The Accelerator Technology Group (ATG), one of the constituents of VECC, Kolkata is dedicated in advancing the R&D in Power Converters, Instrumentation, Superconductors, Magnet Coils, Transformers, Radiofrequency (RF) Systems, Embedded Controllers and Control Systems typically targeted to Cyclotron sub-systems but extends its scope to state-of-the-art energy storage systems, superconducting RF Linac cavity, neutrino physics experiments and radio-chemical process instrumentations as well.

The group has developed expertise on the winding of Superconducting coils and has indigenously developed the largest superconducting coil of the country for the centre’s K-500 Superconducting Cyclotron (SCC) project, able to produce a magnetic field of 5.5 T, more than 100000 times the Earth’s magnetic field. Along with this, the group’s winding facilities has come up with novel facilities for developing high current water-cooled transformer, high voltage resin- cast transformer and high frequency ferrite core transformers and inductors. Currently the group, in the multidisciplinary collaboration environment of VECC, has explored the modern regimes of magnet designs and has indigenously developed and tested a hybrid magnet composed of a High Temperature Superconductor (HTS) coils inserted in the bore of a Low Temperature one as a part of the Superconducting Magnet Energy Storage (SMES) system project.

ATG has also been responsible for developments in the field of RF Systems for both K-500 SCC and K-130 Room Temperature Cyclotron (VEC). A solid-state wideband RF amplifier drives the final amplifier of the VEC (based on BURLE 4648 tetrode) that produces a maximum output power of 250kW. DC bias power supplies for the Filament (4V, 2000A DC), Control Grid (0 to - 160V / 0.5A DC, 50ppm stability class), Screen Grid (1.2kV, 1A DC) and the Anode (0 to 20kV, 20A DC) has been indigenously developed by ATG. Tuning of the system (rated at 5.5 – 16.5 MHz) is achieved by panel movements (coarse) and motorized trimmer capacitor (fine) controls.
Contrary to the single tetrode based design of VEC, the RF system of the SCC features a 3-φ system developed for the frequency range of 9 – 27 MHz with amplitude and phase stability of 100 ppm and ±0.50 respectively. Each dee along with half-wave coaxial cavity develops peak voltage of 100kV having fed with RF power (~80kW) from each of the three high power final RF amplifiers. Like main Dee-cavity, each amplifier is tuned by moveable sliding short. The amplifier (based on Eimac 4CW#150000E tetrode and operated in class-AB mode with power gain 22 dB) is given DC bias by indigenously developed power supplies, viz., Filament P/S (15.5V/215A DC), Grid P/S (-500V/0.5A DC), Anode P/S (20kV/22.5A DC) and Screen P/S (1.5kV/1A). A PC-based stepper motor controlled sliding-short movement system is used for tuning the cavities at different frequencies. The closed-loop amplitude and phase regulators are based on RF modulator and I&Q modulation technique respectively with Dee voltage pick-off signals being used as feedback. The entire supervisory control of the RF systems of both SCC and VEC is being done by independent Programmable Logic Controller (PLC)s, customized for the operation and status monitoring of the process parameters. In addition to the abovementioned power supplies, the ATG has been regularly developing DC regulated Power Supplies, True Bipolar Power Supplies, Choppers, and Power Inverters of various power ratings, diverse topologies and precision classes to cater to general requirements of Electromagnets, RF Systems, Electrostatic Inflectors, Energy Storage Systems and Voltage Restorers.

Another facet of the group’s activities centres on analog instrumentation designs for equipment protection. In addition to traditional comparator and relay based interlock systems, one of the important developments in this field was the quench protection system developed for the SMES project to safeguard the superconducting coils against possible catastrophic consequences of a quench. Fast acting crowbars (operating time ~ 2μs) were also significant contributions that were incorporated in the RF protection systems to avoid damage to the tetrode tubes in case of internal arcings.

In the prevailing age of digital designs, the group has also exploited fixed-point and floating- point DSP controllers and utilized them in design of digital feedback controllers for power converters. Besides these, the group has been developing microcontroller based embedded systems, configured in-house to incorporate functionalities such as serial communication, ADC and DAC interfacing, LCD based display designs, etc. Along with these, PC based Graphical User Interface (GUI)s were also developed for the purpose. The modular architecture, initially targeted for power converter units, has been generalized for its use in process control and automation as well.

Major Activities

Major Activities

Overview:
Computer Control Division is primarily involved in development, maintenance and upgradation of Control, Data Acquisition & Diagnostic Systems for Room Temperature Cyclotron (RTC), Superconducting Cyclotron (SCC), Medical Cyclotron, Electron LINAC and various experimental facilities of the centre. The development of control and data acquisition systems for the Magnetic Field Mapping (MFM) of SCC, RTC and upcoming Medical Cyclotron are the other important activities of this division. The division is also engaged in developing State-of-the-art Instruments e.g. vacuum gauge controller, nano-ammeter, RF power meter, alarm annunciator, etc. and various EPICS software tools.

Accelerator Instrumentation Section:

The main activity of the section is the development of Experimental Physics & Industrial Control System (EPICS) based state-of-the-art distributed control system for Room Temperature Cyclotron (RTC) and Superconducting Cyclotron (SCC). This involves development of Supervisory Control System comprising of Operator Interface (OPI) and Input Output Controller (IOC) for the following subsystems of the cyclotrons.

