Limiting Primary Beam Power

Please see the background page for more information about these specific devices. This page will lead you through how to limit primary beam power using the following devices.

Chopper

Determine needed beam power by consulting AP and/or relevant destination power limits

Note beam current on faraday cup D1102

Using current on faraday cup D1102 calculate current beam power

Use this formula to determine your duty factor: (Needed power)/(Current power)

Adjust repetition rate and pulse width to achieve needed duty factor

Consult with AP, sometimes they will request you use a certain rep. rate or pulse width in your calculations

Double check beam power with beam on D1102

Send!

Attenuators

Determine needed beam power by consulting AP and/or relevant destination power limits

Note beam current on faraday cup D1102

Using current on faraday cup D1102 calculate current beam power

Use this formula to determine your attenuation factor: (Current power)/(Needed power)

Insert attenuator(s) whose product equals your attenuation factor

Put beam back on D1102 and double check beam power, restart at step 5 if needed

Send!

Source Slits

Determine which source is providing primary beam

Determine needed beam power by consulting AP, relevant destination power limits, or users.

These next steps should be done simultaneously and are listed below

Open or close vertical top and bottom source slits in 0.1mm steps

Wait 5 sec. between adjustments and watch beam power like a hawk

Adjust slits in this manner until desired beam power is reached

Some notes that may help you during tuning

It is important you ONLY touch the vertical slits

HPECR source has slit gap control, use this tool unless instructed otherwise

Shane Notes

* Primer on CW Beam might be good to start off the chopper section * It'd be neat to include the “why” of peak power not being affected by the chopper, but probably not necessary here * We can change attenuators with beam on D1102, due to how unreliable attenuators are I would prefer a new operator to keep beam on the cup and see the changes more or less in real time, helps build intuition * All of these should reference the location of the pages, even if it changes in the future attenuators and slits can be hard to find for new guys * Slits should keep the same center, this isn't clearly relayed for ARTEMIS slits * Slits are used for smaller adjustments, this should be laid out more clearly