1. Purpose

    1. Goal
      1. Successfully change the Be Lenses in XPP's lens chamber to the appropriate recipe.
    2. Capabilites Include list capabilities and/or skills that are being developed
      1. Attention to Detailed Instructions
      2. Familiarity with XPP's Vacuum Layout and Valve Configuration
      3. Epics Use through Lowering Lenses, Valve Opening and Closing, Turning ON/OFF gauges and pumps
      4. Familiarity with 2D and 1D Lenses
      5. UHV Cleanliness

  2. Subject Matter Experts - May help provide instruction and guidance for this Training Module

    1. SME : Adam White
      1. Email: adamwh@slac.stanford.edu
      2. SLAC extension :
    2. SME #1: Daniel Stefanescu
      1. Email: awhite@slac.stanford.edu
      2. SLAC extension : 3662
    3. SME : Cynthia Melendrez
      1. Email: cymel123@slac.stanford.edu
      2. SLAC extension 

XPP Lens Change Procedure

Step 1:  Materials Prep

  1. Print your lens change recipe and place the paper in a location where it can be easily read. A lens change recipe looks something similar to the image shown below.
  1. Start preparing your area with the materials needed to do the lens change. Lay down aluminum foil and put clean gloves on. Follow the list of materials below:

Materials

Description/purpose

Be lenses

Beryllium lenses stored in the setup lab near XPP

Be lens removal tools

Tools to remove cassette from XPP lens chamber (should be inside the same ziplock bag as BE lenses)

Aluminium Foil

Foil to keep area clean during lens change

Air Gun

Air to blow any dust particle from lenses before placing them into the lens cassette

Gloves

To keep lenses and tools clean during lens change

Alcohol & wipes

To keep tools and gloves clean during lens change

  1.  Prepare the XPP compressed air gun shown in the image below. Open the compressed air valve and place the air gun near your lens change set up.

Step 2: Venting preparation

  1. Open the flow meter shown in the picture below to start flowing dry air into the XPP vent line. XPP does not have to use nitrogen gas because our compressed air is filtered/dried and goes through a controller that checks the humidity of the gas going through. Check the controller to ensure the air is below the dew point before venting.



  1. Go to the XPP EPICS screen and open the vacuum tech screen. Click on the tech control tab shown in the image below.
  1. The vacuum tech screen should look like the image below. Close both gate valves on the XFLS( X-ray focusing Lens System) section by clicking CLS on the vacuum tech screen. Image (A) below shows what to click to close the two gate valves using epics and image (B) shows the beamline gate valves that are being closed.

Image A:

Image B:



          1. Turn off the cold cathode gauge on the XFLS section by clicking DIS on the vacuum tech screen. Image (C) below shows how to disable the CCG on epics. Image (D) shows where the CC gauge is located on the beamline. 

            Image C:



            Image D:


    1. Before venting we need to equalize the pressure from the turbo section to the XFLS section. The turbo section is between a gate valve and a right-angle valve. This section is usually left vented. Open the right-angle valve leading to the roughing line to equalize the pressure. 



    1. When the pressure is equalized you can open the gate valve to the XFLS section. (This gate valve is opened manual and is not on the tech screen)
    1. Close the right-angle valve that leads to the roughing pump. The RAV is shown below.
    1. Now we can begin venting by manually opening the valve to the dry compressed air line. Follow the red tubbing shown in the image above to locate the vent valve and PRV.

    Step 3: Be lens removal

    1. Once the XFLS section is vented remove the Be lens cassette using the tools provided. If the cassette is too high to be removed, go to the EPICs screen and click on the (-) sign one time, which lowers the cassette 50mm. Image (A) below shows how to lower the cassette on the tech screen.
    1. Make sure you are wearing gloves and you do not touch the side of the chamber when removing the cassette.

    Image (A):

  1. Image (B)


    Step 4: lens change

    1. The lens change may now begin. The order in which you begin removing and replacing lenses does not matter, but completing one row at a time is usually best. 
    1. keep checking that the lenses are sitting flush with each other and there is no misalignment. 
    1. Do not attach the copper clamps until you take a picture of all three completed rows, as shown in the image below. (** Keep the lenses organized and ensure the R= value is displayed before taking a picture). 

    1. After replacing the lenses, put the cassette back into the XFLS chamber and stop venting. Tighten the knobs on both windows of the XFLS section and open the right angle valve to the roughing pump. 
    1. When the pressure reaches mili torr range connect the power cable to the turbo and begin pumping with the turbo.



    1. Turn the cold cathode gauge back on by pressing ENA on the Vacuum tech screen for the XFLS section. (Next to the disable button also shown on step 2 image C). Close the flow meter to stop flowing air.
    1. Let the turbo and roughing line pump the XFLS section until the pressure reaches below x10-8  scale. 
    1. Put all the preparation tools/lenses away and clean your area.
      1. Update the Lense tracker !!! LCLS BE CRLS LENS TRACKER


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