High current power supplies for various magnets
High voltage power supplies
PIG ion source
Beam diagnostic system
Cyclotron control console
vacuum system
LCW system
Cyclotron status monitoring facility
The section is also responsible for day-to-day maintenance and upgradation of control hardware and software  of the above control system. The testing and implementation of latest tools and technologies of EPICS to control system is being done on regular basis. Beside this, the following ARM based EPICS embedded modules are indigenously developed.

Beam Diagnostics Controller,
Vacuum gauge controller,
Alarm Annunciator
Power supply controller
The following EPICS Software Tools have also been developed.

CA Activex components for OPI,
EPICS MySQL Archiver for control system data logging
web based E-Log for operator log
The development of the following electronics/ controller/ position encoder readout electronics, jig movement controller and software for control and data acquisition for MFM system is an important activity of this section. The indigenously developed MFM system for SCC is capable of acquiring 106 field data point in around 180 minutes without human intervention.

The section indigenously develops the following precision instruments as import substitution.

nano ammter
RF power meter
charge integrator
SiPM based phase measurement with latest technology and connectivity
The section is also entrusted with the development of control system for prototype medical cyclotron.

Journal

[1] Anindya Roy, R. B. Bhole, Partha P. Nandy, R. C. Yadav, Sarbajit Pal, and Amitava Roy, "Implementation of EPICS based vacuum control system for Variable Energy Cyclotron Centre, Kolkata", REVIEW OF SCIENTIFIC INSTRUMENTS 86, 033306 (2015)

Seminar/Conferences/Symposia

[1] Anindya Roy, Shantonu Sahoo, Sarbajit Pal, ‘Application of EPICS Control System Studio in VECC’, Proc. of INPAC 2019, Inter-University Accelerator Centre, New Delhi, India,

[2] Shantonu Sahoo, Arihant Jain, Anindya Roy, ‘EPICS based Embedded Control System Architecture for Electron Gun of E-LINAC’, Proc. of INPAC 2019, Inter-University Accelerator Centre, New Delhi, India,

[3] Anindya Roy, Partha Pratim Nandy, R. B. Bhole, Sarbajit Pal, Amitava Roy, ‘Development of EPICS Enabled Alarm Annunciation System’, Proc. InPAC-2018, Raja Ramanna Centre for Advanced Technology, Indore, India.

[4] Niraj Chaddha, R.B.Bhole, J. Pradhan, P. P. Nandy, Sarbajit Pal, ‘Instrumentation for Position Measurement of Magnetic Median Plane of SCC and Error Analysis’, Proc. InPAC-2018, Raja Ramanna Centre for Advanced Technology, Indore, India.

[5] Shantonu Sahoo et. al, "ARM based embedded EPICS controller for beam-diagnostics of cyclotrons at VECC", proc. ICALEPCS-2013, Oct-2013,

[6] Anindya Roy et. Al, "Filed mapping of K=500 superconducting cyclotron magnet for correction of harmonics with trim coils",  Proc. InPAC-2013, pp 752-754.

[7] S. Sahoo, T. Bhattacharjee,S.Pal, “Development and Performance analysis of EPICS Channel Access Server on FPGA based Soft-core Processor”, International Conference on Personal Computers and Particle Accelerators,  PCAPAC’12 , Kolkata, December 4-7 (2012).

[8] N.Chadda, S.Sahoo, R.B.Bhole, S.Pal, “Modular Beam Diagnostics Instrument Design For Cyclotrons”, PCAPAC’12 , Kolkata, December 4-7 (2012).

[9] Anindya Roy, R. B. Bhole, Sarbajit Pal, “Development of EPICS Channel Access Embedded ActiveX Components for GUI Development”, Proc. of International Conference on Personal Computers & Particle Accelerator Control, PCAPAC’12 , p54-56, December 2012

[10] Anindya Roy, R. B. Bhole, Sarbajit Pal, D. Sarkar, VECC, India, “EPICS MySQL Archiver – Integration between EPICS and MySQL”, Proc. of International Conference on Personal Computers & Particle Accelerator Control, PCAPAC’12, p109-111, December 2012

[11] Tanushyam Bhattacharjee, Anindya Roy, Rajendra Balkrishna Bhole, Gaurav Saxena, Kaushik Datta, Tapas Samanta, Sarbajit Pal, Debranjan Sarkar, "Facility Monitoring SystemusingStorage Area Network for VEC and SCC",in the Proceedings of 9th International  Workshop onPersonal Computers and Particle Accelerator Controls (PCaPAC-2012), VECC, Kolkata, December 4-7(2012).

[12] Niraj Chaddha, R. B. Bhole, Sarbajit Pal, ‘Multiple Parameter Control Using Soft-Console’, Proc. of INPAC 2011, Inter-University Accelerator Centre, New Delhi, India, February 2011.

[13] R. B. Bhole, Anindya Roy, Joydeeo Mishra, Sarbajit Pal, ‘Trim Coil Temperature Control System fpr SCC’, roc. of INPAC 2011, Inter-University Accelerator Centre, New Delhi, India, February 2011.

[14] Anindya Roy, R.B. Bhole, J. Akhtar, R.C. Yadav, Sarbajit Pal, D. Sarkar, R.K. Bhandari, ‘Vacuum system of cyclotrons in VECC, Kolkata’, Proc. of XII IEEE International Vacuum Electronics Conference (IVEC-2011), Bangalore, India, February 2011.

[15] Niraj Chaddha, R. B. Bhole, Tanushyam Bhattacharjee, Anindya Roy, Sarbajit Pal, 'Embedded Systems for Diagnostics & Control Used in VEC and SCC', Proc. of SACET-2009, VECC, Kolkata, October 2009.