Malay Dey - Academia.edu (original) (raw)
Papers by Malay Dey
K500 Superconducting Cyclotron (SCC) is already commissioned successfully at VECC, Kolkata by acc... more K500 Superconducting Cyclotron (SCC) is already commissioned successfully at VECC, Kolkata by accelerating Ne³⁺ internal beam with 70 nA beam current at 670 mm extraction radius. The Radio Frequency cavity of SCC is successfully operational since last two years. All these years were very challenging and worthy period from the point of view of gaining experience and knowledge by solving fabrication and assembly problems faced during construction of 10 m tall copper made coaxial RF cavities and tackling RF related commissioning problems. RF system operates within the frequency range of 9 to 27 MHz for generating maximum 100 kV DEE voltage. The construction of the RF system demands making of numerous critical soldering and brazing joints including joints between ceramic and copper along with maintaining close dimensional accuracies, assembly tolerances, mirror symmetricity, surface finish and utmost cleanliness. This paper presents the details of fabrication and installation procedures...
International Journal of Multidisciplinary Research and Development, 2016
A High Temperature Superconductor (HTS) based cryorefrigerator assisted steering magnet sunder de... more A High Temperature Superconductor (HTS) based cryorefrigerator assisted steering magnet sunder development at VECC for the extraction beam line of K500 cyclotron. The magnet designed is specified for ± 3 degree horizontal correction and ± 1.5 degree of vertical correction of the beam of maximum rigidity of 3.3 T-m. The magnet is composed of two sets of double pancake racetrack coil-one set for vertical field (By) and other for horizontal field inside the return iron yoke. Double pancake coils are fabricated in-house using BSCCO-2223 HTS tapes by wet winding technique using cryogenic grade epoxy. The critical characteristics of the coils are tested at liquid nitrogen temperature in terms of critical current and index parameters. The paper describes the winding details of double pancake coils and test results at liquid nitrogen temperature.
Indian Journal of Cryogenics, 2015
Design and development of injector cryomodule(ICM) for the superconducting electron linac (elinac... more Design and development of injector cryomodule(ICM) for the superconducting electron linac (elinac) is going on at VECC. Injector cryomodule is meant to house one nine-cell niobium elliptical SRF cavity operating at 2K. Thermal stability analysis has been carried out to evaluate the effect of the cavity thickness, the residual resistivity ratio(RRR) of the cavity material and the dimension of the impurities present in the cavity surface, on the performance of the cavity. Based on this analysis we have been able to formulate the inspection procedure for the niobium sheet material and the cleaning techniques. The surface impurities size must be kept below the prescribed value to prevent thermal break down of the cavity.
IOP Conference Series: Materials Science and Engineering, 2017
Design and analysis of a compact superconducting cyclotron dedicated for medical applications in ... more Design and analysis of a compact superconducting cyclotron dedicated for medical applications in the fields of nuclear medicine and therapy is presently being pursued in our organization. The novelty of this cyclotron lies in the fact that it does not consist of any iron-pole. The cyclotron magnet will be made of a set of NbTi coils comprising of solenoid and sector coils which are housed in two halves on either sides of the median plane. The average magnetic field is 1.74 T and the maximum extraction energy is 25 MeV, which is sufficient for production of 99mTc from Mo. In this paper, quench analyses of the coils have been discussed in details considering adiabatic condition. The entire cryostat magnet along with coils, formers and support links were modelled for the quench simulation. Self and mutual inductances of all the coils were obtained from a separate magnetic analysis and used in the simulation. Parametric analyses were carried out with different quench initiation energy at various critical locations on the coil surface. The corresponding quench behaviour, i.e. maximum temperature rise, maximum voltage and current decay in each of the coils have been studied.
