Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

RF heating in Paul trap

  1. Sep 25, 2008 #1
    Hello,

    I have a question on rf heating in Paul trap.

    There are papers which say that in a Paul trap, the ion cloud
    eventually comes to a state of thermal equilibrium with the background
    gas. And at the same time there is a concept of "rf heating" in these
    traps. I am slightly confused about it. If the ion cloud is coming to
    an equilibrium, then in what context do we talk of "rf heating"? I
    have read some papers on this issue but all seem to be too obscure on
    this particular issue.

    I would be glad if someone can please reply to this question.

    Thanks,
    Kushal.
     
  2. jcsd
  3. Oct 8, 2008 #2
    On 24 Sep, 16:22, kushal <atmabo...@gmail.com> wrote:
    > Hello,
    >
    > I have a question on rf heating in Paul trap.
    >
    > There are papers which say that in a Paul trap, the ion cloud
    > eventually comes to a state of thermal equilibrium with the background
    > gas. And at the same time there is a concept of "rf heating" in these
    > traps. I am slightly confused about it. If the ion cloud is coming to
    > an equilibrium, then in what context do we talk of "rf heating"? I
    > have read some papers on this issue but all seem to be too obscure on
    > this particular issue.
    >
    > I would be glad if someone can please reply to this question.
    >
    > Thanks,
    > Kushal.


    The rf-heating in a Paul trap would raise the equlibrium temperature
    in a similar sense as a heater raises the equilibrium temperature in a
    room.

    Thomas
     
  4. Oct 8, 2008 #3
    On Oct 7, 8:14 pm, Thomas Smid <thomas.s...@gmail.com> wrote:
    > On 24 Sep, 16:22, kushal <atmabo...@gmail.com> wrote:
    >
    >
    >
    > > Hello,

    >
    > > I have a question on rf heating in Paul trap.

    >
    > > There are papers which say that in a Paul trap, the ion cloud
    > > eventually comes to a state of thermal equilibrium with the background
    > > gas. And at the same time there is a concept of "rf heating" in these
    > > traps. I am slightly confused about it. If the ion cloud is coming to
    > > an equilibrium, then in what context do we talk of "rf heating"? I
    > > have read some papers on this issue but all seem to be too obscure on
    > > this particular issue.

    >
    > > I would be glad if someone can please reply to this question.

    >
    > > Thanks,
    > > Kushal.

    >
    > The rf-heating in a Paul trap would raise the equlibrium temperature
    > in a similar sense as a heater raises the equilibrium temperature in a
    > room.
    >
    > Thomas


    So, do you mean to say that if the background gas temperature was T,
    then after a long time, the plasma will also come to an equilibrium at
    temperature T? Will happen even if the background temperature was lower
    than the plasma temperature? So, its more like a relaxation process that
    takes the plasma to equilibrium and not continuous heating. If that is
    the case, then why is it called rf-heating? Even in the absence of the
    rf field, the equilibration will, anyways, happen. What is the role of
    the rf field in the relaxation process?

    Thanks,
    Kushal.
     
  5. Oct 10, 2008 #4
    kushal wrote:
    > On Oct 7, 8:14 pm, Thomas Smid <thomas.s...@gmail.com> wrote:
    >> On 24 Sep, 16:22, kushal <atmabo...@gmail.com> wrote:
    >>
    >>
    >>
    >>> Hello,
    >>> I have a question on rf heating in Paul trap.
    >>> There are papers which say that in a Paul trap, the ion cloud
    >>> eventually comes to a state of thermal equilibrium with the background
    >>> gas. And at the same time there is a concept of "rf heating" in these
    >>> traps. I am slightly confused about it. If the ion cloud is coming to
    >>> an equilibrium, then in what context do we talk of "rf heating"? I
    >>> have read some papers on this issue but all seem to be too obscure on
    >>> this particular issue.
    >>> I would be glad if someone can please reply to this question.
    >>> Thanks,
    >>> Kushal.

