Docstoc

Low-Energy Linac Upgrade Scenario_s_

Document Sample
Low-Energy Linac Upgrade Scenario_s_ Powered By Docstoc
					Low-Energy Linac
Upgrade Scenarios

     Elliott McCrory
     BD/Proton/Linac
     21 November 2003
Why Another Linac Upgrade?
     The supply of 7835 power amplifiers
      may end soon
           Ingrid Bergman as Mike Witherell: "You're saying this only to make me
            [spend money]."
           Humphrey Bogart as Elliott: "I'm saying it because it's true. Inside of us,
            we both know [Burle will go out of business someday]. If that [happens]
            and you're not [prepared], you'll regret it - maybe not today, maybe not
            tomorrow, but soon, and for the rest of your life."
     Modulator “switch tubes” are no longer available
           We have a 5-10 year supply of these tube
     Activation in the Linac may become a problem
           Matching between 201 MHz and 805 MHz portions is not ideal
           #particles/day is 6X higher in FY03 than FY00
                  And MiniBooNE and NUMI want ~4X more than this
     Many 33-year-old components are difficult & expensive to maintain
         LEL Quad Power supplies ($1M to replace, ASAP)
         LEL LLRF, driver amplifiers, etc., etc.
     Technical staff that built LEL are nearing retirement

21 November 2003                                Elliott McCrory                           2
    Linac Upgrade Possibilities
   Replace the Cockcroft-Walton & prototype tank 1 with a 201 MHz
    RFQ to 10 MeV
        But only solves the activation issue

   Replace the 201 MHz portion of the Linac
    with a 402 MHz Linac
        Solves all issues
        Similar to SNS
        Several possible scenarios
   Add more accelerating modules at the end
        Solves no issues, but would help Booster
        Conventional SCC modules, like existing Module 7, or …
        Superconducting modules, similar (identical?) to 8 GeV Linac injector
    21 November 2003                   Elliott McCrory                           3
New 402 MHz Low-Energy Linac
     Original: Don Young, “PD Study 1” (2002)
     Commercial partner
           AccSys Technologies, Pleasanton, CA
                  80% owned by Hitachi
     Potential collaborations with:
           New Proton Driver efforts
                  Foster and/or Chou
           Fermilab’s NTF (Arlene Lennox)
                  “Fermi Institute of Hadron Therapy”
                  $50M from Hastert?!
           National Taiwan University Hospital, Hsinchu Biomedical
            Science Park
                  Taipei, Taiwan
                  Has ~$100M ready to spend NOW


21 November 2003                        Elliott McCrory               4
       From AccSys Web page

                                  Synchrotron Injector Linac Systems

       The LINSTAR™ series of proton linac systems are designed to provide moderate-energy proton
beams (typically from 2 to 7 MeV) for injection into high energy proton synchrotrons that are used for
proton beam cancer therapy or physics research. These fully integrated systems typically consist of a
carefully designed and selected combination of a radiofrequency quadrupole (RFQ) linac, a drift tube linac
(DTL) for injection energies of >3 MeV, AccSys' standard rf power system, a high energy beam transport
system tailored to the specific requirements of the facility and an optional debuncher cavity. They can
accelerate either H+ or H- ion beams and are also available for polarized H+ or H- beams. Standard
LINSTAR™ units can provide pulsed beam currents up to 25 mA at pulse widths from 3 to 300 µsec.
Operation at pulse repetition rates from 0.1 to 30 pulses per second have been demonstrated, including on-
demand pulsing for breath-mode synchronization in proton cancer therapy.
       LINSTAR™ systems are currently in use at several facilities around the world:
       A Model PL-2i has been operating at Loma Linda University Medical Center since 1990 as the
injector to the high energy proton synchrotron cancer treatment facility. The synchrotron system operates
24 hours a day, 6 days a week and has been described in a number of technical publications. Complete
proton therapy systems based on the Loma Linda installation are commercially available from Optivus
Technology, Inc.
       Two systems are being commissioned in Japan: a Model PL-3i is the injector to the proton
synchrotron cancer treatment facility at the Shizouka Cancer Center, being built by Mitsubishi Electric
Company, and a Model PL-7i is the injector for the proton synchrotron cancer treatment facility being
installed at the Tsukuba Medical Center by Hitachi, Ltd.
       A Model PL-7i has been operating at the Indiana University Cyclotron Facility since 1997 as the
injector for the CIS compact synchrotron which is in turn the injector for the high energy physics cooler
ring.    21 November 2003                            Elliott McCrory                                      5
Two Scenarios: Commonalities
     Replace Cockroft-Walton with two redundant RFQs
           Available from AccSys technologies
           3 MeV
           New LEBT
                  including the “Double Alpha” idea invented by Del Larson
                      No need for a buncher cavity.
     New DTL from 3 to 70 or 89 MeV
           Tank 1: Ramped Gradient Drift Tube Linac
                  RGDTL available from AccSys technologies
           Three or four new 402 MHz DTLs
     New Transition section
           We can “do it right” this time
     One or two new SCC modules to 116 MeV
     Extra room at 400 MeV to add more acceleration
21 November 2003                           Elliott McCrory                    6
Basic Parameters of Today