Hence different particles in the operating region with different charge to mass ratio and energy ... more Hence different particles in the operating region with different charge to mass ratio and energy have different trajectories along the extraction path. At VECC simulation work has been carried out using extraction codes to evaluate this problem and suggest some reasonable solutions to them. The characteristics of the problem is that the beams get over focused at 30 KG field excitation and under focused at 47 KG field excitation. The beams after traversing through 8 passive magnetic channels reach the Ninth channel at different locations and variable inclination of the central trajectory. The extraction system of the K500 Superconducting Cyclotron [1] under construction in Variable Energy Cyclotron Center, Kolkata comprises of two electro-static deflectors and nine magnetic channels. These magnetic channels play very important role in providing adequate horizontal focusing along the extraction path through strong fringing magnetic field. Moreover the active ninth magnetic channel is ...
Extensive Magnetic Field measurement of the K500 Superconducting Cyclotron has been completed. In... more Extensive Magnetic Field measurement of the K500 Superconducting Cyclotron has been completed. In this paper we report the beam dynamical calculations along the extraction system based on the measured magnetic field data. The beam matching to the external beam transport system, for different ion species spanning the operating region is also explored.
Analysis of the magnetic data obtained during the magnetic field mapping of Kolkata superconducti... more Analysis of the magnetic data obtained during the magnetic field mapping of Kolkata superconducting cyclotron showed imperfections in the main magnetic field. Since the main magnet of the superconducting cyclotron is three fold rotationally symmetric, any deviation from this symmetry creates imperfections in the magnetic field. Generally, 1st and 2nd harmonic components are inherently present in the field due to assembling errors in iron/coil. A major portion of these imperfections is attributed to the misplacement/tilting of the iron pole tip with respect to coil. The error in positioning of main superconducting coil with respect to surrounding iron produces another imperfection. Pole tip deformation due to rise of temperature produces field imperfection. This paper reports the various possible sources of imperfection in general and their estimation. The calculation was compared with measured data to find out the actual cause of imperfections and necessary corrections have been car...
VECC has proposed a project for the design and development of a 250 MeV superconducting proton cy... more VECC has proposed a project for the design and development of a 250 MeV superconducting proton cyclotron, which may be used in therapy. In this paper we describe the preliminary design calculations for the superconducting cyclotron magnet. Hard-edge approximation method has been adopted for finding the poletip geometry to meet the basic focusing requirements of the beam. The uniform-magnetization method has been applied to calculate the 3D magnetic field distribution due to saturated iron poletips, to verify the beam dynamical issues and optimize the poletip geometry. GM type closed cycle cryo-cooler technology is being considered for steady state liquefaction of evaporated helium gas from magnet cryostat.
The superconducting Nb-Ti coil is wound on a stainless steel bobbin of about 1.5 m diameter and 1... more The superconducting Nb-Ti coil is wound on a stainless steel bobbin of about 1.5 m diameter and 1.2 m height. The bobbin acts as the liquid helium chamber inside which the coil is dipped. It is suspended with nine support links – six vertical and three horizontal, inside the iron vacuum chamber. These support links can be adjusted in length externally so that the coil can be moved inside the vacuum chamber. The annular cryostat, including the coil, is placed inside the pill box type iron yoke around the upper and lower poles. The cryostat is placed inside the yoke with two locating pins. A jig was made to measure the deviations of the vacuum chamber inner wall with respect to the magnet pole center and the locating pins were adjusted to place it accurately. The coil was then cooled to liquid helium temperature and energized. During energisation process, the coil was centered using the lowest force criterion. After the full current was achieved, the final centering was checked with t...
Indian Journal of Cryogenics, 2015
Design of a ICM for VECC's superconducting electron linac project based on the technology dev... more Design of a ICM for VECC's superconducting electron linac project based on the technology developed for niobium made elliptical TESLA type SRF cavities is underway in collaboration with TRIUMF. There are five connections to a single cavity, operating at 2K temperature, from atmosphere in the form of two beam tubes, two couplers and a tuner. Penetrations were intercepted at 77K temperature and 4K temperature to reduce the heat leak to the cavity.
