Paul Redhead
Bayard-Alpert hot-cathode ionization gauges are widely used for pressure measurements in the 10-3 Torr to 10-10 Torr (≈1.33 × 10-7 kPa to ≈1.33 × 10-14 kPa) pressure range. The ion current I+ in a hot-cathode ionization gauge is given by I+ = KIeP. The gauge constant is K = (I+/Ie )(1/P), where Ie is the electron current, and P the pressure. The sensitivity is given by S = KIe = I+/P. The constant K is independent of pressure below about 10-3 Torr (≈1.33 × 10-7 kPa), but it depends on the gas that is present. This table gives the sensitivity relative to nitrogen for several different gases.
Relative sensitivities for different Bayard-Alpert ionization gauges may differ by as much as ±15% as a result of differences in applied voltages, electron current, and electrode structure. The table presents the average of the measurements of 12 experimenters on Bayard-Alpert ionization gauges in various gases.
The CRC Handbook of Chemistry and Physics (HBCP) contains over 700 tables in over 450 documents which may be divided into several pages, all categorised into 17 major subject areas. The search on this page works by searching the content of each page individually, much like any web search. This provides a challenge if you want to search for multiple terms and those terms exist on different pages, or if you use a synonym/abbreviation that does not exist in the document.
We use metadata to avoid some of these issues by including certain keywords invisibly behind each table. Whilst this approach works well in many situations, like any web search it relies in the terms you have entered existing in the document with the same spelling, abbreviation etc.
Since chemical compounds and their properties are immutable, a single centralised database has been created from all chemical compounds throughout HBCP. This database contains every chemical compound and over 20 of the most common physical properties collated from each of the >700 tables. What's more, the properties can be searched numerically, including range searching, and you can even search by drawing a chemical structure. A complete list of every document table in which the compound occurs is listed, and are hyperlinked to the relevant document table.
The 'Search Chemicals' page can be found by clicking the flask icon in the navigation bar at the top of this page. For more detailed information on how to use the chemical search, including adding properties, saving searches, exporting search results and more, click the help icon in to top right of this page, next to the welcome login message.
Below is an example of a chemical entry, showing its structure, physical properties and document tables in which it appears.
We have developed this cookie policy (the “Cookie Policy”) in order to explain how we use cookies and similar technologies (together, “Cookies”) on this website (the “Website”) and to demonstrate our firm commitment to the privacy of your personal information.
The first time that you visit our Website, we notify you about our use of Cookies through a notification banner. By continuing to use the Website, you consent to our use of Cookies as described in this Cookie Policy. However, you can choose whether or not to continue accepting Cookies at any later time. Information on how to manage Cookies is set out later in this Cookie Policy.
Please note that our use of any personal information we collect about you is subject to our Privacy Policy.
Cookies are small text files containing user IDs that are automatically placed on your computer or other device by when you visit a website. The Cookies are stored by the internet browser. The browser sends the Cookies back to the website on each subsequent visit, allowing the website to recognise your computer or device. This recognition enables the website provider to observe your activity on the website, deliver a personalised, responsive service and improve the website.
Cookies can be ‘Session Cookies’ or ‘Persistent Cookies’. Session Cookies allow a website to link a series of your actions during one browser session, for example to remember the items you have added to a shopping basket. Session Cookies expire after a browser session and are therefore not stored on your computer or device afterwards. Persistent Cookies are stored on your computer or device between browser sessions and can be used when you make subsequent visits to the website, for example to remember your website preferences, such as language or font size.
We use three types of Cookies - ‘Strictly Necessary’ Cookies, ‘Performance’ Cookies and ‘Functionality’ Cookies. Each type of Cookie and the purposes for which we use them are described in this section. To learn about the specific Cookies we use, please see our List of Cookies.
‘Strictly Necessary’ Cookies enable you to move around the Website and use essential features. For example, if you log into the Website, we use a Cookie to keep you logged in and allow you to access restricted areas, without you having to repeatedly enter your login details. If you are registering for or purchasing a product or service, we will use Cookies to remember your information and selections, as you move through the registration or purchase process.
