built in 1985 at the Centre de Recherches du Cyclotron of the University of Louvain (Belgium). This first source used an ECR frequency of 14.3 GHz in the injector stage and 8.5 GHz in the main confinement stage. A new OCTOPUS source has now been built for a new cyclotron to be installed at the Japan Atomic Energy Research Institute (JAERI). The design of this new OCTOPUS source is identical to the first OCTOPUS source, but uses an ECR frequency of 6.4 GHz in the main confinement stage. The experimental results are described, and a comparison is made between the two sources. However, the available data does not allow any clear conclusion to be drawn on frequency scaling

105 GHz Notch Filter Design for Collective Thomson Scattering

DEFF Research Database (Denmark)

Furtula, Vedran; Michelsen, Poul; Leipold, Frank

2011-01-01

A millimeter-wave notch filter with 105-GHz center frequency, >20-GHz passband coverage, and 1-GHz rejection bandwidth has been constructed. The design is based on a fundamental rectangular waveguide with cylindrical cavities coupled by narrow iris gaps, i.e., small elongated holes of negligible...

ITER-like PAM launcher for tore supra's LHCD system

International Nuclear Information System (INIS)

Belo, J.H.; Bibet, Ph.; Missirlian, M.; Achard, J.; Beaumont, B.; Bertrand, B.; Chantant, M.; Chappuis, Ph.; Doceul, L.; Durocher, A.; Gargiulo, L.; Saille, A.; Samaille, F.; Villedieu, E.

2004-01-01

A new launcher based upon the PAM concept (Passive-Active Multijunction) already proposed for ITER has been developed and is currently under realisation at Tore Supra. It was designed for an injection power capability of 2.7 MW CW at 3.7 GHz, a power density of 25 MW/m 2 , to radiate a power spectrum peaked at N || = 1.7 with a maximum power directivity near the electron cut-off density and with very good coupling properties on a wide range of electron densities. In this paper an overall description of the antenna as well as the foreseen manufacturing and assembling processes are given, followed by the results from studies and optimizations of its RF components, and by a stress analysis of its thermomechanical behaviour. (authors)

Development of two series ingnitron based crowbar protection system for 42 GHz and 82.6 GHz gyroton in SST-1

International Nuclear Information System (INIS)

Dhorajiya, Pragnesh; Dalakoti, Shefali; Patel, Harshida; Ingle, Krunal; Patel, Jatin; Sathyanarayana, K.; Rajanbabu; Shukla, B.K.

2013-01-01

Gyrotrons are used to generate the high power at microwave frequency that is used to heat the plasma inside a Tokamak. A conventional high voltage power supply is used for the testing of 82.6 GHz, 200 kW/CW and 42 GHz, 500 kW/500ms gyrotrons at our institute. Its maximum operating cathode parameters are -55 kV DC, 20 A. Like any other High RF power tubes gyrotrons need to be protected against arc faults within the tube. If the energy dumped in such arc fault is more than the critical crater energy of the tube, irreparable damage can occur inside the RF tube or microwave tube and rendering it useless. The specified maximum fault energy for the 42 GHz and 82.6 GHz gyrotrons is 10 joules. When conventional HVDC power supplies feed high power RF tubes or microwave tubes, a reliable crowbar protection is required which is tested separately to limit the energy to the tube in case of any type of fault to assure the tube safety. Two series ignitron (NL-37248) based crowbar system developed in-house is used to limit the arc fault energy under the acceptance level by diverting the fault current from the load or Gyrotron. Fault current diversion and interruption are initiated by the sensing element and protection system. The required protection cards are designed and developed in-house and required performance is achieved. With this crowbar system the high voltage switch-off to the gyrotron is achieved within 5 μsec after occurrence of critical faults. The crowbar is tested for voltage hold-off up to 80 kV DC. This paper presents the critical requirement of the time delay for the fault sensing and crowbar trigger generation and necessary protections that are incorporated with the ignitron switch crowbar like over voltage, pulsed over current and continuous over current. The crowbar system developed in-house, tested at rated value. The results obtained during the stand-alone tests and commissioning tests are also mentioned. Using this crowbar system the high voltage power

Effect of thickness on microwave absorptive behavior of La-Na doped Co-Zr barium hexaferrites in 18.0–26.5 GHz band

Energy Technology Data Exchange (ETDEWEB)

Arora, Amit [D.A.V. Institute of Engineering and Technology, Jalandhar (India); Narang, Sukhleen Bindra, E-mail: sukhleen2@yahoo.com [Department of Electronics Technology, Guru Nanak Dev University, Amritsar (India); Pubby, Kunal [Department of Electronics Technology, Guru Nanak Dev University, Amritsar (India)

2017-02-01

In this research, the microwave properties of Lanthanum-Sodium doped Cobalt-Zirconium barium hexaferrites, intended as microwave absorbers, are analyzed on Vector Network Analyzer in K-band. The results indicate that the doping has resulted in lowering of real permittivity and enhancement of dielectric losses. Real permeability has shown increase while magnetic losses have shown decrease in value with doping. All these four properties have shown very small variation with frequency in the scanned frequency range which indicates the relaxation type of behavior. Microwave absorption characteristics of these compositions are analyzed with change in sample thickness. The results demonstrate that the matching frequency of the microwave absorber shifts towards lower side of frequency band with increase in thickness. The complete analysis of the prepared microwave absorbers shows a striking achievement with very low reflection loss and wide absorption bandwidth for all the six compositions in 18–26.5 GHz frequency band. - Highlights: • Electromagnetic Characterization of M-hexaferrites in K-band (18–26.5 GHz) • Variation of absorption properties with thickness of sample. • Satisfaction of quarter-wavelength condition for absorption properties • Results of double-layer absorbers (not reports till day by anyone).

Deep 20-GHz survey of the Chandra Deep Field South and SDSS Stripe 82: source catalogue and spectral properties

Science.gov (United States)

Franzen, Thomas M. O.; Sadler, Elaine M.; Chhetri, Rajan; Ekers, Ronald D.; Mahony, Elizabeth K.; Murphy, Tara; Norris, Ray P.; Waldram, Elizabeth M.; Whittam, Imogen H.

2014-04-01

We present a source catalogue and first results from a deep, blind radio survey carried out at 20 GHz with the Australia Telescope Compact Array, with follow-up observations at 5.5, 9 and 18 GHz. The Australia Telescope 20 GHz (AT20G) deep pilot survey covers a total area of 5 deg2 in the Chandra Deep Field South and in Stripe 82 of the Sloan Digital Sky Survey. We estimate the survey to be 90 per cent complete above 2.5 mJy. Of the 85 sources detected, 55 per cent have steep spectra (α _{1.4}^{20} law spectra between 1.4 and 18 GHz, while the spectral indices of the flat- or inverted-spectrum sources tend to steepen with frequency. Among the 18 inverted-spectrum (α _{1.4}^{20} ≥ 0.0) sources, 10 have clearly defined peaks in their spectra with α _{1.4}^{5.5} > 0.15 and α 9^{18} Cambridge and Tenth Cambridge surveys: there is a shift towards a steeper-spectrum population when going from ˜1 Jy to ˜5 mJy, which is followed by a shift back towards a flatter-spectrum population below ˜5 mJy. The 5-GHz source-count model by Jackson & Wall, which only includes contributions from FRI and FRII sources, and star-forming galaxies, does not reproduce the observed flattening of the flat-spectrum counts below ˜5 mJy. It is therefore possible that another population of sources is contributing to this effect.

High sensitivity broadband 360GHz passive receiver for TeraSCREEN

Science.gov (United States)

Wang, Hui; Oldfield, Matthew; Maestrojuán, Itziar; Platt, Duncan; Brewster, Nick; Viegas, Colin; Alderman, Byron; Ellison, Brian N.

2016-05-01

TeraSCREEN is an EU FP7 Security project aimed at developing a combined active, with frequency channel centered at 360 GHz, and passive, with frequency channels centered at 94, 220 and 360 GHz, imaging system for border controls in airport and commercial ferry ports. The system will include automatic threat detection and classification and has been designed with a strong focus on the ethical, legal and practical aspects of operating in these environments and with the potential threats in mind. Furthermore, both the passive and active systems are based on array receivers with the active system consisting of a 16 element MIMO FMCW radar centered at 360 GHz with a bandwidth of 30 GHz utilizing a custom made direct digital synthesizer. The 16 element passive receiver system at 360 GHz uses commercial Gunn diode oscillators at 90 GHz followed by custom made 90 to 180 GHz frequency doublers supplying the local oscillator for 360 GHz sub-harmonic mixers. This paper describes the development of the passive antenna module, local oscillator chain, frequency mixers and detectors used in the passive receiver array of this system. The complete passive receiver chain is characterized in this paper.

Channel Measurements and Modeling at 6 GHz in the Tunnel Environments for 5G Wireless Systems

Directory of Open Access Journals (Sweden)

Shuang-de Li

2017-01-01

Full Text Available Propagation measurements of wireless channels performed in the tunnel environments at 6 GHz are presented in this paper. Propagation characteristics are simulated and analyzed based on the method of shooting and bouncing ray tracing/image (SBR/IM. A good agreement is achieved between the measured results and simulated results, so the correctness of SBR/IM method has been validated. The measured results and simulated results are analyzed in terms of path loss models, received power, root mean square (RMS delay spread, Ricean K-factor, and angle of arrival (AOA. The omnidirectional path loss models are characterized based on close-in (CI free-space reference distance model and the alpha-beta-gamma (ABG model. Path loss exponents (PLEs are 1.50–1.74 in line-of-sight (LOS scenarios and 2.18–2.20 in non-line-of-sight (NLOS scenarios. Results show that CI model with the reference distance of 1 m provides more accuracy and stability in tunnel scenarios. The RMS delay spread values vary between 2.77 ns and 18.76 ns. Specially, the Poisson distribution best fits the measured data of RMS delay spreads for LOS scenarios and the Gaussian distribution best fits the measured data of RMS delay spreads for NLOS scenarios. Moreover, the normal distribution provides good fits to the Ricean K-factor. The analysis of the abovementioned results from channel measurements and simulations may be utilized for the design of wireless communications of future 5G radio systems at 6 GHz.

Optoelectronic time-domain characterization of a 100 GHz sampling oscilloscope

International Nuclear Information System (INIS)

Füser, H; Baaske, K; Kuhlmann, K; Judaschke, R; Pierz, K; Bieler, M; Eichstädt, S; Elster, C

2012-01-01

We have carried out an optoelectronic measurement of the impulse response of an ultrafast sampling oscilloscope with a nominal bandwidth of 100 GHz within a time window of approximately 100 ps. Our experimental technique also considers frequency components above the cut-off frequency of higher order modes of the 1.0 mm coaxial line, which is shown to be important for the specification of the impulse response of ultrafast sampling oscilloscopes. Additionally, we have measured the reflection coefficient of the sampling head induced by the mismatch of the sampling circuit and the coaxial connector which is larger than 0.5 for certain frequencies. The uncertainty analysis has been performed using the Monte Carlo method of Supplement 1 to the 'Guide to the Expression of Uncertainty in Measurement' and correlations in the estimated impulse response have been determined. Our measurements extend previous work which deals with the characterization of 70 GHz oscilloscopes and the measurement of 100 GHz oscilloscopes up to the cut-off frequency of higher order modes

A 4 × 2 switch matrix in QFN24 package for 0.5–3 GHz application

International Nuclear Information System (INIS)

Liu Yuzhe; Mu Pengfei; Gong Renjie; Wan Jing; Zhang Yulin; Yan Yuepeng

2014-01-01

This paper presents a 4 × 2 switching matrix implemented in the Win 0.5 μm GaAs pseudomorphic high electron mobility transistor process, it covers the 0.5–3 GHz frequency range. The switch matrix is composed of 4 SPDT switch whose two output ports can simultaneously select the input port and a 4 to 8 bit digital decoder, both the radio frequency (RF) part and the digital part are integrated into one single chip. The chip is packaged in a low cost QFN24 plastic package. On chip shunt, capacitors at the input ports are taken to compensate for the bonding wire inductance effect. The designed switch matrix shows a good measured performance: the insertion loss is less than 5.5 dB, the isolation is no worse than 30 dB, the return loss of input ports and output ports is better than −10 dB, the input 1 dB compression point is better than 25.6 dBm, and the OIP3 is better than 37 dBm. The chip size of the switch matrix is only 1.45 × 1.45 mm 2 . (semiconductor integrated circuits)

THE ZEEMAN EFFECT IN THE 44 GHZ CLASS I METHANOL MASER LINE TOWARD DR21(OH)

Energy Technology Data Exchange (ETDEWEB)

Momjian, E. [National Radio Astronomy Observatory, P.O. Box O, Socorro, NM 87801 (United States); Sarma, A. P., E-mail: emomjian@nrao.edu, E-mail: asarma@depaul.edu [Physics Department, DePaul University, 2219 N. Kenmore Avenue, Byrne Hall 211, Chicago, IL 60614 (United States)

2017-01-10

We report detection of the Zeeman effect in the 44 GHz Class I methanol maser line, toward the star-forming region DR21(OH). In a 219 Jy beam{sup −1} maser centered at an LSR velocity of 0.83 km s{sup −1}, we find a 20- σ detection of zB {sub los} = 53.5 ± 2.7 Hz. If 44 GHz methanol masers are excited at n ∼ 10{sup 7–8} cm{sup −3}, then the B versus n {sup 1/2} relation would imply, from comparison with Zeeman effect detections in the CN(1 − 0) line toward DR21(OH), that magnetic fields traced by 44 GHz methanol masers in DR21(OH) should be ∼10 mG. Combined with our detected zB {sub los} = 53.5 Hz, this would imply that the value of the 44 GHz methanol Zeeman splitting factor z is ∼5 Hz mG{sup −1}. Such small values of z would not be a surprise, as the methanol molecule is non-paramagnetic, like H{sub 2}O. Empirical attempts to determine z , as demonstrated, are important because there currently are no laboratory measurements or theoretically calculated values of z for the 44 GHz CH{sub 3}OH transition. Data from observations of a larger number of sources are needed to make such empirical determinations robust.

41 GHz and 10.6 GHz low threshold and low noise InAs/InP quantum dash two-section mode-locked lasers in L band

DEFF Research Database (Denmark)

Dontabactouny, M.; Piron, R.; Klaime, K.

2012-01-01

This paper reports recent results on InAs/InP quantum dash-based, two-section, passively mode-locked lasers pulsing at 41 GHz and 10.6 GHz and emitting at 1.59 mu m at 20 degrees C. The 41-GHz device (1 mm long) starts lasing at 25 mA under uniform injection and the 10.6 GHz (4 mm long) at 71 m...

Radiation damage of the PCO Pixelfly VGA CCD camera of the BES system on KSTAR tokamak

Energy Technology Data Exchange (ETDEWEB)

Náfrádi, Gábor, E-mail: nafradi@reak.bme.hu [NTI, BME, EURATOM Association, H-1111 Budapest (Hungary); Kovácsik, Ákos, E-mail: kovacsik.akos@reak.bme.hu [NTI, BME, EURATOM Association, H-1111 Budapest (Hungary); Pór, Gábor, E-mail: por@reak.bme.hu [NTI, BME, EURATOM Association, H-1111 Budapest (Hungary); Lampert, Máté, E-mail: lampert.mate@wigner.mta.hu [Wigner RCP, RMI, EURATOM Association, POB 49, 1525 Budapest (Hungary); Un Nam, Yong, E-mail: yunam@nfri.re.kr [NFRI, 169-148 Gwahak-Ro, Yuseong-Gu, Daejeon 305-806 (Korea, Republic of); Zoletnik, Sándor, E-mail: zoletnik.sandor@wigner.mta.hu [Wigner RCP, RMI, EURATOM Association, POB 49, 1525 Budapest (Hungary)

2015-01-11

A PCO Pixelfly VGA CCD camera which is part a of the Beam Emission Spectroscopy (BES) diagnostic system of the Korea Superconducting Tokamak Advanced Research (KSTAR) used for spatial calibrations, suffered from serious radiation damage, white pixel defects have been generated in it. The main goal of this work was to identify the origin of the radiation damage and to give solutions to avoid it. Monte Carlo N-Particle eXtended (MCNPX) model was built using Monte Carlo Modeling Interface Program (MCAM) and calculations were carried out to predict the neutron and gamma-ray fields in the camera position. Besides the MCNPX calculations pure gamma-ray irradiations of the CCD camera were carried out in the Training Reactor of BME. Before, during and after the irradiations numerous frames were taken with the camera with 5 s long exposure times. The evaluation of these frames showed that with the applied high gamma-ray dose (1.7 Gy) and dose rate levels (up to 2 Gy/h) the number of the white pixels did not increase. We have found that the origin of the white pixel generation was the neutron-induced thermal hopping of the electrons which means that in the future only neutron shielding is necessary around the CCD camera. Another solution could be to replace the CCD camera with a more radiation tolerant one for example with a suitable CMOS camera or apply both solutions simultaneously.

Arbitrary waveform modulated pulse EPR at 200 GHz

Science.gov (United States)

Kaminker, Ilia; Barnes, Ryan; Han, Songi

2017-06-01

We report here on the implementation of arbitrary waveform generation (AWG) capabilities at ∼200 GHz into an Electron Paramagnetic Resonance (EPR) and Dynamic Nuclear Polarization (DNP) instrument platform operating at 7 T. This is achieved with the integration of a 1 GHz, 2 channel, digital to analog converter (DAC) board that enables the generation of coherent arbitrary waveforms at Ku-band frequencies with 1 ns resolution into an existing architecture of a solid state amplifier multiplier chain (AMC). This allows for the generation of arbitrary phase- and amplitude-modulated waveforms at 200 GHz with >150 mW power. We find that the non-linearity of the AMC poses significant difficulties in generating amplitude-modulated pulses at 200 GHz. We demonstrate that in the power-limited regime of ω1 10 MHz) spin manipulation in incoherent (inversion), as well as coherent (echo formation) experiments. Highlights include the improvement by one order of magnitude in inversion bandwidth compared to that of conventional rectangular pulses, as well as a factor of two in improvement in the refocused echo intensity at 200 GHz.

Design of Jet lower hybrid current drive generator and operation of high power test bed

International Nuclear Information System (INIS)

Dobbing, J.A.; Bosia, G.; Brandon, M.; Gammelin, M.; Gormezano, C.; Jacquinot, J.; Jessop, G.; Lennholm, M.; Pain, M.; Sibley, A.

