Superconducting Linear Accelerator

Superconducting Linear Accelerator

About Superconducting Linear Accelerator

The superconducting linear accelerator (SC Linac) at Inter University Accelerator Centre (IUAC) serves as a booster to the 15 UD Pelletron and is designed to accelerate ion beams upto mass 80 above the coulomb barrier of 5MeV/nucleon for symmetric systems. The SC linac consists of three accelerating modules each housing eight Niobium Quarter Wave Resonators (QWR) and an 8 Tesla superconducting solenoid, a superbuncher and a rebuncher module housing one and two QWRs respectively.

The design and development of the linac started in early 90’s in collaboration with Argonne National Laboratory (ANL), USA. IUAC personnel were stationed at ANL to carry out the design and subsequent fabrication of the QWRs. The first milestone was the successful testing of the superbuncher in 2001. This was followed by the first beam acceleration in 2005. The complete linac has been operational since 2012 and delivering ions beams for user experiments on a routine basis.

Schematic Layout and three installed cryomodule
Figure 1. Schematic Layout and three installed cryomodule
Schematic Layout and three installed cryomodule
Figure 2. Schematic Layout and three installed cryomodule

Niobium Quarter Wave Resonators

The SC Linac uses Quarter Wave Resonators (QWR) as the accelerating and bunching element. These operate at 97 MHz and are variants of a coaxial transmission line shorted at one end and open at the other. The high voltage at the open end is used for particle acceleration. The length of the central element of the resonators is approximately equal to one fourth of the free space wavelength of the electromagnetic wave propagating inside the cavities and hence the name quarter wave resonators. The resonators are constructed from bulk niobium and are jacketed by an outer vessel of stainless steel. Transitions from stainless steel to niobium are provided through explosively bonded Nb-SS transition flanges. During operation the resonators are bath cooled at 4.2 K with liquid helium.

Schematic of the QWR and its picture
Figure 3A. Schematic of the QWR and its picture
Schematic of the QWR and its picture
Figure 3B. Schematic of the QWR and its picture

Table 1. Electromagnetic parameters of the QWR

Operating frequency 97 MHz
Optimum beta (v/c) 0.08
Stored energy @ 1 MV/m accelerating field 0.110 J/(MV/m)2
Peak surface magnetic field @ 1 MV/m accelerating field 13.2 mT
Peak surface electric field @ 1 MV/m accelerating field 3.9 MV/m
Geometric factor (QRs) 15.1 
Shunt Impedance ( RSh/Q) 382 
Effective accelerating length (Leff) 159 mm
Operating Temperature 4.2 K
Design value of operating accelerating field (Ea) 4 MV/m
Quality factor @ Ea >2x108

Beams Accelerated through Linac

Ever since the SC Linac has been operational several ion beams have been accelerated and delivered for user experiments in the Hybrid Recoil Mass Analyzer (HYRA) and the Neutron Detector Array (NAND) facilities at the centre. Table 2 below lists the various beam species accelerated through the linac alongside its charge state, the total energy, the maximum energy gain from linac, the experimental facility using the beam and the year of delivery:

S. No. Beam species Charge state Total beam energy Max. Egain from Linac Experimental facility (year)
1 48Ti 15+ 300 MeV 132 MeV NAND (2015)
2 37Cl 13+ 245 MeV 95 MeV HYRA (2015)
3 35Cl 13+ 259 MeV 109 MeV HYRA (2015)
4 18O 8+ 155 MeV 55 MeV HYRA/NAND (2017)
5 16O 8+ 150 MeV 50 MeV HYRA/NAND (2017)
6 30Si 11+ 212 MeV 92 MeV HYRA (2020)
7 28Si 11+ 210 MeV 85 MeV NAND (2020)
8 19F 9+ 190 MeV 90 MeV HYRA (2020)

* Energy gain are as per user requirement and is not the maximum achievable value.

Group Members and Contact Details

Dr P N Prakash

Dr P N Prakash

Scientist-H

prakash@iuac.res.in

Ext:316

Mr. R Mehta

Mr. Rajeev Mehta

Scientist-G

rajeev@iuac.res.in

Ext:309

Dr B K Sahu

Dr B K Sahu

Scientist-G

bhuban@iuac.res.in

Ext:333

Mr. Abhishek Rai

Mr. Abhishek Rai

Scientist-F

abhishek@iuac.res.in

Ext:405

Mr. Ashutosh Pandey

Mr. Ashutosh Pandey

Scientist-E

ashu@iuac.res.in

Ext:123

Mr. G K Chaudhari

Mr. G K Chaudhari

Jr Engineer-F

gajanan@iuac.res.in

Ext:405

Mr. R N Dutt

Mr. R N Dutt

Jr Engineer-F

raj@iuac.res.in

Ext:405

Mr. D S Mathuria

Mr. D S Mathuria

Jr Engineer-E

mathuria@iuac.res.in

Ext:115

Mr. S S K Sonti

Mr. S S K Sonti

Jr Engineer-F

sundaram@iuac.res.in

Ext:403

Mr. K K Mistri

Mr. K K Mistri

Jr Engineer-F

kishore@iuac.res.in

Ext:414

Dr. Joby Anthony

Dr. Joby Anthony

Engineer-E

joby@iuac.res.in

Ext:115

Mr. Manoj Kumar

Mr. Manoj Kumar

Jr Engineer-F

manoj@iuac.res.in

Ext:120

Mr. M V Suresh Babu

Mr. M V Suresh Babu

Jr Engineer-F

suresh@iuac.res.in

Ext:120

Mr. R Nirdoshi

Mr. R Nirdoshi

Engineer-C

nirdoshi@iuac.res.in

Ext:115

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