, V. Avagyan, B. Grigoryan, A. Gevorgyan, G. Amatuni, T. Mkrtchyan, A. Simonyan,
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.
The AREAL facility is a laser driven RF electron linear
accelerator for the advanced research in the field of
accelerator technology and ultrafast processes . 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
Each device and equipment of AREAL has its
individual cooling requirements.
Table 1: The Main Cooling Requirements of the AREAL
<4.2 <4.2 1.5-3
The design and fabrication of cooling systems are based
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
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.
The main technical parameters of RF gun
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
* Work supported by State Committee of Science MES RA in frame of
07 Accelerator Technology Main Systems
T31 Subsystems, Technology and Components, Other
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
C at 0
presented in Fig. 2.
Figure 2: Temperature sensors locations on the gun:
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
Cooling capacity (W)
Temperature range (
Temperature stability (
Not exeed 4.2kg/cm
Part of the temperature measurement results on the
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
C. The gun in-out temperature difference
temperature at the accelerator tunnel kept at 22.7
The thermoregulation system of RF gun has
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
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 . To increase the
water purification level during the long time operation the
hoses of thermoregulation system are changed by the
Another important cooling system for the AREAL
facility is the cooling system of RF klystron .
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
Temperature sensor type
Water deionization range
with distilled water circulation the stainless steel, copper,
bronze and plastic are used. The influence of those
System of RF Gun
Proceedings of IPAC2014, Dresden, Germany
saves the water purity level during long time (1400
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
Figure 4: Operation scheme of klystron cooling system.
The water purification level is very important for the
efficient and reliable operation of accelerator devices and
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
Figure 5: Specific resistance level depends on pH for
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
, level of pH,
temperature, flow velocity of water and imposed
electrical and galvanic potentials difference (different
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.
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.
 B. Grigoryan, et al,. "Advanced Research Electron
Accelerator Laboratory based on Photocathode RF
 Luigi Pellegrino, "A case of corrosion in accelerator
cooling water system: the Daphne Wiggler magnet"
Desy, April 20, 2004.
 T. Sakai, et al,. "Precise Control of Cooling Water
System for Stabilization of 125Mev Linac at
LEBRA", Proceedings of LINAC08, Victoria, BC,
 V. Vardanyan, V. Avagyan, et al., "Precise cooling
system for Electro-Magnetic Equipment", ISSN
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of Armenia (PEAA). 2013,V.10,N3. Yerevan, p537-