1989-01-01

The JET Lower Hybrid Current Drive (LHCD) generator consists of 24 klystrons each rated for 650 KW operating at 3.7 GHz, giving a nominal generator power of 15.6 MW for 10 seconds or 12 MW for 20 seconds. This power will be transmitted through 24 waveguides to a phased array launcher on one of the main ports of the JET machine. In addition, two klystrons are currently being operated on a high power test bed to establish reliable operation of the generators components and test high power microwave components prior to their installation

60-GHz integrated-circuit high data rate quadriphase shift keying exciter and modulator

Science.gov (United States)

Grote, A.; Chang, K.

1984-01-01

An integrated-circuit quadriphase shift keying (QPSK) exciter and modulator have demonstrated excellent performance directly modulating a carrier frequency of 60 GHz with an output phase error of less than 3 degrees and maximum amplitude error of 0.5 dB. The circuit consists of a 60-GHz Gunn VCO phase-locked to a low-frequency reference source, a 4th subharmonic mixer, and a QPSK modlator packaged into a small volume of 1.8 x 2.5 x 0.35 in. The use of microstrip has the advantages of small size, light-weight, and low-cost fabrication. The unit has the potential for multigigabit data rate applications.

Commissioning of the superconducting ECR ion source VENUS at 18 GHz

International Nuclear Information System (INIS)

Leitner, Daniela; Abbott, Steven R.; Dwinell, Roger D.; Leitner, Matthaeus; Taylor, Clyde E.; Lyneis, Claude M.

2004-01-01

During the last year, the VENUS ECR ion source was commissioned at 18 GHz and preparations for 28 GHz operation are now underway. During the commissioning phase with 18 GHz, tests with various gases and metals have been performed with up to 2000 W RF power. The ion source performance is very promising [1,2]. VENUS (Versatile ECR ion source for Nuclear Science) is a next generation superconducting ECR ion source, designed to produce high current, high charge state ions for the 88-Inch Cyclotron at the Lawrence Berkeley National Laboratory. VENUS also serves as the prototype ion source for the RIA (Rare Isotope Accelerator) front end. The goal of the VENUS ECR ion source project as the RIA R and D injector is the production of 240e(micro)A of U 30+ , a high current medium charge state beam. On the other hand, as an injector ion source for the 88-Inch Cyclotron the design objective is the production of 5e(micro)A of U 48+ , a low current, very high charge state beam. To meet these ambitious goals, VENUS has been designed for optimum operation at 28 GHz. This frequency choice has several design consequences. To achieve the required magnetic confinement, superconducting magnets have to be used. The size of the superconducting magnet structure implies a relatively large plasma volume. Consequently, high power microwave coupling becomes necessary to achieve sufficient plasma heating power densities. The 28 GHz power supply has been delivered in April 2004

60 GHz gyrotron development program. Final report, April 1979-June 1984

International Nuclear Information System (INIS)

Shively, J.F.; Bier, R.E.; Caplan, M.

1986-01-01

The original objective of this program was to develop a microwave amplifier or oscillator capable of producing 200 kW CW power output at 110 GHz. The use of cyclotron resonance interaction was pursued, and the design phases of this effort are discussed. Later, however, the program's objective was changed to develop a family of oscillators capable of producing 200 kw of peak output power at 60 GHz. Gyrotron behavior studies were performed at 28 GHz to obtain generic design information as quickly as possible. The first experimental device at 60 GHz produced over 200 kw of peak power at a pulse duration of 20 μs. Heating problems and mode interference were encountered. The second experimental tube incorporated an optimized gun location but also suffered from mode interference. The third experimental tube included modifications that reduced mode interference. It demonstrated 200 kw of peak output at 100 ms pulse duration. The fourth experimental tube, which used an older rf circuit design but in a CW configuration, produced 71.5 kW CW. The fifth experimental tube incorporated a thinner double-disc output window which improved window bandwidth and reduced window loss. This tube also incorporated modifications to the drift tunnel and cavity coupling, which had proven successful in the third experimental pulse tube tests. It produced 123 kW of CW output power at 60 GHz rf load coolant boiling and tube window failure terminated the tests. A new waterload was designed and constructed, and alternative window designs were explored

The influence of the reflective environment on the absorption of a human male exposed to representative base station antennas from 300 MHz to 5 GHz.

Science.gov (United States)

Vermeeren, G; Gosselin, M C; Kühn, S; Kellerman, V; Hadjem, A; Gati, A; Joseph, W; Wiart, J; Meyer, F; Kuster, N; Martens, L

2010-09-21

The environment is an important parameter when evaluating the exposure to radio-frequency electromagnetic fields. This study investigates numerically the variation on the whole-body and peak spatially averaged-specific absorption rate (SAR) in the heterogeneous virtual family male placed in front of a base station antenna in a reflective environment. The SAR values in a reflective environment are also compared to the values obtained when no environment is present (free space). The virtual family male has been placed at four distances (30 cm, 1 m, 3 m and 10 m) in front of six base station antennas (operating at 300 MHz, 450 MHz, 900 MHz, 2.1 GHz, 3.5 GHz and 5.0 GHz, respectively) and in three reflective environments (a perfectly conducting wall, a perfectly conducting ground and a perfectly conducting ground + wall). A total of 72 configurations are examined. The absorption in the heterogeneous body model is determined using the 3D electromagnetic (EM) finite-difference time-domain (FDTD) solver Semcad-X. For the larger simulations, requirements in terms of computer resources are reduced by using a generalized Huygens' box approach. It has been observed that the ratio of the SAR in the virtual family male in a reflective environment and the SAR in the virtual family male in the free-space environment ranged from -8.7 dB up to 8.0 dB. A worst-case reflective environment could not be determined. ICNIRP reference levels not always showed to be compliant with the basic restrictions.

The influence of the reflective environment on the absorption of a human male exposed to representative base station antennas from 300 MHz to 5 GHz

International Nuclear Information System (INIS)

Vermeeren, G; Joseph, W; Martens, L; Gosselin, M C; Kuehn, S; Kuster, N; Kellerman, V; Meyer, F; Hadjem, A; Gati, A; Wiart, J

2010-01-01

The environment is an important parameter when evaluating the exposure to radio-frequency electromagnetic fields. This study investigates numerically the variation on the whole-body and peak spatially averaged-specific absorption rate (SAR) in the heterogeneous virtual family male placed in front of a base station antenna in a reflective environment. The SAR values in a reflective environment are also compared to the values obtained when no environment is present (free space). The virtual family male has been placed at four distances (30 cm, 1 m, 3 m and 10 m) in front of six base station antennas (operating at 300 MHz, 450 MHz, 900 MHz, 2.1 GHz, 3.5 GHz and 5.0 GHz, respectively) and in three reflective environments (a perfectly conducting wall, a perfectly conducting ground and a perfectly conducting ground + wall). A total of 72 configurations are examined. The absorption in the heterogeneous body model is determined using the 3D electromagnetic (EM) finite-difference time-domain (FDTD) solver Semcad-X. For the larger simulations, requirements in terms of computer resources are reduced by using a generalized Huygens' box approach. It has been observed that the ratio of the SAR in the virtual family male in a reflective environment and the SAR in the virtual family male in the free-space environment ranged from -8.7 dB up to 8.0 dB. A worst-case reflective environment could not be determined. ICNIRP reference levels not always showed to be compliant with the basic restrictions.

The influence of the reflective environment on the absorption of a human male exposed to representative base station antennas from 300 MHz to 5 GHz

Energy Technology Data Exchange (ETDEWEB)

Vermeeren, G; Joseph, W; Martens, L [Ghent University-INTEC/IBBT, Gaston Crommenlaan 8 box 201, B-9050 Ghent (Belgium); Gosselin, M C; Kuehn, S; Kuster, N [IT' IS Foundation, Zurich (Switzerland); Kellerman, V; Meyer, F [EMSS, Stellenbosch (South Africa); Hadjem, A; Gati, A; Wiart, J, E-mail: Gunter.Vermeeren@intec.UGent.b [Orange Labs, Paris (France)

2010-09-21

The environment is an important parameter when evaluating the exposure to radio-frequency electromagnetic fields. This study investigates numerically the variation on the whole-body and peak spatially averaged-specific absorption rate (SAR) in the heterogeneous virtual family male placed in front of a base station antenna in a reflective environment. The SAR values in a reflective environment are also compared to the values obtained when no environment is present (free space). The virtual family male has been placed at four distances (30 cm, 1 m, 3 m and 10 m) in front of six base station antennas (operating at 300 MHz, 450 MHz, 900 MHz, 2.1 GHz, 3.5 GHz and 5.0 GHz, respectively) and in three reflective environments (a perfectly conducting wall, a perfectly conducting ground and a perfectly conducting ground + wall). A total of 72 configurations are examined. The absorption in the heterogeneous body model is determined using the 3D electromagnetic (EM) finite-difference time-domain (FDTD) solver Semcad-X. For the larger simulations, requirements in terms of computer resources are reduced by using a generalized Huygens' box approach. It has been observed that the ratio of the SAR in the virtual family male in a reflective environment and the SAR in the virtual family male in the free-space environment ranged from -8.7 dB up to 8.0 dB. A worst-case reflective environment could not be determined. ICNIRP reference levels not always showed to be compliant with the basic restrictions.

THz photonic wireless links with 16-QAM modulation in the 375-450 GHz band

DEFF Research Database (Denmark)

Jia, Shi; Yu, Xianbin; Hu, Hao

2016-01-01

forward error correction (HD-FEC) threshold of 3.8e-3 with 7% overhead. In addition, we also successfully demonstrate hybrid photonic wireless transmission of 40 Gbit/s 16-QAM signal at carrier frequencies of 400 GHz and 425 GHz over 30 km standard single mode fiber (SSMF) between the optical baseband...... signal transmitter and the THz wireless transmitter with negligible induced power penalty.......We propose and experimentally demonstrate THz photonic wireless communication systems with 16-QAM modulation in the 375-450 GHz band. The overall throughput reaches as high as 80 Gbit/s by exploiting four THz channels with 5 Gbaud 16-QAM baseband modulation per channel. We create a coherent optical...

UGC galaxies stronger than 25 mJy at 4.85 GHz

International Nuclear Information System (INIS)

Condon, J.J.; Frayer, D.T.; Broderick, J.J.

1991-01-01

UGC galaxies in the declination band +5 to +75 deg were identified by position coincidence with radio sources stronger than 25 mJy on the Green Bank 4.85 GHz sky maps. Candidate identifications were confirmed or rejected with the aid of published aperture-synthesis maps and new 4.86 GHz VLA maps having 15 or 18 arcsec resolution, resulting in a sample of 347 nearby radio galaxies plus five new quasar-galaxy pairs. The radio energy sources in UGC galaxies were classified as starbursts or monsters on the basis of their infrared-radio flux ratios, infrared spectral indices, and radio morphologies. The rms scatter in the logarithmic infrared-radio ratio q is not more than 0.16 for starburst galaxies selected at 4.85 GHz. Radio spectral indices were obtained for nearly all of the UGC galaxies, and S0 galaxies account for a disproportionate share of the compact flat-spectrum (alpha less than 0.5) radio sources. The extended radio jets and lobes produced by monsters are preferentially, but not exclusively, aligned within about 30 deg of the optical minor axes of their host galaxies. The tendency toward minor-axis ejection appears to be independent of radio-source size and is strongest for elliptical galaxies. 230 refs

GHz-rate optical parametric amplifier in hydrogenated amorphous silicon

International Nuclear Information System (INIS)

Wang, Ke-Yao; Foster, Amy C

2015-01-01

We demonstrate optical parametric amplification operating at GHz-rates at telecommunications wavelengths using a hydrogenated amorphous silicon waveguide through the nonlinear optical process of four-wave mixing. We investigate how the parametric amplification scales with repetition rate. The ability to achieve amplification at GHz-repetition rates shows hydrogenated amorphous silicon’s potential for telecommunication applications and a GHz-rate optical parametric oscillator. (paper)

Indicators of Macromolecular Oxidative Damage and Antioxidant Defence Examinees Exposed to the Radar Frequencies 1.5 - 10.9 GHz

International Nuclear Information System (INIS)

Marjanovic, A.M.; Flajs, D.; Pavicic, I.; Domijan, A.

2011-01-01

Radar is an object-detection system which uses microwaves (Mw). As a result of increased use of radar there is a rising concern regarding health effects of Mw radiation on human body. Living organisms are complex electrochemical systems being evolved in a relatively narrow range of well-defined environmental parameters. For life to be maintained these parameters must be kept within their normal range, since deviations can induce biochemical effects causing cell function impairment and disease. Some theories indicate connection between Mw radiation, oxidative damage as well as antioxidant defence of organism. Aim of this study was to evaluate level and damage of macromolecular structures - proteins and lipids in blood of men occupationally exposed to Mw radiation. Concentration of glutathione (GSH), a known indicator of organism antioxidant defence, was also determined. Blood samples were collected from 27 male workers occupationally exposed to radar frequencies 1.5 to 10.9 GHz. Corresponding control group (N = 8) was a part of study. Concentrations of total and oxidised proteins, protein carbonyls, and GSH were measured by spectrophotometric method, while malondialdeyde (MDA), product of lipid peroxidation, was determined by high performance liquid chromatography (HPLC). Gained concentrations of oxidised proteins, GSH and MDA were presented in relation to total proteins. Concentration of oxidised proteins between control and exposed group of examinees did not show any significant statistical difference. However, concentration of GSH in exposed group was found considerably decreased, while concentration of MDA was found to be increased. Results indicate that Mw radiation of radar operating at frequencies 1.5 - 10.9 GHz could cause damage to proteins and lipids in addition to impairment of antioxidant defence of organism. (author)

VizieR Online Data Catalog: 22GHz image of 3C 273 (Bruni+, 2017)

Science.gov (United States)

Bruni, G.; Gomez, J. L.; Casadio, C.; Lobanov, A.; Kovalev, Y. Y.; Sokolovsky, K. V.; Lisakov, M. M.; Bach, U.; Marscher, A.; Jorstad, S.; Anderson, J. M.; Krichbaum, T. P.; Savolainen, T.; Vega-Garcia, L.; Fuentes, A.; Zensus, J. A.; Alberdi, A.; Lee, S.-S.; Lu, R.-S.; Perez-Torres, M.; Ros, E.

2017-07-01

A global ground array of 22 antennas was used to perform observations, including VLBA (Sc, Hn, Nl, Fd, La, Kp, Pt, Ov, Br, Mk), EVN (Hh, Mc, Nt, Tr, Jb, Ef, Ys), Long Baseline Array (-LBA- At, Mp, Ho, Cd), and two Kvazar antennas (Sv, Zc), plus Kalyazin (managed by ASC, Russia), and Green Bank (NRAO, USA). The observations took place on January 18-19, 2014, for a total of 16.8 hours, and at three different frequencies: 15GHz, 22GHz, and 43GHz. RA was involved only for the 22GHz part, while for the other bands only the VLBA was used. Both the Green Bank and Pushchino tracking station took part in the experiment. A RA-compatible total bandwidth of 32MHz, split into two 16-MHz IFs, was used. RA was scheduled to observe three consecutive 9.5 minute scans every 1.25 hours, to allow for antenna cooling. (2 data files).

Design and Characterization of a 5.2 GHz/2.4 GHz ΣΔ Fractional- N Frequency Synthesizer for Low-Phase Noise Performance

Directory of Open Access Journals (Sweden)

2006-01-01

Full Text Available This paper presents a complete noise analysis of a ΣΔ -based fractional- N phase-locked loop (PLL based frequency synthesizer. Rigorous analytical and empirical formulas have been given to model various phase noise sources and spurious components and to predict their impact on the overall synthesizer noise performance. These formulas have been applied to an integrated multiband WLAN frequency synthesizer RFIC to demonstrate noise minimization through judicious choice of loop parameters. Finally, predicted and measured phase jitter showed good agreement. For an LO frequency of 4.3 GHz, predicted and measured phase noise was 0.50 ° rms and 0.535 ° rms, respectively.

Development of Low-Noise Small-Area 24 GHz CMOS Radar Sensor

Directory of Open Access Journals (Sweden)

Min Yoon

2016-01-01

Full Text Available We present a low-noise small-area 24 GHz CMOS radar sensor for automotive collision avoidance. This sensor is based on direct-conversion pulsed-radar architecture. The proposed circuit is implemented using TSMC 0.13 μm RF (radio frequency CMOS (fT/fmax=120/140 GHz technology, and it is powered by a 1.5 V supply. This circuit uses transmission lines to reduce total chip size instead of real bulky inductors for input and output impedance matching. The layout techniques for RF are used to reduce parasitic capacitance at the band of 24 GHz. The proposed sensor has low cost and low power dissipation since it is realized using CMOS process. The proposed sensor showed the lowest noise figure of 2.9 dB and the highest conversion gain of 40.2 dB as compared to recently reported research results. It also showed small chip size of 0.56 mm2, low power dissipation of 39.5 mW, and wide operating temperature range of −40 to +125°C.

A New 95 GHz Methanol Maser Catalog. I. Data

Energy Technology Data Exchange (ETDEWEB)

Yang, Wenjin; Xu, Ye; Lu, Dengrong; Ju, Binggang; Li, Yingjie [Purple Mountain Observatory, Chinese Academy of Science, Nanjing 210008 (China); Chen, Xi [Center for Astrophysics, GuangZhou University, Guangzhou 510006 (China); Ellingsen, Simon P., E-mail: wjyang@pmo.ac.cn, E-mail: xuye@pmo.ac.cn, E-mail: chenxi@shao.ac.cn [School of Physical Sciences, University of Tasmania, Hobart, Tasmania (Australia)

2017-08-01

The Purple Mountain Observatory 13.7 m radio telescope has been used to search for 95 GHz (8{sub 0}–7{sub 1}A{sup +}) class I methanol masers toward 1020 Bolocam Galactic Plane Survey (BGPS) sources, leading to 213 detections. We have compared the line width of the methanol and HCO{sup +} thermal emission in all of the methanol detections, and on that basis, we find that 205 of the 213 detections are very likely to be masers. This corresponds to an overall detection rate of 95 GHz methanol masers toward our BGPS sample of 20%. Of the 205 detected masers, 144 (70%) are new discoveries. Combining our results with those of previous 95 GHz methanol maser searches, a total of 481 95 GHz methanol masers are now known. We have compiled a catalog listing the locations and properties of all known 95 GHz methanol masers.