Review of Scientific Instruments, 2013
In an isochronous cyclotron, measurements of central phase of the ion beam with respect to rf and... more In an isochronous cyclotron, measurements of central phase of the ion beam with respect to rf and the phase width provide a way to tune the cyclotron for maximum energy gain per turn and efficient extraction. We report here the development of a phase measurement system and the measurements carried out at the Variable Energy Cyclotron Centre's (VECC's) K = 500 superconducting cyclotron. The technique comprises detecting prompt γ-rays resulting from the interaction of cyclotron ion beam with an aluminium target mounted on a radial probe in coincidence with cyclotron rf. An assembly comprising a fast scintillator and a liquid light-guide inserted inside the cyclotron was used to detect the γ-rays and to transfer the light signal outside the cyclotron where a matching photo-multiplier tube was used for light to electrical signal conversion. The typical beam intensity for this measurement was a few times 10 11 pps.
physica status solidi (c), 2009
Abstract A 30 MeV proton cyclotron facility is being set up by this centre in Kolkata. This high ... more Abstract A 30 MeV proton cyclotron facility is being set up by this centre in Kolkata. This high current cyclotron will be used to produce PET (Positron Emission Tomography and SPECT (Single Photon Emission Computed Tomography) isotopes for medical diagnostics ...
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2014
Proc. of APAC, 2007
The magnetic field at median plane of SCC Magnet (Peak field 5.8T) is measured over its operating... more The magnetic field at median plane of SCC Magnet (Peak field 5.8T) is measured over its operating range and upto 29 inch radius. The magnetic field is mapped at radial interval of 0.1 inch and angular interval of 1 degree. The complete map of 360 degree comprised of ...
… on cyclotrons and …, 2007
INTRODUCTION The Superconducting cyclotron magnet at VECC, Kolkata was commissioned in July 2005 ... more INTRODUCTION The Superconducting cyclotron magnet at VECC, Kolkata was commissioned in July 2005 and magnetic field measurement and correction program was undertaken since then. The mapping task involved fabricating mapping jig and a reliable and automatic ...
Physical Review Special Topics - Accelerators and Beams, 2013
K500 Superconducting Cyclotron (SCC) is already commissioned successfully at VECC, Kolkata by acc... more K500 Superconducting Cyclotron (SCC) is already commissioned successfully at VECC, Kolkata by accelerating Ne³⁺ internal beam with 70 nA beam current at 670 mm extraction radius. The Radio Frequency cavity of SCC is successfully operational since last two years. All these years were very challenging and worthy period from the point of view of gaining experience and knowledge by solving fabrication and assembly problems faced during construction of 10 m tall copper made coaxial RF cavities and tackling RF related commissioning problems. RF system operates within the frequency range of 9 to 27 MHz for generating maximum 100 kV DEE voltage. The construction of the RF system demands making of numerous critical soldering and brazing joints including joints between ceramic and copper along with maintaining close dimensional accuracies, assembly tolerances, mirror symmetricity, surface finish and utmost cleanliness. This paper presents the details of fabrication and installation procedures...
International Journal of Multidisciplinary Research and Development, 2016
A High Temperature Superconductor (HTS) based cryorefrigerator assisted steering magnet sunder de... more A High Temperature Superconductor (HTS) based cryorefrigerator assisted steering magnet sunder development at VECC for the extraction beam line of K500 cyclotron. The magnet designed is specified for ± 3 degree horizontal correction and ± 1.5 degree of vertical correction of the beam of maximum rigidity of 3.3 T-m. The magnet is composed of two sets of double pancake racetrack coil-one set for vertical field (By) and other for horizontal field inside the return iron yoke. Double pancake coils are fabricated in-house using BSCCO-2223 HTS tapes by wet winding technique using cryogenic grade epoxy. The critical characteristics of the coils are tested at liquid nitrogen temperature in terms of critical current and index parameters. The paper describes the winding details of double pancake coils and test results at liquid nitrogen temperature.