Length of existing LEL                             78.8    m
Length, SCC Module 1                                6.7    m
Length, SCC Module 7                                9      m
Length of HEL                                       55     m
Input Energy to existing HEL                       116     MeV
Linac Output Energy                                401.5   MeV
Energy gain in Module 7                             40     MeV
“SCC” == “Side Coupled Cavity”
“LEL” == “Low Energy Linac”
21 November 2003                 Elliott McCrory                 7
     Three Scenarios

1.    Modest
           2 RFQ, RGDTL, 4 DTL, 2 LE SCC
2.    Luxury
           2 RFQ, RGDTL, 5 DTL, 1 LE SCC, 2 new modules at
            400 MeV
           Shift existing SCC modules upstream by ~18 m
3.    More aggressive ideas (not explored here)
           800 MeV??
                Move everything upstream into C-W pit (+ ~ 100m?)
                Add Superconducting accelerating cavities at end
     21 November 2003                  Elliott McCrory               8
   Schematic Layout of #2
                                                                   Solid: NEW

                                                                 Hatched: Existing




     RGDTL          DTL Tank 2   DTL Tank 3   DTL Tank 4   DTL Tank 5



      RFQ 2


      RFQ 1
                                                                  ~89 MeV



Trans0    TransV        New Module 1     Existing Module 1 […]



                                                              To Booster
Existing Module 7     New Module 8      New Module 9          at ~480 MeV
Benefits of a new LE Linac
    Replaces all 33-year-old Linac equipment
          SOA technology
          NO MORE 7835’s!
    Increase beam brightness
          Probably: 2 to 4 X smaller transverse emittance
    Existing technical staff: Days are numbered
          New technical staff can “own” this new machine
                  New machinery and new people might last another 30+ years
    402 MHz Klystrons exist
          And our 805 MHz klystrons last “forever”
    Significantly shorter than existing LEL
          Could add more modules at the end to give an energy boost
          Higher injection energy into Booster is better
    Reduced losses/activation throughout the Linac
          Transition section is our predominant loss now
          Lower emittance would mean lower 400 MeV-line losses
21 November 2003                           Elliott McCrory                     10
Higher Energy Linac Benefits

     The space charge limit for constant
      aperture at Booster injection scales
      like β2γ3
    Energy          beta gamma b^2g^3 S-C Limit
     401.5         0.714   1.427 1.481   100%
     441.5         0.733   1.470 1.706   115%
     481.5         0.750   1.513 1.948   132%
     521.5         0.766   1.555 2.206   149%
     561.5         0.780   1.598 2.480   168%
     601.5         0.793   1.640 2.773   187%
21 November 2003            Elliott McCrory       11
Pet Project (1996)




                   RFQs
21 November 2003     Elliott McCrory   12
Double α Magnet: Del Larson




21 November 2003   Elliott McCrory   13
MEBT Parameters
        Trace-3D Run of PET MEBT




                                             Longitudinal

RFQ 1                                        RFQ 2


        21 November 2003   Elliott McCrory            15
From Larson‟s „96 MEBT paper
      6.1. Longitudinal Control.
      […] some control over the longitudinal phase space can be exercised by
using the trim quads located in the cross over arm. The MEBT has been designed
to have a high dispersion in this region, and quadrupole variations in this region
therefore have a large effect on the dispersion function. The dispersion is
introduced in the first alpha magnet, and the magnet and optics have been
nominally designed so that the dispersion function has zero gradient in the middle
of the cross over arm. With zero dispersion gradient and transverse waists in the
center of the cross over arm, the beam will have symmetric optics about this point,
leading to zero dispersion and zero dispersion gradient at the end of the second
alpha magnet. While the first goal of the trim quads is to ensure a symmetric
dispersion function, so as to eliminate dispersion at the end of the MEBT, a second
function can be to control the position of the longitudinal waist. Since small trim
quad variations have a large effect on the dispersion and a small effect on the
transverse beam optics, the longitudinal control exercised by the trim quads is
largely independent of the transverse optics.

