RESONANCE CONTROL FOR THE COUPLED CAVITY LINAC AND DRIFT TUBE LINAC STRUCTURES OF THE SPALLATION NEUTRON SOURCE LINAC USING A CLOSED-LOOP WATER COOLING SYSTEM Page: 4 of 4
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be used to direct all of the water flow through the heater
when it is in use.
The Linac water-cooling purification system was
designed with the intent of minimizing erosion, corrosion,
scaling, biological growth, and hardware activation. Each
component was selected to target the removal of a specific
impurity, and in some cases, multiple impurities. Critical
parameters to be controlled include electrical resistivity,
pressure, pH, and dissolved 02 content. Approximately 1-
5% of the main water flow will be diverted to the water
purification loop, the quantity being monitored with a
The basic mechanical design of the cooling loop
has helped to minimize erosion and scaling. Water flows
in the cooling systems will be kept below 2.5 m/s on
surface impingement areas such as tees and elbows, and
less than 5 m/s in straight sections to reduce the effects of
erosion. The narrow temperature band of the cooling
water, 10 to 250C, reduces scaling.
A resonance control system will employ a
control system that can be operated by a local,
programmable logic controller, interfaced through a
touchscreen interface, or it can be operated through the
SNS global control system network.
3 MANIFOLDS/TRANSFER LINES
Connecting the water skid to the RF structure
manifolds, are water supply and return lines. The transfer
lines are routed from the klystron gallery, where the skid
is located, to the linac tunnel through circular chases
located in the ground between the buildings
(approximately 20 feet in length). In the klystron gallery,
the transfer lines are routed overhead, around other
plumbing, cable trays, waveguides, etc. In the Linac
tunnel, the transfer lines are routed along the floor
between the chase exit and the RF structure manifold
junctions. The transfer lines will contain isolation valves
on either end for maintenance purposes. In addition, they
will contain short flexible sections to aid in their
installation and minimize the transmission of mechanical
The transfer lines deliver water to a main supply
manifold. From the main supply manifold, the water is
diverted to a number of sub-manifolds, which in turn feed
various components such as the drift tubes, post couplers,
tank walls, slug tuners, dipole electro-magnets, RF
window, Faraday cup, and drive iris. Proportional valves
in combination with flow meters are used to accurately
meter the correct amount of water to each sub-manifold.
The ultrapure deionized water, 10 to 14 Mn, is
very aggressive and will attack materials such as copper,
brass, bronze, and solders. Copper, stainless steel, brass,
carbon steel, and PVC have been evaluated for use as the
potential plumbing material. Copper tubing is desirable
because of its mechanical properties of high strength and
its ease in forming and joining, as well as being
economical. Stainless steel is used in specialized water
transfer systems such as those found in chemical
processing facilities, microchip processing facilities,
power plants, nuclear reactors, synchrotrons, and particle
accelerators. Brass and mild carbon steels are susceptible
to corrosion or erosion when the fluid is ultra high purity
water and therefore is not recommended for use on the
SNS project. Plastic and PVC materials are being
avoided because each lacks strength and have a high
diffusion rate for oxygen (oxygen promotes bacteria
growth and enhances corrosion of copper).
The radiation emanating from a particle
accelerator beam can degrade the mechanical properties
of materials in close proximity to the beam centerline.
This is especially true for many types of electronic
components. The extent of this degradation will depend
on the dose rate and cumulative radiation dose, as well as
other factors such as operating temperature, mechanical
stress, and exposure to air . Scientists and Engineers at
CERN have compiled a fairly extensive database, which
relates radiation damage to cumulative dose rate for a
variety of materials .
Copper and stainless steel, as well as many of the
nonmetallic materials such as Buna-N, Hypalon, Nylon,
and Neoprene meet the cumulative dose criteria of
4.3x106 Rads for SNS. However, among the nonmetallic
materials, Buna-N and Neoprene have an historical usage
base which indicates good results. Both have been used
on the LANSCE 800 MeV particle accelerator at Los
Alamos National Laboratory with good success. The
flexible Buna-N lines on the LANSCE CCL have been
observed to harden over time by a combination of
radiation and atmospheric damage, however they have
maintained working lifetimes of well over ten years .
In addition, Buna-N/Neoprene hoses have been used as
flexible jumper lines for the majority of the focusing and
steering magnets on the LANSCE accelerator for the last
twenty years .
Work supported by the Office of Basic Energy
Science, Office of Science of the US Department of
Energy, and by Oak Ridge National Laboratory.
 Wangler, T., 1998, Principles of RF Linear
Accelerators, John Wiley and Sons, Inc., NY.
 Sullivan, A.H., 1992, "A Guide to Radiation and
Radioactivity Levels Near High Energy Particle
Accelerators," Nuclear Technology Publishing, Ashford,
 Beynel, P., Meyer, P., Schonbacher, H. and Tavelet,
M., 1982, "Compilation of Radiation Damage Test Data,"
Published as CERN Yellow Reports. Part 3, Accelerator
 Boedeker, W., Meetings on LANSCE Purification
Systems 6/01/99 - 8/13/99, LANSCE-2 Group, Los
Alamos National Laboratory, Los Alamos, NM
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Bernardin, J. D. (John D.); Brown, R. L. (Richard L.); Brown, S. K. (Stanley K.); Bustos, G. R. (Gerald R.); Crow, M.L. (Martin L.); Gregory, W. S. et al. RESONANCE CONTROL FOR THE COUPLED CAVITY LINAC AND DRIFT TUBE LINAC STRUCTURES OF THE SPALLATION NEUTRON SOURCE LINAC USING A CLOSED-LOOP WATER COOLING SYSTEM, article, January 1, 2001; United States. (digital.library.unt.edu/ark:/67531/metadc932765/m1/4/: accessed November 13, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.