Stripline Review

### Target Hall

### April 23,2003

### By: Bill Boettinger

The design for the target hall stripline falls into 5 separate areas,
which are:

1.  Connections

2.  Electrical Isolation Considerations

3.  Supports

4.  Vibration

5.  Thermal Expansion

6.  Service Considerations

# Connections

All connections in the target hall stripline have a minimum of 1 1/8
inch contact wide area and .005-inch thick silver-plating so as to aid
in conduction across the joint. The connection to the power supply has a
removable (non-adjustable) link that can be removed in the event that
work has to occur on the penetration or target hall portions of the
stripline. The minimum clamping force on the joint with the specified
contact area is

approximately 3000 psi (**[see example 1]{.underline}**). The clamps in
these sections are being used at MI-8 without a failure during the past
2 years worth of pulsing. Some of the connections are adjustable, but
the designs for that are discussed later.

# Electrical Isolation Considerations

All air gaps between conductor (both like and oppositely charged
conductors) maintain a 3/8-inch air gap. All joints (with the exception
of the power supply joint) have a minimum of 3/8-inch stacked G-10
insulator gap with a minimum creep path length of 1/2-inch. The
connections to the power supply have a 1/8-inch G-10 insulator stack
height with the same 1/2-inch creep distance. In an effort to minimize
inductance effects, the like charged conductor pairs have been separated
(rather than dislike charged pairs) in order to effect connections where
a horn is being hooked up to the main conduction line that runs along
the wall in the target hall. (**[See example 1]{.underline}**).

# Supports

There are 5 types of supports for the stripline, which are:

Floor stands ..........................(**[example #4]{.underline}**)

Penetration pipe stands .............(**[example #5]{.underline}**)

Power supply room wall mount \....(**[example #6]{.underline}**)

Chase support .....................\....(**[example #7]{.underline}**)

Wedge Clamp ........................(**[example #8]{.underline}**)

## 

## Floor stands

The floor stands are located on the walkway and support the main
stripline in the target hall at a height of 53 inches off the walkway
floor. The current design for these stands is

2 pieces of double Unistrut as the vertical support sections and a
horizontal piece to transfer the load from the weight of the stripline
sections (approximately 75 #/foot) to the

vertical sections. The stripline is mounted to the horizontal section
with a "swinging link" that has polyurethane isolation mounts so as to
affect the thermal expansion as well as the vibration chacteristic that
the stripline will exhibit while pulsing. (**[see example
4]{.underline}**).

## Penetration pipe stands

The penetration pipe stands are constructed of 3 bolt on bracket/wheel
combinations that are mounted on every stabilization clamp that is in
the penetration pipe. The wheels are polyurethane coated so as to absorb
some of the shock loading that is cause from the vibration due to
pulsing the stripline during operation. The two lower wheels are a fixed
mount and take all of the weight of the stripline that is in the pipe.
The remaining 3^rd^ wheel is mounted on top of the stripline with a
spring adjustable mount so as to allow the mount to compensate for
irregularities for the manufacturing of the pipe. This mounting system
can compensate for +- 3/4-inch differences in the inside diameter of the
pipe. Three-point contact (with the wheels) was chosen because 3 points
define a plane and if 2 points was chosen there would still be the
ability to move in the direction perpendicular to the mount positions of
the 2-wheel system. Four-point contact wasn't implemented due to the
fact that it would be very difficult to get the same pressure on all 4
wheels (sort of like a 3 legged table vs. a 4 legged table) (**[see
example 5]{.underline}**). This design could be redesigned pending
roundness specification of the steel pipe.