    >> The rf-heating in a Paul trap would raise the equlibrium temperature
    >> in a similar sense as a heater raises the equilibrium temperature in a
    >> room.
    >>
    >> Thomas

    >
    > So, do you mean to say that if the background gas temperature was T,
    > then after a long time, the plasma will also come to an equilibrium at
    > temperature T? Will happen even if the background temperature was lower
    > than the plasma temperature? So, its more like a relaxation process that
    > takes the plasma to equilibrium and not continuous heating. If that is
    > the case, then why is it called rf-heating? Even in the absence of the
    > rf field, the equilibration will, anyways, happen. What is the role of
    > the rf field in the relaxation process?
    >
    > Thanks,
    > Kushal.
    >

    Each atomic, molecular, ionic, nonionic entity absorbs RF (or EM in
    general) at characteristic frequencies related to its vibrational,
    rotational, translational modes. At a particular RF spectrum, one
    entity may be 'hotter' than another but with time and constant RF input,
    all entities should come to thermal equilibrium.

    Consider a frozen dinner in a microwave oven. The meat, vegetables and
    dessert each heat a different rates (cover some and not others) such
    that after the instructed cook time, all are at a different but
    acceptable temperatures.

    Now for arguments sake, keep the dinner in the microwave oven for an
    extended period of time (hours?) and the whole thing would be at some
    type of unpalatable thermal equilibrium.

    Richard D. Saam
     
  6. Oct 15, 2008 #5
    On Oct 9, 9:58 pm, Richard Saam <rds...@att.net> wrote:
    > kushal wrote:
    > > On Oct 7, 8:14 pm, Thomas Smid <thomas.s...@gmail.com> wrote:
    > >> On 24 Sep, 16:22, kushal <atmabo...@gmail.com> wrote:

    >
    > Each atomic, molecular, ionic, nonionic entity absorbs RF (or EM in
    > general) at characteristic frequencies related to its vibrational,
    > rotational, translational modes. At a particular RF spectrum, one
    > entity may be 'hotter' than another but with time and constant RF input,
    > all entities should come to thermal equilibrium.
    >
    > Consider a frozen dinner in a microwave oven. The meat, vegetables and
    > dessert each heat a different rates (cover some and not others) such
    > that after the instructed cook time, all are at a different but
    > acceptable temperatures.
    >
    > Now for arguments sake, keep the dinner in the microwave oven for an
    > extended period of time (hours?) and the whole thing would be at some
    > type of unpalatable thermal equilibrium.
    >
    > Richard D. Saam


    Yeah, that makes sense if one accepts that the plasma comes to some
    kind of thermal equilibrium.

    However, I was going through the literature on rf traps and came
    across two statements that seem to say different things:

    1) I. Siemers, R. Blatt, Th. Sauter and W. Neuhauser, Phys. Rev. A 38,
    5121 (1988)
    "On the other hand, in experiments on ion clouds in rf traps,
    efficient cooling is impossible, since collisions between the ions and
    with the surrounding background gas in the presence of the time-
    dependent trap potential leads to heating."

    2) F. Vedel, International Journal of Mass Spectroscopy and Ion
    Processes 106, 33 (1991)
    "Since the earliest experiments with Paul traps, it has been
    recognized that collisions with a light buffer gas enhance the
    lifetime by reducing ion kinetic energy"

    How does one reconcile these two statements?

    Thanks,
    Kushal.
     
  7. Nov 18, 2011 #6
    These two statements have different criterion of what is efficient cooling.
    In the first case, it means the ions can not be cooled at efficient as MOT trap, which could achieve 10^-12 K on atoms.

    In the second case, it means buffer gas reducing ion kinetic energy compared with NO buffer gas.

    It's like to say, A human is "bigger" than an ant, but "smaller" than an elephant.


    ---------------------------Quoted--------------------------------

    However, I was going through the literature on rf traps and came
    across two statements that seem to say different things:

    1) I. Siemers, R. Blatt, Th. Sauter and W. Neuhauser, Phys. Rev. A 38,
    5121 (1988)
    "On the other hand, in experiments on ion clouds in rf traps,
    efficient cooling is impossible, since collisions between the ions and
    with the surrounding background gas in the presence of the time-
    dependent trap potential leads to heating."

    2) F. Vedel, International Journal of Mass Spectroscopy and Ion
    Processes 106, 33 (1991)
    "Since the earliest experiments with Paul traps, it has been
    recognized that collisions with a light buffer gas enhance the
    lifetime by reducing ion kinetic energy"

    How does one reconcile these two statements?

    Thanks,
    Kushal.[/QUOTE]
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: RF heating in Paul trap
  1. Magnetic Traps (Replies: 5)

  2. Trapped Light (Replies: 13)

  3. Trap light (Replies: 18)

Loading...