{"id":3221,"date":"2021-04-13T08:00:40","date_gmt":"2021-04-13T15:00:40","guid":{"rendered":"https:\/\/www.rbdinstruments.com\/blog\/?p=3221"},"modified":"2021-04-12T20:02:49","modified_gmt":"2021-04-13T03:02:49","slug":"72-030-neutralizer-current-limit-procedure","status":"publish","type":"post","link":"https:\/\/www.rbdinstruments.com\/blog\/72-030-neutralizer-current-limit-procedure\/","title":{"rendered":"72-030 Neutralizer Current limit procedure"},"content":{"rendered":"\n

After you replace the filament<\/a> in the 04-085 or 04-090 neutralizer you may need to readjust the current limit on the 72-030 neutralizer board. The 72-030 provides the filament current and bias voltage to the neutralizer. This procedure shows you how to set the current limit on the 72-030 so that you generate enough electrons to neutralize the sample and also maximize the filament lifetime.<\/p>\n\n\n\n

Tools Needed:<\/strong><\/p>\n\n\n\n

HV card rack extender board<\/p>\n\n\n\n

Voltmeter with 2 clip leads<\/p>\n\n\n\n

Potentiometer adjustment tool<\/p>\n\n\n\n

72-030 Calibration procedure<\/strong><\/p>\n\n\n\n

  1. Turn off the card rack power<\/li>
  2. Extend the 72-030 neutralizer card (located in the card rack)<\/li>
  3. Connect the DVM across R59 \/ E6<\/li>
  4. Make sure that the filament cable is connected to the neutralizer on the system<\/li>
  5. Turn on the card rack power<\/li>
  6. Turn on the 147 PC Interface unit<\/li>
  7. Open AugerScan software<\/li>
  8. Turn on the neutralizer in AugerScan <\/li>
  9. Monitor the target current with a picoammeter and a +90V bias<\/li>
  10. Turn up the Emission in the Augerscan Neutralizer dialog box to 20 to 23 mA while monitoring the DC voltage in millivolts across R59 \/ E6.<\/li>
  11. There should be approximately 34 mV across R59 \/ E6 and you should also be able to see the end of the neutralizer glowing orange to white in the vacuum chamber.<\/li>
  12. Set the Emission to 25 mA and if necessary adjust R48 \/ B6 so that you have 2 to 3 uA of target current.\u00a0\u00a0 Do not adjust R48 \/ B6 to exceed 36mV across R59 \/ E6. 36mV corresponds to 3.6 amps of filament current. The lower the filament current, the longer the filament lifetime. <\/li>
  13. Turn off the card rack power and reinstall the 72-030 neutralizer card in the card rack. <\/li><\/ol>\n\n\n\n

    Ideally, adjusting R48 for a value that provides a few uA of target current and with less than 36mV across R59 \/ E6 will result in the longest filament lifetime.<\/p>\n\n\n\n

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