[en] New, high stability, dc current controlled power supplies of rating 25 V, 80 A are developed to energize quadrupole magnets in Transport Line-2 (TL-2) of INDUS. They are developed using two switch forward converter topology operating at 50 kHz. This paper describes design principles, peculiarities in power supply fabrication, salient features and results of various tests conducted on the power supplies. (author)

[en] Four numbers of three terminal triggered spark gap based crowbar system are employed for protecting the 505 MHz, 64 kW CW klystron amplifiers of Indus-2 Synchrotron Radiation Source and are operating satisfactorily for last five years. Suitable crowbar limiting elements are incorporated to keep minimum header voltage across spark gap switch even under transient conditions as well as to make the crowbar circuit over damped, ensuring complete discharge of stored energies under unfavorable conditions. Common problems encountered with most of the crowbar based system like substantial input supply dips and line notches during crowbar and switching operations etc, are effectively taken care of in this paper. Stringent wire burn tests were carried out to ensure suitability of klystron bias power supplies for feeding to their respective klystron amplifiers. This indigenous crowbar development with simpler trigger mechanism will be quite useful for effective protection of low and medium power CW klystron amplifiers. PSIM Simulation of voltage and current waveforms for crowbar circuit has been carried out and is presented in this paper. Several experiments were conducted in actual klystron bias power supplies and a close match between simulated and experimental waveforms has been witnessed. (author)

[en] Flexible co-axial lines are required for compensating axial, lateral misalignment and thermal expansion of transmission line system. A 3-1/8 inch flexible co-axial line is designed and fabricated. An 80 kW four way high power waveguide combiner is also designed and developed for combining power at 505.8 ± 5MHz. Four input ports are of 3-1/8 inch co-axial type and each port is capable of handling 20 kW average power. The output port is standard WR1800 waveguide. Design simulations are carried out using the commercial electromagnetic simulation software ANSYS HFSS and CST Microwave studio. A very good combining efficiency (better than 98%) is achieved for ± 10° phase variation at either port. Achieved return loss is also better than 45 dB in common mode at co-axial ports or at waveguide port. The co-axial components and waveguide parts have been fabricated with high positional and dimensional accuracies. The waveguide is constructed using 5mm thick four plates with corner MIG welding and the coaxial parts are mostly machined from brass and PTFE. To increase the electrical conductivity co-axial parts and the capacitive probe are coated with silver. The waveguide inner walls are treated with chromate conversion to resist oxidation. The paper presents the detailed design simulation and graphical results for this combiner, electromagnetic simulation results, bellow fabrication and RF measurements. (author)

[en] This paper reports the optical design of a Photo-Emission Electron Microscopy (PEEM) beamline in the energy range from 10 eV to 4000 eV for Indus-2 synchrotron radiation source at RRCAT, Indore. The major subsystems of the beamline are mirrors, grating/double crystal monochromator (PGM/DCM), experimental station, vacuum lines, and auxiliary systems. The first optical element encountered by the beam is a cylindrical mirror that collimates the beam which subsequently falls on PGM and DCM used to monochromatise it in the low (10-2100 eV) and high (2100-4000 eV) energy ranges, respectively. After monochromator, the beam is focused by a toroidal mirror to an intermediate focus. To get the desired spot size between 3-200 μm with highest possible flux (∼10¹⁴-10¹⁶ Ph/s/0.l % BW at the rate 300 mA), final focusing has been achieved with a Kirkpatrick-Baez (K-B) mirror system. The optical design of the beamline (36 m in length) is carried out using software program SHADOW VUI 2.1 and XOP 2.1. (author)