On-chip patch antenna on InP substrate for short-range wireless communication at 140 GHz

DEFF Research Database (Denmark)

Dong, Yunfeng; Johansen, Tom Keinicke; Zhurbenko, Vitaliy

2017-01-01

This paper presents the design of an on-chip patch antenna on indium phosphide (InP) substrate for short-range wireless communication at 140 GHz. The antenna shows a simulated gain of 5.3 dBi with 23% bandwidth at 140 GHz and it can be used for either direct chip-to-chip communication or chip...

77 FR 45558 - 4.9 GHz Band

Science.gov (United States)

2012-08-01

..., our rules currently require 4.9 GHz licensees to ``cooperate in the selection and use of channels in... directional and thus can be represented as narrow paths on a coordination map; in contrast, they note, the low-power, less- directional, geographically-dispersed links in a 4.9 GHz network must be represented as a...

Design of a high speed, high resolution thermometry system for 1.5 GHz superconducting radio frequency cavities

Science.gov (United States)

Knobloch, Jens; Muller, Henry; Padamsee, Hasan

1994-11-01

Presented in this paper are the description and the test results of a new stationary thermometry system used to map the temperature of the outer surface of 1.5 GHz superconducting single-cell cavities during operation at 1.6 K. The system comprises 764 removable carbon thermometers whose signals are multiplexed and scanned by a Macintosh computer. A complete temperature map can be obtained in as little as 0.1 s at a temperature resolution of about 0.2 mK. Alternatively, it has been demonstrated that if the acquisition time is increased to several seconds, then a temperature resolution on the order of 30 μK is possible. To our knowledge, these are the fastest acquisition times so far achieved with L-band cavities at these resolutions.

A 1.8 GHz Voltage-Controlled Oscillator using CMOS Technology

Science.gov (United States)

Maisurah, M. H. Siti; Emran, F. Nazif; Norman Fadhil, Idham M.; Rahim, A. I. Abdul; Razman, Y. Mohamed

2011-05-01

A Voltage-Controlled Oscillator (VCO) for 1.8 GHz application has been designed using a combination of both 0.13 μm and 0.35 μm CMOS technology. The VCO has a large tuning range, which is from 1.39 GHz to 1.91 GHz, using a control voltage from 0 to 3V. The VCO exhibits a low phase-noise at 1.8 GHz which is around -119.8dBc/Hz at a frequency offset of 1 MHz.

Optimum concentric circular array antenna with high gain and side lobe reduction at 5.8 GHz

Science.gov (United States)

Zaid, Mohammed; Rafiqul Islam, Md; Habaebi, Mohamed H.; Zahirul Alam, AHM; Abdullah, Khaizuran

2017-11-01

The significance of high gain directional antennas stems from the need to cope up with the everyday progressing wireless communication systems. Due to low gain of the widely used microstrip antenna, combining multiple antennas in proper geometry increases the gain with good directive property. Over other array forms, this paper uses concentric circular array configuration for its compact structure and inherent symmetry in azimuth. This proposed array is composed of 9 elements on FR-4 substrate, which is designed for WLAN applications at 5.8GHz. Antenna Magus software is used for synthesis, while CST software is used for optimization. The proposed array is designed with optimum inter-element spacing and number of elements achieving a high directional gain of 15.7 dB compared to 14.2 dB of available literature, with a high reduction in side lobe level of -17.6 dB.

A low noise 665 GHz SIS quasi-particle waveguide receiver

Science.gov (United States)

Kooi, J. W.; Walker, C. K.; Leduc, H. G.; Hunter, T. R.; Benford, D. J.; Phillips, T. G.

1993-01-01

Recent results on a 565-690 GHz SIS heterodyne receiver employing a 0.36 micron(sup 2) Nb/AlOx/Nb SIS tunnel junction with high quality circular non-contacting back short and E-plane tuners in a full height wave guide mount are reported. No resonant tuning structures were incorporated in the junction design at this time, even though such structures are expected to help the performance of the receiver. The receiver operates to at least the gap frequency of Niobium, approximately 680 GHz. Typical receiver noise temperatures from 565-690 GHz range from 160K to 230K with a best value of 185K DSB at 648 GHz. With the mixer cooled from 4.3K to 2K the measured receiver noise temperatures decreased by approximately 15 percent, giving roughly 180K DSB from 660 to 680 GHz. The receiver has a full 1 GHz IF pass band and was successfully installed at the Caltech Submillimeter Observatory in Hawaii.

39GHz ECRH system for breakdown studies on the TCA tokamak

International Nuclear Information System (INIS)

Pochelon, A.; Goodman, T.; Whaley, D.; Tran, M.Q.; Reinhard, D.; Perrenoud, A.; Joedicke, B.; Mathews, H.G.; Kasparek, W.; Thumm, M.

1990-01-01

The design construction and first operation of a 39GHz ECRH system (300 kW, 100 ms) for low loop-voltage breakdown and startup-assist experiments on the TCA tokamak is described. (author) 5 refs., 6 figs., 1 tab

A spectroscopic survey of Orion KL between 41.5 and 50 GHz.

Science.gov (United States)

Rizzo, J R; Tercero, B; Cernicharo, J

2017-09-01

The nearby massive star-forming region Orion KL is one of the richest molecular reservoirs known in our Galaxy. The region hosts newly formed protostars, and the strong interaction between their radiation and their outflows with the environment results in a series of complex chemical processes leading to a high diversity of interstellar tracers. The region is therefore one of the most frequently observed sources, and the site where many molecular species have been discovered for the first time. With the availability of powerful wideband backends, it is nowadays possible to complete spectral surveys in the entire mm-range to obtain a spectroscopically unbiased chemical picture of the region. In this paper we present a sensitive spectral survey of Orion KL, made with one of the 34 m antennas of the Madrid Deep Space Communications Complex in Robledo de Chavela, Spain. The spectral range surveyed is from 41.5 to 50 GHz, with a frequency spacing of 180 kHz (equivalent to ≈ 1.2 km s -1 , depending on the exact frequency). The rms achieved ranges from 8 to 12 mK. The spectrum is dominated by the J = 1 → 0 SiO maser lines and by radio recombination lines (RRLs), which were detected up to Δ n = 11. Above a 3 σ level, we identified 66 RRLs and 161 molecular lines corresponding to 39 isotopologues from 20 molecules; a total of 18 lines remain unidentified, two of them above a 5 σ level. Results of radiative modelling of the detected molecular lines (excluding masers) are presented. At this frequency range, this is the most sensitive survey and also the one with the widest band. Although some complex molecules like CH 3 CH 2 CN and CH 2 CHCN arise from the hot core, most of the detected molecules originate from the low temperature components in Orion KL.

Magnetic films for GHz applications (abstract)

International Nuclear Information System (INIS)

Korenivski, V.; van Dover, R.B.

1997-01-01

Tremendous growth of the communications industry and the increasingly high demand for low-cost light-weight/small-size products drive technology to designs with a high degree of integration. In particular, planar inductors used in integrated circuits with significantly improved inductance per unit area characteristics are needed for further miniaturization of cellular phones operating at 0.95 and 1.9 GHz. Little has been done, however, to use magnetic films to improve the performance and/or reduce size of planar magnetic flux devices. The successful thin-film material would have a high ferromagnetic resonance (FMR) frequency (well above the operating frequency of the device), large permaeability, and low magnetic loss, and very importantly be technologically attractive, i.e., be process compatible with IC technology and have as few preparation steps as possible. Here, we report on fabrication of metallic ferromagnetic films of CoNbZr, CoNbZr/AlN mulitilayered laminates, and exchange-biased structures suitable for GHz applications. Lamination of CoNbZr with thin insulating layers of AlN is shown to significantly improve the microstructure and dc magnetic properties of the films having thicknesses >0.2 μm, as well as to be effective in suppressing eddy current losses at frequencies up to 1 endash 2 GHz. We use exchange biasing to increase the FMR frequency of soft CoNbZr. In-plane unidirectional anisotropy fields of ∼50 Oe are achieved, which result in FMR frequencies >2 GHz. Permeability values of ∼200 with quality factors of ∼10 at 1 GHz are demonstrated. The films are deposited at room temperature and require no postdeposition processing. Application of these films in planar inductors is discussed.copyright 1997 American Institute of Physics

Observation of total electron content and irregularities in electron density using GHz band radiowaves emitted from satellite

International Nuclear Information System (INIS)

Ogawa, Tadahiko; Fujita, Masaharu; Awaka, Jun.

1978-01-01

The experiments to investigate the influence of troposphere on millimeter and sub-millimeter wave propagation were carried out, using the engineering test satellite -- 2 (ETS-2) which became the Japanese first stationary satellite and carries the transmitter emitting beacon waves of 1.7, 11.5 and 34.5 GHz coherent each other. By these experiments, it was found that the waves of 1.7 and 11.5 GHz were affected by the ionosphere. The measurement of total electron content using GHz band waves was the first trial in the world, and is capable of grasping its change with higher accuracy than conventional methods. Scintillation of 1.7 GHz is mainly the phenomenon during night, and it was revealed that it has a peak at 22.30 local time and occurred through the radiowave scattering owing to the irregularities of the ionosphere. It is also suggested that some plasma instability is generated in the place where electron density gradient in the ionosphere is large, and the irregularities of fine scale are produced, assuming from GHz band scintillations at the time of magnetic storm. The relations among wave number spectrum, scintillation frequency spectrum and S4 index (statistical quantity to give estimate for scintillation amplitude) can be derived by the weak scattering theory (Simple scattering theory). As seen above, the diagnosis of plasma disturbances in the ionosphere is feasible by the simultaneous observations of total electron content and scintillation. (Wakatsuki, Y.)

Future mobile satellite communication concepts at 20/30 GHz

Science.gov (United States)

Barton, S. K.; Norbury, J. R.

1990-01-01

The outline of a design of a system using ultra small earth stations (picoterminals) for data traffic at 20/30 GHz is discussed. The picoterminals would be battery powered, have an RF transmitter power of 0.5 W, use a 10 cm square patch antenna, and have a receiver G/T of about -8 dB/K. Spread spectrum modulation would be required (due to interference consideration) to allow a telex type data link (less than 200 bit/s data rate) from the picoterminal to the hub station of the network and about 40 kbit/s on the outbound patch. An Olympus type transponder at 20/30 GHz could maintain several thousand simultaneous picoterminal circuits. The possibility of demonstrating a picoterminal network with voice traffic using Olympus is discussed together with fully mobile systems based on this concept.

Robust Sub-harmonic Mixer at 340 GHz Using Intrinsic Resonances of Hammer-Head Filter and Improved Diode Model

Science.gov (United States)

Wang, Cheng; He, Yue; Lu, Bin; Jiang, Jun; Miao, Li; Deng, Xian-Jin; Xiong, Yong-zhong; Zhang, Jian

2017-11-01

This paper presents a sub-harmonic mixer at 340 GHz based on anti-parallel Schottky diodes (SBDs). Intrinsic resonances in low-pass hammer-head filter have been adopted to enhance the isolation for different harmonic components, while greatly minimizing the transmission loss. The application of new DC grounding structure, impedance matching structure, and suspended micro-strip mitigates the negative influences of fabrication errors from metal cavity, quartz substrate, and micro-assembly. An improved lumped element equivalent circuit model of SBDs guarantees the accuracy of simulation, which takes current-voltage (I/V) behavior, capacitance-voltage (C/V) behavior, carrier velocity saturation, DC series resistor, plasma resonance, skin effect, and four kinds of noise generation mechanisms into consideration thoroughly. The measurement indicates that with local oscillating signal of 2 mW, the lowest double sideband conversion loss is 5.5 dB at 339 GHz; the corresponding DSB noise temperature is 757 K. The 3 dB bandwidth of conversion loss is 50 GHz from 317 to 367 GHz.

A low power 20 GHz comparator in 90 nm COMS technology

Science.gov (United States)

Kai, Tang; Qiao, Meng; Zhigong, Wang; Ting, Guo

2014-05-01

A low power 20 GHz CMOS dynamic latched regeneration comparator for ultra-high-speed, low-power analog-to-digital converters (ADCs) is proposed. The time constant in both the tracking and regeneration phases of the latch are analyzed based on the small signal model. A dynamic source-common logic (SCL) topology is adopted in the master-slave latch to increase the tracking and regeneration speeds. Implemented in 90 nm CMOS technology, this comparator only occupies a die area of 65 × 150 μm2 with a power dissipation of 14 mW from a 1.2 V power supply. The measurement results show that the comparator can work up to 20 GHz. Operating with an input frequency of 1 GHz, the circuit can oversample up to 20 Giga-sampling-per-second (GSps) with 5 bits resolution; while operating at Nyquist, the comparator can sample up to 20 GSps with 4 bits resolution. The comparator has been successfully used in a 20 GSps flash ADC and the circuit can be also used in other high speed applications.

Cold test of deep groove plarizer for 170 GHz ECCD system

International Nuclear Information System (INIS)

Saigusa, M.; Ookouti, K.; Sazawa, S.; Yuasa, S.; Takei, N.; Takahashi, K.; Sakamoto, K.; Imai, T.

2001-01-01

The single deep groove mirror was proposed as a new concept polarizer instead of the conventional two mirror polarizers for producing ordinary (or extraordinary) wave with high mode purity at an arbitrary injection angle in electron cyclotron current drive (ECCD) experiments. The estimated mode purity of O and X waves on the plasma surface is expected to be higher than about 93% for reasonable ECCD experimental conditions. The three types of deep groove mirrors, which are the rectangular groove mirror and the non-rectangular one, are manufactured and tested at the frequency range from 140 GHz to 170 GHz and the power level of 30 mW. The groove parameters are the period of 0.9-1 mm, the ridge width of 0.45-0.5 mm, and the groove depth of 1.98 mm, which is deeper than a wavelength at 170 GHz. The measured results of deep groove polarizers agree with the theoretical predictions, qualitatively. Those prove the feasibility of a single mirror polarizer for ECCD system

A study of 60 GHz intersatellite link applications

Science.gov (United States)

Anzic, G.; Connolly, D. J.; Haugland, E. J.; Kosmahl, H. G.; Chitwood, J. S.

Applications of intersatellite links operating at 60 GHz are reviewed. Likely scenarios, ranging from transmission of moderate and high data rates over long distances to low data rates over short distances are examined. A limited parametric tradeoff is performed with system variables such as radiofrequency power, receiver noise temperature, link distance, data rate, and antenna size. Present status is discussed and projections are given for both electron tube and solid state transmitter technologies. Monolithic transmit and receive module technology, already under development at 20 to 30 GHz, is reviewed and its extension to 60 GHz, and possible applicability is discussed.

A study of 60 GHz intersatellite link applications

Science.gov (United States)

Anzic, G.; Connolly, D. J.; Haugland, E. J.; Kosmahl, H. G.; Chitwood, J. S.

1983-01-01

Applications of intersatellite links operating at 60 GHz are reviewed. Likely scenarios, ranging from transmission of moderate and high data rates over long distances to low data rates over short distances are examined. A limited parametric tradeoff is performed with system variables such as radiofrequency power, receiver noise temperature, link distance, data rate, and antenna size. Present status is discussed and projections are given for both electron tube and solid state transmitter technologies. Monolithic transmit and receive module technology, already under development at 20 to 30 GHz, is reviewed and its extension to 60 GHz, and possible applicability is discussed.

The 30/20 GHz communications system functional requirements

Science.gov (United States)

Siperko, C. M.; Frankfort, M.; Markham, R.; Wall, M.

1981-01-01

The characteristics of 30/20 GHz usage in satellite systems to be used in support of projected communication requirements of the 1990's are defined. A requirements analysis which develops projected market demand for satellite services by general and specialized carriers and an analysis of the impact of propagation and system constraints on 30/20 GHz operation are included. A set of technical performance characteristics for the 30/20 GHz systems which can serve the resulting market demand and the experimental program necessary to verify technical and operational aspects of the proposed systems is also discussed.

5.2-GHz RF Power Harvester in 0.18-/spl mu/m CMOS for Implantable Intraocular Pressure Monitoring

KAUST Repository

Ouda, Mahmoud H.

2013-04-17

A first fully integrated 5.2-GHz CMOS-based RF power harvester with an on-chip antenna is presented in this paper. The design is optimized for sensors implanted inside the eye to wirelessly monitor the intraocular pressure of glaucoma patients. It includes a five-stage RF rectifier with an on-chip antenna, a dc voltage limiter, two voltage sensors, a low dropout voltage regulator, and MOSCAP based on-chip storage. The chip has been designed and fabricated in a standard 0.18-μm CMOS technology. To emulate the eye environment in measurements, a custom test setup is developed that comprises Plexiglass cavities filled with saline solution. Measurements in this setup show that the proposed chip can be charged to 1 V wirelessly from a 5-W transmitter 3 cm away from the harvester chip. The energy that is stored on the 5-nF on-chip MOSCAP when charged to 1 V is 2.5 nJ, which is sufficient to drive an arbitrary 100-μW load for 9 μs at regulated 0.8 V. Simulated efficiency of the rectifier is 42% at -7 dBm of input power.

Quantitative relationship between SAR and temperature rise inside eyeball in a realistic human heat model for 1.5 GHz-microwave exposure; 1.5GHz maikuroha wo abita tobu real model ni okeru gankyunai no hikyushuritsu to josho ondo tono teiryo kankei

Energy Technology Data Exchange (ETDEWEB)

Takai, K.; Fujiwara, O. [Nagoya Institute of Technology, Nagoya (Japan)

1997-12-20

For investigating biological effects of a localized SAR (specific absorption rate) deposited in a human body for electromagnetic wave exposure, it is indispensable to graps a temperature-rise inside a human brain including the control center for the body temperature. This paper numerically analyzes a temperature-rise inside an eyeball of our developed realistic head model for 1.5 GHz microwave exposure, using the FD-TD (finite-difference time-domain) method. The computed results are validated in comparison with the data obtained by Taflove and his colleague. In order to examine a quantitative relationship between the localized SAR and temperature-rise, we also obtained a tissue amount over which the localized SAR should be averaged so as to well reflect the temperature-rise distribution inside the eyeball. 15 refs., 9 figs., 3 tabs.

2 MW 110 GHz ECH heating system for DIII-D

International Nuclear Information System (INIS)

Moeller, C.; Prater, R.; Callis, R.; Remsen, D.; Doane, J.; Cary, W.; Phelps, R.; Tupper, M.

