Distributed Cooling System for the areal test Facility

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DISTRIBUTED COOLING SYSTEM FOR THE AREAL TEST FACILITY

*

 

V. Vardanyan

#

, V. Avagyan, B. Grigoryan, A. Gevorgyan, G. Amatuni, T. Mkrtchyan, A. Simonyan, 

A. Tsakanian, V. Sahakyan, A. Vardanyan, CANDLE SRI, Yerevan Armenia 

Abstract 

Following the design specifications of the Advanced 

Research Electron Accelerator Laboratory (AREAL), a 

reliable distributed cooling system for the AREAL linear 

accelerator has been developed. The cooling system 

provides a high accuracy temperature control for the 

electron gun, klystron and the magnets. The main 

requirements and technical solutions for various 

accelerator components cooling units are presented, 

including the local and remote control. 

INTRODUCTION 

The AREAL facility is a laser driven RF electron linear 

accelerator for the advanced research in the field of 

accelerator technology and ultrafast processes [1]. The 

design specifications of the facility implies the stringent 

requirements to the facility performance, in particular to 

the cooling system. For phase 1 of the AREAL facility 

(electrons energy of 5 MeV) the stable and reliable 

cooling for the RF gun, klystron and solenoid magnet are 

required. The main parts of the AREAL cooling system 

have been developed and fabricated at CANDLE 

Institute.  

MAIN REQUIREMENTS TO COOLING 

SYSTEM 

Each device and equipment of AREAL has its 

individual cooling requirements.  

Table 1: The Main Cooling Requirements of the AREAL 

Parameters 

RF gun 

Klystron Solenoid 

magnet

 

Reson, 

Magnet 

Cooling 

capacity (W) 

300 500-

 

 

Temperature 

30-55 30-55  15-40 

Temp. 

stability (

0

C) 

+/-0.1 

+/-0.5 

+/-0.1 

+/-1 

Water flow 

rate (l/min) 

11 3.64 

20.5 2-30 

Pressure 

(kg/cm

2

) 

<4.2 <4.2  1.5-3 

Coolant 

Deionized 

water 

Distilled water 

Deminera-

lized water 

Deionization 

level 

 

5.6 

m 

 

The design and fabrication of cooling systems are based 

on the AREAL performance specifications which imply 

the temperature control of the facility subsystems. 

Main cooling requirements of the AREAL equipments 

are presented in Table 1. 

Cooling system of the AREAL linear accelerator is 

divided into three main parts: RF gun thermoregulation 

system, klystron cooling systems and solenoid magnet 

cooling system. Each cooling system has its individual 

parameters depending on specifications of accelerator 

parts. The cooling systems are located in the AREAL 

laboratory main building. 

THERMOREGULATION SYSTEM OF RF 

GUN 

The AREAL linear accelerator is based on the laser 

driven RF gun and for high-end performance efficiency 

the thermoregulation system of RF gun must satisfy all 

cooling-heating requirements presented above (Table 1).  

The hydraulic scheme of thermoregulation system of 

laser driven RF gun is presented in Fig. 1. 

 

 

Figure 1: Thermoregulation system-circuit for RF gun. 

 

The main technical parameters of RF gun 

thermoregulation system are presented in Table 2. 

Thermoregulation system of RF gun is reliable and 

flexible system and can be controlled locally or remotely 

from control room. Depending on generated heat level 

from electron gun the thermoregulation system can 

provide in electron gun laminar water flow rate with 

accurate temperature.  

 ___________________________________________   

* Work supported by State Committee of Science MES RA in frame of 

 

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Components 

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Considering the thermal requirements of electron gun 

as coolant, the de-ionized water with 

nominal specific resistance is chosen. 

As temperature sensors the Pt100 platinum resistance 

thermometers are used. Pt100 temperature sensors are 

very precise and sensitive with the measurement accuracy 

of +/-0.03

0

C at 0

0

C.  

Temperature sensors locations on the electron gun are 

presented in Fig. 2.   

 

 

Figure 2: Temperature sensors locations on the gun: 

1. Temperature sensor of water flow entrance into the 

gun, 2. Temperature sensor of water flow exit from the 

gun, 3. Sensor is located in the middle of the gun. 

 

Table 2: Main Technical Parameters of Thermoregulation 

Characteristics  

Value  

Cooling capacity (W) 

500 

Temperature range (

0

C) 30-55 

Temperature stability (

0

C) +/-0.1 

Water flow rate (l/min) 

2-15 

Pressure  

Not exeed 4.2kg/cm

2 

Coolant  

De-ionized water 

De-ionization level 

 

Part of the temperature measurement results on the 

electron gun obtained during the accelerator May 2014 

operation is presented in Fig. 3. The cooling water 

temperature at the gun entrance (a), exit (b), middle point 

(c), tunnel temperature (d), the in-out difference (e) are 

shown. As it is seen, the cooling system provides the 

temperature stability at the gun entrance of 37.5 

0

C with 

accuracy of 0.1

0

C. The gun in-out temperature difference 

is about 1.5. Fig. 2d presents the stability of air 

temperature at the accelerator tunnel kept at 22.7 

0

C.

