7900 extinguishes plasma during Auto RF matching

Hello everyone,

7900 extinguishes plasma when trying to perform Auto RF matching in any mode. Error code: Plasma was shutoff during Analysis (Vacuum), Warning code 2150: Interface Vacuum is too low.
Plasma ignition is well. Orifices are in good condition. All gas connections are tight. Torch position as usual. IF/bk pressure - no issues. RF matching value = 2.0 (in range). Reflected power after ignition and transition to the Analysis mode is 50 - 110 W, Front power 1550 W

What could be the cause of the problem? What additional parameters should I check?

  • Hi Mag,

    I would check the geometry of the work coil. There is a small tool (white or orange) and a manual how to use it, within the tool set of the instrument.

    Then i would clean the bottom of the torch box with the blue sandpaper.



  • Hello Cschulz,

    Thank you for the answer!
    RF coil is OK

    According your advice, I had sand the torch box bottom with blue sandpaper and remove the stain with paper towel soaked in EtOH. Did you supposed some grounding problems?

    No effect. Plasma that looks stable immediately extinguishes after attempt to perform Auto RF matching. Reflected power ~ 100 W, which is no good.

    Last Performance Report shows that RF matching recently had changed from 2.0 to 1.2 V. Other parameters are as usual

    What can be the source of the problem?

  • Hi, 

    sounds like a Problem with the Matching Box.

    More precisely, with the zero position of shunt C.
    A sensor is responsible for this, and sometimes this is defective or dirty. To change or clean it, the entire matching box has to be removed, which is a job for an Agilent technician.

  • Hello, 

    Understood. Thank you for an answer! Unfortunately, a service engineer visit option will not be available for some time. Is there anything else that I can check or fix on my own?

  • Hi,

    You can manually change the RF matching in tune.  Be very careful when doing the change.  Do it with very small increment 0.1 and wait for the RF power meter to lower or increase.  You want the RF power meter to be lower than 25 W in analysis.  Also, save all your batch with the optimal found value.  So, it does not trigger.  You can also update the user tune and send value to icpms to be sure the value is change.  If nothing works.  Then no choice to change the Matching box or the sensor.   At last check all your contact with shield plate, torch box and torch box cover.  They need no ground spot.

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