1990-09-01

A 2 MW 110 GHz ECH system using Varian 0.5 MW gyrotrons is under construction for use on the DIII-D tokamak by late 1991. Most of the components are being design and fabricated at General Atomics, including the gyrotron tanks, superconducting magnets, and transmission line. These components are intended for operation with 10 second pulses and, in the future, with 1 MW gyrotrons. 6 refs., 5 figs

Analysis of line integrated electron density using plasma position data on Korea Superconducting Tokamak Advanced Research

International Nuclear Information System (INIS)

Nam, Y. U.; Chung, J.

2010-01-01

A 280 GHz single-channel horizontal millimeter-wave interferometer system has been installed for plasma electron density measurements on the Korea Superconducting Tokamak Advanced Research (KSTAR) device. This system has a triangular beam path that does not pass through the plasma axis due to geometrical constraints in the superconducting tokamak. The term line density on KSTAR has a different meaning from the line density of other tokamaks. To estimate the peak density and the mean density from the measured line density, information on the position of the plasma is needed. The information has been calculated from tangentially viewed visible images using the toroidal symmetry of the plasma. Interface definition language routines have been developed for this purpose. The calculated plasma position data correspond well to calculation results from magnetic analysis. With the position data and an estimated plasma profile, the peak density and the mean density have been obtained from the line density. From these results, changes of plasma density themselves can be separated from effects of the plasma movements, so they can give valuable information on the plasma status.

Traveling-Wave Maser for 32 GHz

Science.gov (United States)

Shell, James; Clauss, Robert

2009-01-01

The figure depicts a traveling-wave ruby maser that has been designed (though not yet implemented in hardware) to serve as a low-noise amplifier for reception of weak radio signals in the frequency band of 31.8 to 32.3 GHz. The design offers significant improvements over previous designs of 32-GHz traveling-wave masers. In addition, relative to prior designs of 32-GHz amplifiers based on high-electron-mobility transistors, this design affords higher immunity to radio-frequency interference and lower equivalent input noise temperature. In addition to the basic frequency-band and low-noise requirements, the initial design problem included a requirement for capability of operation in a closed-cycle helium refrigerator at a temperature .4 K and a requirement that the design be mechanically simplified, relative to prior designs, in order to minimize the cost of fabrication and assembly. Previous attempts to build 32- GHz traveling-wave masers involved the use of metallic slow-wave structures comprising coupled transverse electromagnetic (TEM)-mode resonators that were subject to very tight tolerances and, hence, were expensive to fabricate and assemble. Impedance matching for coupling signals into and out of these earlier masers was very difficult. A key feature of the design is a slow-wave structure, the metallic portions of which would be mechanically relatively simple in that, unlike in prior slow-wave structures, there would be no internal metal steps, irises, or posts. The metallic portions of the slow-wave structure would consist only of two rectangular metal waveguide arms. The arms would contain sections filled with the active material (ruby) alternating with evanescent-wave sections. This structure would be transparent in both the signal-frequency band (the aforementioned range of 31.8 to 32.3 GHz) and the pump-frequency band (65.75 to 66.75 GHz), and would impose large slowing factors in both frequency bands. Resonant ferrite isolators would be placed in the

47 CFR 25.143 - Licensing provisions for the 1.6/2.4 GHz mobile-satellite service and 2 GHz mobile-satellite...

Science.gov (United States)

2010-10-01

... 47 Telecommunication 2 2010-10-01 2010-10-01 false Licensing provisions for the 1.6/2.4 GHz mobile-satellite service and 2 GHz mobile-satellite service. 25.143 Section 25.143 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Applications and Licenses...

CMOS 60-GHz and E-band power amplifiers and transmitters

CERN Document Server

Zhao, Dixian

2015-01-01

This book focuses on the development of design techniques and methodologies for 60-GHz and E-band power amplifiers and transmitters at device, circuit and layout levels. The authors show the recent development of millimeter-wave design techniques, especially of power amplifiers and transmitters, and presents novel design concepts, such as “power transistor layout” and “4-way parallel-series power combiner”, that can enhance the output power and efficiency of power amplifiers in a compact silicon area. Five state-of-the-art 60-GHz and E-band designs with measured results are demonstrated to prove the effectiveness of the design concepts and hands-on methodologies presented. This book serves as a valuable reference for circuit designers to develop millimeter-wave building blocks for future 5G applications.

Energy confinement in JT-60 lower hybrid current driven plasmas

International Nuclear Information System (INIS)

Ushigusa, K.; Imai, T.; Naito, O.; Ikeda, Y.; Tsuji, S.; Uehara, K.

1990-01-01

The energy confinement in high power lower hybrid current driven (LHCD) plasmas has been studied in the JT-60 tokamak. At a plasma current of 1 MA, the diamagnetically estimated energy confinement time in LHCD plasmas has almost the same value as the confinement time in ohmically heated plasmas at n-bar e ∼ 1.0x10 19 m -3 . The confinement time of high power LHCD plasmas (P LH E varies as to P LH α n e β I p 0 with α + β ∼ -0.3. (author). Letter-to-the-editor. 12 refs, 5 figs

200 and 270 GHz SIS receivers development for atmospheric observation

International Nuclear Information System (INIS)

Ochiai, S.; Masuko, H.

1993-01-01

Superconducting mixers have been developed for observations of atmospheric minor constituents such as ClO and ozone at Communications Research Laboratory. This paper describes the work at development of 200 and 270 GHz SIS mixers. Nb/AlOx/Nb junctions were fabricated at Nobeyama Radio Observatory. The base Nb layer 200 nm, the Al (AlOx) insulation layer, and the counter Nb electrode 150 nm are sputtered. The area outside of a junction defined by etching of the counter electrode is insulated by anodized Nb layer and sputtered SiO 2 . After sputtering thick SiO 2 layer on the whole wafer, a contact hole is made by etching. The thickness of the wiring Nb layer is 500 nm. The junctions are formed on the 250 μm thick fused quartz substrate. After the process of the junction fabrication, the quartz substrate is shaved from the back side until 150 μm thickness. Each junction for 270 GHz mixer has an area of about 1 μm 2 . The normal resistance of the six junctions series array is around 70 Ω. The mixer block has a reduced waveguide (1.2 x 0.1 mm for 200 GHz and 0.98 x 0. 1 mm for 270 GHz). The waveguide has two tuners in addition to a fixed backshort cavity. This configuration can allow to realize the lower embedding impedance, and less sensitive to the position of the tuners. The SIS mixers are cooled in a closed cycle He refrigerator. The LO is optically injected through a Fabry Perot interferometer. The 5--7 GHz IF is fed to a HEMT amplifier cooled at 15 K. The authors have started a preliminary measurement of the noise temperature of the SIS receivers, and comparing with calculated DSB receiver noise temperature assuming 3-port model. They continue to improve the performance of the SIS mixers now. They intend that the receivers shall be utilized for atmospheric monitor from next winter

1.3 GHz superconducting RF cavity program at Fermilab

Energy Technology Data Exchange (ETDEWEB)

Ginsburg, C.M.; Arkan, T.; Barbanotti, S.; Carter, H.; Champion, M.; Cooley, L.; Cooper, C.; Foley, M.; Ge, M.; Grimm, C.; Harms, E.; /Fermilab

2011-03-01

At Fermilab, 9-cell 1.3 GHz superconducting RF (SRF) cavities are prepared, qualified, and assembled into cryomodules (CMs) for Project X, an International Linear Collider (ILC), or other future projects. The 1.3 GHz SRF cavity program includes targeted R&D on 1-cell 1.3 GHz cavities for cavity performance improvement. Production cavity qualification includes cavity inspection, surface processing, clean assembly, and one or more cryogenic low-power CW qualification tests which typically include performance diagnostics. Qualified cavities are welded into helium vessels and are cryogenically tested with pulsed high-power. Well performing cavities are assembled into cryomodules for pulsed high-power testing in a cryomodule test facility, and possible installation into a beamline. The overall goals of the 1.3 GHz SRF cavity program, supporting facilities, and accomplishments are described.

VizieR Online Data Catalog: Jet kinematics of blazars at 43GHz with the VLBA (Jorstad+, 2017)

Science.gov (United States)

Jorstad, S. G.; Marscher, A. P.; Morozova, D. A.; Troitsky, I. S.; Agudo, I.; Casadio, C.; Foord, A.; Gomez, J. L.; MacDonald, N. R.; Molina, S. N.; Lahteenmaki, A.; Tammi, J.; Tornikoski, M.

2018-04-01

The VLBA-BU-BLAZAR monitoring program consists of approximately monthly observations with the VLBA at 43GHz of a sample of AGNs detected as γ-ray sources. In this paper, we present the results of observations from 2007 June to 2013 January. The sample consists of 21 FSRQs, 12 BLLacs, and 3 radio galaxies (RGs). It includes the blazars and radio galaxies detected at γ-ray energies by EGRET with average flux density at 43GHz exceeding 0.5Jy, declination north of -30°, and optical magnitude in the R band brighter than 18.5. (5 data files).

Analogue demonstration of a high temperature superconducting sigma-delta modulator with 27 GHz sampling

Energy Technology Data Exchange (ETDEWEB)

Forrester, M.G.; Hunt, B.D.; Miller, D.L.; Talvacchio, J.; Young, R.M. [Northrop Grumman Science and Technology Center, Pittsburgh, PA 15235-5098 (United States)

1999-11-01

We have successfully fabricated and tested a high temperature superconducting (HTS) sigma-delta modulator for analogue-to-digital conversion. This is the first demonstration of a GHz sampling A-to-D in HTS. The 15-junction single-flux-quantum (SFQ) circuit, fabricated using an epitaxial multilayer HTS process with YBCO/Co-YBCO/YBCO edge junctions, was internally clocked at 27 GHz and used to convert a 5.01 MHz signal. The modulator demonstrated a spur-free dynamic range of more than 75 dB. Two-tone measurements with 5.01 MHz and 5.51 MHz signals demonstrated third-order intermodulation products to be lower than -59 dBc. Demonstration of a functional HTS modulator represents a significant milestone in the development of high dynamic range ADCs suitable for such applications as surveillance radar. (author)

Lower hybrid current drive in tokamak plasmas

International Nuclear Information System (INIS)

Ushigusa, Kenkichi

1999-03-01

Past ten years progress on Lower Hybrid Current Drive (LHCD) experiments have demonstrated the largest non-inductive current (3.6 MA, JT-60U), the longest current sustainment (2 hours, TRIAM-1M), non-inductive current drive at the highest density (n-bar e - 10 20 m -3 , ALCATOR-C) and the highest current drive efficiency (η CD = 3.5x10 19 m -2 A/W, JT-60). These results indicate that LHCD is one of the most promising methods to drive non-inductive current in the present tokamak plasmas. This paper presents recent experimental results on LHCD experiments. Basic theories of LH waves, the wave propagation and the current drive are briefly summarized. The main part of this paper describes several important results and their physical pictures on recent LHCD experiments; 1) the experimental set-up, 2) the current drive efficiency, 3) the control of current profile and MHD activities, 4) the global energy confinement, 5) the global power flow, 6) fast electron behavior, 7) interaction between LH waves and thermal/fast ions, 8) combination with other CD method. (author)

A low power and low phase-noise 91 96 GHz VCO in 90 nm CMOS

Science.gov (United States)

Lin, Yo-Sheng; Lan, Kai-Siang; Chuang, Ming-Yuan; Lin, Yu-Ching

2018-06-01

This paper reports a 94 GHz CMOS voltage-controlled oscillator (VCO) using both the negative capacitance (NC) technique and series-peaking output power and phase noise (PN) enhancement technique. NC is achieved by adding two variable LC networks to the source nodes of the active circuit of the VCO. NMOSFET varicaps are adopted as the required capacitors of the LC networks. In comparison with the conventional one, the proposed active circuit substantially decreases the input capacitance (Cin) to zero or even a negative value. This leads to operation (or oscillation) frequency (OF) increase and tuning range (TR) enhancement of the VCO. The VCO dissipates 8.3 mW at 1 V supply. The measured TR of the VCO is 91 96 GHz, close to the simulated (92.1 96.7 GHz) and the calculated one (92.2 98.2 GHz). In addition, at 1 MHz offset from 95.16 GHz, the VCO attains an excellent PN of - 98.3 dBc/Hz. This leads to a figure-of-merit (FOM) of -188.5 dBc/Hz, a remarkable result for a V- or W-band CMOS VCO. The chip size of the VCO is 0.75 × 0.42 mm2, i.e. 0.315 mm2.

400-GHz wireless transmission of 60-Gb/s nyquist-QPSK signals using UTC-PD and heterodyne mixer

DEFF Research Database (Denmark)

Yu, Xianbin; Asif, Rameez; Piels, Molly

2016-01-01

We experimentally demonstrate an optical network compatible high-speed optoelectronics THz wireless transmission system operating at 400-GHz band. In the experiment, optical Nyquist quadrature phase-shift keying signals in a 12.5-GHz ultradense wavelength-division multiplexing grid is converted...... to the THz wireless radiation by photomixing in an antenna integrated unitravelling photodiode. The photomixing is transparent to optical modulation formats. We also demonstrate in the experiment the scalability of our system by applying single to four channels, as well as mixed three channels. Wireless...... transmission of a capacity of 60 Gb/s for four channels (15 Gb/s per channel) at 400-GHz band is successfully achieved, which pushes the data rates enabled by optoelectronics approach beyond the envelope in the frequency range above 300 GHz. Besides those, this study also validates the potential of bridging...

47 CFR 25.139 - NGSO FSS coordination and information sharing between MVDDS licensees in the 12.2 GHz to 12.7 GHz...

Science.gov (United States)

2010-10-01

... 47 Telecommunication 2 2010-10-01 2010-10-01 false NGSO FSS coordination and information sharing between MVDDS licensees in the 12.2 GHz to 12.7 GHz band. 25.139 Section 25.139 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS Applications and Licenses...

Low noise 874 GHz receivers for the International Submillimetre Airborne Radiometer (ISMAR)

Science.gov (United States)

Hammar, A.; Sobis, P.; Drakinskiy, V.; Emrich, A.; Wadefalk, N.; Schleeh, J.; Stake, J.

2018-05-01

We report on the development of two 874 GHz receiver channels with orthogonal polarizations for the International Submillimetre Airborne Radiometer. A spline horn antenna and dielectric lens, a Schottky diode mixer circuit, and an intermediate frequency (IF) low noise amplifier circuit were integrated in the same metallic split block housing. This resulted in a receiver mean double sideband (DSB) noise temperature of 3300 K (minimum 2770 K, maximum 3400 K), achieved at an operation temperature of 40 °C and across a 10 GHz wide IF band. A minimum DSB noise temperature of 2260 K at 20 °C was measured without the lens. Three different dielectric lens materials were tested and compared with respect to the radiation pattern and noise temperature. All three lenses were compliant in terms of radiation pattern, but one of the materials led to a reduction in noise temperature of approximately 200 K compared to the others. The loss in this lens was estimated to be 0.42 dB. The local oscillator chains have a power consumption of 24 W and consist of custom-designed Schottky diode quadruplers (5% power efficiency in operation, 8%-9% peak), commercial heterostructure barrier varactor (HBV) triplers, and power amplifiers that are pumped by using a common dielectric resonator oscillator at 36.43 GHz. Measurements of the radiation pattern showed a symmetric main beam lobe with full width half maximum <5° and side lobe levels below -20 dB. Return loss of a prototype of the spline horn and lens was measured using a network analyzer and frequency extenders to 750-1100 GHz. Time-domain analysis of the reflection coefficients shows that the reflections are below -25 dB and are dominated by the external waveguide interface.

Monitoring middle-atmospheric water vapor over Seoul by using a 22 GHz ground-based radiometer SWARA

Science.gov (United States)

Ka, Soohyun; de Wachter, Evelyn; Kaempfer, Niklaus; Oh, Jung Jin

2010-10-01

Water vapor is the strongest natural greenhouse gas in the atmosphere. It is most abundant in the troposphere at low altitudes, due to evaporation at the ocean surface, with maximum values of around 6 g/kg. The amount of water vapor reaches a minimum at tropopause level and increases again in the middle atmosphere through oxidation of methane and vertical transport. Water vapor has both positive and negative effects on global warming, and we need to study how it works on climate change by monitoring water vapor concentration in the middle atmosphere. In this paper, we focus on the 22 GHz ground-based radiometer called SWARA (Seoul Water vapor Radiometer) which has been operated at Sookmyung women's university in Seoul, Korea since Oct. 2006. It is a joint project of the University of Bern, Switzerland, and the Sookmyung Women's University of Seoul, South Korea. The SWARA receives 22.235 GHz emitted from water vapor spontaneously and converts down to 1.5 GHz with +/- 0.5 GHz band width in 61 kHz resolution. To represent 22.235 GHz water vapor spectrum precisely, we need some calibration methods because the signal shows very weak intensity in ~0.1 K on the ground. For SWARA, we have used the balancing and the tipping curve methods for a calibration. To retrieve the water vapor profile, we have applied ARTS and Qpack software. In this paper, we will present the calibration methods and water vapor variation over Seoul for the last 4 years.

