{"id":359,"date":"2013-02-17T10:07:24","date_gmt":"2013-02-17T18:07:24","guid":{"rendered":"http:\/\/www.rbdinstruments.com\/blog\/?p=359"},"modified":"2014-11-06T09:02:19","modified_gmt":"2014-11-06T17:02:19","slug":"lab6-filament-rejuvenation","status":"publish","type":"post","link":"https:\/\/www.rbdinstruments.com\/blog\/lab6-filament-rejuvenation\/","title":{"rendered":"LaB6 filament Rejuvenation"},"content":{"rendered":"

Lanthanum hexaboride (LaB6 <\/sub>) filaments provide a very stable emission of electron current in the hot cathode electron sources used in many scanning Auger electron spectrometers. However, this type of filament is susceptible to deactivation from vacuum contaminants such as fluorine.<\/p>\n

If your LaB6 <\/sub>filament becomes contaminated it may exhibit symptoms such as unstable emission current or no emission current at all.\u00a0 The Auger data below shows instability in the background that was caused by unstable emission current from the cathode.<\/p>\n

\"Unstable

Usually it is possible to rejuvenate a LaB6<\/sub> filament by backfilling the chamber with Oxygen while monitoring the emission current as outlined in the procedure below.<\/p>\n

LaB6<\/sub> filament: rejuvenation procedure:<\/p>\n

    \n
  1. Set the beam voltage to 1kV and the emission voltage to 100% (or the maximum for that beam voltage).<\/li>\n
  2. Increase the filament current up to the normal operating value. 1.3 to 1.5 amps is typical for a PHI 600 or 660 scanning auger spectrometer.<\/li>\n
  3. Bleed O2<\/sub> into the system to about 5 X 10 -7<\/sup> Torr.<\/li>\n
  4. Slowly reduce the emission voltage until you get about 50uA of emission current.\u00a0 Keep an eye on it, as the O2<\/sub> cleans the filament the emission will rise and you will need to increase the emission voltage in order to keep the emission current from going up too much. The maximum recommended emission current is 100uA.<\/li>\n<\/ol>\n

    Once the emission current is stable then you can turn off the O2<\/sub>. This process typically takes 5 to 20 minutes. In some cases the vacuum chamber may have some low level contamination where the emission current of the filament will drop once the O2<\/sub> is turned off. In those cases, you may want to leave the O2 on for an extended period of time at a higher vacuum such as 2 X10-8<\/sup> Torr.<\/p>\n

    If rejuvenating the filament does not work then the filament may need to be replaced. RBD Instruments Inc. provides LaB6<\/sub> filaments for the Physical Electronics PHI 590 through 660 series scanning auger spectrometers. \u00a0Visit\u00a0 us at rbdinstruments dot com<\/p>\n","protected":false},"excerpt":{"rendered":"

    Lanthanum hexaboride (LaB6 ) filaments provide a very stable emission of electron current in the hot cathode electron sources used in many scanning Auger electron spectrometers. However, this type of filament is susceptible to deactivation from vacuum contaminants such as … Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":361,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[162],"tags":[53,54],"class_list":["post-359","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-operation-and-calibration-procedures","tag-lab6","tag-lab6-filament"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"https:\/\/i0.wp.com\/www.rbdinstruments.com\/blog\/wp-content\/uploads\/2013\/02\/bad-590-lab6-no-emmsion.jpg?fit=320%2C240&ssl=1","jetpack_shortlink":"https:\/\/wp.me\/p2DEXo-5N","jetpack_sharing_enabled":true,"jetpack_likes_enabled":true,"jetpack-related-posts":[],"_links":{"self":[{"href":"https:\/\/www.rbdinstruments.com\/blog\/wp-json\/wp\/v2\/posts\/359","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.rbdinstruments.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.rbdinstruments.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.rbdinstruments.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.rbdinstruments.com\/blog\/wp-json\/wp\/v2\/comments?post=359"}],"version-history":[{"count":1,"href":"https:\/\/www.rbdinstruments.com\/blog\/wp-json\/wp\/v2\/posts\/359\/revisions"}],"predecessor-version":[{"id":362,"href":"https:\/\/www.rbdinstruments.com\/blog\/wp-json\/wp\/v2\/posts\/359\/revisions\/362"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.rbdinstruments.com\/blog\/wp-json\/wp\/v2\/media\/361"}],"wp:attachment":[{"href":"https:\/\/www.rbdinstruments.com\/blog\/wp-json\/wp\/v2\/media?parent=359"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.rbdinstruments.com\/blog\/wp-json\/wp\/v2\/categories?post=359"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.rbdinstruments.com\/blog\/wp-json\/wp\/v2\/tags?post=359"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}