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In this issue:
Reminder: Emergency Response System Test Today
Keeping Power Levels Smooth and Steady
Recycling Tip of the Week: What Does the Recycling Symbol on Plastic Mean?

SLAC Today

Thursday - August 27, 2009

Reminder:
Emergency Response System Test Today

Emergency vehicles began entering the SLAC campus at 7:30 a.m. this morning and will be on campus until noon as part of "Dark Matter," the first full-scale test of SLAC's new Emergency Response Organization. The drill will take place in the Research Yard area and will include both internal and external emergency response agencies.

Please keep an eye out and make way for emergency response vehicles and personnel participating in the drill. Your patience and cooperation will help us to run a smooth and successful exercise

Keeping Power Levels Smooth and Steady

(Photo)
Power Conversion Engineering technician Tao Tang with the Marx Modulator's vernier regulator. (Photo by Nicholas Bock.)

Two months into what will be a year of intensive testing, researchers and engineers with SLAC's Power Conversion Engineering group are making strides in improving the stability of the Marx modulator. The modulator, which is designed to provide power for the proposed International Linear Collider, converts out-of-the-wall AC power into the 120,000-volt pulses of energy that would be needed to drive the ILC klystrons.

The goals is to demonstrate that the modulator is capable of providing reliable power over long-term use. The work comes as a follow up to initial testing conducted earlier this year.

The Marx modulator consists of 16 identical cells, each capable of delivering up to 11,000 volts. The cells store energy serially, one at a time, but discharge all at once, producing enormous pulses of energy. The cells recharge after each pulse and within a fraction of a second are ready to go again. Because the cells recharge only after the end of the pulse, the energy output decreases across the length of each pulse, with the voltage falling by as much as 40 percent from beginning to end. According to Power Conversion Engineering head Craig Burkhart, in order for the modulators to provide reliable energy for the ILC klystrons, that number has to come down dramatically.

"The output voltage of [the Marx modulator] has to be carefully controlled within plus or minus half a percent," Burkhart said. "That's important for the stability of the microwave source that it powers."  Read more...

(Image - ISEMS leaves)

Recycling Tip of the Week:
What Does the Recycling Symbol on Plastic Mean?

The "chasing arrow" representing the universal recycling symbol, followed by a number and letter acronym, represent a plastic's resin identification code. This code was introduced in 1988 to assist recyclers in sorting through similar looking plastics. It indicates the type of plastic that an item is made of. In the example to the right, #1 PETE stands for polyethylene terephthalate, a plastic commonly used for single-use water and soda bottles.

(Image - chasing arrow logo)

The presence of a recycling symbol and resin code does not always mean an item can be recycled. The recyclability of the plastic is dependent on technology and the recycling market.

Currently at SLAC, plastics labeled as #1 and #2 may be recycled in SLAC's green, bottles & cans recycling bins. Plastics #3–7 may also be recycled in the bins if the plastic is in a bottle form (narrow neck).

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