Indian Journal of Cryogenics, 2015
Design and development of injector cryomodule(ICM) for the superconducting electron linac (elinac... more Design and development of injector cryomodule(ICM) for the superconducting electron linac (elinac) is going on at VECC. Injector cryomodule is meant to house one nine-cell niobium elliptical SRF cavity operating at 2K. Thermal stability analysis has been carried out to evaluate the effect of the cavity thickness, the residual resistivity ratio(RRR) of the cavity material and the dimension of the impurities present in the cavity surface, on the performance of the cavity. Based on this analysis we have been able to formulate the inspection procedure for the niobium sheet material and the cleaning techniques. The surface impurities size must be kept below the prescribed value to prevent thermal break down of the cavity.
IOP Conference Series: Materials Science and Engineering, 2017
Design and analysis of a compact superconducting cyclotron dedicated for medical applications in ... more Design and analysis of a compact superconducting cyclotron dedicated for medical applications in the fields of nuclear medicine and therapy is presently being pursued in our organization. The novelty of this cyclotron lies in the fact that it does not consist of any iron-pole. The cyclotron magnet will be made of a set of NbTi coils comprising of solenoid and sector coils which are housed in two halves on either sides of the median plane. The average magnetic field is 1.74 T and the maximum extraction energy is 25 MeV, which is sufficient for production of 99mTc from Mo. In this paper, quench analyses of the coils have been discussed in details considering adiabatic condition. The entire cryostat magnet along with coils, formers and support links were modelled for the quench simulation. Self and mutual inductances of all the coils were obtained from a separate magnetic analysis and used in the simulation. Parametric analyses were carried out with different quench initiation energy at various critical locations on the coil surface. The corresponding quench behaviour, i.e. maximum temperature rise, maximum voltage and current decay in each of the coils have been studied.
Hence different particles in the operating region with different charge to mass ratio and energy ... more Hence different particles in the operating region with different charge to mass ratio and energy have different trajectories along the extraction path. At VECC simulation work has been carried out using extraction codes to evaluate this problem and suggest some reasonable solutions to them. The characteristics of the problem is that the beams get over focused at 30 KG field excitation and under focused at 47 KG field excitation. The beams after traversing through 8 passive magnetic channels reach the Ninth channel at different locations and variable inclination of the central trajectory. The extraction system of the K500 Superconducting Cyclotron [1] under construction in Variable Energy Cyclotron Center, Kolkata comprises of two electro-static deflectors and nine magnetic channels. These magnetic channels play very important role in providing adequate horizontal focusing along the extraction path through strong fringing magnetic field. Moreover the active ninth magnetic channel is ...
Extensive Magnetic Field measurement of the K500 Superconducting Cyclotron has been completed. In... more Extensive Magnetic Field measurement of the K500 Superconducting Cyclotron has been completed. In this paper we report the beam dynamical calculations along the extraction system based on the measured magnetic field data. The beam matching to the external beam transport system, for different ion species spanning the operating region is also explored.
Analysis of the magnetic data obtained during the magnetic field mapping of Kolkata superconducti... more Analysis of the magnetic data obtained during the magnetic field mapping of Kolkata superconducting cyclotron showed imperfections in the main magnetic field. Since the main magnet of the superconducting cyclotron is three fold rotationally symmetric, any deviation from this symmetry creates imperfections in the magnetic field. Generally, 1st and 2nd harmonic components are inherently present in the field due to assembling errors in iron/coil. A major portion of these imperfections is attributed to the misplacement/tilting of the iron pole tip with respect to coil. The error in positioning of main superconducting coil with respect to surrounding iron produces another imperfection. Pole tip deformation due to rise of temperature produces field imperfection. This paper reports the various possible sources of imperfection in general and their estimation. The calculation was compared with measured data to find out the actual cause of imperfections and necessary corrections have been car...