       6.2. Transverse Control.
       Once dispersion has been minimized (by arranging for symmetric optics
within and between the dipoles) the quadrupoles placed downstream of the dipoles
will have no effect on the longitudinal optics and can therefore be used solely for
transverse optics matching. Since there are three such quads, one can in principle
exercise control over three linear combinations of the four independent transverse
phase space variables. […]
 21 November 2003                       Elliott McCrory                             16
 Linac Upgrade Params (#1)
                                                   DTL                                       SCC
                              RFQ     Tank 1   Tank 2 Tank 3            Tank 4    Match      Mod 1   Mod 2
                                                                                 Section
Input Energy           MeV    0.035        3      13.4       32.9         51.6      70.3      70.3    93.3
Output Energy          MeV        3     13.4      32.9       51.6         70.3      70.3      93.3   116.5
Delta E                MeV    2.965     10.4      19.5       18.7         18.7          0       23    23.2
Beam Current            mA       70       60        60         60           60         60       60      60
Frequency              MHz    402.5    402.5     402.5      402.5        402.5       805       805     805
Beam Pulse Length      usec      90       90        90         90           90         90       90      90
RF Pulse Length        usec     130      130       130        130          130       125       125     125
Rep Rate                Hz       15       15        15         15           15         15       15      15
RF Duty Factor                 0.2%     0.2%      0.2%       0.2%         0.2%      0.2%      0.2%    0.2%
Average Axial Field    MV/m           2.4 to       4.6        4.6          4.6    7.5 to         8       8
                                         4.6                                        7.35
Length                  m                4.5         6            6.1      6.2      3.25       4.8      4.9
Structure Power        MW                  1      1.75              2        2                 5.4      5.4
Beam Power             MW               0.63      1.17           1.12     1.12                1.38     1.39
Total Klystron Power   MW                2.5       3.8              4        4                 8.8      8.8
                                                                                            Length: 42.9




  21 November 2003                             Elliott McCrory                                                17
            Linac Upgrade Params (#2)
                                                         DTL                                       SCC
                                                                                         Match
                               RFQ     Tank 1   Tank 2   Tank 3    Tank 4      Tank 5            Mod 1 Mod 8 Mod 9
                                                                                        Section
Input Energy            MeV    0.035        3     13.4     32.9         51.6     70.3         89     89 401.5 441.2
Output Energy           MeV        3     13.4     32.9     51.6         70.3       89         89 116.5 441.2     480
Delta E                 MeV    2.965     10.4     19.5     18.7         18.7     18.7          0  27.5   39.7   38.8
Beam Current             mA       70       60       60       60           60       60         60     60    60     60
Frequency               MHz    402.5    402.5    402.5    402.5        402.5    402.5       805    805    805    805
Beam Pulse Length       usec      90       90       90       90           90       90         90     90    90     90
RF Pulse Length         usec     130      130      130      130          130      130       125    125    125    125
Rep Rate                 Hz       15       15       15       15           15       15         15     15    15     15
RF Duty Factor                  0.2%     0.2%     0.2%     0.2%         0.2%     0.2%      0.2%   0.2%   0.2%   0.2%
                                       2.4 to                                           7.5 to
Average Axial Field     MV/m                       4.6      4.6         4.6       4.6                 8     8      8
                                          4.6                                              7.35
Length                    m               4.5        6      6.1          6.2      6.3      3.25       7   9.5    9.8
Structure Power          MW                 1     1.75        2            2        2              7.5     10     10
Beam Power               MW             0.624     1.17    1.122        1.122    1.122             1.65 2.382 2.328
Total Klystron Power     MW               2.5      3.8    3.122        3.122    3.122             9.15 12.382 12.328
                                                                                                      Length: 70.38




            21 November 2003                         Elliott McCrory                                          18
             Rough Cost Estimate
                                            Scenario 1     Scenario 2
                Item                Unit$ Num       Cost Num       Cost                               Notes
R&D Contract with AccSys               100 1         100 1          100                 FY04 R&D on this idea
AccSys RFQs (2)                        750 2       1,500 2        1,500                 Standard PL-7 Linac from AccSys
AccSys RGDTL                           750 1         750 1          750                 Standard PL-7 Linac from AccSys
MEBT, including double alphas        1,500 1       1,500 1        1,500
402 MHz DTL cavities                 1,900 3       5,700 4        7,600
402 MHz RF Systems                   1,400 5       7,000 6        8,400
SCC Matching Section modules           375 2         750 2          750
805 MHz RF systems for Transition    1,500 0           0 0            0                 Reuse existing RF systems
New SCC module(s) to 116 MeV         1,500 2       3,000 1        1,500
New SCC module(s) at 400 MeV         1,500 0           0 2        3,000
New 805 MHz rf systems               1,500 2       3,000 3        4,500
Controls, diagnostics, other
                                     1,000     1       1,000      1           1,000
infrastructure
Installation & Commissioning                           2,500                  4,000
Building modifications                  500    1         500      1             700
Total, FY 2002$                                    $ 27,200               $ 35,200      FY 2002 $
Inflation/year                            4%   3   $   30,596             $   39,595    Scale to FY05 $ (4% inflation)
401 MHz RF System Cost              $ 1,400
SCC Cavity Cost                     $ 1,500                                            Most: "SWAG"
805 MHz RF system Cost              $ 1,500




                 21 November 2003                       Elliott McCrory                                                  19
Final Thoughts

     Collaborators galore!
           NTF/Lennox
           Taiwan
           AccSys (but not for free)
     How much longer can we get 7835 power
      amplifiers?
     How much longer can we maintain the old
      Linac?
     The time is right to proceed on this
21 November 2003               Elliott McCrory   20

				
DOCUMENT INFO
Shared By:
Categories:
Stats:
views:9
posted:2/4/2010
language:English
pages:20