8.64-11.62 GHz CMOS VCO and divider in a zero-IF 802.11a/b/g WLAN and Bluetooth application

International Nuclear Information System (INIS)

Sun Yu; Mei Niansong; Lu Bo; Huang Yumei; Hong Zhiliang

2010-01-01

A fully integrated VCO and divider implemented in SMIC 0.13-μm RFCMOS 1P8M technology with a 1.2 V supply voltage is presented. The frequency of the VCO is tuning from 8.64 to 11.62 GHz while the quadrature LO signals for 802.11a WLAN in 5.8 GHz band or for 802.11b/g WLAN and Bluetooth in 2.4 GHz band can be obtained by a frequency division by 2 or 4, respectively. A 6 bit switched capacitor array is applied for precise tuning of all necessary frequency bands. The testing results show that the VCO has a phase noise of-113 dBc - 1 MHz offset from the carrier of 5.5 GHz by dividing VCO output by two and the VCO core consumes 3.72 mW. The figure-of-merit for the tuning-range (FOM T ) of the VCO is -192.6 dBc/Hz. (semiconductor integrated circuits)

8.64-11.62 GHz CMOS VCO and divider in a zero-IF 802.11a/b/g WLAN and Bluetooth application

Energy Technology Data Exchange (ETDEWEB)

Sun Yu; Mei Niansong; Lu Bo; Huang Yumei; Hong Zhiliang, E-mail: yumeihuang@fudan.edu.c [ASIC and System State Key Laboratory, Fudan University, Shanghai 201203 (China)

2010-10-15

A fully integrated VCO and divider implemented in SMIC 0.13-{mu}m RFCMOS 1P8M technology with a 1.2 V supply voltage is presented. The frequency of the VCO is tuning from 8.64 to 11.62 GHz while the quadrature LO signals for 802.11a WLAN in 5.8 GHz band or for 802.11b/g WLAN and Bluetooth in 2.4 GHz band can be obtained by a frequency division by 2 or 4, respectively. A 6 bit switched capacitor array is applied for precise tuning of all necessary frequency bands. The testing results show that the VCO has a phase noise of-113 dBc - 1 MHz offset from the carrier of 5.5 GHz by dividing VCO output by two and the VCO core consumes 3.72 mW. The figure-of-merit for the tuning-range (FOM{sub T}) of the VCO is -192.6 dBc/Hz. (semiconductor integrated circuits)

Comparison of Stationarity Regions for Wireless Channels From 2 GHz to 30 GHz

DEFF Research Database (Denmark)

Yi, Tan; Wang, Chengxiang; Nielsen, Jesper Ødum

2017-01-01

Millimeter wave (mmWave) communication works in the frequencies above 6 gigahertz (GHz), with the system bandwidth up to 500 megahertz (MHz) or wider. In this case, the channel situations are dramatically different from the existing wireless channels in Third Generation/Fourth Generation (3G/4G...

The EUMETSAT OSI SAF near 50 GHz sea ice emissivity model

Directory of Open Access Journals (Sweden)

Rasums T. Tonboe

2013-02-01

Full Text Available A sea ice thermal microwave emission model for 50 GHz was developed under EUMETSAT's Ocean and Sea Ice Satellite Application Facility (OSI SAF programme. The model is based on correlations between the surface brightness temperature at 18, 36 and 50 GHz. The model coefficients are estimated using simulated data from a combined thermodynamic and emission model. The intention with the model is to provide a first guess sea ice surface emissivity estimate for atmospheric temperature sounding applications in the troposphere in numerical weather prediction (NWP models assimilating Advanced Microwave Sounding Unit (AMSU and Special Sensor Microwave Imager/Sounder (SSMIS data. The spectral gradient ratio is defined as the difference over the sum of the SSMIS brightness temperatures at 18 and 36 GHz vertical linear polarisation (GR1836. The GR1836 is related to the emissivity at the atmospheric temperature sounding channels at around 50 GHz. Furthermore, the brightness temperatures and the polarisation ratio (PR at the neighbouring 18, 36 and 50 GHz channels are highly correlated. Both the gradient ratio at 18 and 36 GHz and the PR at 36 GHz measured by SSMIS are input into the model predicting the 50 GHz emissivity for horizontal and vertical linear polarisations and incidence angles between 0° and 60° The simulated emissivity is compared to the emissivity derived with alternative methods. The fit to real AMSU observations is investigated using the different emissivity estimates for simulating the observations with atmospheric data from a regional weather prediction model.

Enhanced direct-modulated bandwidth of 37 GHz by a multi-section laser with a coupled-cavity-injection-grating design

DEFF Research Database (Denmark)

Bach, L.; Kaiser, W.; Reithmaier, J.P.

2003-01-01

Using a new multi-section laser concept based on a coupled-cavity-injection-grating design, the material related intrinsic 3 dB modulation bandwidth can be enhanced up to 37 GHz for a 1.5 mm long device.......Using a new multi-section laser concept based on a coupled-cavity-injection-grating design, the material related intrinsic 3 dB modulation bandwidth can be enhanced up to 37 GHz for a 1.5 mm long device....

77 FR 48097 - Operation of Radar Systems in the 76-77 GHz Band

Science.gov (United States)

2012-08-13

... modify the emission limits for vehicular radar systems operating within the 76-77 GHz band. Specifically.... 15.253 of the rules for vehicular radar systems operating in the 76-77 GHz band. Vehicular radars can... sensors operating in the 76-77 GHz band, the spectrum shall be investigated up to 231 GHz. (f) Fundamental...

Design of a 40-nm CMOS integrated on-chip oscilloscope for 5-50 GHz spin wave characterization

Science.gov (United States)

Egel, Eugen; Csaba, György; Dietz, Andreas; Breitkreutz-von Gamm, Stephan; Russer, Johannes; Russer, Peter; Kreupl, Franz; Becherer, Markus

2018-05-01

Spin wave (SW) devices are receiving growing attention in research as a strong candidate for low power applications in the beyond-CMOS era. All SW applications would require an efficient, low power, on-chip read-out circuitry. Thus, we provide a concept for an on-chip oscilloscope (OCO) allowing parallel detection of the SWs at different frequencies. The readout system is designed in 40-nm CMOS technology and is capable of SW device characterization. First, the SWs are picked up by near field loop antennas, placed below yttrium iron garnet (YIG) film, and amplified by a low noise amplifier (LNA). Second, a mixer down-converts the radio frequency (RF) signal of 5 - 50 GHz to lower intermediate frequencies (IF) around 10 - 50 MHz. Finally, the IF signal can be digitized and analyzed regarding the frequency, amplitude and phase variation of the SWs. The power consumption and chip area of the whole OCO are estimated to 166.4 mW and 1.31 mm2, respectively.

Development of Vertical Buffered Electropolishing for Its Post-Treatment Technology on 1.5 GHz Niobium SRF Cavities

International Nuclear Information System (INIS)

Jin Song; Lu Xiang-Yang; Lin Lin; Zhao Kui; Wu, A. T.; Rimmer, R. A.

2011-01-01

We report the latest research development of vertical buffered electropolishing on its post-treatment procedure as well as the effects of several major post-treatment techniques for buffered electropolishing (BEP) processed 1.5 GHz niobium (Nb) superconducting radio frequency (SRF) cavities. With the established post-treatment procedure, an accelerating gradient of 28.4 MV/m is obtained on a single cell cavity of the cebaf shape. This is the best result in the history of BEP development. The cavity is limited by quench with a high quality factor over 1.2 × 10 10 at the quench point. Analyses from optical inspection and temperature-mapping show that the quench should be originated from the pits that were already present on the cavity before this BEP treatment. All of these factors indicate that this procedure will have a great potential to produce better results if cavities without intrinsic performance limiting imperfections are used. (nuclear physics)

InP-DHBT-on-BiCMOS technology with fT/fmax of 400/350 GHz for heterogeneous integrated millimeter-wave sources

DEFF Research Database (Denmark)

Kraemer, Tomas; Ostermay, Ina; Jensen, Thomas

2013-01-01

-100 GHz. The 0.8 × 5 μm2 InP DHBTs show fT/fmax of 400/350 GHz with an output power of more than 26 mW at 96 GHz. These are record values for a heterogeneously integrated transistor on silicon. As a circuit example, a 164-GHz signal source is presented. It features a voltage-controlled oscillator in Bi......This paper presents a novel InP-SiGe BiCMOS technology using wafer-scale heterogeneous integration. The vertical stacking of the InP double heterojunction bipolar transistor (DHBT) circuitry directly on top of the BiCMOS wafer enables ultra-broadband interconnects with

47 CFR 15.251 - Operation within the bands 2.9-3.26 GHz, 3.267-3.332 GHz, 3.339-3.3458 GHz, and 3.358-3.6 GHz.

Science.gov (United States)

2010-10-01

... exceed 3000 microvolts/meter/MHz at 3 meters in any direction. Further, an AVIS, when in its operating position, shall not produce a field strength greater than 400 microvolts/meter/MHz at 3 meters in any... maximum of 100 microvolts/meter/MHz at 3 meters, measured from 30 MHz to 20 GHz for the complete system...

Towards low-cost gigabit wireless systems at 60 GHz

NARCIS (Netherlands)

Yang, Haibing

2008-01-01

The world-wide availability of the huge amount of license-free spectral space in the 60 GHz band provides wide room for gigabit-per-second (Gb/s) wireless applications. A commercial (read: low-cost) 60-GHz transceiver will, however, provide limited system performance due to the stringent link budget

Multiparty quantum secret sharing based on GHZ states

Energy Technology Data Exchange (ETDEWEB)

Hwang, Tzonelih; Hwang, Cheng-Chieh [Department of Computer Science and Information Engineering, National Cheng Kung University, Tainan, 701 Taiwan (China); Li, Chuan-Ming, E-mail: hwangtl@ismail.csie.ncku.edu.tw [Department of Information Management, Shu-Zen College of Medicine and Management, Kaohsiung, 821 Taiwan (China)

2011-04-15

Gao (2009 Commun. Theor. Phys. 52 421-4) has proposed an efficient multiparty quantum secret sharing (MQSS) with two-photon three-dimensional Einstein-Podolsky-Rosen (EPR) pairs. This work shows that a similar idea can also be used to construct an MQSS using the Greenberger-Horne-Zeilinger (GHZ) states. Compared to other MQSSs using GHZ-related states, the newly proposed protocol is more efficient in the aspect of qubit utilization.

Construction of an integrated down-converter for operation at 200 GHz

International Nuclear Information System (INIS)

Digby, J.W.

1999-05-01

There is currently considerable interest in the part of the electromagnetic spectrum known as the terahertz region (100 GHz to 10 THz). Traditionally, terahertz radiation was the preserve of specialist applications in astronomy, atmospheric studies and plasma diagnostics. However, potential or actual applications in such diverse fields as medicine, security, communications and military applications are now emerging. At present there are very few devices and systems that operate in this spectral region and those which exist are expensive and difficult to manufacture. For the potential of terahertz radiation to be realised by industry, a low-cost (i.e. 'manufacturable') method of constructing terahertz systems is needed; new methods of generating radiation at terahertz frequencies are also urgently required. This thesis presents the development of a novel technique for producing passive and active devices and systems for use at terahertz frequencies. This novel approach utilises standard semiconductor techniques to fabricate metal-pipe waveguides directly onto semiconductor wafers. As standard semiconductor techniques are used, it provides a possible low-cost and highly manufacturable method of producing terahertz devices and systems. The key processes that are needed to produce components and devices for terahertz systems have been developed and presented in this work. Metal-pipe rectangular waveguides for use at W-band (70 GHz - 110 GHz) and G-band (140 GHz - 220 GHz) have been fabricated and S-parameter measurements have been performed on them using a specially designed test fixture. The measured attenuation for these waveguides is approximately 0.2 dB to 5 dB per guide wavelength for W-band and 0.6 dB per guide wavelength for G-band; these results suggest that these components could be used in practical systems. A method of interfacing with terahertz systems and free-space is needed in real applications, so a horn antenna has been designed which can be

Polarisation observations of VY Canis Majoris H2O 532-441 620.701 GHz maser emission with HIFI

Science.gov (United States)

Harwit, M.; Houde, M.; Sonnentrucker, P.; Boogert, A. C. A.; Cernicharo, J.; De Beck, E.; Decin, L.; Henkel, C.; Higgins, R. D.; Jellema, W.; Kraus, A.; McCoey, C.; Melnick, G. J.; Menten, K. M.; Risacher, C.; Teyssier, D.; Vaillancourt, J. E.; Alcolea, J.; Bujarrabal, V.; Dominik, C.; Justtanont, K.; de Koter, A.; Marston, A. P.; Olofsson, H.; Planesas, P.; Schmidt, M.; Schöier, F. L.; Szczerba, R.; Waters, L. B. F. M.

2010-10-01

Context. Water vapour maser emission from evolved oxygen-rich stars remains poorly understood. Additional observations, including polarisation studies and simultaneous observation of different maser transitions may ultimately lead to greater insight. Aims: We have aimed to elucidate the nature and structure of the VY CMa water vapour masers in part by observationally testing a theoretical prediction of the relative strengths of the 620.701 GHz and the 22.235 GHz maser components of ortho H2O. Methods: In its high-resolution mode (HRS) the Herschel Heterodyne Instrument for the Far Infrared (HIFI) offers a frequency resolution of 0.125 MHz, corresponding to a line-of-sight velocity of 0.06 km s-1, which we employed to obtain the strength and linear polarisation of maser spikes in the spectrum of VY CMa at 620.701 GHz. Simultaneous ground based observations of the 22.235 GHz maser with the Max-Planck-Institut für Radioastronomie 100-m telescope at Effelsberg, provided a ratio of 620.701 GHz to 22.235 GHz emission. Results: We report the first astronomical detection to date of H2O maser emission at 620.701 GHz. In VY CMa both the 620.701 and the 22.235 GHz polarisation are weak. At 620.701 GHz the maser peaks are superposed on what appears to be a broad emission component, jointly ejected from the star. We observed the 620.701 GHz emission at two epochs 21 days apart, both to measure the potential direction of linearly polarised maser components and to obtain a measure of the longevity of these components. Although we do not detect significant polarisation levels in the core of the line, they rise up to approximately 6% in its wings. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.Appendix (page 5) is only available in electronic form at http://www.aanda.org

Lower hybrid current drive in tokamak plasmas

Energy Technology Data Exchange (ETDEWEB)

Ushigusa, Kenkichi [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment

1999-03-01

Past ten years progress on Lower Hybrid Current Drive (LHCD) experiments have demonstrated the largest non-inductive current (3.6 MA, JT-60U), the longest current sustainment (2 hours, TRIAM-1M), non-inductive current drive at the highest density (n-bar{sub e} - 10{sup 20}m{sup -3}, ALCATOR-C) and the highest current drive efficiency ({eta}{sub CD} = 3.5x10{sup 19} m{sup -2}A/W, JT-60). These results indicate that LHCD is one of the most promising methods to drive non-inductive current in the present tokamak plasmas. This paper presents recent experimental results on LHCD experiments. Basic theories of LH waves, the wave propagation and the current drive are briefly summarized. The main part of this paper describes several important results and their physical pictures on recent LHCD experiments; 1) the experimental set-up, 2) the current drive efficiency, 3) the control of current profile and MHD activities, 4) the global energy confinement, 5) the global power flow, 6) fast electron behavior, 7) interaction between LH waves and thermal/fast ions, 8) combination with other CD method. (author)

Design of a 17.14 GHz quasi-optical pulse compressor

International Nuclear Information System (INIS)

Petelin, M. I.; Kuzikov, S. V.; Danilov, Yu. Yu.; Granatstein, V. L.; Nusinovich, G. S.

1999-01-01

A quasi-optical version of the ring cavity pulse compressor is considered. This concept is based on the coupling of the input wave to a whispering gallery mode of a barrel-like cavity due to helical corrugations of the cavity wall. Low-power tests of the prototype were carried out at 11.4 GHz and demonstrated reasonable agree-ment between experimental data and theoretical predictions. The design of a similar pulse compressor at 17.14 GHz compatible with the 17.14 GHz, 100 MW gyroklystron currently under development at the University of Maryland is presented

Analisis Kelayakan Implementasi Teknologi LTE 1.8 GHz Bagi Operator Seluler di Indonesia [Feasibility Analysis of LTE 1.8 GHz for Mobile Operators in Indonesia

Directory of Open Access Journals (Sweden)

Sri Ariyanti

2015-06-01

Full Text Available Peningkatan kebutuhan layanan data mendorong operator telekomunikasi berusaha mengimplementasikan jaringan akses broadband yang lebih handal.  Teknologi LTE merupakan salah satu teknologi dengan kecepatan mencapai tiga kali dibanding teknologi HSDPA, sehingga diharapkan dapat memenuhi kebutuhan pelanggan data mobile. Refarming frekuensi 1.8 GHz  untuk penerapan teknologi LTE memberikan efisiensi karena tidak perlu membayar BHP lagi untuk menyewa frekuensi baru. Teknologi 2G GSM selama ini juga semakin ditinggalkan, masyarakat di daerah perkotaan cenderung lebih banyak menggunakan layanan data.  Sebelum diterapkannya teknologi LTE pada frekuensi 1.8 GHz perlu adanya kajian untuk mengetahui kelayakan teknologi LTE pada frekuensi 1.8 GHz. Penelitian ini bertujuan untuk melakukan cost-benefit analysis implementasi LTE pada frekuensi 1.8 GHz.  Metode penelitian menggunakan pendekatan kualitataif yang didukung dengan data kuantitatif.  Hasil penelitian menunjukkan bahwa minimal bandiwdth yang diperlukan agar implementasi LTE layak digunakan adalah 15 MHz.  Meskipun tanpa Global Frequency Returning, penggunaan bandwidth 10 MHz tidak layak digunakan untuk implementasi LTE.      *****The incresing of data demand drives mobile operators to implement more reliable broadband access network. LTE technology has downlink peak rate up to three times than HSDPA,  hence it may fulfill the mobile data user requirement. Frequency 1.8 GHz refarming can be implemented to provide efficiency because They do not need to pay licence fee for leasing new frequency. GSM technology will be abandoned since it is not growing anymore. Besides that, dense urban users tend to use data mobile.  Before implementing LTE technology  on 1.8 GHz frequency, It is necessary to analysis the feasibility such technology. This research used qualitative method supported by quantitative  approach.  The result of this research showed that minimum bandwidth to implement 1.8 GHz LTE

Test results from the LLNL 250 GHz CARM experiment

International Nuclear Information System (INIS)

Kulke, B.; Caplan, M.; Bubp, D.; Houck, T.; Rogers, D.; Trimble, D.; VanMaren, R.; Westenskow, G.; McDermott, D.B.; Luhmann, N.C. Jr.; Danly, B.

1991-05-01

We have completed the initial phase of a 250 GHz CARM experiment, driven by the 2 MeV, 1 kA, 30 ns induction linac at the LLNL ARC facility. A non-Brillouin, solid, electron beam is generated from a flux-threaded, thermionic cathode. As the beam traverses a 10 kG plateau produced by a superconducting magnet, ten percent of the beam energy is converted into rotational energy in a bifilar helix wiggler that produces a spiraling, 50 G, transverse magnetic field. The beam is then compressed to a 5 mm diameter as it drifts into a 30 kG plateau. For the present experiment, the CARM interaction region consisted of a single Bragg section resonator, followed by a smooth-bore amplifier section. Using high-pass filters, we have observed broadband output signals estimated to be at the several megawatt level in the range 140 to over 230 GHz. This is consistent with operation as a superradiant amplifier. Simultaneously, we also observed K a band power levels near 3 MW

Test results from the LLNL 250 GHz CARM experiment

International Nuclear Information System (INIS)

Kulke, B.; Caplan, M.; Bubp, D.; Houck, T.; Rogers, D.; Trimble, D.; VanMaren, R.; Westenskow, G.; McDermott, D.B.; Luhmann, N.C. Jr.; Danly, B.