## Power supply room wall mount

The power supply room wall mount anchors the stripline to the power
supply room's wall and prevents any reactionary force due to vibration
or thermal expansion from entering the power supply itself. The mount is
constructed of double Unistrut on the top and bottom surfaces with
adjustable brackets mounted to the wall and to the stripline
stabilization clamps. (**[see example 6]{.underline}**)

## Chase support

The chase support is the I-beam section that supports the section of
stripline that goes from the main stripline over to the module itself.
This section of removable stripline (also called the Z-section) is
attached to a 6-inch W flange beam that is attached to the chase ledge
and the module. Engineering calculations need to be done to see if the
beam is sufficient for vibration. The chase support is also isolated by
the same polyurethane "swinging links" as the main stripline is, but the
links are inverted due to space constraints that are imposed by the
shielding blocks that surround it (it is not possible to attach to the
shielding block roof, because the block is removed to get access to the
"Z-section) (**[see example 7]{.underline}**).

## Wedge clamp

The wedge clamp is used in the stripline shielding block and provides
support to the stripline in the shielding block while allowing assembly
of the clamp from one side of the block. The wedge clamp 'pushes'
against the walls of the chase and generates a 1500 lb. force with only
16 ft. lbs. of bolt torque. The wedge clamp can do this because it is
coated with tungsten disulfide so as to allow the coefficient of
friction to be low, but still allow high radiation hardness (**[see
example 8]{.underline}**).

# Vibration

The vibration in this system should be damped in 2 separate manners,
which are:

Attachment points to ground

Isolation mounts

## 

## Attachment points to ground

Most of the vibration can be effectively damped by attaching the
stripline (via the support system) to ground. Using one set of support
stands on the main stripline in the target hall every six feet, which is
the same unsupported length as the original horn 1 joint that has been
rigorously tested with no apparent detrimental effects, does this. In
the power supply room, the wall mount should effectively damp harmful
vibration from entering the room, much less the power supply. (The
current wall mount should incorporate polyurethane isolator bushings so
as to further damp the amplitude of the vibration) (**[see example
4]{.underline}**).

## 

## Isolation mounts

The isolation mounts consist of a steel separator bushing that is
mounted on a suspension rod with polyurethane compression bushings that
isolate the vibration generated by the stripline from being transmitted
down the stripline and also to the floor. These isolation mounts are
also called "swinging links' and not to be confused with "smoky
links"(see example 8). The wheels on the penetration pipe stands are
coated (about ½ inch thick) with the same type of polyurethane as the
"swinging links" are, so vibrations in the penetration pipe section
should be minimized with the use of this material (**[see example 4 &
5]{.underline}**).

# Thermal expansion

The convoluted shapes that are present in the design take up most
thermal expansion; these areas are the stripline in the chase and the
"z-bar link" that connects the main stripline to the module. The
expansion can be taken up in the turns of these pieces.

In the straight areas, the isolation mounts can absorb thermal expansion
due to the fact that they are allowed to pivot due to the polyurethane
bushings that are at the ends. This method of "swinging links" works
well for the main stripline area, but is not necessary for the 28-foot
long penetration section of the stripline. The stripline that is in the
penetration is mounted on wheels with being firmly attached to the power
supply room wall at one end. This type of mounting allows the 28-foot
section to expand out into the target hall rather than expanding into
the power supply room and possibly damaging the power supply.

# Service considerations

All of the joints in the stripline design are adjustable to +- 1 1/2
inches so as to effect misalignments that can occur between as built
conditions and existing drawings. There

are, however 2 areas that don't have this amount of adjustment. These 2
areas are where the power supply attaches and where the top of the
module attaches. The reason for not making these areas adjustable was
due to space limitations (**see example 1**).

There are 2 removable links in the design; both are located at opposite
ends of the 28-foot long section that goes through the penetration.
These links are removable so as to allow removal of the 28 foot long
piece of stripline should there be a reason to service that section of
stripline (**[see examples 9,10,11]{.underline}**).

There are 2 removable "z-bar links" that allow the operators the ability
to remove the stripline before they remove the horn carriage assemblies
for servicing. These "z-bar links" are designed in such a manner as to
allow the operator to lift the 1 piece section while the link is
balanced about it's midpoint (under crane coverage) in both x and y
planes so as to make the piece easier to remove and then reinstall
without damaging the silver plated ends (**[see examples
12,13,14]{.underline}**).