RRCAT- Raja Ramanna Centre for Advanced Technology, Indore

The specifications and number of the magnet power supplies required for Indus-2 storage ring (SR) and transport line 3 (TL3) are listed in the following tables.

Magnet Type	No. of magnets	No. of P/S	PS Current Min-Max. (A) Stability		Load R(Ω) L (mH) LF HF
Dipole magnets (including one reference magnet) all in series	16 + 1	1	200-900	+5x10^-5	0.72	1615	1020
Quadrupole magnets. Two Q1 magnets per cell (8 such cells) 2 magnets in series	2 x 8	8	30-180	+5x10^-5	0.48	160	100
Two Q2 magnets per cell (8 such cells)	2 x 8	8	30-180	+5x10^-5	0.66	240	160
Two Q3 magnets per cell (8 such cells)	2 x 8	8	30-180	+5x10^-5	0.54	200	120
Two Q4 magnets per cell (8 such cells - all in series)	16	1	30-180	+5x10^-5	4.35	1600	960
One Q5 magnet per cell (8 such cells- all in series)	8	1	30-180	+5x10^-5	2.18	800	480
Skew quadrupole magnets	32	4	0-200	+1x10^-3	0.1	-	-
Four sextupoles per cell (8 such cells - 16 in series)	32	2	40-230	+1x10^-3	1.31	-	-
Steering coils	42 nos. CF+24SF 16 nos. DP	108 42	+ 10 + 10	+5x10^-4 +5x10^-4	1.5 4.2	200 400

Magnet Type	No. of magnets	No. of P/S	PS Current Min-Max. (A) Stability		Load R(Ω)
1. Dipole Magnets
a) Type BM-1	1	1	0-190	+5x10^-4	0.11
b) Type BM-2	1	1	0-190	+5x10^-4	0.11
c) Type BM-3	1	1	0-170	+5x10^-4	0.22
2. Quadrupole Magnets
QD1,QF1,QD2,QD4,QF4,QD5,QF5,QD6,QF6	9	1	18-72	+5x10^-4	0.93
QF2,QF3	2	1	52-170	+5x10^-4	0.24
QD3	1	1	52170	+5x10^-4	0.12
QF7,QD7,QF8,QF9,QD8,QF10	6	6	19-155	+5x10^-4	0.12
3. Steering Coils
Steering coils	24	24	+ 10	+5x10^-4	0.7

There are 16 dipole magnets in the ring and one in the power supply equipment room, all connected in series. The power supply works in constant current mode most of the time. In order to achieve required performance, a low voltage series pass power supply is used in series with 12-pulse fully controlled thyristor converter.

There are five families of quadrupole magnets, named Q1, Q2, Q3, Q4 and Q5 in each cell. Out of 9 quadrupole magnets in each cell there are 2 numbers each of Q1, Q2, Q3, Q4 and one number of Q5 type. Type Q1, Q2, Q3 and Q4 Quadrupole in each cell are put in series and are energized by a single power supply. All the Q5 type magnet are connected in series and energized by a single power supply. In addition to these skew quadrupoles are also used for beam correction. Power supplies for Q1 and Q2 type are developed using transistor series pass scheme with twelve-pulse SCR rectifier as pre-regulator. Q3 type power supplies are developed using high-frequency LCC resonant converter. Two Q3 type power supplies are housed in one cabinet. The Q4 and Q5 power supplies have in the first stage, phase-controlled twelve-pulsed output which is filtered with an actively damped LC passive filter. The output of the passive filter is fed to the load via an active filter stage that filters out primarily low-frequency ripple and regulates the output against sudden line voltage changes.

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. Attenuation of this ripple with passive filter necessitates increase in size of L and C and leads to sluggishness of the system. Two D.C. side active filters has been developed for INDUS-II Q4 and Q5 power supplies wherein low frequency attenuation has been 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.

Skew quardrupole coils are fitted on 16 sextupole magnets. Total 4 power supplies (each feeding 4 skew-quadrupole coils) are required to energize these coils. These power supplies are developed using high-frequency resonant converter. Input three-phase line is rectified using six-pulse SCR rectifier to get coarsely regulated DC input for the resonant converter stage. Two independent power supplies are housed in one cabinet - they only share a common LCW connection for cooling.

There are two families of 16 sextupole magnets in the ring. All the 16 magnets in each family are connected in series. Each family is energized by separate power supplies. The power supplies are developed using high-frequency three-phase LCC resonant converter. Two independently controlled resonant converters are put in parallel. All power devices and magnetic components are water-cooled. Two sextupole magnet power supplies are housed in one cabinet.

TheTL3 dipole magnet power supplies energize three dipole magnets of Transport Line-3. These power supplies are developed using high frequency resonant converter. Input three-phase line is rectified using six-pulse SCR rectifier to get coarsely regulated DC input for the resonant converter stage. All power devices and magnetic components are water-cooled. Two independent power supplies for BM1 and BM2 are housed in one cabinet - they only share a common LCW connection for cooling. Power supply for BM3 is housed in another cabinet.

TL-3 magnet lattice has eighteen quadrupole magnets which take electron bunches of 700MeV from the booster synchrotron and transport to 2.5 GeV synchrotron ring. In all, nine dc current power supplies feed these magnets. The power supplies are developed using high-frequency phase-shifted PWM full bridge converter. A six-pulse controlled rectifier feeds H-Bridge IGBT inverter operating at 25 kHz. The SCR converter helps in inrush current control, and in the active damping of input filter. Addition of two auxiliary chokes in the switching circuit enable zero-voltage-switching of IGBTs even at light loads. A scheme for sensing DC current through power transformer primary to avert its saturation by balancing volt-sec product with the help of modifying gate drive is introduced and implemented successfully. Power semiconductors and magnetic components are water-cooled. Two power supplies are housed in one cabinet.

Correction Coil Power supplies are used to energies the correction coils to correct the beam position at different locations in the line, if it deviates from its orbit. Salient features of these power supplies are: unity power factor at the input, bipolar load current ability with smooth transition from one polarity to other, higher load current stability and higher efficiency. Power stage of the power supply consists of a boost converter in the input to ensure unity power factor, a full-bridge inverter to achieve isolation as well as required voltage at the load followed by full bridge inverter for changing polarity of the load current. Total 148 power supplies required are arranged in 19 numbers of 32U cabinets. Each 32U cabinet is equipped with 4 numbers of 4U boxes. Each 4U box contains two power supplies. All these power supplies are operated by single phase, 230V, 50Hz.