1991-01-01

The authors have completed the initial phase of a 250 GHz CARM experiment, driven by the 2 MeV, 1 kA, 30 ns induction linac at the LLNL ARC facility. A non-Brillouin, solid, electron beam is generated from a flux-threaded, thermionic cathode. As the beam traverses a 10 kG plateau produced by a superconducting magnet, ten percent of the beam energy is converted into rotational energy in a bifilar helix wiggler that produces a spiraling, 50 G, transverse magnetic field. The beam is then compressed to a 5 mm diameter as it drifts into a 30 kG plateau. For the present experiment, the CARM interaction region consisted of a single Bragg section resonator, followed by a smooth-bore amplifier section. Using high-pass filters, they have observed broadband output signals estimated to be at the several megawatt level in the range 140 to over 230 GHz. This is consistent with operation as a superradiant amplifier. Simultaneously, they also observed K a band power levels near 3 MW

A dual-mode 6-9 GHz transmitter for OFDM-UWB

International Nuclear Information System (INIS)

Chen Yunfeng; Gao Ting; Li Wei; Li Ning; Ren Junyan

2011-01-01

This paper presents a fully integrated dual-mode 6 to 9 GHz transmitter for both WiMedia and China MB-OFDM UWB applications. The proposed transmitter consists of a dual-mode I/QLPF, an up-conversion mixer, a two-stage power driver amplifier and a broadband high-speed frequency divider with LO buffers for I/Q LO carrier generation. The measurement results show that the gain ripple of the transmitter is within ±1.5/±2.8 dB from 6 to 8.7/9 GHz. The output IP3 is about +13.2 dBm, the output 1dBCP is around +2.8 dBm, and the LO leakage/sideband rejection ratio is about -35/-38 dBc. The ESD protected chip is fabricated with a TSMC 0.13 μm RFCMOS process with a die size of 1.6 x 1.3 mm 2 and the core circuit consumes only 46 mA under a 1.2 V supply. (semiconductor integrated circuits)

A dual-mode 6-9 GHz transmitter for OFDM-UWB

Energy Technology Data Exchange (ETDEWEB)

Chen Yunfeng; Gao Ting; Li Wei; Li Ning; Ren Junyan, E-mail: jyren@fudan.edu.cn, E-mail: w-li@fudan.edu.cn [State Key Laboratory of ASIC and System, Fudan University, Shanghai 201203 (China)

2011-05-15

This paper presents a fully integrated dual-mode 6 to 9 GHz transmitter for both WiMedia and China MB-OFDM UWB applications. The proposed transmitter consists of a dual-mode I/QLPF, an up-conversion mixer, a two-stage power driver amplifier and a broadband high-speed frequency divider with LO buffers for I/Q LO carrier generation. The measurement results show that the gain ripple of the transmitter is within {+-}1.5/{+-}2.8 dB from 6 to 8.7/9 GHz. The output IP3 is about +13.2 dBm, the output 1dBCP is around +2.8 dBm, and the LO leakage/sideband rejection ratio is about -35/-38 dBc. The ESD protected chip is fabricated with a TSMC 0.13 {mu}m RFCMOS process with a die size of 1.6 x 1.3 mm{sup 2} and the core circuit consumes only 46 mA under a 1.2 V supply. (semiconductor integrated circuits)

1.5-V-threshold-voltage Schottky barrier normally-off AlGaN/GaN high-electron-mobility transistors with f T/f max of 41/125 GHz

Science.gov (United States)

Hou, Bin; Ma, Xiaohua; Yang, Ling; Zhu, Jiejie; Zhu, Qing; Chen, Lixiang; Mi, Minhan; Zhang, Hengshuang; Zhang, Meng; Zhang, Peng; Zhou, Xiaowei; Hao, Yue

2017-07-01

In this paper, a normally-off AlGaN/GaN high-electron-mobility transistors (HEMT) fabricated using inductively coupled plasma (ICP) CF4 plasma recessing and an implantation technique is reported. A gate-to-channel distance of ˜10 nm and an equivalent negative fluorine sheet charge density of -1.21 × 1013 cm-2 extracted using a simple threshold voltage (V th) analytical model result in a high V th of 1.5 V, a peak transconductance of 356 mS/mm, and a subthreshold slope of 133 mV/decade. A small degradation of channel mobility leads to a high RF performance with f T/f max of 41/125 GHz, resulting in a record high f T × L g product of 10.66 GHz·µm among Schottky barrier AlGaN/GaN normally-off HEMTs with V th exceeding 1 V, to the best of our knowledge.

The 1.4 GHZ light curve of GRB 970508

NARCIS (Netherlands)

Galama, TJ; Wijers, RAMJ; Groot, PJ; Strom, RG; De Bruyn, AG; Kouveliotou, C; Robinson, CR; van Paradus, J

1998-01-01

We report on Westerbork 1.4 GHz radio observations of the radio counterpart to gamma-ray burst GRB 970508, between 0.80 and 138 days after this event. The 1.4 GHz light curve shows a transition from optically thick to thin emission between 39 and 54 days after the event. We derive the slope p of the

Fabrication and installment of hard-wired I and C works for the neutral beam injection system of the KSTAR project

International Nuclear Information System (INIS)

Jung, Ki Sok; Oh, Byung Hun; In, Sang Ryul; Yoon, Jae Sung

2004-01-01

Instrumentation and Control(I and C) of the neutral beam injection(NBI) system for the K-STAR national fusion research project has been working from the start of the project to answer diverse requests arising from various facets of the development and construction phases of the project. In a parallel effort with the software oriented I and C development, there has been existing an enormous amount of hard-wiring I and C works for the NBI facility to be developed and fabricated in schedule. Circuits and hardwired functions have been designed, tested, fabricated, and finally installed to the relevant parts of the system. Some examples of those hard-wired I and C works are related to the vacuum system, gas feeding system, arc detector circuit, ion source monitoring, bending magnet and calorimeter. They are one of those integral parts for the proper operation of the NBI system. Examples of those hard-wired I and C works are introduced in this presentation

Simulasi Penggunaan Frekuensi Milimeter Wave Untuk Akses Komunikasi Jaringan 5G Indoor

Directory of Open Access Journals (Sweden)

Toha Ardi Nugraha

2017-02-01

Full Text Available Millimeter Wave (mmWave is a solution to overcome of frequency limitations in 5G technology implementations using high frequency domain. This research discusses about mmWave frequency selection for 5G technology using empirical models in indoor propagation model. Several MmWave frequencies are simulated on indoor office environment. Based on simulation with InH placed in each room 5x5 meter size, it will be more effective using 60GHz, compared to 38Ghz, 28GHz, and 5GHz and also unlicenced 2.4. The average SIR will better at mmWave frequencies in the 60GHz with 33.97 dB and the average received signal is -73.87 dBm. Overall, it can also be concluded that the InH device with low frequency is not suitable applied indoors with massive deployement, it can be interference, for exampe using unlicenced 2.4GHz and 5GHz,  receiver only gets average SIR of approximately 5dB. Keywords-5G, Indoor, Milimeter Wave, Indoor Hotspot

Operation of a 1.3 GHz, 10 MW Multiple Beam Klystron

CERN Document Server

Bohlen, H P; Cattelino, M; Cox, L; Cusick, M; Forrest, S; Friedlander, F; Staprans, A; Wright, E; Zitelli, L

2004-01-01

Results will be reported for a 1.3 GHz, 10 MW multiple beam klystron that is being developed for the TESLA linear accelerator facility. The design parameters for the device are 10 MW peak RF output power with 150 kW average power, 1.5 ms pulse length, 65% efficiency, 50 dB gain, and 2.0 A/cm2

HIGH RESOLUTION 36 GHz IMAGING OF THE SUPERNOVA REMNANT OF SN 1987A

International Nuclear Information System (INIS)

Potter, T. M.; Staveley-Smith, L.; Zanardo, G.; Ng, C.-Y.; Gaensler, B. M.; Ball, Lewis; Kesteven, M. J.; Manchester, R. N.; Tzioumis, A. K.

2009-01-01

The aftermath of supernova (SN) 1987A continues to provide spectacular insights into the interaction between an SN blastwave and its circumstellar environment. We here present 36 GHz observations from the Australia Telescope Compact Array of the radio remnant of SN 1987A. These new images, taken in 2008 April and 2008 October, substantially extend the frequency range of an ongoing monitoring and imaging program conducted between 1.4 and 20 GHz. Our 36.2 GHz images have a diffraction-limited angular resolution of 0.''3-0.''4, which covers the gap between high resolution, low dynamic range VLBI images of the remnant and low resolution, high dynamic range images at frequencies between 1 and 20 GHz. The radio morphology of the remnant at 36 GHz is an elliptical ring with enhanced emission on the eastern and western sides, similar to that seen previously at lower frequencies. Model fits to the data in the Fourier domain show that the emitting region is consistent with a thick inclined torus of mean radius 0.''85, and a 2008 October flux density of 27 ± 6 mJy at 36.2 GHz. The spectral index for the remnant at this epoch, determined between 1.4 GHz and 36.2 GHz, is α = -0.83. There is tentative evidence for an unresolved central source with flatter spectral index.

Measurements of the cosmic microwave background temperature at 1.47 GHz

Science.gov (United States)

Bensadoun, M.; Bersanelli, M.; De Amici, G.; Kogut, A.; Levin, S. M.; Limon, M.; Smoot, G. F.; Witebsky, C.

1993-01-01

We have used a radio-frequency-gain total-power radiometer to measure the intensity of the cosmic microwave background (CMB) at a frequency of 1.47 GHz (20.4 cm wavelength) from White Mountain, California in 1988 September and from the South Pole in 1989 December. The CMB thermodynamic temperature, T(CMB), is 2.27 +/- 0.25 K (68 percent confidence limit) measured from White Mountain and 2.26 +/- 0.20 K from the South Pole site. The combined result is 2.26 +/- 0.19 K. The correction for Galactic emission has been derived from scaled low-frequency maps and constitutes the main source of error. The atmospheric signal is extrapolated from our zenith scan measurements at higher frequencies. These results are consistent with our previous measurement at 1.41 GHz and about 2.5 sigma from the 2.74 +/- 0.01 K global average CMB temperature.

Towards a 1 MW, 170 GHz gyrotron design for fusion application

Science.gov (United States)

Kumar, Anil; Kumar, Nitin; Singh, Udaybir; Bhattacharya, Ranajoy; Yadav, Vivek; Sinha, A. K.

2013-03-01

The electrical design of different components of 1 MW, 170 GHz gyrotron such as, magnetron injection gun, cylindrical interaction cavity and collector and RF window is presented in this article. Recently, a new project related to the development of 170 GHz, 1 MW gyrotron has been started for the Indian Tokamak. TE34,10 mode is selected as the operating mode after studied the problem of mode competition. The triode type geometry is selected for the design of magnetron injection gun (MIG) to achieve the required beam parameters. The maximum transverse velocity spread of 3.28% at the velocity ratio of 1.34 is obtained in simulations for a 40 A, 80 kV electron beam. The RF output power of more than 1 MW with 36.5% interaction efficiency without depressed collector is predicted by simulation in single-mode operation at 170 GHz frequency. The simulated single-stage depressed collector of the gyrotron predicted the overall device efficiencies >55%. Due to the very good thermal conductivity and very weak dependency of the dielectric parameters on temperature, PACVD diamond is selected for window design for the transmission of RF power. The in-house developed code MIGSYN and GCOMS are used for initial geometry design of MIG and mode selection respectively. Commercially available simulation tools MAGIC and ANSYS are used for beam-wave interaction and mechanical analysis respectively.

An FDMA system concept for 30/20 GHz high capacity domestic satellite service

Science.gov (United States)

Berk, G.; Jean, P. N.; Rotholz, E.; White, B. E.

1982-01-01

The paper summarizes a feasibility study of a multibeam FDMA satellite system operating in the 30/20 GHz band. The system must accommodate a very high volume of traffic within the restrictions of a 5 kW solar cell array and a 2.5 GHz bandwidth. Multibeam satellite operation reduces the DC power demand and allows reuse of the available bandwidth. Interferences among the beams are brought to acceptable levels by appropriate frequency assignments. A transponder design is presented; it is greatly simplified by the application of a regional concept. System analysis shows that MSK modulation is appropriate for a high-capacity system because it conserves the frequency spectrum. Rain attenuation, a serious problem in this frequency band, is combatted with sufficient power margins and with coding. Link budgets, cost analysis, and weight and power calculations are also discussed. A satellite-routed FDMA system compares favorably in performance and cost with a satellite-switched TDMA system.

Multiband Split-Ring Resonator Based Planar Inverted-F Antenna for 5G Applications

Directory of Open Access Journals (Sweden)

Muhammad Kamran Ishfaq

2017-01-01

Full Text Available 5G, the fifth generation of wireless communications, is focusing on multiple frequency bands, such as 6 GHz, 10 GHz, 15 GHz, 28 GHz, and 38 GHz, to achieve high data rates up to 10 Gbps or more. The industry demands multiband antennas to cover these distant frequency bands, which is a task much more challenging. In this paper, we have designed a novel multiband split-ring resonator (SRR based planar inverted-F antenna (PIFA for 5G applications. It is composed of a PIFA, an inverted-L parasitic element, a rectangular shaped parasitic element, and a split-ring resonator (SRR etched on the top plate of the PIFA. The basic PIFA structure resonates at 6 GHz. An addition of a rectangular shaped parasitic element produces a resonance at 15 GHz. The introduction of a split-ring resonator produces a band notch at 8 GHz, and a resonance at 10 GHz, while the insertion of an inverted-L shaped parasitic element further enhances the impedance bandwidth in the 10 GHz band. The frequency bands covered, each with more than 1 GHz impedance bandwidth, are 6 GHz (5–7 GHz, 10 GHz (9–10.8 GHz, and 15 GHz (14-15 GHz, expected for inclusion in next-generation wireless communications, that is, 5G. The design is simulated using Ansys Electromagnetic Suite 17 simulation software package. The simulated and the measured results are compared and analyzed which are generally in good agreement.

Studies of Current Induced Magnetization reversal and generation of GHz radiation in magnetic nanopillars

Science.gov (United States)

Alhajdarwish, Mustafa Yousef

justifying such scaling; and (5) designing and constructing a system for frequency domain studies up to 40 GHz and for time domain studies.

Results of RIKEN superconducting electron cyclotron resonance ion source with 28 GHz.

Science.gov (United States)

Higurashi, Y; Ohnishi, J; Nakagawa, T; Haba, H; Tamura, M; Aihara, T; Fujimaki, M; Komiyama, M; Uchiyama, A; Kamigaito, O

2012-02-01

We measured the beam intensity of highly charged heavy ions and x-ray heat load for RIKEN superconducting electron cyclotron resonance ion source with 28 GHz microwaves under the various conditions. The beam intensity of Xe(20+) became maximum at B(min) ∼ 0.65 T, which was ∼65% of the magnetic field strength of electron cyclotron resonance (B(ECR)) for 28 GHz microwaves. We observed that the heat load of x-ray increased with decreasing gas pressure and field gradient at resonance zone. It seems that the beam intensity of highly charged heavy ions with 28 GHz is higher than that with 18 GHz at same RF power.

A propagation-measurement-based evaluation of channel characteristics and models pertinent to the expansion of mobile radio systems to frequencies beyond 2 GHz

NARCIS (Netherlands)

Bultitude, R.J.C.; Schenk, T.C.W.; Op de Kamp, N.A.A.; Adnani, N.

2007-01-01

64This paper concerns the measurement-based comparison of urban microcellular mobile radio channel characteristics at 1.9 GHz and a higher frequency, i.e., 5.8 GHz, where future wireless systems could operate. Characteristics that are reported include transmission loss, root-mean-square delay

SEMICONDUCTOR INTEGRATED CIRCUITS 8.64-11.62 GHz CMOS VCO and divider in a zero-IF 802.11a/b/g WLAN and Bluetooth application

Science.gov (United States)

Yu, Sun; Niansong, Mei; Bo, Lu; Yumei, Huang; Zhiliang, Hong

2010-10-01

A fully integrated VCO and divider implemented in SMIC 0.13-μm RFCMOS 1P8M technology with a 1.2 V supply voltage is presented. The frequency of the VCO is tuning from 8.64 to 11.62 GHz while the quadrature LO signals for 802.11a WLAN in 5.8 GHz band or for 802.11b/g WLAN and Bluetooth in 2.4 GHz band can be obtained by a frequency division by 2 or 4, respectively. A 6 bit switched capacitor array is applied for precise tuning of all necessary frequency bands. The testing results show that the VCO has a phase noise of—113 dBc @ 1 MHz offset from the carrier of 5.5 GHz by dividing VCO output by two and the VCO core consumes 3.72 mW. The figure-of-merit for the tuning-range (FOMT) of the VCO is -192.6 dBc/Hz.

Electron-beam buncher to operate over the frequency range 1-4 GHz

International Nuclear Information System (INIS)

Goldberg, D.A.; Arthur, A.A.; Flood, W.S.; Voelker, F.

1983-03-01

We present a description of an electron buncher to be installed in the terminal of a Van de Graaff, which is to produce a modulated beam over the frequency range 1-4 GHz. The modulator geometry has been optimized so that the modulation amplitude should be nearly constant over the frequency ranges 1-2 GHz and 2-4 GHz. Preliminary results indicate the device works as predicted

GHz Yb:KYW oscillators in time-resolved spectroscopy

Science.gov (United States)

Li, Changxiu; Krauß, Nico; Schäfer, Gerhard; Ebner, Lukas; Kliebisch, Oliver; Schmidt, Johannes; Winnerl, Stephan; Hettich, Mike; Dekorsy, Thomas

2018-02-01

A high-speed asynchronous optical sampling system (ASOPS) based on Yb:KYW oscillators with 1-GHz repetition rate is reported. Two frequency-offset-stabilized diode-pumped Yb:KYW oscillators are employed as pump and probe source, respectively. The temporal resolution of this system within 1-ns time window is limited to 500 fs and the noise floor around 10-6 (ΔR/R) close to the shot-noise level is obtained within an acquisition time of a few seconds. Coherent acoustic phonons are investigated by measuring multilayer semiconductor structures with multiple quantum wells and aluminum/silicon membranes in this ASOPS system. A wavepacket-like phonon sequence at 360 GHz range is detected in the semiconductor structures and a decaying sequence of acoustic oscillations up to 200 GHz is obtained in the aluminum/silicon membranes. Coherent acoustic phonons generated from semiconductor structures are further manipulated by a double pump scheme through pump time delay control.