Strictly Necessary Cookies are necessary for our Website to provide you with a full service. If you disable them, certain essential features of the Website will not be available to you and the performance of the Website will be impeded.
‘Performance’ Cookies collect information about how you use our Website, for example which pages you visit and if you experience any errors. These Cookies don’t collect any information that could identify you – all the information collected is anonymous. We may use these Cookies to help us understand how you use the Website and assess how well the Website performs and how it could be improved.
‘Functionality’ Cookies enable a website to provide you with specific services or a customised experience. We may use these Cookies to provide you with services such as watching a video or adding user comments. We may also use such Cookies to remember changes you make to your settings or preferences (for example, changes to text size or your choice of language or region) or offer you time-saving or personalised features.
You can control whether or not Functionality Cookies are used, but disabling them may mean we are unable to provide you with some services or features of the Website.
The Cookies placed on your computer or device include ‘First Party’ Cookies, meaning Cookies that are placed there by us, or by third party service providers acting on our behalf. Where such Cookies are being managed by third parties, we only allow the third parties to use the Cookies for our purposes, as described in this Cookie Policy, and not for their own purposes.
The Cookies placed on your computer or device may also include ‘Third Party’ Cookies, meaning Cookies that are placed there by third parties. These Cookies may include third party advertisers who display adverts on our Website and/or social network providers who provide ‘like’ or ‘share’ capabilities (see the above section on Targeting or Advertising Cookies). They may also include third parties who provide video content which is embedded on our Website (such as YouTube). Please see the website terms and policies of these third parties for further information on their use of Cookies.
To learn about the specific First Party and Third Party Cookies used by our, please see our List of Cookies.
You always have a choice over whether or not to accept Cookies. When you first visit the Website and we notify you about our use of Cookies, you can choose not to consent to such use. If you continue to use the Website, you are consenting to our use of Cookies for the time being. However, you can choose not to continue accepting Cookies at any later time. In this section, we describe ways to manage Cookies, including how to disable them.
You can manage Cookies through the settings of your internet browser. You can choose to block or restrict Cookies from being placed on your computer or device. You can also review periodically review the Cookies that have been placed there and disable some or all of them.
You can learn more about how to manage Cookies on the following websites: www.allaboutcookies.org and www.youronlinechoices.com.
Please be aware that if you choose not to accept certain Cookies, it may mean we are unable to provide you with some services or features of the Website.
In order to keep up with changing legislation and best practice, we may revise this Cookie Policy at any time without notice by posting a revised version on this Website. Please check back periodically so that you are aware of any changes.
If you have any questions or concerns about this Cookie Policy or our use of Cookies on the Website, please contact us by email to [email protected]
You can also contact the Privacy Officer for the Informa PLC group at [email protected].
Here is a list of cookies we have defined as 'Strictly Necessary':
JSESSIONID
TandF.ACCT.CNB.cookieId
TandF.WS.CNB.cookieId
TandF.SU.CNB.cookieId
TandF.PORTAL.cookiesAgreed
TandF.LOGIN.cookiesAgreed
TandF.HBCP.cookiesAgreed
TandF.CCD.cookiesAgreed
TandF.DNP.cookiesAgreed
TandF.DOC.cookiesAgreed
TandF.DOD.cookiesAgreed
TandF.DIOC.cookiesAgreed
TandF.POLY.cookiesAgreed
TandF.DFC.cookiesAgreed
TandF.DMNP.cookiesAgreed
TandF.DCCC.cookiesAgreed
TandF.POC.cookiesAgreed
Here is a list of the cookies we have defined as 'Performance'.
Google Analytics:
_ga
_gid
_gat
The Voluntary Product Accessibility Template (VPAT) is a self-assessment document which discloses how accessible Information and Communication Technology products are in accordance with global standards.
The VPAT disclosure templates do not guarantee product accessibility but provide transparency around the product(s) and enables direction when accessing accessibility requirements.
Taylor & Francis has chosen to complete the International version of VPAT which encompasses Section 508 (US), EN 301 549 (EU) and WCAG2.1 (Web Content Accessibility Guidelines) for its products.
Click here for more information about how to use this web application using the keyboard.
Please move your cursor to continue.