The thermoregulation system of RF gun has 

proportional integral difference (PID) controller and all 

measurement data are recorded in control room. 

 

Figure 3: The gun temperature measurement results. 

 

The thermoregulation system of RF gun is located 3.5 

meters above from electron gun in the area for cooling 

systems. 

The main drawback of thermoregulation system of RF 

gun is the water purity decreasing in time. The main 

influence on the specific resistance of de-ionized water is 

caused by the corrosion of the cooling system 

components. For the efficient and reliable operation, the 

cleaning of gun thermoregulation system before the de-

ionized water inlet is very important [3]. To increase the 

water purification level during the long time operation the 

hoses of thermoregulation system are changed by the 

plastic pipes. 

COOLING SYSTEM OF RF KLYSTRON 

Another important cooling system for the AREAL 

facility is the cooling system of RF klystron [4].  

The main technical parameters of cooling system of RF 

klystron are shown in Table 3. The klystron cooling 

system is located near klystron in the RF room.  

As the coolant for the klystron cooling system a 

distilled water is used.  

Table 3: Main  echnical  arameters of RF  

Characteristics  

Value  

Temperature range  

30-55 

Temperature stability 

+/-0.5 

Temperature sensor type  

Pt100 

Coolant  

Distilled water 

Water deionization range  

 

-cm 

Nominal pressure (bar) 

3.3 

As construction materials of klystron cooling system 

with distilled water circulation the stainless steel, copper, 

bronze and plastic are used. The influence of those 

System of RF Gun 

T

P

Cooling System 

Klystron

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materials on the distilled water quality is very low which 

saves the water purity level during long time (1400 

hours). 

Fig. 4 presents the scheme of klystron cooling system. 

All components, subsystems and junctions of cooling 

system are tested in laboratory conditions before the final 

assembly. 

 

Figure 4: Operation scheme of klystron cooling system. 

 

WATER PURIFICATION LEVEL 

The water purification level is very important for the 

efficient and reliable operation of accelerator devices and 

equipments [2]. 

Cooling laboratory of the CANDLE Institute contains 

water treatment system: de-ionizer, distiller and the 

measurement equipments (water conductometer, etc.). 

Other laboratory equipments and conditions for 

processing the appropriate purified water are available as 

well.  

 

 

 Figure 5: Specific resistance level depends on pH for 

ultra pure water. 

The pipes of cooling systems for RF gun, klystron and 

solenoid magnet consist of copper, plastic, bronze and 

brass. Cooper and other materials corrosion rate depends 

on conductivity, dissolved O

2

, CO

2

, level of pH, 

temperature, flow velocity of water and imposed 

electrical and galvanic potentials difference (different 

metallurgy). 

 

 

Figure 6: Ultra-pure water contamination level depends 

on time. 

In the accelerator cooling systems the components 

corrosion in de-ionized and distilled water is unavoidable 

but can be limited. 

The specific resistance level dependence on the pH 

level is presented in Figure 5. The contamination level of 

purified water is shown in Figure 6.  

The cooling laboratory of CANDLE Research Institute 

is providing the appropriate ultra pure water for the 

cooling systems of AREAL.  

CONCLUSIONS 

The AREAL water cooling systems for RF gun, 

klystron and solenoid magnet are reliable, flexible and 

stable systems which provide facility operation according 

to the design specification. It also gives the possibility to 

do advanced experiments and obtain desirable results 

from accelerator. All cooling parts, junctions, components 

and subsystems of cooling systems are selected and tested 

in the test bench of cooling laboratory before 

implementing into the facility. Stable and reliable 

parameters for cooling systems during accelerator 

operation were achieved. 

REFERENCES 

[1]  B. Grigoryan, et al,. "Advanced Research Electron 

Accelerator Laboratory based on Photocathode RF 

Spain, p1066-1068. 

[2]  Luigi Pellegrino, "A case of corrosion in accelerator 

cooling water system: the Daphne Wiggler magnet" 

Desy, April 20, 2004. 

[3]  T. Sakai, et al,. "Precise Control of Cooling Water 

System for Stabilization of 125Mev Linac at 

LEBRA", Proceedings of LINAC08, Victoria, BC, 

Canada, p331-333. 

[4]  V. Vardanyan, V. Avagyan, et al., "Precise cooling 

system for Electro-Magnetic Equipment", ISSN 

1829-0043 PROCEEDING of Engineering Academy 

of Armenia (PEAA). 2013,V.10,N3. Yerevan, p537-

541. 

THPRI100

Proceedings of IPAC2014, Dresden, Germany

ISBN 978-3-95450-132-8

4012

Copyright

©

2014

CC-BY

-3.0

and

by

the

respecti

v

e

authors

07 Accelerator Technology Main Systems

T31 Subsystems, Technology and Components, Other