2-D temperature distribution and heat flux of PFC in 2011 KSTAR campaign

Energy Technology Data Exchange (ETDEWEB)

Bang, Eunnam, E-mail: bang14@nfri.re.kr; Hong, Suk-Ho; Yu, Yaowei; Kim, Kyungmin; Kim, Hongtack; Kim, Hakkun; Lee, Kunsu; Yang, Hyunglyul

2013-10-15

Highlights: • The heat flux on PFC tiles of 12 s pulse duration and 630 kA plasma current is about 0.02 MW/m{sup 2}. • When the cryopump is operated, the heat flux of CD is higher than without cryopump. • The more H-mode duration is long, the more heat flux on divertor is high. -- Abstract: KSTAR has reached a plasma current up to 630 kA, plasma duration up to 12 s, and has achieved high confinement mode (H-mode) in 2011 campaign. The heat flux of PFC tile was estimated from the temperature increase of PFC since 2010. The heat flux of PFC tiles increases significantly with higher plasma current and longer pulse duration. The time-averaged heat flux of shots in 2010 campaign (with 3 s pulse durations and I{sub p} of 611 kA) is 0.01 MW/m{sup 2} while that in 2011 campaign (with 12 s pulse duration and I{sub p} of 630 kA) is about 0.02 MW/m{sup 2}. The heat flux at divertor is 1.4–2 times higher than that at inboard limiter or passive stabilizer. With the cryopump operation, the heat flux at the central divertor is higher than that without cryopump. The heat flux at divertor is proportional to, of course, the duration of H-mode. Furthermore, a software tool, which visualizes the 2D temperature distribution of PFC tile and estimates the heat flux in real time, is developed.

Efficient Low-Voltage Operation of a CW Gyrotron Oscillator at 233 GHz.

Science.gov (United States)

Hornstein, Melissa K; Bajaj, Vikram S; Griffin, Robert G; Temkin, Richard J

2007-02-01

The gyrotron oscillator is a source of high average power millimeter-wave through terahertz radiation. In this paper, we report low beam power and high-efficiency operation of a tunable gyrotron oscillator at 233 GHz. The low-voltage operating mode provides a path to further miniaturization of the gyrotron through reduction in the size of the electron gun, power supply, collector, and cooling system, which will benefit industrial and scientific applications requiring portability. Detailed studies of low-voltage operation in the TE(2) (,) (3) (,) (1) mode reveal that the mode can be excited with less than 7 W of beam power at 3.5 kV. During CW operation with 3.5-kV beam voltage and 50-mA beam current, the gyrotron generates 12 W of RF power at 233.2 GHz. The EGUN electron optics code describes the low-voltage operation of the electron gun. Using gun-operating parameters derived from EGUN simulations, we show that a linear theory adequately predicts the low experimental starting currents.

Tunable Twin Matching Frequency (fm1/fm2) Behavior of Ni1-xZnxFe2O4/NBR Composites over 2-12.4 GHz: A Strategic Material System for Stealth Applications

Science.gov (United States)

Saini, Lokesh; Patra, Manoj Kumar; Jani, Raj Kumar; Gupta, Goutam Kumar; Dixit, Ambesh; Vadera, Sampat Raj

2017-03-01

The gel to carbonate precipitate route has been used for the synthesis of Ni1-xZnxFe2O4 (x = 0, 0.25, 0.5 and 0.75) bulk inverse spinel ferrite powder samples. The optimal zinc (50%) substitution has shown the maximum saturation magnetic moment and resulted into the maximum magnetic loss tangent (tanδm) > -1.2 over the entire 2-10 GHz frequency range with an optimum value ~-1.75 at 6 GHz. Ni0.5Zn0.5Fe2O4- Acrylo-Nitrile Butadiene Rubber (NBR) composite samples are prepared at different weight percentage (wt%) of ferrite loading fractions in rubber for microwave absorption evaluation. The 80 wt% loaded Ni0.5Zn0.5Fe2O4/NBR composite (FMAR80) sample has shown two reflection loss (RL) peaks at 5 and 10 GHz. Interestingly, a single peak at 10 GHz for 3.25 mm thickness, can be scaled down to 5 GHz by increasing the thickness up to 4.6 mm. The onset of such twin matching frequencies in FMAR80 composite sample is attributed to the spin resonance relaxation at ~5 GHz (fm1) and destructive interference at λm/4 matched thickness near ~10 GHz (fm2) in these composite systems. These studies suggest the potential of tuning the twin frequencies in Ni0.5Zn0.5Fe2O4/NBR composite samples for possible microwave absorption applications.

Performance and operation of advanced superconducting electron cyclotron resonance ion source SECRAL at 24 GHz

International Nuclear Information System (INIS)

Zhao, H. W.; Zhang, X. Z.; Feng, Y. C.; Guo, J. W.; Li, J. Y.; Guo, X. H.; Sha, S.; Sun, L. T.; Xie, D. Z.; Lu, W.; Cao, Y.

2012-01-01

SECRAL (superconducting ECR ion source with advanced design in Lanzhou) ion source has been in routine operation for Heavy Ion Research Facility in Lanzhou (HIRFL) accelerator complex since May 2007. To further enhance the SECRAL performance in order to satisfy the increasing demand for intensive highly charged ion beams, 3-5 kW high power 24 GHz single frequency and 24 GHz +18 GHz double frequency with an aluminum plasma chamber were tested, and some exciting results were produced with quite a few new record highly charged ion beam intensities, such as 129 Xe 35+ of 64 eμA, 129 Xe 42+ of 3 eμA, 209 Bi 41+ of 50 eμA, 209 Bi 50+ of 4.3 eμA and 209 Bi 54+ of 0.2 eμA. In most cases SECRAL is operated at 18 GHz to deliver highly charged heavy ion beams for the HIRFL accelerator, only for those very high charge states and very heavy ion beams such as 209 Bi 36+ and 209 Bi 41+ , SECRAL has been operated at 24 GHz. The total operation beam time provided by SECRAL up to July 2011 has exceeded 7720 hours. In this paper, the latest performance, development, and operation status of SECRAL ion source are presented. The latest results and reliable long-term operation for the HIRFL accelerator have demonstrated that SECRAL performance for production of highly charged heavy ion beams remains improving at higher RF power with optimized tuning.

A CMOS frequency generation module for 60-GHz applications

International Nuclear Information System (INIS)

Zhou Chunyuan; Zhang Lei; Wang Hongrui; Qian He

2012-01-01

A frequency generation module for 60-GHz transceivers and phased array systems is presented in this paper. It is composed of a divide-by-2 current mode logic divider (CML) and a doubler in push-push configuration. Benefiting from the CML structure and push-push configuration, the proposed frequency generation module has a wide operating frequency range to cover process, voltage, and temperature variation. It is implemented in a 90-nm CMOS process, and occupies a chip area of 0.64 × 0.65 mm 2 including pads. The measurement results show that the designed frequency generation module functions properly with input frequency over 15 GHz to 25 GHz. The whole chip dissipates 12.1 mW from a 1.2-V supply excluding the output buffers. (semiconductor integrated circuits)

Quantum limited quasiparticle mixers at 100 GHz

International Nuclear Information System (INIS)

Mears, C.A; Hu, Qing; Richards, P.L.; Worsham, A.H.; Prober, D.E.; Raeisaenen, A.V.

1990-09-01

We have made accurate measurements of the noise and gain of superconducting-insulating-superconducting (SIS) mixers employing small area (1μm 2 ) Ta/Ta 2 O 5 /Pb 0.9 Bi 0.1 tunnel junctions. We have measured an added mixer noise of 0.61 +/- 0.31 quanta at 95.0 GHz, which is within 25 percent of the quantum limit of 0.5 quanta. We have carried out a detailed comparison between theoretical predictions of the quantum theory of mixing and experimentally measured noise and gain. We used the shapes of I-V curves pumped at the upper and lower sideband frequencies to deduce values of the embedding admittances at these frequencies. Using these admittances, the mixer noise and gain predicted by quantum theory are in excellent agreement with experiment. 21 refs., 9 figs

Feasibility of automotive radar at frequencies beyond 100 GHz

OpenAIRE

Köhler, Mike; Hasch, Jürgen; Blöcher, Hans Ludwig; Schmidt, Lorenz-Peter

2014-01-01

Radar sensors are used widely in modern driver assistance systems. Available sensors nowadays often operate in the 77 GHz band and can accurately provide distance, velocity, and angle information about remote objects. Increasing the operation frequency allows improving the angular resolution and accuracy. In this paper, the technical feasibility to move the operation frequency beyond 100 GHz is discussed, by investigating dielectric properties of radome materials, the attenuation of rain and ...

Development of a thermionic magnicon amplifier at 11.4 GHz

International Nuclear Information System (INIS)

Gold, S.H.; Hafizi, B.; Fliflet, A.W.; Kinkead, A.K.; True, R.

1997-01-01

The magnicon is a scanning-beam microwave amplifier tube that is being developed as an rf source for the proposed TeV Next Linear Collider. In it, a solid electron beam is spun up to high transverse momentum in a series of deflection cavities containing synchronously rotating TM modes, and then spun down again in an output cavity whose mode is synchronous with that of the deflection cavities. A recent magnicon experiment at NRL, using a ∼ 650 kV, 225 A, 5.5-mm-diam. electron beam produced from a cold cathode driven by a single-shot Marx generator, demonstrated 14 MW (±3 dB) at 11.12 GHz with 105 efficiency in the synchronous magnicon mode, but was limited by plasma loading in the deflection cavities to a regime in which the last cavity of the deflection system (the penultimate cavity) was unstable. A new 11.4 GHz rep-rated thermionic magnicon experiment is being assembled, using an advanced ultra-high-convergence electron gun driven by a 10 Hz, 1.5 microsecond modulator top produce a 500 kV, 210 A, 2-mm diameter electron beam. The magnicon circuit has been optimized for minimum surface rf fields and maximum efficiency, and will be engineered for high temperature bakeout and high vacuum operation. This experiment should begin operation in the Summer of 1997. The predicted power is 60 MW at ∼ 60% efficiency

High power, 140 GHz gyrotron

International Nuclear Information System (INIS)

Kreischer, K.E.; Temkin, R.J.; Mulligan, W.J.; MacCabe, S.; Chaplya, R.

1982-01-01

The design and construction of a pulsed 100 kW, 140 GHz gyrotron is described. Initial gyrotron operation is expected in early 1982. Advances in gyrotron theory have also been carried out in support of this experimental research. The application of gyrotrons to plasma diagnostics is also under investigation. (author)

On the performance of telemedicine system using 17-GHz orthogonally polarized microwave links under the influence of heavy rainfall.

Science.gov (United States)

Fong, Bernard; Fong, A C M; Hong, G Y

2005-09-01

This paper describes the design of a telemedicine system based on next-generation wireless local area networks (WLANs) operating at 17 GHz. Seventeen gigahertz is proposed for next-generation WLAN services offering numerous advantages over traditional IEEE 802.11 networks that operate in the range of 2.4-5 GHz. Orthogonal polarization is often used to increase spectrum efficiency by utilizing signal paths of horizontal and vertical polarization. Radio waves exceeding 10 GHz are particularly vulnerable to signal degradation under the influence of rain which causes an effective reduction in isolation between polarized signal paths. This paper investigates the influence of heavy rain in a tropical region on wide-band microwave signals at 17 GHz using two links provided by a fixed broad-band wireless access system for two-way data exchange between paramedics attending an accident scene and the hospital via microwave equipment installed in the ambulance. We also study the effects of cross polarization and phase rotation due to persistent heavy rainfall in tropical regions.

Prospect for a 60 GHz multicharged ECR ion source

Science.gov (United States)

Thuillier, T.; Bondoux, D.; Angot, J.; Baylac, M.; Froidefond, E.; Jacob, J.; Lamy, T.; Leduc, A.; Sole, P.; Debray, F.; Trophime, C.; Skalyga, V.; Izotov, I.

2018-05-01

The conceptual design of a fourth generation hybrid electron cyclotron resonance (ECR) ion source operated at 60 GHz is proposed. The axial magnetic mirror is generated with a set of three Nb3Sn coils, while the hexapole is made with room temperature (RT) copper coils. The motivations for such a hybrid development are to study further the ECR plasma physics and the intense multicharged ion beams' production and transport at a time when a superconducting (SC) hexapole appears unrealistic at 60 GHz. The RT hexapole coil designed is an evolution of the polyhelix technology developed at the French High Magnetic Field Facility. The axial magnetic field is generated by means of 3 Nb3Sn SC coils operated with a maximum current density of 350 A/mm2 and a maximum coil load line factor of 81%. The ECR plasma chamber resulting from the design features an inner radius of 94 mm and a length of 500 mm. The radial magnetic intensity is 4.1 T at the wall. Characteristic axial mirror peaks are 8 and 4.5 T, with 1.45 T minimum in between.

Steganalysis and improvement of a quantum steganography protocol via a GHZ4 state

International Nuclear Information System (INIS)

Xu Shu-Jiang; Chen Xiu-Bo; Niu Xin-Xin; Yang Yi-Xian

2013-01-01

Quantum steganography that utilizes the quantum mechanical effect to achieve the purpose of information hiding is a popular topic of quantum information. Recently, El Allati et al. proposed a new quantum steganography using the GHZ 4 state. Since all of the 8 groups of unitary transformations used in the secret message encoding rule change the GHZ 4 state into 6 instead of 8 different quantum states when the global phase is not considered, we point out that a 2-bit instead of a 3-bit secret message can be encoded by one group of the given unitary transformations. To encode a 3-bit secret message by performing a group of unitary transformations on the GHZ 4 state, we give another 8 groups of unitary transformations that can change the GHZ 4 state into 8 different quantum states. Due to the symmetry of the GHZ 4 state, all the possible 16 groups of unitary transformations change the GHZ 4 state into 8 different quantum states, so the improved protocol achieves a high efficiency

24 GHz cmWave Radio Propagation Through Vegetation

DEFF Research Database (Denmark)

Rodriguez, Ignacio; Abreu, Renato Barbosa; Portela Lopes de Almeida, Erika

2016-01-01

This paper presents a measurement-based analysis of cm-wave radio propagation through vegetation at 24 GHz. A set of dedicated directional measurements were performed with horn antennas located close to street level inside a densely-vegetated area illuminated from above. The full azimuth was exam......This paper presents a measurement-based analysis of cm-wave radio propagation through vegetation at 24 GHz. A set of dedicated directional measurements were performed with horn antennas located close to street level inside a densely-vegetated area illuminated from above. The full azimuth...

TWT design requirements for 30/20 GHz digital communications' satellite

Science.gov (United States)

Stankiewicz, N.; Anzic, G.

1979-01-01

The rapid growth of communication traffic (voice, data, and video) requires the development of additional frequency bands before the 1990's. The frequencies currently in use for satellite communications at 6/4 GHz are crowded and demands for 14/12 GHz systems are increasing. Projections are that these bands will be filled to capacity by the late 1980's. The next higher frequency band allocated for satellite communications is at 30/20 GHz. For interrelated reasons of efficiency, power level, and system reliability criteria, a candidate for the downlink amplifier in a 30/20 GHz communications' satellite is a dual mode traveling wave tube (TWT) equipped with a highly efficient depressed collector. A summary is given of the analyses which determine the TWT design requirements. The overall efficiency of such a tube is then inferred from a parametric study and from experimental data on multistaged depressed collectors. The expected TWT efficiency at 4 dB below output saturation is 24 percent in the high mode and 22 percent in the low mode.

Measurements of the cosmic microwave background temperature at 1.47 GHz

Energy Technology Data Exchange (ETDEWEB)

Bensadoun, Marc John [Univ. of California, Berkeley, CA (United States)

1991-11-01

A radiofrequency-gain total power radiometer measured the intensity of the cosmic microwave background (CMB) at a frequency of 1.47 GHz (20.4 cm wavelength) from White Mountain, California, in September 1988 and from the South Pole, Antarctica, in December 1989. The CMB thermodynamic temperature, TCMB, is 2.27 ± 0.25 K (68% C.L.) measured from White Mountain and 2.26 ± 0.21 K from the South Pole site. The combined result is 2.27 ± 0.19 K. The correction for galactic emission has been derived from scaled low-frequency maps and constitutes the main source, of error. The atmospheric signal is found by extrapolation from zenith scan measurements at higher frequencies. The result is consistent with previous low-frequency measurements, including a measurement at 1.41 GHz (Levin et al. 1988) made with an earlier version of this instrument. The result is ~2.5 σ (~l% probability) from the 2.74 ± 0.02,K global average CMB temperature.

Characterization of a high-intensity three-qubit GHZ state using state tomography and Gisin's inequality

Energy Technology Data Exchange (ETDEWEB)

Lu Huaixin, E-mail: huaixinlu@wfu.edu.c [Department of Physics and Electronic Science, Weifang University, Weifang, Shandong 261061 (China); Zhao Jiaqiang; Wang Xiaoqin [Department of Physics and Electronic Science, Weifang University, Weifang, Shandong 261061 (China)

2011-05-02

We experimentally characterized a high-intensity optical three-qubit Greenberger-Horne-Zeilinger (GHZ) states with a count of {approx}25/s by using the method of over-complete state tomography. Furthermore, based on the state, a convincing, 3.5 standard deviations, violation of Gisin's inequality has been measured, thus confirming the validity of Gisin's inequality for three-qubit GHZ states. From the data, we verified the good agreement of the experimental violation with the value predicted by quantum mechanics given the reconstructed density matrix. This result represents the first step towards the experimental implementation of Gisin's theorem. - Highlights: We have characterized a high-intensity three-qubit GHZ states. We have achieved convincing results of the violation of Gisin's inequalities. We verified the agreement of the experimental violation with theoretical value.