VECC has proposed a project for the design and development of a 250 MeV superconducting proton cy... more VECC has proposed a project for the design and development of a 250 MeV superconducting proton cyclotron, which may be used in therapy. In this paper we describe the preliminary design calculations for the superconducting cyclotron magnet. Hard-edge approximation method has been adopted for finding the poletip geometry to meet the basic focusing requirements of the beam. The uniform-magnetization method has been applied to calculate the 3D magnetic field distribution due to saturated iron poletips, to verify the beam dynamical issues and optimize the poletip geometry. GM type closed cycle cryo-cooler technology is being considered for steady state liquefaction of evaporated helium gas from magnet cryostat.
The superconducting Nb-Ti coil is wound on a stainless steel bobbin of about 1.5 m diameter and 1... more The superconducting Nb-Ti coil is wound on a stainless steel bobbin of about 1.5 m diameter and 1.2 m height. The bobbin acts as the liquid helium chamber inside which the coil is dipped. It is suspended with nine support links – six vertical and three horizontal, inside the iron vacuum chamber. These support links can be adjusted in length externally so that the coil can be moved inside the vacuum chamber. The annular cryostat, including the coil, is placed inside the pill box type iron yoke around the upper and lower poles. The cryostat is placed inside the yoke with two locating pins. A jig was made to measure the deviations of the vacuum chamber inner wall with respect to the magnet pole center and the locating pins were adjusted to place it accurately. The coil was then cooled to liquid helium temperature and energized. During energisation process, the coil was centered using the lowest force criterion. After the full current was achieved, the final centering was checked with t...
Indian Journal of Cryogenics, 2015
Design of a ICM for VECC's superconducting electron linac project based on the technology dev... more Design of a ICM for VECC's superconducting electron linac project based on the technology developed for niobium made elliptical TESLA type SRF cavities is underway in collaboration with TRIUMF. There are five connections to a single cavity, operating at 2K temperature, from atmosphere in the form of two beam tubes, two couplers and a tuner. Penetrations were intercepted at 77K temperature and 4K temperature to reduce the heat leak to the cavity.
Review of Scientific Instruments, 2013
In an isochronous cyclotron, measurements of central phase of the ion beam with respect to rf and... more In an isochronous cyclotron, measurements of central phase of the ion beam with respect to rf and the phase width provide a way to tune the cyclotron for maximum energy gain per turn and efficient extraction. We report here the development of a phase measurement system and the measurements carried out at the Variable Energy Cyclotron Centre's (VECC's) K = 500 superconducting cyclotron. The technique comprises detecting prompt γ-rays resulting from the interaction of cyclotron ion beam with an aluminium target mounted on a radial probe in coincidence with cyclotron rf. An assembly comprising a fast scintillator and a liquid light-guide inserted inside the cyclotron was used to detect the γ-rays and to transfer the light signal outside the cyclotron where a matching photo-multiplier tube was used for light to electrical signal conversion. The typical beam intensity for this measurement was a few times 10 11 pps.
physica status solidi (c), 2009
Abstract A 30 MeV proton cyclotron facility is being set up by this centre in Kolkata. This high ... more Abstract A 30 MeV proton cyclotron facility is being set up by this centre in Kolkata. This high current cyclotron will be used to produce PET (Positron Emission Tomography and SPECT (Single Photon Emission Computed Tomography) isotopes for medical diagnostics ...
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2014
Proc. of APAC, 2007
The magnetic field at median plane of SCC Magnet (Peak field 5.8T) is measured over its operating... more The magnetic field at median plane of SCC Magnet (Peak field 5.8T) is measured over its operating range and upto 29 inch radius. The magnetic field is mapped at radial interval of 0.1 inch and angular interval of 1 degree. The complete map of 360 degree comprised of ...
… on cyclotrons and …, 2007
INTRODUCTION The Superconducting cyclotron magnet at VECC, Kolkata was commissioned in July 2005 ... more INTRODUCTION The Superconducting cyclotron magnet at VECC, Kolkata was commissioned in July 2005 and magnetic field measurement and correction program was undertaken since then. The mapping task involved fabricating mapping jig and a reliable and automatic ...
Physical Review Special Topics - Accelerators and Beams, 2013