[en] Radio frequency shield is installed inside the corrugated stainless steel bellows in the Indus-2 at 40 places throughout the ring by Ultra High Vacuum section. RF shield is a telescopic finger contact type having contact at the tip of stainless steel stub. Rhodium plating is applied on the stainless steel stub for wear resistance due to high hardness and to reduce contact resistance to facilitate smooth flow of image current without sparking. Electrodeposition over stainless steel is difficult due to the presence of passive oxide film. Adhesion is one of the most important considerations in electroplating, as without adequate adhesion the coating will not perform the task for which intended. An adherent rhodium coating can be obtained after employing a series of chemical cleaning methods. Nickel is used as an intermediate strike coating to improve adhesion of rhodium over stainless steel. Analysis of the electroplating solution during deposition and its replenishment for rhodium content is essential in maintaining the deposit properties. All the stainless steel stubs have been electrodeposited with rhodium and is working satisfactorily. (author)

[en] In a double bend achromat, Chasman-Green (CG) lattice represents the basic structure for low emittance synchrotron radiation sources. In the basic structure of CG lattice single focussing quadrupole (QF) magnet is used to form an achromat. In this paper, this CG lattice is discussed and an analytical relation is presented, showing the limitation of basic CG lattice to provide the theoretical minimum beam emittance in achromatic condition. To satisfy theoretical minimum beam emittance parameters, achromat having two, three, and four quadrupole structures is presented. In this structure, different arrangements of QF and defocusing quadruple (QD) are used. An analytical approach assuming quadrupoles as thin lenses has been followed for studying these structures. A study of Indus-2 lattice in which QF-QD-QF configuration in the achromat part has been adopted is also presented

[en] An Apple II type undulator is proposed for 2.5 GeV SRS. For initial studies of magnetic parameters and manufacturing feasibilities, a 6 periods prototype undulator of period length 72 mm and pole gap 20 mm is under development. Mechanical structure with stringent tolerances is required to achieve the required field quality. Stress analysis has been done to study the deflection under the magnetic forces. The prototype structure along with the magnet block holders has been made and mechanical dimensions and geometric tolerances have been measured. In this paper we present the preliminary mechanical design and assembly of static parts of prototype undulator structure. (author)

[en] For orbit correction in Indus-2 a 2.5 GeV synchrotron radiation source, there are 56 button type beam position monitors (BPMs), 48 horizontal and 40 vertical corrector magnets. The closed orbit correction is necessary to get maximum possible aperture and a good beam lifetime. There are many algorithms like least square minimisation, harmonic correction, local orbit bumps, best orbit corrector method or MICADO etc. to correct the closed orbit distortion in the ring. Currently, algorithm based on singular value decomposition (SVD) of the response matrix is very widely used at various accelerators around the world. In this paper, we present the closed orbit correction in Indus-2 by combining the MICADO and SVD algorithms. By using MICADO algorithm best orbit correctors will be identified and an SVD analysis of the response matrix between best orbit correctors and BPMs will reduce the corrector strengths. A graphical user interface in MATLAB has been developed to interactively control the orbit and strength of the best orbit correctors. The simulation study using Accelerator Toolbox and preliminary result of orbit correction will be presented. (author)

[en] In this work, high quality (Q) factor microwave air filled rectangular cavity resonator (RCR) for the frequency of 7.8 GHz and 26 GHz is designed, analyzed and developed using X-ray LIGA. For fabrication, polyimide-Au X-ray mask is made. To obtain RCR structure, X-ray exposure is done on PMMA at BL-07 in Indus-2 using X-ray mask. The challenges in the fabrication of RCR of 7.8 GHz and 26 GHz are discussed. The analytical, simulation and experimental result of 7.8 GHz RCR are compared and discussed. (author)

[en] Accelerator d.c, magnets have to produce a highly stable magnetic field which in turn needs highly stable d.c. current sources to energise them. Indus-II Q4 and Q5 power supplies are SCR based power supplies wherein the rectified voltage is fed to a passive filter to reduce the ripple voltage. The output of the passive filter still contains some ripple particularly on the low frequency side. The design and the test results of an active filter module have been discussed wherein the low frequency attenuation can be very effectively taken care of by allowing this to be absorbed in a coupling transformer put after the passive filter. Considerable size reduction has been achieved by using switching techniques. Low frequency attenuation has been made quite a simple task. This filter also helps in handling transients from input. (author)