Compact 84 GHz passive mode-locked fiber laser using dual-fiber coupled fused-quartz microresonator

Science.gov (United States)

Liu, Tze-An; Hsu, Yung; Chow, Chi-Wai; Chuang, Yi-Chen; Ting, Wei-Jo; Wang, Bo-Chun; Peng, Jin-Long; Chen, Guan-Hong; Chang, Yuan-Chia

2017-10-01

We propose and demonstrate a compact and portable-size 84-GHz passive mode-locked fiber laser, in which a dual-fiber coupled fused-quartz microresonator is employed as the intracavity optical comb filter as well as the optical nonlinear material for optical frequency comb generation. About eight coherent optical tones can be generated in the proposed fiber laser. The 20-dB bandwidth is larger than 588 GHz. The full-width half-maximum pulse-width of the proposed laser is 2.5 ps. We also demonstrate the feasibility of using the proposed passive mode-locked fiber laser to carry a 5-Gbit/s on-off-keying signal and transmit over 20-km standard single mode fiber. A 7% forward error correction requirement can be achieved, showing the proposed fiber laser can be a potential candidate for fiber-wireless applications.

Megawatt Power Level 120 GHz Gyrotrons for ITER Start-Up

Energy Technology Data Exchange (ETDEWEB)

Choi, E M; Marchewka, C; Mastovsky, I; Shapiro, M A; Sirigiri, J R; Temkin, R J [MIT - Plasma Science and Fusion Center, NW16-186, 167 Albany Street, Cambridge, MA 02139 (United States)

2005-01-01

We report operation of a 110 GHz gyrotron with 1.67 MW of output power measured in short pulses (3{mu}s) at an efficiency of 42% in the TE{sub 22,6} mode. We also present a preliminary design of a 1 MW, 120 GHz gyrotron for ITER start-up with an efficiency greater than 50%.

Megawatt Power Level 120 GHz Gyrotrons for ITER Start-Up

International Nuclear Information System (INIS)

Choi, E M; Marchewka, C; Mastovsky, I; Shapiro, M A; Sirigiri, J R; Temkin, R J

2005-01-01

We report operation of a 110 GHz gyrotron with 1.67 MW of output power measured in short pulses (3μs) at an efficiency of 42% in the TE 22,6 mode. We also present a preliminary design of a 1 MW, 120 GHz gyrotron for ITER start-up with an efficiency greater than 50%

Design and RF test result of High Power Hybrid Combiner for Helicon Wave Current Drive in KSTAR Plasmas

Energy Technology Data Exchange (ETDEWEB)

Park, S. Y.; Kim, H. J.; Wi, H. H.; Wang, S. J.; Kwak, J. G. [NFRI, Daejeon (Korea, Republic of)

2016-05-15

200 kW RF power will be injected to plasmas through the traveling wave antenna after combining four klystrons output powers using three hybrid combiners. Each klystron produces 60 kW output at the frequency of 500 MHz. RF power combiners commonly used to divide or combine output powers for various rf and microwave applications. It is divided into several types according to the design type such as Wilkinson combiner, radial and quadrature hybrid combiner. We designed high power hybrid combiners using 6-1/8 inch coaxial line. The power combiner has many advantages such as high isolation, low insertion loss and high power handling capability. In this paper design and rf test results of high power combiners will be described. High power combiners using three coaxial hybrid couplers will be utilized for effectively combining of 500 MHz, 200 kW output powers generated by four klystrons. We have designed, fabricated, and tested a 6-1/8 inch coaxial hybrid combiners at 500 MHz for efficiently off-axis Helicon wave current drive in KSTAR. Simulation and test results of high power coaxial hybrid combiners are good agreement.

Miniature Packaging Concept for LNAs in the 200-300 GHz Range

Science.gov (United States)

Samoska, Lorene; Fung, Andy; Varonen, Mikko; Lin, Robert; Peralta, Alejandro; Soria, Mary; Lee, Choonsup; Padmanabhan, Sharmila; Sarkozy, Stephen; Lai, Richard

2016-01-01

In this work, we describe new miniaturized low noise amplifier modules which we developed for incorporation in small-scale satellites or Cubesats, and which exhibit similar or better performance compared to previously reported LNAs in the literature. We have targeted the WR4 (170-260 GHz) and WR3 (220-325 GHz) waveguide bands for the module development. The modules include two different methods of E-plane probes which have been developed for low loss, and stability at high frequencies. MMIC LNAs were also developed for these frequency ranges and fabricated in Northrop Grumman Corporation's 35 nm InP HEMT technology, and we have experimentally verified that noise performance is lower than reported in prior work. The best results include a miniature LNA module with 550K noise at 224 GHz, and a wideband LNA module with 15 dB gain from 230-280 GHz.

Development of 24GHz Rectenna for Receiving and Rectifying Modulated Waves

International Nuclear Information System (INIS)

Shinohara, Naoki; Hatano, Ken

2014-01-01

In this paper, we show experimental results of RF-DC conversion with modulated 24GHz waves. We have already developed class-F MMIC rectenna with resonators for higher harmonics at no modulated 24GHz microwave for RF energy transfer. Dimensions of the MMIC rectifying circuit is 1 mm × 3 mm on GaAs. Maximum RF-DC conversion efficiency is measured 47.9% for a 210 mW microwave input of 24 GHz with a 120 Ω load. The class-F rectenna is based on a single shunt full-wave rectifier. For future application of a simultaneous energy and information transfer system or an energy harvesting from broadcasting waves, input microwave will be modulated. In this paper, we show an experimental result of RF-DC conversion of the class-F rectenna with 24GHz waves modulated by 16QAM as 1st modulation and OFDM as 2nd modulation

Development of 24GHz Rectenna for Receiving and Rectifying Modulated Waves

Science.gov (United States)

Shinohara, Naoki; Hatano, Ken

2014-11-01

In this paper, we show experimental results of RF-DC conversion with modulated 24GHz waves. We have already developed class-F MMIC rectenna with resonators for higher harmonics at no modulated 24GHz microwave for RF energy transfer. Dimensions of the MMIC rectifying circuit is 1 mm × 3 mm on GaAs. Maximum RF-DC conversion efficiency is measured 47.9% for a 210 mW microwave input of 24 GHz with a 120 Ω load. The class-F rectenna is based on a single shunt full-wave rectifier. For future application of a simultaneous energy and information transfer system or an energy harvesting from broadcasting waves, input microwave will be modulated. In this paper, we show an experimental result of RF-DC conversion of the class-F rectenna with 24GHz waves modulated by 16QAM as 1st modulation and OFDM as 2nd modulation.

A program of high power microwave source research and development from 8 GHz to 600 GHz

International Nuclear Information System (INIS)

Granatstein, V.L.; Antonsen, T.M. Jr.; Bidwell, S.; Booske, J.; Carmel, Y.; Destler, W.W.; Kehs, R.A.; Latham, P.E.; Levush, B.; Lou, W.R.; Mayergoyz, I.D.; Minami, K.; Radack, D.J.

1990-01-01

We review research results both on a plasma filled, backward wave oscillator (BWO), and on a free electron laser (FEL) driven by a sheet electron beam. Recently, it was demonstrated that a plasma filled BWO driven by an intense relativistic electron beam can generate hundreds of megawatts of microwave radiation at an unusually high efficiency of 40% compared with a typical efficiency of ∼10% in a BWO without a background plasma. Furthermore, the enhanced efficiency can be maintained even for large electron beam currents approaching the vacuum space charge limiting current, and we anticipate this might hold even for larger current values. Theoretical studies and numerical simulations indicate that the enhanced efficiency as well as a lower value for the start oscillation current in the linear regime may be due to the finite length of the BWO circuit coupled with modification of the dispersion relation due to the background plasma. In the case of our FEL studies, we present designs for a 1 MW, CW, tapered FEL amplifier operating at frequencies of 280 GHz and 560 GHz. A short wiggler period (ell w ∼ 1 cm) is combined with a sheet beam of electrons having energy ∼1 MeV. Depressed collector techniques would allow the main power supply rating to be reduced to ∼200 kV. Efficient sheet beam transport (>99%) has been demonstrated through 10 wiggler periods, and transport through 60 wiggler periods is currently under study. Finally, plans for a proof-of-principle tapered FEL amplifier experiment at 94 GHz are presented. 8 refs., 7 figs

160 Gbit/s photonics wireless transmission in the 300-500 GHz band

Directory of Open Access Journals (Sweden)

X. Yu

2016-11-01

Full Text Available To accommodate the ever increasing wireless traffic in the access networks, considerable efforts have been recently invested in developing photonics-assisted wireless communication systems with very high data rates. Superior to photonic millimeter-wave systems, terahertz (THz band (300 GHz-10 THz provides a much larger bandwidth and thus promises an extremely high capacity. However, the capacity potential of THz wireless systems has by no means been achieved yet. Here, we successfully demonstrate 160 Gbit/s wireless transmission by using a single THz emitter and modulating 25 GHz spaced 8 channels (20 Gbps per channel in the 300-500 GHz band, which is the highest bitrate in the frequency band above 300 GHz, to the best of our knowledge.

Miniaturized printed K shaped monopole antenna with truncated ground plane for 2.4/5.2/5.5/5.8 wireless lan applications

Science.gov (United States)

Chandan, Bharti, Gagandeep; Srivastava, Toolika; Rai, B. S.

2018-04-01

A novel truncated ground plane monopole antenna is proposed for wide band wireless local area network (WLAN) applications. The antenna contains a rectangular patch with a rectangular ring, a circular slot and a truncated ground plane printed on opposite sides of a low cost substrate FR4. The operating frequency bands for the antenna are band1 (2.4-2.88 GHz) and band 2 (4.8-6.3 GHz) with ≤ - 10 dB return loss which covers 2.4/5.2/5.5/5.8 GHz WLAN bands. The antenna is compact with overall dimension 26×40×0.8 mmł and with the dimension of patch 16×16×0.8 mm3. The two bands of antenna is obtained by cutting a rectangular ring and a circular slot in the patch and return loss is improved by cutting two rectangular slot in the ground plane. Performance measures of the antenna are shown in terms of return loss, current distribution, radiation pattern and gain. To verify the simulated results, the antenna is also fabricated and tested. The simulated and fabricated results have been found in good agreement.

A 90 GHz photoinjector

International Nuclear Information System (INIS)

Palmer, D.T.; Hogan, M.J.; Ferrario, M.; Serafini, L.

1999-01-01

Photocathode rf guns depend on mode locked laser systems to produce an electron beam at a given phase of the rf. In general, the laser pulse is less than σ 2 = 10'' of rf phase in length and the required stability is on the order of Δφ = 1 At 90 GHz (W-band), these requirements correspond to σ 2 = 333 fsec and Δφ = 33 fsec. Laser system with pulse lengths in the fsec regime are commercially available, the timing stability is a major concern. It is proposed a multi-cell W-band photoinjector that does not require a mode locked laser system. Thereby eliminating the stability requirements at W-band. The laser pulse is allowed to be many rf periods long. In principle, the photoinjector can now be considered as a thermionic rf gun. Instead of using an alpha magnet to compress the electron bunch, which would have a detrimental effect on the transverse hase space quality due to longitudinal phase space mixing, it is here proposed to use long pulse laser system and a pair of undulators to produce a low emittance, high current, ultra-short electron bunch for beam dynamics experiments in the 90 GHz regime

Tunable Twin Matching Frequency (fm1/fm2) Behavior of Ni1−xZnxFe2O4/NBR Composites over 2–12.4 GHz: A Strategic Material System for Stealth Applications

Science.gov (United States)

Saini, Lokesh; Patra, Manoj Kumar; Jani, Raj Kumar; Gupta, Goutam Kumar; Dixit, Ambesh; Vadera, Sampat Raj

2017-01-01

The gel to carbonate precipitate route has been used for the synthesis of Ni1−xZnxFe2O4 (x = 0, 0.25, 0.5 and 0.75) bulk inverse spinel ferrite powder samples. The optimal zinc (50%) substitution has shown the maximum saturation magnetic moment and resulted into the maximum magnetic loss tangent (tanδm) > −1.2 over the entire 2–10 GHz frequency range with an optimum value ~−1.75 at 6 GHz. Ni0.5Zn0.5Fe2O4- Acrylo-Nitrile Butadiene Rubber (NBR) composite samples are prepared at different weight percentage (wt%) of ferrite loading fractions in rubber for microwave absorption evaluation. The 80 wt% loaded Ni0.5Zn0.5Fe2O4/NBR composite (FMAR80) sample has shown two reflection loss (RL) peaks at 5 and 10 GHz. Interestingly, a single peak at 10 GHz for 3.25 mm thickness, can be scaled down to 5 GHz by increasing the thickness up to 4.6 mm. The onset of such twin matching frequencies in FMAR80 composite sample is attributed to the spin resonance relaxation at ~5 GHz (fm1) and destructive interference at λm/4 matched thickness near ~10 GHz (fm2) in these composite systems. These studies suggest the potential of tuning the twin frequencies in Ni0.5Zn0.5Fe2O4/NBR composite samples for possible microwave absorption applications. PMID:28294151

High-performance CPW MMIC LNA using GaAs-based metamorphic HEMTs for 94-GHz applications

International Nuclear Information System (INIS)

Ryu, Keun-Kwan; Kim, Sung-Chan; An, Dan; Rhee, Jin-Koo

2010-01-01

In this paper, we report on a high-performance low-noise amplifier (LNA) using metamorphic high-electron-mobility transistor (MHEMT) technology for 94-GHz applications. The 100 nm x 60 μm MHEMT devices for the coplanar MMIC LNA exhibited DC characteristics with a drain current density of 655 mA/mm and an extrinsic transconductance of 720 mS/mm. The current gain cutoff frequency (f T ) and the maximum oscillation frequency (f max ) were 195 GHz and 305 GHz, respectively. Based on this MHEMT technology, coplanar 94-GHz MMIC LNAs were realized, achieving a small signal gain of more than 13 dB between 90 and 100 GHz and a small signal gain of 14.8 dB and a noise figure of 4.7 dB at 94 GHz.

Herschel/HIFI Observations of a New Interstellar Water Maser : The 532-441 Transition at 620.701 GHz

NARCIS (Netherlands)

Neufeld, David A.; Wu, Yuanwei; Kraus, Alex; Menten, Karl M.; Tolls, Volker; Melnick, Gary J.; Nagy, Zsofia

2013-01-01

Using the Herschel Space Observatory's Heterodyne Instrument for the Far-Infrared, we have performed mapping observations of the 620.701 GHz 5(32)-4(41) transition of ortho-H2O within a similar to 1'.5 x 1'.5 region encompassing the Kleinmann-Low nebula in Orion (Orion-KL), and pointed observations

A study on the NB heating and current drive in fusion plasmas

International Nuclear Information System (INIS)

Jeong, Seung Ho; In, S. R.; Lee, K. W.; Oh, B. H.; Jin, J. T.; Chang, D. H.; Chang, D. S.; Kim, T. S.; Song, W. S.

2013-03-01

Final destination of the project is to establish the research basis of heating and current drive for large tokamak, such as KSTAR, or next generation fusion reactor through the neutral beam injection (NBI). On the 1 st -stage to achieve the objectives: 1) Required capability of an ion source(with an output power of 2 MW neutral beam, a beam energy of 100 keV) which is a main component of KSTAR NBI-1 system was proven by the design, manufacturing, and performance test during the past three years. 2) Until the development of new ion source, the NB heating experiments were performed to achieve the NB heating of KSTAR plasma with more than 1.0 MW for the 2 nd -year and more than 1.5 MW for the 3 rd -year by using a prototype ion source upgraded for the 1 st -year. From these experiments, the heating power above the H-mode threshold was supplied to the H-mode operation of KSTAR plasma and contributed to the NB diagnostics, such as CES and MSE, by using the NB. Finally, the basis of NB heating and current drive for the KSTAR was prepared by the 1 st -stage research

8-12 GHz Radio Observations of Flare Activity On M dwarf CN Leo

Science.gov (United States)

Wofford, Alia; Villadsen, Jackie; Quintana, Elisa; Barclay, Thomas; Thackeray, Beverly

2018-01-01

Red dwarfs are cool stars that make up 70% of all stars. Red dwarfs can be utilized to detect potentially habitable planets but they have particularly strong magnetic activity that can be detrimental to orbiting planets’ atmospheres and habitability. A coronal mass ejection (CME) is an eruption of magnetized plasma from the star that is ejected into the interplanetary medium which can erode a planet’s atmosphere daily. Based on the sun CMEs are expected to produce very bright radio bursts along with optical flares. We are using M dwarf CN Leo, a well studied flare star that was in the K2 campaign field in summer 2017, as a template to understand the relationship between radio and optical flares and the space weather conditions impacting M dwarf planets. Using radio frequencies ranging from 0.22 GHz-12 GHz we search for simultaneous radio bursts and optical flares to infer if CMEs, flares or aurorae are occurring on the star. I will present the 8-12 GHz radio data from eight 1.5-hour observations with simultaneous optical data. CN Leo produced a bright non-thermal radio flare that lasted approximately for a day during two consecutive observations, with a gyrosynchrotron emission mechanism.

Lightning and 85-GHz MCSs in the Global Tropics

Science.gov (United States)

Toracinta, E. Richard; Zipser, E. J.

1999-01-01

Numerous observations of tropical convection show that tropical continental mesoscale convective systems (MCSs) are much more prolific lightning producers than their oceanic counterparts. Satellite-based climatologies using 85-GHz passive microwave ice-scattering signatures from the Special Sensor Microwave/Imager (SSM/I) indicate that MCSs of various size and intensity are found throughout the global tropics. In contrast, global lightning distributions show a strong land bias with an order of magnitude difference between land and ocean lightning. This is somewhat puzzling, since 85-GHz ice-scattering and the charge separation processes that lead to lightning are both thought to depend upon the existence of large graupel particles. The fact that low 85-GHz brightness temperatures are observed in tropical oceanic MCSs containing virtually no lightning leads to the postulate that tropical oceanic and tropical continental MCSs have fundamentally different hydrometeor profiles through the mixed phase region of the cloud (0 C Lightning Imaging Sensor (LIS), and the first space-borne radar, facilitates high-resolution case studies of MCS structure throughout the global tropics. An important precursor, however, is to better understand the distribution of MCSs and lightning in the tropics. With that objective in mind, this research undertakes a systematic comparison of 85-GHz-defined MCSs and lightning over the global tropics for a full year, as an initial step toward quantifying differences between land and ocean convective systems.

Analysis of 38 GHz mmWave Propagation Characteristics of Urban Scenarios

DEFF Research Database (Denmark)